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Full text of "Biology and population dynamics of tea scale, Fiorinia theae Green (Diaspididae: Coccoidea: Homoptera)"

BIOLOGY AND POPULATION DYNAMICS OF TEA SCALE, 

Fiorinia theae GREEN 

(DIASPIDIDAE : COCCOIDEA :HOMOPTERA) 



By 
BADAR MUNIR 



A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF 
THE UNIVERSITY OF FLORIDA IN 
PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR 
THE DEGREE OF DOCTOR OF PHILOSOPHY 

UNIVERSITY OF FLORIDA 

1980 



DEDICATION 
This dissertation is dedicated to my father, Choudhry Murad Ali, 
whose support, love, and goodwill enabled me to complete this work. 



ACKNOWLEDGEMENTS 
I am deeply indebted to the Chairman of my graduate committee, 
Dr. Reece I. Sailer, for his continuous guidance and advice throughout 
the studies. I am also extremely grateful to Dr. T. E. Freeman and 
Dr. A. B. Hamon for critical review of the first draft of the disserta- 
tion; to Dr. T. J. Walker and Dr. S. L. Poe for help and valuable sug- 
gestions in the preparations of life tables. I wish to express my 
gratitude to Mrs. Helen Huseman for preparing the figures, and to 
Miss Mary Davis for her patience and dedication while typing the 
dissertation. Last, but not least, I extend my sincerest appreciation 
to my wife, Rafia, for her support and enthusiasm during these studies. 



iii 



TABLE OF CONTENTS 

Page 

ACKNOWLEDGEMENTS iii 

LIST OF TABLES vi 

LIST OF FIGURES vii 

ABSTRACT ix 

INTRODUCTION 1 

LITERATURE REVIEW 9 

Fiorinia theae Green 9 

General Review 9 

Description 9 

Distribution 11 

Host Plants 12 

Economic Importance 12 

Biology 16 

Laboratory Rearing 16 

Natural Enemies 17 

Chemical Control 18 

Aphytis theae (Cameron) 18 

Description 18 

Redescription 19 

Life Tables 19 

METHODS 22 

Biology 22 

Parthenogenesis 23 

Population Dynamics 23 

RESULTS AND DISCUSSION 26 

Biology 26 

Parthenogenesis 34 



iv 



Population Dynamics Page 

General Characteristics of Tea Scale 

Populations 36 

Populations of Adult Males 39 

Populations of Mature Females 44 

Introduced Parasites 48 

Aphytis theae (Cameron) 48 

Aspidiotiphagus sp 55 

Life Tables ■ •* 57 

K-Factor Analysis of Life Tables 77 

Survivorship Curves 80 

Fertility Tables 87 

Age Composition 98 

Methodology to Calculate Survival Rates of 

Female and Male Tea Scale Populations 104 

SUMMARY AND CONCLUSIONS 108 



REFERENCES CITED 
APPENDICES 



110 



1. Number of Male and Female Tea Scale, Fiorinia theae , survived 

on Camellia japonica at different temperatures H-> 

2. Side Preference of Tea Scale, Fiorinia theae 116 

3. Values (log) of Various Mortality Factors (k's) and the 

Generation Mortality (K) for Tea Scale, Fiorinia theae , 117 

at Wilmot Garden, Gainesville 

4. Data for the Survivorship Curves. Number of Tea Scale, 

Fiorinia theae , per 30 cm area of leaves of Camellia 

j aponica at Wilmot Garden, Gainesville 118 

5. Number of Male and Female Tea Scales, Fiorinia theae , per 

30 cm 2 area of Camellia j aponica at Wilmot Garden, 

Gainesville 119 

6. Data for the Age Composition. Number of Live Male and Female 

Tea Scales, Fiorinia theae , per 30 cm 2 area of Leaves of 
Camellia japonica at Wilmot Garden, Gainesville 120 

7. Reproductive Value of the Ovipositing Females of the Tea Scale, 

Fiorinia theae , at Wilmot Garden 121 

8. Number of Female Tea Scale, Fiorinia theae , in 3 cm 2 area, 

and on Whole Leaves of Camellia japonica at Wilmot Garden, 
Gainesville - 123 

BIOGRAPHICAL SKETCH 125 



LIST OF TABLES 
Table Pa S e 

1. Host Plants of Tea Scale, Florinia theae 13 

2. Total Fecundity of Tea Scale, Fiorlnia theae 29 

3. Comparison of Numbers of Male F_. theae Adults 
Emerged from Colonies on Leaves of Camellia 

japonica at Wilmot Garden in 1977 and 1979 43 



4. Number of Mature Females of F. theae in 
Pre-oviposition, Oviposition, and Post- 
Oviposition Stages • 

5. Larval and Pupal Mortality of Aphytis theae 
per 30 cm 2 of Leaves of Camellia japonica 

at Wilmot Garden 

6. Monthly and Annual Life Tables for Tea Scale, 
Fiorinia theae , at Wilmot Garden, Gainesville 

7. Specific and Crude Sex- Ratios of Tea Scale, 
Fiorinia theae 

8. Number of Female Tea Scale, Fiorinia theae , 
per 30 cm 2 Area of Leaves of Camellia 
japonica at Wilmot Garden, Gainesville 

9. Monthly and Annual Fertility Tables for 

Tea Scale, F. theae 



46 



51 



64 



91 



93 



vi 



LIST OF FIGURES 
Figures Page 

1. Adult Populations of Aphytis theae and 
Male Fiorinia theae Observed on Leaves of 

Camellia japonica at Wilmot Garden, Gainesville 40 

2. Number of Male Adults of Fiorinia theae , Adults 

of Aphytis theae , Larvae of Microweisea coccidivora 

and Lindorus lophanthae on Leaves of Camellia 

japonica , and Percent Parasitism by A. theae at 

Wilmot Garden, Gainesville 42 

3. Number of Ovipositing Females of Tea Scale, 
Fiorinia theae , on Leaves of Camellia japonica at 

Wilmot Garden, Gainesville 45 

4. Life Cycle and Survival of Different Stages of 
Tea Scale, Fiorinia theae Green, at Gainesville. 
The Area of Circles is Proportional to the Size 
of Populations. Decrease in Size of Circles is 

Due to Mortality Occurred Between Successive Stages 47 

5. Larval and Pupal Populations of Aphytis theae on 
Leaves of Camellia japonica at Wilmot Garden, 

Gainesville 49 

6. Average Monthly Rainfall and Minimum Temperature 
at Jorhat (India) and Gainesville (Florida) . 
Data for Jorhat were Obtained from CIBC (Indian 
Station), and for Gainesville from Agronomy 

Department, University of Florida 52 

7. Key Factor Analysis. The Recognition of Key 
Factors in the Life Tables for Tea Scale, 
Fiorinia theae , by Visual Correlation of Various 

Mortality Factors (ks) with the Generation Mortality (K) 78 

8. General Types of Survivorship Curves 81 



vii 



LIST OF FIGURES 
(continued) 



Figures 



9. Monthly and Annual Survivorhip Curves of 
Tea Scale, Fiorinia theae , at Wilmot 
Garden, Gainesville 83 

10. Specific and Crude Sex-Ratio of Tea Scale, 

Fiorinia theae , at Wilmot Garden, Gainesville 89 

11. Monthly and Annual Age Composition of Tea Scale, 

Fiorinia theae, at Wilmot Garden, Gainesville 100 



Abstract of Dissertation Presented to the Graduate 
Council of the University of Florida in Partial Fulfillment of the 
Requirements for the Degree of Doctor of Philosophy 



BIOLOGY AND POPULATION DYNAMICS OF TEA SCALE, 
Fiorinia theae GREEN 
(DIASPIDIDAE:COCCOIDEA:HOMOPTERA) 

By 

BADAR MUNIR 

March 1980 

Chairman: R. I. Sailer 

Major Department: Entomology and Nematology 

Tea scale, Fiorinia theae Green, is the most important pest of 
camellias and hollies in the eastern United States. Because chemical 
control is costly and otherwise less than satisfactory, an attempt was 
made to import natural enemies for biological control of this pest. Two 
aphelinids, Aphytis theae (Cameron) and Aspidiotiphagus sp., were im- 
ported from India and cultured in greenhouses at Gainesville. Both 
species attack male nymphs of tea scale. Field releases of A. theae and 
Aspidiotiphagus sp. were made in May 1976 and January 1977, respectively. 
A. theae was colonized but failed to survive the second winter; Aspidi - 
otiphagus sp. seems to have become established. 

A mite and a thrips feed on settlers, while male nymphs are preyed 
on by 3 species of predators. A local parasite that attacks female nymphs 
is very rare and consequently ineffective in population regulation of tea 
scale. 



ix 



Biology of tea scale was studied. Development in males and females 
is asynchronous, the species being protandrous. Dimorphism is exhibited 
in the immature as well as mature stages. Females deposited an average 
of 28.82 eggs which were retained under the armor where they hatched in 
9-10 days. Male nymphs molt 4 times; females 2 times. Male adults 
emerged in 34 days; females began ovipositing in 65 days. 

Data generated by field and laboratory studies are utilized to con- 
struct 12 monthly and 1 annual life tables. Generation mortality ranged 
from 92.65% in April to 96.92% in February, with an annual average of 
95.15%. Index of population trend varied from 0.71 to 1.39, with an 
average of 0.98. Major mortality factors were dispersion loss at crawler 
stage and parasitization of male nymphs by A. theae . Mortality in male 
nymphs did not affect the overall population level because of male 
biased sex-ratio and polygyny. Survivorship curves and fertility tables 
for tea scale were also prepared. Net replacement rate (Rq) ranged from 
1.80 in February to 4.45 in May, with an annual average of 2.86. Specific 
sex-ratio in the tea scale varied at all stages; there were more males 
at nymphal stages but females were more abundant as adults. Crude sex- 
ratio indicated a constant preponderance of males. Major cause of vari- 
ation in sex-ratio was mortality of the male nymphs by A. theae . Age 
composition figures for tea scale were prepared for each month and for 
mean annual populations. A schematic representation of life cycle 
depicting the salient features of biology and population dynamics of tea 
scale was developed. Methods to calculate the survival rates of males 
and females are described. 



INTRODUCTION 
The tea scale, Fiorinia theae Green, is a member of Diaspididae, a 
family that contains many damaging and unmanageable pests of perennial 
crops and ornamentals. Tea scale is regarded as one of the principal 
armored scale insect pests of the world (Beardsley & Gonzalez, 1975). 
In North Florida and a large part of the Southeastern United States, 
including Alabama, Georgia, and South Carolina, it is placed among the 
10 most important pests of nurseries and home landscape plantings 
(Dekle, 1965). 

Tea scale is a polyphagous insect and at least 43 different ornament- 
als and fruit trees are known to serve as its hosts. The most seriously 
affected plants are camellias and hollies which are highly desirable 
broad-leaf evergreen ornamentals. 

Being stenomerous, it feeds only on leaves of the host plants. The 
feeding on lower surfaces of leaves invariably results in discoloration 
on the upper side, followed by defoliation. Infested camellias assume 
an unthrifty appearance and flower poorly. In cases of severe infesta- 
tions, dieback of twig terminals occurs and ultimately results in the 
death of the plants. 

Tea scale is known to have originated in the Oriental region, where 
it is associated with tea and related plants. Nowhere in the region from 
India to Japan has the tea scale been found to be a serious pest. This 
suggests that natural control factors provide effective control of tea 
scale in that area. Although a number of natural enemies have been found 



in association with tea scale in Florida, they are not effective in keeping 
the populations at non-economic levels. 

Efforts to control tea scale infestations have, so far, been confined 
to chemical control; a number of insecticides have been tested, utilized, 
and recommended by various workers. However, chemical control is not a 
suitable long-term strategy for suppression of pests such as tea scale. 
The fact that tea scale is a pest of ornamentals, normally grown around 
homes, offices, and other public buildings, makes use of chemical insecti- 
cides undesirable, for more people, especially children, are likely to 
come into physical contact with the toxic compounds. Moreover, the nature 
of tea scale infestations is such that chemical control does not offer 
much promise of success. For instance, camellia and holly plants are 
usually quite large and densely foliated, with tea scale colonies located 
on the underside of leaves. These characteristics render many insecticides 
ineffective because of poor spray coverage. Also, new foliage in some 
varieties of host plants is sensitive to certain chemicals. In addition, 
chemical treatments are costly, especially for homeowners, and must be 
repeated at regular intervals. 

Despite the fact that tea scale is a pest of foreign origin, belonging 
to a group that provides numerous examples of successful control by intro- 
duced natural enemies, and is an unsuitable candidate for chemical control, 
no effort was made to introduce exotic natural enemies. Various species 
of Aphytis have proved to be key agents in regulating the densities of 
numerous diaspid pests of citrus and other crops in various parts of the 
world (Rosen, 1973). In Florida similar scale pest problems on citrus 
have been eliminated through the action of introduced parasites of the 
genus Aphytis , the two most notable examples being the control of Florida 



red scale by A. holoxanthus DeBach, and of purple scale by A. lepidosaphes 
Compere. These were the circumstances that prompted initiation in 1976 
of an effort to introduce parasites of tea scale from India. As a 
result of a joint IFAS-ARS-CIBC effort, A. theae and a still unidentified 
species of Aspidiotiphagus were obtained and released in Gainesville. 
Both species proved specific to male nymphs of tea scale. Although the 
limitations of male specific parasites were recognized, it was hoped that 
male mortality would be sufficient to prevent fertilization of females 
and thus bring about reductions in tea scale populations. Had such 
proved the case, it would have been the first example of control through 
the agency of male specific mortality caused by parasites. 

The initiation of a biological control program and subsequent evalua- 
tion of its results require detailed information on the biology, seasonal 
history, and population dynamics of the candidate pest species. In 
Florida such information for the tea scale was at best fragmentary, and 
no attempt has ever been made anywhere in the world to study bionomics 
of the species in the detail needed for purposes of biological control. 

Post-colonization studies designed to assess the efficacy of intro- 
duced natural enemies are very useful in understanding the success or 
failure of biological control programs. Such studies provide information 
on the role of various mortality factors in regulating the population of 
pest species, and, if the previously introduced species are proven inef- 
fective, demonstrate the need for introduction of different species of 
natural enemies. Although there are many examples of successful biolo- 
gical control programs, a larger number have met with failure. Seldom 
has it been possible to adequately document reasons for either success 
or failure, and in the words of Krebs (1972), "biological control will 
remain an art until we can do so" (p. 374). 



Biology of tea scale was studied in the laboratory, and observations 
on the seasonal changes and population dynamics were carried out at 
Wilmot Garden, Gainesville, Florida. The data obtained through these 
studies were utilized in the construction of life tables, survivorship 
curves, fertility tables, and age composition. These are very convenient 
and useful methods to describe the dynamics of populations. 

Ecological life tables are one of the most useful methods of descrip- 
tion and analysis of population dynamics of an insect. These tables con- 
tain a series of sequential measurements that indicate changes in the 
population in its natural envirnment. These measurements, when related 
to the mortality factors and presented in the form of life tables, reveal 
the presence of successive processes that operate in the populations. 
Life tables were initially developed for the quantitative analysis of 
human populations. Their importance lies in the fact that each stage in 
the life history of a species is affected by different mortality factors 
and at different rates. 

Life tables for humans and insects fundamentally differ only in 
objectives. In human life tables the objective is to determine the average 
expected life remaining for an individual and therefore the most important 
feature is the e x column. In the case of insects, the major interest lies 
in the mortality factors and their rates, and therefore the most important 
features are the d x and d x F columns. Life tables for non-human populations 
are termed ecological life tables because of the emphasis on mortality 
factors and the actual numbers used. The ecological life table is really 
an organized summary of the life of a typical cohort of individuals in a 
population. It describes in precise detail the stages in the life history 
and reveals which contribute most to the population, and at the same time 



reveals the mortality factors — biotic or abiotic — responsible for 
regulation of the population. Trends in populations can be better under- 
stood once the causes of mortality during each age interval are quantified. 

An ecological life table usually consists of 6 columns. The first 
column is labeled x and lists the pivotal age for the age class or age 
interval under consideration. For insects it consists of various stages, 
i. e., egg, nymph or larva, pupa, and adult. The next column labeled l x 
contains the number of individuals of the original cohort which were alive 
at the beginning of age class x. Mortality factors are listed in the 
third column which is labeled d x F. The fourth column, which represents 
the number of individuals dying during the age interval, is labeled d x . 
The fifth column, headed 100q x , is the proportion of individuals dying by 
cause listed in d x F expressed as the percentage of l x . The last column 

is labeled lOOd /N, and gives the percentage of the generation mortality; 
x 1 

in some life tables, this column is labeled s x and records the survival 
at age interval x. 

Three types of data are used in the construction of life tables: 

1) Survival of a reasonably large cohort born more or less simultaneously 
is followed at fairly close intervals throughout its existence. Since 
this does not involve the assumption that the population is stable in 
time, this is considered the best form of information. 

2) Age at death is directly observed for a large and reasonably random 
sample of individuals in the population. This requires the assumption 
that the population is stable in time and that the birth and death rates 
remain constant. 



3) Age structure is obtained directly from a random sample of population 
and the number of dead individuals is inferred from the reduction in the 
number of living individuals between successive age intervals. It requires 
the assumption that the population has a stable age distribution. 

Data for the construction of tea scale life tables were obtained by 
the combination of the above techniques in order to avoid unnecessary 
assumptions. Death in different age intervals can be accurately deter- 
mined because dead individuals remain attached to leaves and can be 
easily counted. Because of stable age distribution, all stages are 
present simultaneously, thus age structure can be observed directly. 
The only assumption made was that the ovipositing females represent the 
terminal individuals of a cohort that contained all dead individuals of 
each age interval found on the sampled leaves. In view of the fact that 
life cycle of the tea scale lasts for about 2 months, and that only new 
colonies were sampled, this assumption does not seem unreasonable. 

In general, there are 2 types of life tables, the age-specific and 
the time-specific. These 2 kinds are different in meaning and form except 
under unusual circumstances. The age-specific life tables are also called 
cohort, generation, or horizontal life tables, and are constructed on the 
basis of data obtained by following a cohort or designated members of a 
population with discrete generations. The time-specific life tables are 
also called stationary, static, current, or vertical life tables. Data 
for these are collected on the basis of a cross-section of a multivoltine 
population with overlapping generations. 

Among diaspids, life tables are available only for the oystershell 
scale, Lepidosaphes ulmi (L.) in Quebec, Canada, where this species is 
univoltine and undergoes diapause in the egg stage. Tea scale, on the other 
hand, is a multivoltine species and does not undergo diapause at any stage. 



Life tables are very useful in understanding the dynamics of animal 
and plant populations. Their concise and organized form presents much 
information that is otherwise difficult to handle and comprehend. They 
also help in determining the survival strategies of species, and evolution 
of characteristics, such as fecundity and parental care. Data for life 
tables are utilized by population theorists to test the validity of their 
conceptual models. Life tables of pest species reveal the most vulnerable 
stage in the life history and leads to emphasis on control at that stage 
in order to influence survival rates of pests through management strate- 
gies. 

In order to understand the effect that any one environmental factor 
has on the trend of a population, a series of age-specific life tables 
is required covering a number of generations. The analysis of a series 
of this sort enables one to assess the effect of each component of the 
environment. A number of different techniques have been used to analyze 
life table data. One method in particular is now widely used, namely, 
the "K" factor analysis of Varley and Gradwell (1960). The other popu- 
lar methods involving regression analysis were developed by Morris (1963) 
and Watt (1963) . 

Adequate sampling techniques to study changes in population density 
and interaction of various factors were not available for tea scale, which 
is a multivoltine, beisexual, and dimorphic species. Sampling techniques 
are further complicated by the fact that distribution of tea scale on 
host plants is not uniform. Both interplant and intraplant variations 
are large. Many potential host plants are not infested, while on in- 
fested plants 1 or 2 twigs may be infested, the rest of the plant being 
free of the scale. Invensive survey and sampling of small, arbitrarily 



8 



delineated populations on individual plants over time, is therefore 
necessary. 

The parasites Aphytis theae (Cameron) and Aspidiotiphagus sp . , origi- 
nally imported from India and later released in Gainesville, exhibited 
a marked preference for male nymphs of tea scale. This necessitated 
ascertaining the importance of males in the reproductive biology of tea 
scale. Consequently, an experiment was designed to determine if females 
were capable of reproducing without fertilization. Results of this 
experiment also provided information on relative survival of tea scale 
at different temperatures and preference of crawlers to settle on lower 
sides of leaves. All information on biology and population dynamics 
of tea scale obtained through these studies was summarized in a schematic 
representation. The data and information on the biology and ecology of 
tea scale obtained in these studies will prove very valuable as a founda- 
tion for future attempts to control this pest through importation of 
additional enemy species and for comparing results of such attempts. 



LITERATURE REVIEWS 
Fiorinia theae , Green 
General Review 

The published history of Fiorinia theae Green contains 3 major 
landmarks: its discovery as a pest of tea in India by Watt in 1898, a 
formal description as a new species by Green in 1900, and comprehensive 
studies on its biology in India by Das and Das in 1962. The remainder 
of the articles on tea scale contains either original records or reviews 
on local and geographical distribution, host plants, descriptions of 
female and male' armors, and chemical control measures. Borchsenius 
(1966), Fernald (1903), Lobdel (1937), Merrill and Chaffin (1923), and 
Riddick (1955) included F. theae in their lists of coccids ; while 
Kuwana (1925) and MacGillivary (1921) presented keys to separate species 
of Fiorinia , including theae . 
Description 

Green's (1900) original description of F. theae was based on speci- 
mens from Kangra Valley, India. He stated, "when this insect was first 
submitted to me I supposed it to be merely a local form of the world-wide 
F_. f ioriniae . A more critical examination shows me that it is quite 
distinct. It differs from f ioriniae in the absence of lateral lobes on 
the pygidium; in the form of the antenna which has no stout spine, and 
in the presence between the antennae of a proboscis-like projection. The 
scale also is larger, stouter and more opaque. I now describe the species 
under the name F. theae " (p. 3). 



10 



He described the female armor as "consisting of the indurated 
pellicle of the second stage which completely encloses the adult 
insect and is without any secretionary margin. Elongate; narrow; 
with a moderately distinct median longitudinal carina. Colour bright 
castaneous to dark ferruginous brown, median longitudinal area darkest; 
opaque; not revealing the form of the insect beneath. First pellicle 
colourless or very pale yellow; projecting from anterior extremity of 
scale. Length 1.25 to 1.50 mm. Breadth 0.50 mm" (p. 3-4). 

In his description of the adult females, he wrote: 

Antennae close together, on anterior margin; each antenna consisting of 
an irregular tubercle with a single curved bristle on one side. From 
between the antennae springs a stout spatulate process . . . which is 
not chitinous but of the same consistency as the surrounding parts of 
the body. Margin of thorax and abdomen with a series of minute spin- 
neret ducts opening on to small conical tubercles. Pygidium . . . with 
a conspicuous median cleft, on the margins of which are situated the 
moderately large serrate thickenings of the margin; second lateral lobes 
obsolete. Spines normal, the dorsal series rather long; one pair spring- 
ing from within the median cleft. Circumgenital glands in five groups; 
the median and upper lateral groups together forming an almost continu- 
ous arch. Median group with 4 or 5 orifices; upper laterals 10 to 13; 
lower laterals 15 to 18. A very few circular pores with accompanying 
ducts, on dorsal surface, near the margin. Length 0.50 to 0.75mm. 
(p. 3-4). 

Neither the male scale nor the male armor were represented in the material 

examined by Green. 

Sasscer (1912) published the first descriptive account of the male 

armor. Later, many workers provided descriptions of females and males 



11 

and their armor, and keys to separate F. theae from other species of 
Fiorinia . Das and Das (1962) were the first workers to describe the 
immature stages of tea scale in detail. 

Tippins (1970) described the second instar males of _F. theae , 
F. externa , and F. pinicola , and presented a key to separate these species 
on the basis of morphological differences in the second instar males. 
Distribution 

Tea scale is widely distributed in the warmer parts of the world 
except Africa and Australia. According to Das and Das (1962), it is 
present in all of the tea growing districts of India. Tapia (1968) 
was the first to record the tea scale damaging camellias in Argentina. 
In the United States, Sasscer (1912) stated that tea scale was present 
in Alabama, the District of Columbia, Georgia, Louisiana, North Carolina, 
and South Carolina, and Lawson (1917) reported it from Kansas. Tea scale 
has also been recorded from Japan (Ferris, 1942), China, Taiwan, Mexico, 
and Costa Rica (Merrill, 1953), and Sri Lanka (Ceylon) and the Philippines 
(Sasscer, 1912). 

F. theae is considered to have originated in the Orient. On the 
basis of the number of described species, Takagi (1970) concluded that 
the origin of the genus was evidently centered in eastern Asia, with most 
of the species occurring in India through China to Japan. He stated that 
none of the genuine members of the genus was native to the New World and 
the Ethiopean region. Commenting on the introduction of the tea scale 
in the United States, Sasscer (1912) remarked that "since no (tea) plants 
have been introduced from Asiatic regions, all being grown from seed, it is 
extremely probable that its (tea scale) introduction was through the agency 
of the camellias, which have been for a number of years greatly in demand 
as ornamental plants in this country Cp« 10). 



12 

Sasscer (1914) reported interception of _F. theae at quarantine 
in the District of Columbia in a shipment of mango plants from Java. 
Host Plants 

Tea scale is a polyphagous species and has, so far, been found to 
feed on some 43 species of plants in 25 genera belonging to 16 families 
(Table 1). 
Economic Importance 

Watt and Mann (1903) regarded the tea scale as a destructive pest 
of tea in India, but Das and Das (1962) disagreed and maintained that 
it was destructive only in rare instances. With the exception of 
Argentina, where Camellia japonica was reported as seriously damaged 
(Tapia, 1968), there are no published records describing tea scale as 
a serious pest in parts of the world other than the United States. 
Sasscer (1912) reported that in the northwestern Himalayas, tea scale 
infestations on the olive, Plea grandulif era , frequently caused leaves 
to turn yellow and drop off. 

In the United States, specialists on insects of ornamentals are 
unanimous in their opinion that scale insects are the most important 
group of pests infesting camellias. Tea scale holds a prominent posi- 
tion within the group and is, in all likelihood, the most important 
pest of camellias (Kouskolekas, 1971). Sasscer (1912) reported that 
tea scale was a serious pest of camellias and warranted frequent appli- 
cation of control measures. English and Turnipseed (1940) considered 
the tea scale as the most important pest of camellias and stated that 
infestation by tea scale impaired the vitality of the plant and pro- 
duction of bloom, thereby greatly reducing the sale value of the plants. 
Merrill (1953) remarked that the tea scale was a serious pest in Florida 



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15 

and required frequent application of chemical insecticides. Kuitert 
and Dekle (1972) considered it to be the most destructive pest of 
camellias and hollies in Florida. Because of the importance of 
camellias and hollies in landscape plantings in Alabama, Florida, 
Georgia, and South Carolina, the tea scale is clearly one of the 10 
most important pests of nurseries and ornamental shrubs in the south- 
eastern United States. 

Collins (unpublished) claimed that the natural enemies kept tea 
scale under control in other parts of the world, and it was because of 
the absence of natural enemies that the tea scale was an economic pest 
in Florida. 

My studies on tea scale, in which infested potted camellias were 
held in a greenhouse from which all natural enemies were excluded, con- 
firm Collins' view. Within weeks both sides of the leaves on these 
plants were densely covered with colonies of tea scale. Subsequent 
death of the plants was attributed to the curtailment of photosynthetic 
activity of the leaves and ultimate loss of all foliage. Under field 
conditions, leaf drop results from the scale infestations, which greatly 
depreciates the ornamental value of the plants, but seldom causes 
death. 



16 



Biology 

English and Turnipseed (1940) published a partial life history of 
F. theae on camellia in Alabama. They stated that each female deposited 
10-16 eggs which hatched within 7-21 days. Crawlers settled within 2-3 
days and secreted thin white coverings. Later, they secreted great 
quantities of white woolly filaments which covered the undersides of 
leaves. Nymphs molted within 13-36 days after hatching. Second molt 
occurred a week later. The females started laying eggs within 41-65 
days, and life cycle was completed in 60-70 days. 

Das and Das (1962) carried out comprehensive studies on the biology 
of tea scale on potted tea plants in India. They found that pre-ovipo- 
sition periods lasted 12-14 days. Females laid 22-43 eggs with an 
average of 32.1 eggs per female. Males molted 4 times and completed 
development in 22-24 days, while females molted 2 times and completed 
the life cycle in 24-27 days. They also described the eggs, crawlers, 
nymphs, and adults of both sexes in some detail. 
Laboratory Rearing 

Accounts of rearing tea scale in the laboratory on artificial hosts 
are scanty. Nagarkatti (personal communication, 1977), Collins (unpub- 
lished), and Chiu and Kouskolekas (1978) experienced considerable diffi- 
culties in establishing laboratory colonies. 

Nagarkatti (personal communication, 1977) commented that tea scale 
colonies could be established on pumpkin if relative humidity was main- 
tained at about 70%. Chiu and Kouskolekas (1978) tested a number of 
artificial hosts and found that butternut squash was the most suitable 
laboratory host for tea scale. 



17 



Natural Enemies 

Watt (1898) reported on a fungus parasitizing a tea scale female 
which was sent to him by Green, probably from Ceylon. He also commented 
that the fungus was not present in India and that "it certainly would 
be worthwhile to obtain a supply if the blight (tea scale) becomes 
serious" (p. 325) . 

In the United States, Sasscer (1912) reported that the Darjeeling 
tea, which was grown in moist lowlands in South Carolina, was frequently 
found covered with a brown fungus which was apparently parasitic on tea 
scale and was quite effective in holding the pest in check. He also 
listed Chilocorus bivulnerus Muls., Microweisea misella Lee. (Coccinelli- 
dae) , and Cybocephalus nigritulus Lee. (Cybocephalidae) as predators of 
the tea scale. 

Das and Das (1962) stated that in India an aphelinid, Aphytis sp., 
parasitized the second instar nymphs. They noticed that about 38% of the 
males and 4% of the females in the field were killed by this parasite. 
They also reported Scymnus sp. and Jauravia quadrinotata Kapur (Cocci- 
nellidae) as predators of the immature stages of tea scale and a fungus 
that occasionally attacked second instar female nymphs and mature 
females. 

Nagarkatti (personal communication) informed that Aphytis sp. and 
Aspidiotiphagus sp. parasitized male nymphs, while a species of 
Prospaltella attacked the female nymphs of tea scale in India. 

In Florida, Collins and Whitcomb (unpublished) conducted a survey 
of natural enemies and observed Aspidiotiphagus sp. nr. lounsburyi 
(Berlese & Paoli) and Aphytis sp. nr. lignanensis (Compere) (Aphelinidae) , 
Aleurodothrips fasciapennis (Franklin) (Phlaeothripidae) , Chrysopa 
bicarnea (Banks), C. claveri (Navas) , C. harrisii (Fitch), and 



18 



C^. rufilabris (Burm.) (Chrysopidae) , Cybocephalus nigritulus (Cybo- 
cephalidae), Chilocorus stigma (Say), Llndorus lophanthae (Blaisdell) , 
and Microweisea coccidivora (Ashmead) (Coccinellidae) , and a parasitic 
fungus, Aschersonia aleyrodis (Webber) (Zythiaceae) associated with 
tea scale. 
Chemical Control 

Of the literature concerning tea scale, by far the largest part 
concerns chemical control. English and Turnipseed (1940) , and Kuitert 
(1949) in Alabama; Tippins (1969) and Kouskolekas (1971) in Georgia; 
Kuitert and Dekle (1972) and Vaughan, Short and McConnell (1976) in 
Florida; and Das and Das (1962) in India offered suggestions and 
recommendations for suppressing the tea scale infestations by means 
of insecticides. Kouskolekas (1973) and Kouskolekas and Self (1973) 
conducted experiments designed to improve methods of application of 
insecticides, while Tippins and Dupree (1973) evaluated the effective- 
ness of different types of sprayers. 

Aphytis theae (Cameron) 
Description 

Cameron (1891) described an aphelinid which was "bred from the tea 
scale insect Aspidiotus theae from Janygo (India)" (p. 3). His description 
was based on a single specimen mounted in balsam that was so flattened that 
its exact shape could not be seen satisfactorily. Although he placed the 
specimen in the genus Aphelinus , but because of certain peculiarities, he 
was confident that on further examination of fresh specimens the peculiari- 
ties would prove to be of generic value and that the species would form 
the type of a new genus. 



19 



Redescription 

On the basis of the original description, Compere (1955) transferred 
Aphelinus theae to the genus Aphytis . He stated that Aphytis and 
Aphelinus were not closely related to each other. He further elaborated 
that members of the two genera differed from each other in basic structu- 
ral characters of the abdomen and ovipositor. According to him, Aphytis 
and Aphelinus differed also in the manner of oviposition which was cor- 
related with fundamental differences in the structural features of the 
abdomen and ovipositor. He observed that when Aphelinus oviposited, the 
entire ovipositor everted and the whole apparatus swung outward. On the 
other hand, when Aphytis oviposited, only the shaft swung downward, but 
the other components of the ovipositor did not evert. 

Rosen and DeBach (1977) redescribed Aphytis theae from a female 
neotype and a male allotype, because the original type was lost, and 
the description and figures presented by Cameron were very confusing. 
They established the group Funicularis for the species of Aphytis with 
5-segmented antenna and reduced mouth parts. The group includes Aphytis 
funicularis , A. gordoni , A. ulianovi , and A. theae . A key for the iden- 
tification of the 4 members of the new group was also presented. 

Life Tables 

Life tables were originally devised by demographers to study human 
populations. They were used extensively in the field of life insurance 
to determine the average expected life of clients. Pearl and Parker (1921) 
introduced the life tables to ecologists by studying the population fluc- 
tuations of Drosophila in the laboratory cultures. Leopold (1933) was 
the first ecologist to recognize the value of the life tables in the 
study of natural populations, and although he used the term "life 



20 



equation," he was indeed talking about life tables. Pearl and Miner (1935) 
attempted to formulate a general theory of mortality of lower organisms 
on the basis of life tables. However, they gave up the attempt after 
realizing that the environmental detriments of life duration could not, 
at least then, be disentangled from such biological detriments as gene- 
tic constitution and rate of living. They pleaded for more observation- 
al data, carefully and critically collected for different species that 
will follow throughout the life of each individual in a cohort. Deevey 
(1947) also recognized the difficulty of comparing life tables of dif- 
ferent species because the basic data of life tables were sometimes of 
the "age-specific" type and sometimes of the "time-specific" type; the 
point of origin of life tables was also different-birth for mammals, 
egg laying for insects, etc. He was the first worker to apply the life 
tables technique to growing populations in nature. His paper includes 
many examples of the life table format. 

The first life table for an insect species was prepared by Morris 
and Miller (1954) for the spruce budworm, Choristoneura fumiferana in 
Canada. They were more interested in the causes of mortality at partic- 
ular age intervals, and therefore used the stages of life cycle, i.e., 
eggs, larvae, pupae, etc., instead of dividing the age interval into 
equal lengths of time. They also added the d x F column to the life table 
which listed all quantifiable mortality factors at each age interval. 

There are only 3 reviews in the literature that deal with the 
development of insect life tables; the monograph by Morris (1963), the 
textbook on ecological methods by Southwood (1966), and the review 
article by Harcourt (1969). 



21 



As for the diaspids, life tables are available for only one species. 
Samarasinghe and LeRoux (1966) prepared the life tables of Lepidosaphes 
ulmi (L.) which is a univoltine species and undergoes diapause in the 
egg stage during winter in Quebec, Canada. Atkinson (1977) proposed a 
method of making life tables for Aonidiella aurantii (Mask.) in Swaziland 
where the generations of the scale were more or less discrete in spring 
but became increasingly overlapped as the season advanced. 



METHODS 
Biology 

The biology of tea scale was studied in the laboratory at 25 - 1,5 C 
and 69 - 6.5% relative humidity. Colonies of the scale insect were es- 
tablished on butternut squash using the method described by Chiu and 
Kouskolekas (1978). Infested leaves of Camellia japonica were collected 
at Wilraot Garden, Gainesville, Florida. In the laboratory these leaves 
were lightly brushed to remove natural enemies, contaminants and male 
tea scales, and then placed on cleaned butternut squash. After 4 days 
the leaves were removed from the squash. During this interval enough 
eggs hatched to allow completion of life cycle observations. 

Details of development were obtained by daily removal of 20 indivi- 
duals for microscopic examination. However, when nymphs became distin- 
guishable as males and females, 10 individuals of each sex were examined 
daily. Since the tea scale is a protandrous species, males emerge long 
before, females become receptive to mating. To ensure fertilization of 
females some infested leaves containing abundant males near emergence 
were placed around the squash to provide mates as the females became 
sexually mature. 

Fecundity of the females was estimated by counting the number of egg 
shells, unhatched eggs, and eggs still present in the ovaries of 40 field 
collected females. 

The incubation period was studied by removing the last egg from under 
the armor of actively ovipositing females. The removed eggs were kept in 

22 



23 

covered plastic dishes for hatching. The incubation period of eggs 
allowed to remain under the armor was also studied, Gravid females were 
removed from leaves and placed in plastic dishes. Once removed, the 
females could lay only 2 iqore eggs before dying. Laying and hatching 
dates were recorded to determine the incubation period under more or 
less natural conditions. 

Parthenogenesis 

To study the possibility of parthenogenetic reproduction by the tea 
scale females, 5 potted Camellia japonica plants of uniform size and vigor 
were implanted with field collected gravid females. The females were 
placed on pieces of cheesecloth and secured on the upper surfaces of, 
leaves with hairpins. Each plant was supplied with 100 females at 20 
females per leaf. Plants were kept in different environators indivi- 
dually set at temperatures of 15, 20, 25, and 35°C. The relative 
humidity was about 70%, with a light period of 15 hours and dark period 
of 9 hours in each environator. The cheesecloth was removed after 10 
days. Males were counted and removed as soon as they could be recognized. 
Females were also counted but left on the leaves undisturbed to determine 
if they could reproduce without fertilization. The number of immatures 
settled on upper and lower surfaces of the leaves was also recorded to 
evaluate the site preference. The experiment was repeated a second time, 
but only 4 plants were used at temperatures of 15, 20, 25, and 30°C. 

Population Dynamics 

Studies on population dynamics were conducted on the natural field 
populations of tea sclae on Camellia japonica at Wilmot Garden, Gainesville, 
Florida. The garden covers approximately 5 acres of a 10-acre green belt; 
the remaining 5 acres are natural woodland. In addition to numerous 



24 

varieties of camellias, azaleas, and hollies, the garden contains many 
other groups represented by one or more genera. 

Populations of A. theae and male JF. theae adults were studied in 
the field. Five Camellia japonica plants growing in a row at Wilmot 
Garden were selected for regular observations. Each week, 20 infested 
leaves on each of the 5 plants were randomly selected and thoroughly 
examined with the aid of a lOx lens. The number of A. theae and male 
F_. theae adults present on the leaves was recorded. 

Since both A. theae and male F. theae adults migrate to other 
locations, their populations were studied by another technique also. 
At regular intervals, 5 infested leaves of C^. japonica were picked up 
10 times each month from September 1977 - August 1978. The leaves were 
placed in covered plastic containers, and kept in the laboratory for 
7 days, and then placed in the freezer for a day to kill the emerged 
adults to facilitate counting. The number of A. theae , male F_. theae 
adults, mites, thrips, Lindorus , and Microweisea , was recorded. After- 
ward, the leaves were lightly brushed to remove male scales and other 
contaminants, and an area of 3 cm 2 was delineated in the center of each 
leaf with a circular corer. The number of mature females present in the 
3 cm area was recorded. 

For studying the population structure of tea scale and its natural 
enemies, 10 infested leaves containing new colonies of tea scale were 

o 

picked up at random during the month. In the laboratory, a 3 cnr- area 
was marked in the center of each leaf and examined under a microscope. 
Each tea scale individual was probed and examined to record its age 
class (crawler, settler, etc.), sex, and whether it was dead or alive. 



25 



The data for life tables were obtained by counting the number of dead 
and live individuals of all stages present in a 3 cm 2 area per leaf on 
10 leaves each month. Ovipositing females were regarded as the final 
survivors of a cohort which contained all the dead members in previous 
stages. The number of crawlers that settled successfully was obtained 
by adding up numbers of all dead individuals backward in time. For 
example, the total number of successfully settling crawlers = the number 
of live ovipositing females + the number of dead females (preoviposition 
stage) + the number of dead female nymphs + the number of male pupae + 
the number of dead male nymphs + the number of dead settlers. The 
number of crawlers is assumed to be the same as the number of eggs be- 
cause all eggs hatch successfully due to protection provided by the 
females. The amount of eggs was obtained by multiplying the number of 
live ovipositing females in the previous generation with the average 
fecundity value (28.82). The number of crawlers lost during dispersion 
was calculated by subtracting the number of settlers from the number of 
eggs. 



RESULTS AND DISCUSSION 
Biology 

Biology of the tea scale has been studied in some detail by Das and 
Das (1962) in India. An earlier less complete life cycle study was 
made in Alabama by English and Tumipseed (1940) . The following studies 
on biology of tea scale were made in the Biocontrol Laboratory at the 
Division of Plant Industry, Gainesville, Florida. 
Mating 

There is no recorded account of mating between male and female tea 
scale. In the course of these studies, mating was observed only once, 
when, during examination of an infested leaf, a male was seen attempting 
to mate, but mating behavior could not be recorded in detail. 

The male is probably attracted by a sex pheromone emanating from the 
raised posterior end of the receptive female. Antennae of the male, which 
are well developed and as long as the body, are probably used to detect 
the pheromone . 

The presence of a sex pheromone has so far been demonstrated in only 
two species of armored scale insects. The first suggestion that males of 
armored scale insects locate the females in response to sex pheromones 
was that of Bodenheimer (1951), who noted the chemotactic response of 
California red scale males to virgin females. The conclusive evidence 
of the sex pheromones in the California red scale, Aonidiella aurantii 
(Maskell), was provided by Tashiro and Chambers (1967). Their results 
were confirmed in the laboratory by Rice and Moreno (1969) and in the 



26 



27 

field by Rice and Moreno (1970). Later on Moreno et al. (1972) also 
demonstrated the presence of a sex pheromone in the yellow scale, 
Aonidiella citrina (Coquillett) . 

Males of armored scale insects are polygamous. Tashiro and Moffitt 
(1968) conducted laboratory tests on Aonidiella aurantii and found that 
individual males were able to inseminate up to 30 females. The average 
number of females fertilized per male was 11.9. 
Oviposition 

Eggs are extruded from the body of the female, but retained under 
the armor, and arranged in 2 rows, probably with the aid of the pygidial 
plates and lobes. Before depositing any eggs the female occupies the 
greater part of the space under the armor, but as eggs are laid the body 
begins to shrivel, ultimately occupying only a small part of the anterior 

end. 

Das and Das (1962) stated that eggs were deposited singly at intervals, 
at a rate of not more than 4 per day; the rate was highest at the be- 
ginning but declined gradually. By following the oviposition activity 
of a single female they found that 39 eggs were laid in 21 days. 

Oviposition by tea scale is typical oviparity. In oviparous insects 
the eggs are extruded from the genital tract and deposited outside the 
body. In ovoviviparous insects the eggs are retained in the genital 
tract until larvae hatch or are ready to hatch. In the case of tea 
scale, the eggs are laid outside the genital tract but retained under the 
armor. Thus parental care and a suitable incubation environment is pro- 
vided for the eggs to a certain extent. 
Fecundity 

Fecundity of the tea scale was calculated by counting the number of 
eggshells, unhatched eggs and eggs still present in the ovaries of 40 



28 



field collected females (Table 2). Females lay from 17-43 (average 
28.82 1 7.82) eggs during their life span. 

In India, Das and Das (1962) studied the tea scale fecundity by 
daily removal of eggs from the posterior part of the armor. Contending 
that the method did not appreciably affect the oviposition potential, 
they found that the average fecundity of 14 females was 29. They also 
counted the eggshells under the armor of 15 females that had met natural 
death and recorded 22-43 (average 32.1) eggshells per female. English 
and Turnipseed (1940) reported from Alabama that tea scale females laid 
10-16 eggs. Vaughan (1975), commenting on this discrepancy between 
fecundity figures given by the above authors, noted that Das and Das 
(1962) conducted their studies on potted tea plants in the laboratory, 
whereas English and Turnipseed (1940) observed natural field populations 
on camellias, and believed this explained the discrepancy. However, the 
more probable explanation for this discrepancy may relate to the amount 
of space under the female armor. This can accommodate not more than 17 
unhatched eggs. Room for additional eggs is made when the earlier eggs 
hatch and crawlers emerge. The casual observer can easily and errone- 
ously conclude that the maximum number of unhatched eggs present is the 
actual total fecundity. 

Ms 

The newly laid egg is shiny yellow, more or less oval in shape and 
broader at one end. It measures 0.21 mm in length and 0.13 mm in width 
at the broadest point. Near hatching, the color changes to dull yellow, 
and the pinkish eyes can be seen through the chorion. Shortly before 
hatching, the fully formed crawler is visible through the flattened 
eggshell. The crawler hatches out by splitting the chorion, and empty 



29 



TABLE 2 
Total Fecundity of tea scale, Fiorinia theae 



Female # 


# Eggshells 


# Eggs 0S0* 


# Eggs ISO** 


Total I 


1 


14 


8 


3 


25 


2 


13 


9 


5 


27 


3 


9 


8 


2 


19 


4 


24 





2 


26 


5 


21 


3 


2 


26 


6 


22 


11 





33 


7 


41 


1 





42 


8 


13 


8 


1 


22 


9 


14 


10 


3 


27 


10 


32 


7 





39 


11 


32 








32 


12 


20 


4 





24 


13 


30 








30 


14 


36 


3 





39 


15 


37 


6 





43 


16 


14 


6 


1 


21 


17 


32 


8 





40 


18 


15 


6 





21 


19 


36 


7 





43 


20 


30 


4 





34 


21 


9 


11 





20 


22 


9 


8 





17 


23 


24 








24 


24 


22 


4 





26 


25 


11 


10 





21 


26 


12 


7 





19 


27 


22 


5 





27 


28 


16 


10 





26 


29 


23 


1 


2 


26 


30 


40 


2 





42 


31 


15 


8 





23 


32 


30 


9 





39 


33 


34 


7 





41 


34 


10 


9 





19 


35 


19 


8 





27 


36 


14 


8 


1 


23 


37 


24 


5 





29 


38 


31 








31 


39 


13 


8 


3 


24 


40 


35 


1 





36 



* - outside the ovary 
** - inside the ovary 



Std. 



Mean = 28.82 
Dev. = 7.82 



30 

eggshells are pushed to the rear and compressed in rows, one on either 
side in the posterior space under the armor. 
Incubation Period 

The incubation period of the 14 eggs that were removed from under 
the female armor ranged from 10-14 days (average 11.2-1.3). In the 
case of the eggs that were left undisturbed under the armor, the incu- 
bation period for 10 eggs lasted for 9-10 days (average 9.8 - 0.4). The 
latter figures are closer to the natural conditions and indicate that 
the female provides not only protection and care but also a suitable 
environment to incubate the eggs. The difference in the two incubation 
periods was statistically significant at a 95% level. 

According to English and Turnipseed (1940) , temperature appears to be 
an important factor in determining the length of incubation periods. 
They recorded an incubation period of 7-21 days for the tea scale. Das 
and Das (1962) working in India, reported that tea scale eggs hatched in 
4-6 days at 30-32. 7°C and 73.5-80.7% relative humidity. 
Crawler (Free-Living First Instar) 

Immediately after hatching, the crawler emerges from under the female 
armor through the raised posterior end. It is flat and somewhat oval in 
shape, yellow in color, and measures 0.26 mm in length and 0.14 mm in 
width. It has 6 well-developed legs and two normal antennae. 

After emergence, the crawlers move around for 1-4 days. On finding a 
suitable place, they insert the mouth part stylets into the plant tissue 
and settle down. Crawlers from the same female tend to settle in close 
proximity to each other, forming a new colony. 

As in the other diaspids, the crawler represents an important stage 
in the life history of the tea scale, since only through crawlers can 



31 



infestations actively spread. They are said to be dispersed by other 
insects and birds, but the dispersal of crawlers by means of the often 
airborne silken mass secreted by male nymphs is also a possibility. Al- 
though the amount of dispersion by this method has not been estimated, 
some live crawlers were found entangled in masses of gossamer-like waxen 
thread flying about on windy days. Another method of dispersal and colo- 
nization is, of course, through the transfer of infested host material. 

No sex-differentiation can be made at crawler stage. However, 
Ferris (1942) believed that some armored scales might exhibit some dif- 
ferences at this stage, and Stickney (1934) observed an additional spur 
on the legs of the male of first instar larva of Parlatoria blanchardi 
Targioni-Tozzetti. Stoetzel and Davidson (1974) stated that sexual di- 
morphism in the crawlers of certain aspidiotine species could be differen- 
tiated by the difference in the dorsal setal patterns of both sexes. 
Settler (Sedentary First Instar) 

Soon after successfully inserting their stylets, the crawlers change 
into settlers. Both the free-living crawler and the sedentary settler 
belong to the same stage, the first instar. In other words, the first 
instar has 2 phases, being first motile then sedentary. The first in- 
star changes into the second instar (first molt) after 10 days, i. e., 
14 days after hatching. As in other diaspids, the legs disappear and 
antennae are much reduced during the first molt. 
Second Instar (Male) Nymphs 

The second instar nymph is yellowish in color and measures 0.53 mm 
in length and 0.25 mm in width. The armor is thin and felted white. The 
pale yellow exuvia remains attached to its anterior end. This stage 
molts into third instar after about 11 days, i. e., 25 days after hatching. 



32 



Third Instar (Male) Prepupa 

At this stage the rudimentary wing pads become visible. The prepupa 
is 0.68 mm in length and 0.35 mm in width. The armor is almost rectang- 
ular with parallel sides. There is a prominent ridge along the mid dorsal 
line. One less-prominent ridge is also present laterally on either side. 
Because of the presence of the rudimentary wing pads, this stage is termed 
a prepupa. The prepupa molts into pupa in 5 days, i. e., 30 days after 
hatching. 
Fourth Instar (Male) Pupa 

In the beginning, the color of the pupa is yellow like that of the 
prepupa, but later the color changes to orange-yellow. Wing pads become 
elongated and a conical stylus develops at the end of the abdomen. 

The pupa, including the stylus, measures 0.72 mm in length and 
0.21 mm in width. Armor is similar to that of the third instar. The 
pupa changes into a pharate adult in 2 days, i. e., 32 days after 
hatching, and, on day 34, the adult male emerges from under the posterior 
end of the armor. 
Adult Male 

Adult male measures on an average 0.72 mm in length and 0.21 mm in 
width, with a wing span of 1.4 mm. It is a gnat-like creature of orange- 
yellow color, and has one pair of glassy, white forewings with reduced 
venation. The hind pair of wings is represented by a pair of halteres. 
A long stylus, or penis sheath, is present at the end of the abdomen. 

Tea scale males are probably nocturnal, as are the males of other 
armored scales (Bodenheimer, 1951). Since the mouth parts are non-func- 
tional, adult males do not feed, their only purpose being to fertilize 
the females. According to Das and Das (1962), adult males live for 2-3 days, 



33 

Second Instar (Female) Nymph 

After the first molt, a thin membranous covering is formed over the 
body of the female nymph. As in the male, pale yellow exuvia of the 
first stage remains attached to the anterior end of the female armor. 
In the early second instar, the body is light yellow and measures 0.59 mm 
in length and 0.28 mm in width. This stage lasts for 6 days, i. e., 20 
days after hatching. Following the second molt, the skin of the second 
instar female is not shed but remains intact, forming a cover that com- 
pletely encloses the adult insect which shrinks, thus leaving a vacant 
space at the posterior end of the armor. 
Female (Mature) 

The body of the female starts increasing on day 22 and becomes fully 
elongated by day 26. 

The covering of the female is at first thin and light yellow in 
color, but after sclerotization becomes hard and covered with a thin film 
of wax. Sclerotization occurs between day 31-36 after hatching. The 
armor is narrow and elongate with a distinct median longitudinal carina, 
and is dark brown, the median longitudinal area being the darkest. The 
female armor measures 1.2 mm in length and 0.43 mm in width. The yellow 
female lies under this protective armor. Because of shrinkage to provide 
room under the armor for the forthcoming eggs, the adult female is shorter 
in length than the mature nymph. 

During maturation, the armor of the female adheres firmly to the leaf 
surface. Upon reaching maturity on or about day 46, the posterior end of 
the armor becomes slightly raised. This change may be for emanating 
pheromones to attract males. Raising of the posterior end may serve some 
additional purposes as well, such as facilitating the intromission of the 
penis and egression of crawlers. 



34 



Eggs become mature in the ovaries in about 62 days after hatching, 
and females start laying eggs on or about day 65, completing the life 
cycle. English and Turnipseed (1940) reported that tea scale completed 
its life cycle in 60-70 days in Alabama. In India, the life cycle was 
completed in 24-27 days (Das and Das, 1972). 

During the maturation of females, it was noticed that some individuals 
had liquified bodies under the armor. No such individual was found when 
females had matured. This liquified stage may be an interval of re-organ- 
ization of nymphal body into adult body, i. e. , an incipient pupal stage. 
Comprehensive studies, however, are required to confirm this finding. 

The asynchronous maturation of males and females of the same brood 
effectively prevents the fertilization of females by males of the same 
colony. Males emerge much earlier and are extremely short-lived; when 
females of the same brood mature, males are not available to fertilize 
the females in the laboratory colonies. To establish successful cultures, 
a succession of implantations at suitable intervals, preferably weekly, 
is essential to ensure the availability of males to fertilize the females. 

Parthenogenesis 

Results of the experiments indicated that unmated females of tea scale 
are unable to reproduce, because no crawlers developed on any of the plants. 
The plant kept at 35°C was killed by heat; therefore no plant was used at 
this temperature in the replication of the experiment. 

Sex-ratio in the absence of natural mortality factors was 1.9:1 at 
15°C, 1.8:1 at 20 and 25°C, and 1.4:1 at 30°C. 

A multiple regression analysis of the data indicated that the temper- 
ature (15-30°C) failed to produce any effect on the sex-ratio. 

Relative survival of the immatures at different temperatures was also 
evaluated. Maximum survival was observed at 25 °C, while the lowest survival 



35 



occurred at 30°C. Data are presented in Appendix 1. Number of im- 
matures present on the upper and lower surfaces of the leaves indicated 
that the lower surface was preferred by tea scale. Of 865 nymphs ex- 
amined, 315 (36.4%) had settled on upper surfaces, whereas, 550 (63.6%) 
had settled on the lower surfaces. There were, on an average, 8.75 nymphs 
per leaf on the upper surfaces and 15.28 nymphs per leaf on the lower sur- 
faces (Appendix 2). A 't' test indicated that the difference in these 
values was significant at 95% level of confidence. 



36 



Population Dynamics 
Gene ral Characteristics of Tea Scale Populations 

Tea scale colonies, in general, have a whitish appearance caused 
by the white armors and the profuse white wax secretions of the males. 
This characteristic cottony mass usually occurs on the under side of 
the leaves and, in heavy infestations, hangs from the leaves, especially 
on the lower parts of the plants. 

On camellias the tea scale usually behaves as a stenomorous species 
because the only part of the plant attacked is the leaf. However, in 
cases of heavy infestations, some individuals may be found on the upper 
side of the leaves as well as on the buds. In the greenhouse, where 
natural control is non-operative, both lower and upper sides of camellia 
leaves became profusely covered with tea scale colonies. In nature, the 
upper surface of the leaves is kept clean probably by the rain, sunlight, 
and various natural enemies. 

During 1977 some 10,589 leaves on 1320 randomly selected twigs of 
Camellia japonica at Wilmot Garden were examined for tea scale infesta- 
tions. Of these, 1450 (13.69%) were found to be infested. Rate of in- 
festation varied from 1.75-88.14% of leaves on individual plants. 

Tea scale is a polyphagous species with a host list consisting of 
43 species of plants in 25 genera belonging to 16 families. In spite of 
the long host plant list, it occurs in high numbers only on camellias 
and hollies, and on these plants it exists virtually without any compe- 
tition from other phytophagous insects. It may be that on these hosts 
it eliminates the competitors, while on other host plants, it is elimi- 
nated; for instance, as on Euonymus sp. by Coccus hesperidum and on 
Citrus sp. by whiteflies. 



37 



The life history is markedly different in both sexes. Except for 
the egg and possibly the first instar, all other stages, including adults, 
exhibit sexual dimorphism. During most of its life span, tea scale re- 
mains attached to the leaf. Only crawlers and male adults are the mobile 
stages. Both of these stages, however, last only for a short time. Non- 
feeding stages include the egg, crawler, and pre-pupa (third instar male 
nymph), and male pupa, while the feeding stages include the settlers 
(sedentary first instar), male nymphs, and all stages of the female. 

The most conspicuous sign of feeding is the irregular, yellowish 
splotches on the upper surface of the leaves. These discolored areas 
correspond to the tea scale colonies present directly on the lower side, 
and are obviously caused by their feeding on the leaf tissue. On heavily 
infested leaves, these splotches coalesce and the entire upper surface 
of the leaves becomes mottled or discolored. Sometimes males and females 
were found developing on portions of leaf that had earlier been nibbled 
by some caterpillars. This obviously means that stylets are inserted 
into the vascular strands of the leaf for feeding. 

Tea scale is a multivoltine species with several overlapping gen- 
erations breeding more or less uninterruptedly throughout the year in 
Florida. Though cold weather decreases developmental activity, hatching 
does occur during the winter. During any part of the year all develop- 
mental stages can be found in the field. In the winter, camellias and 
hollies appear to be heavily infested. This is because no new foliage 
appears during winter and crawlers must settle on the same leaves near 
the mother colonies. Crawler dispersal may also be reduced by effects 
of temperature during the cold season. In India, Das and Das (1962) also 
found the same pattern of higher levels of infestation during winter. 



38 

Tea scale populations are characterized by highly male-biased sex- 
ratios and marked sexual dimorphism; the males being white, soft-bodied, 
and ultimately emerging as winged adults, while the less conspicuous, 
heavily armored females remain in place as neotenic adults. These 
attributes would appear well suited to divert attention of predators 
away from the less expendable and better protected females. Aspidioti - 
phagus sp. nr. lounsburyi is the only native parasite that attacks females 
but it is very rare, killing no more than 1.25% of the females by direct 
parasitization and destroying about 19% of the females by host feeding. 
As a result of diversion of predation to the more numerous soft-bodied 
males, and the resistance of the less conspicuous, heavily armored females 
to both predation and parasitization, and protection of the eggs during 
incubation, the tea scale has developed a remarkably successful strategy 
for survival. 

Tea scale is a protandrous species, males emerging long before the 
females of the same brood become sexually mature. Despite the shorter 
developmental period, males molt 4 times while females molt only twice. 
This asynchrony in the life cycles of the sexes creates some problems 
in the study of population dynamics. In the interest of clarity and 
consistency, the following simplified terminology has been adopted: 

Egg 

Crawler - free-living first instar nymph 

Settler - sedentary first instar nymph 

Male nymph - second and third instar nymph 

Female nymph - second instar nymph with unsclerotized armor 

Male pre-reproductive - intact pupa (fourth instar) 



39 



Female pre-reproductive - second instar with fully sclerotlzed 
armor, pre-oviposltion stage 

Male reproductive - emerged adult (empty pupal armor) 

Female reproductive - ovipositing female 

Populations of Adult Males 



The population surveys of adult male tea scale were carried out at 
Wilmot Garden during March 1977 through August 1978. Under field con- 
ditions, males began to emerge in April when new foliage was appearing 
on host plants. Adults were present in fluctuating numbers during April • 
January, with peaks of population occurring in May, July, and November. 

The curves representing the adult male populations shown in Fig. 1 
and Fig. 2 do not conform due to the difference in sampling techniques. 
In Fig. 2 the curve for adult population indicates the presence of males 
throughout the year because of continuous emergence of males from pupae 
in the laboratory. In Fig. 1 the curve represents the number of adult 
males observed on leaves and shows an absence of males during February - 
April, indicating a disruption of emergence from pupae in the field. 

Male populations were greatly affected by the destruction of nymphs 
due to parasitism following introduction of Aphytis theae and Aspidioti - 
phagus sp . During September - December 1977, when A. theae was present, 
male populations were much smaller than those of the corresponding months 
in 1979 when A. theae was no longer present (Table 3) . Average number 
of adult males emerging from 200 leaves (50 leaves per month) was 650 
in 1977, and 1625 in 1979. A ' t 1 test indicated that the difference in 
means was statistically significant at 95% level of confidence. 



40 




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43 



TABLE 3 
Comparison of Numbers of Male F. theae Adults Emerged from Colonies on 
Leaves of Camellia japonica at Wilmot Garden in 1977 and 1979. 



Number of males emerged per 50 leaves 

Month 1977 1979 

Sept. 295 1439 

Oct. 786 2071 

Nov. 675 1398 

Dec. 843 1591 

Total 2599 6499 

Mean 650 1625 



44 



Populations of Mature Females 

Populations of mature females fluctuated through the season. Peak 
of population occurred during January (Fig. 3). This peak was the result 
of decreased reproductive activity which causes accumulation of females 
during winter. The percent of ovipositing females in the total female 
population varies from 49.24 in November to 66.48 in April, with an 
average of 56.54 - 6.1%. The number of mature females in pre-oviposition, 
oviposition, and post-oviposition is given in Table 4. 

Mortality in the mature females occurs mostly in the pre-oviposition 
stage by parasitization and host feeding of Aspidiotiphagus sp . nr. 
lounsburyi , and ranges from 14.28% in May to 23.94% in October, with an 
annual average of 19.7 * 3.1%. 

Life cycle and survival of different stages are summarized graphi- 
cally in Fig. 4. 







45 




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46 



TABLE 4 

Number of Mature Females of F_. theae in Pre-Oviposition, Oviposition, 

and Post-Oviposition Stages 



Month 



Number of females/ 30 cm 
Pre-Oviposition Oviposition Post-Oviposition Total 







live 


dead 








Sep. 


77 


20 


38 


98 


13 


169 


Oct. 


77 


12 


51 


137 


13 


213 


Nov. 


77 


53 


41 


97 


6 


197 


Dec. 


77 


61 


41 


121 


11 


234 


Jan. 


78 


62 


68 


160 


11 


301 


Feb. 


78 


49 


50 


126 


9 


234 


Mar. 


78 


32 


30 


113 


9 


184 


Apr. 


78 


24 


28 


121 


9 


182 


May 


78 


26 


19 


86 


2 


133 


Jun. 


78 


27 


28 


66 


9 


130 


Jul. 


78 


17 


25 


71 


15 


128 


Aug. 


78 


38 


36 


85 


11 


170 


Total 


421 


455 


1281 


118 


2275 


Mean 


35 


38 


107 


10 


190 


Std. Dev 


17.3 


13.6 


27.9 


11.8 


50. 



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48 

Introduced Parasites 
Aphytis theae (Cameron) 

A. theae was introduced into Florida from Jorhat, India, in 1976. 
It was successfully cultured in a greenhouse and then released at several 
locations in Gainesville during May 1976. Population surveys during the 
summer indicated that it was rapidly increasing in numbers and dispersing 
to other locations. However, with the advent of winter, its populations 
started declining, and during late winter only dead pupae were encountered 
in the field, indicating that the parasite failed to survive the winter 
(Fig. 5). 

Re-colonization of A. theae was initiated in March 1977. For this 
purpose infested Camellia japonica leaves harboring pupae and adults of 
A. theae from the greenhouse culture were securely placed on infested 
leaves of C. japonica at Wilmot Garden. Results of intensive surveys 
indicated a rapid increase in population numbers reaching a peak in 
October 1977. A sudden decline in population occurred during the second 
week of November when adults were killed in large numbers by freezing 
temperatures at night. The decline in population continued until 
January (Fig. 1). No adults were seen in the field during January - 
March. However, A. theae adults did emerge in the laboratory from the 
50-leaf sample collected in January and March. No adult emerged from 
the material sampled in February. 

Live larvae and pupae were present in the field during January and 
February, but most of the live pupae seen during this period had been 
denuded (host scale removed) by the predators. A few eggs were recorded 
in March, indicating that A. theae had barely survived the winter of 
1977 - 1978. This seems to have been a consequence of momentum imparted 



49 




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by the extremely high numbers of _A. theae present in late fall, the small 
percent surviving winter mortality being sufficient to maintain a viable 
population. 

The larger population present in the fall of 1977 may be explained 
by the date of re-colonization which was about 6 weeks earlier than the 
first release in 1976. This provided time for about 3 more generations 
during the 1977 season. 

During 1978, adults were not seen in the field until late May 
(Fig. 1). The subsequent pattern of population increase was similar to 
that of the two preceding seasons; however, intensive survey was termi- 
nated in August 1978. No adult of A. theae was seen in the field during 
January - March 1979, and later observations revealed that _A. theae 
failed to survive the winter of 1978 - 1979. 

Mortality of A. theae larvae ranged from in September to 57.14% 
in February. Average larval mortality was 7.16%. Pupal mortality 
ranged from 8.33% in June to 100% in March. The major cause of larval 
and pupal death was cold, seemingly accentuated in the case of pupae by 
activity of predators which resulted in removal of the protective host 
scale cover from many of the parasites. Details of larval and pupal 
mortality are presented in Table 5. 

The failure of A. theae to survive in Gainesville can be attributed 
to the winter weather conditions. A comparison of 20-year averages of 
minimum temperatures and rainfall in Jorhat (India) and Gainesville 
(Florida) is presented in Fig. 6. The curves for temperature and 
rainfall indicate that winters are cooler and wetter in Gainesville. 
Another striking feature exhibited by the temperature curves is the 
straight line representing the months from December through February 



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53 



at Gainesville and indicating a prolonged period of low temperatures. 
The corresponding portion of the Jorhat temperature curve indicates that 
winter temperatures are somewhat warmer and the period of adverse temper- 
atures is of shorter duration. This difference no doubt accounts for 
failure of A. theae to persist at Gainesville. 

In the field, mating was observed in the morning and forenoon. 
In the laboratory, 10 matings lasted for 25-53 seconds with an average 
of 39.5 seconds. Egg laying occurs during evening hours. The egg is 
deposited under the armor on the dorsal side of the second instar male 
nymph. On hatching, the parasite larva migrates to the ventral side 
and starts feeding ectoparasitically. On completion of feeding, it 
molts into the pupal stage; two black fecal pellets (meconia) are 
excreted before the molt. At this stage the head of the parasite pupa 
can be seen protruding from under the posterior end of the host armor. 
Adults emerge after a week. For emergence, adults do not drill any 
holes, but crawl out from under the host armor. The life cycle is com- 
pleted in about 2 weeks. 

Because of the atrophied mouthparts, adult A. theae is not capable 

of host feeding. 

Aphytis theae exhibits host relationships of more than usual 
interest as it shows a marked preference for parasitizing male nymphs 
of its host species. While originally collected from tea scale it is 
not in any sense restricted to this species. Near the end of the 1977 
season it was observed to attack male nymphs of the false oleander 
scale, Pseudaulacaspis cockerelli (Cooley) as readily as those of tea 
scale. A. theae appears, therefore, to be a representative of a group 
of scale parasites that are adapted to exploit the male sex of diaspine 



54 

scales. This kind of host-parasite association may represent another 
example of resource partitioning (Schoener, 1974) in which other related 
parasite species are restricted to the host females. Direct competition 
between parasites would thus be minimized by host sex rather than host 
species specificity. As an alternative explanation, restriction of a 
parasite such as A. theae to males of host species may have evolved 
as regulative mechanicism facilitating coexistence of host and parasite. 

Such sex specific parasites also afford an interesting opportunity 
to investiage the effect of male mortality on host populations. Although 
there is no documented evidence that such mortality has significant 
generation to generation effects on host populations, two possible 
effects can be hypothesized. First, the population of host species will 
decline due to reduced mating. This effect would most likely occur if 
females were polyandrous and normally the more numerous sex. Secondly, 
the host species might in due time evolve a uniparental strain. 

Failure of A. theae to produce any effect on tea scale populations 
in spite of high male mortality can be attributed to the fact that male 
tea scale, like other male diaspids, is polygamous, and normally present 
in numbers that considerably exceed the number of females. 

Tashiro and Moffitt (1968) proved that males of the California 
red scale are polygamous. They found that a single male could fertilize 
up to 30 females, with an average of 11.9 females per male. 

Effect of A. theae on tea scale populations was studied during 
September 1977 through August 1978. This period can be divided into 
two parts. First, the period lasting from January through May when 
A. theae was inactive due to winter, and second, the period lasting 
from June through December when A. theae was active. Comparison of 



55 

numbers of live male nymphs in the two intervals was made. On the average, 

2 
there were 167 live male nymphs per 30 cm of leaf surface present during 

January through May, whereas, the corresponding number during June through 

December was 80. A 't' test indicated that the difference in numbers of 

live male nymphs was statistically significant at 95% level of confidence. 

A similar test on numbers of female nymphs present in the respective 
periods indicated a statistically insignificant difference. 

Comparison of numbers of male J?, theae emerging from the colonies 
present on 50 leaves during each month of the 2 seasonal periods was 
also made. On the average, 1320.8 males per 50 leaves emerged during 
January - May, and the corresponding numbers during June through 
December was 699.2. The difference was found to be statistically sig- 
nificant. 

On rare occasions adults of Aphytis sp. nr. lignanensis were found 
in the 5-leaf samples. These were probably chance visitors which 
happened to be present on the leaves at the time of collection. There 
are many Aphytis species attacking different species of armored scales 
in Florida, but there is no local species of Aphytis specific to tea 
scale in North America. A systematic search of Asian areas where the 
tea scale originated would almost certainly reveal a species of Aphytis 
adapted to fill this vacant niche. 
Aspidiotiphagus sp. 

Aspidiotiphagus sp. (Indian) is uniparental species; no males are 
present in this species, and unfertilized females produce only female 
progeny. A culture was established in the laboratory at Gainesville 
using Aspidiotus nerii Bouche as host which was in turn bred on Irish 
potato tubers. 



56 

To record the duration of life cycle and fecundity, 30 females were 
released individually on A. nerii on potatoes. Females were observed 
ovipositing, and took 70-140 (average 103) seconds to deposit a single 
egg. The progeny started emerging after 28 days. Each female produced 
11-41 (average 22.1 _ 8.5) daughters. When Aspidiotiphagus sp. was re- 
leased on tea scale on potted camellia in the laboratory, females were 
seen ovipositing in both male and female nymphs of tea scale. 

Field releases were made in Gainesville during January - June 1977. 

No data on population dynamics of tea scale were collected during 
September 1978 - August 1979, but observations were resumed in September 
1979 and carried out through December 1979. 

During this period, Aspidiotiphagus sp. emerged in abundant numbers. 
From a 50-leaf sample per month, 204 Aspidiotiphagus sp. adults emerged 
in September, 398 in October, 247 in November, and 55 in December. The 
percent of parasitism on males was 12.4 in September, 16.1 in October, 
15.0 in November, and 3.3 in December 1979. The decrease in numbers was 
due to overwintering of the parasite in the pupal stages. All emerging 
adults were females. Adult parasites emerge from male nymphs of tea 
scale by making a hole on the dorsal side of the armor. 

Although re-colonization of A. theae and releases of Aspidiotiphagus 
sp. (Indian) were made during the same period in 1977, there was no evi- 
dence that the latter had established until September 1979. In the 
meantime, A. theae increased rapidly during 1977 - 1978, and maintained 
high population levels until winter. This indicates the superiority of 
A. theae as a competitor of Aspidiotiphagus sp., which did not increase 
to detectable levels until relieved of competition from A. theae . 



57 



Life Tables 



In developing the life tables, 5 age intervals are used, namely, 
egg, crawler, settler, pre-reproductive, and reproductive. Since tea 
scale exhibits distinct sexual dimorphism, nymph, pre-reproductive, and 
reproductive age intervals are divided into male and female categories. 

Egg . The number of eggs was estimated as the product of the aver- 
age fecundity value (28.82) and the number of live ovipositing parent 
females. Since the number of such females was not known for September, 
1977, it was arbitrarily calculated as the average number of live ovi- 
positing females for 11 months (October 1977 - August 1978). This is 
the only assumed number in the life table figures for September, 1977. 
All other numbers in the rest of the life tables are real figures. All 
eggs under the female armor hatched successfully and emerged as crawlers. 

Crawler . Since crawlers are mobile, their number cannot be 
accurately estimated by the sampling method used to calculate numbers 
of the sedentary stages. Any other sampling technique employed to esti- 
mate the number of crawlers would have been statistically inappropriate. 
Because all eggs hatch successfully, their number also represents the 
number of crawlers. 

A large number of crawlers die before settling. They are probably 
blown away by wind, washed away by rain, and lost by misadventure during 
dispersal and leaf fall. Their mortality ranged from 62.41% in July to 
86.44% in September with an annual average of 77.35%. This high early 
mortality is a characteristic of all species with free-living and exposed 
individuals. Samarasinghe and LeRoux (1966) found the same trend of 
crawler mortality for Lepidosaphes ulmi (L.) in Quebec, Canada. 



58 



Settler. These are sedentary individuals with thin armors. As 
sex differentiation is not apparent at this stage, the numbers in the 
l x and d columns represent the density of settlers of both sexes. They 
are preyed upon by a phytoseiid mite, Iphiseides sp., and a thrips, 
Aleurodothrips fasciapennis (Franklin) (Phalaeothripidae) . 

The extent of mortality caused by each species could not be ascer- 
tained. Combined mortality caused by these 2 predators ranged from 
16.50% in July to 36.76% in October with an annual average of 24.08%. 

Nymph . Dimorphism is quite distinct at this age, and male and 
female nymphs can be distinguished from each other. 

Male nymphs: This stage includes both second and third ins tar 
nymphs. The major cause of mortality was the temporarily established 
introduced parasite, A. theae . The percentage of nymphs parasitized by 
A. theae ranged from 8.78 in May to 58.52 in December with an annual 
average percentage of 37.47. However, this parasite was not most active 
in December as indicated by the rate of parasitism for that month. The 
figures were obtained by counting the number of dead nymphs containing 
all stages of the parasite, namely, eggs, larvae, pupae, and exuviae of 
the emerged adults. Peak numbers of the adult parasite were observed 
during October, but populations started declining with the advent of 
winter . 

Major predators feeding on male nymphs are 2 species of coccinellids, 
namely, Lindorus lophanthae (Blaisdell) and Microweisea coccidivora 
(Ashmead) . These are regularly present among the tea scale colonies. 
Usually a single larva of L. lophanthae is found feeding on tea scale. 
It ploughs through the colonies, denuding and destroying more male 
nymphs that it feeds on. This habit of Lindorus probably slows down the 



59 

growth rate of Aphytis populations because of indiscriminate destruction 
of unparasitized as well as parasitized tea scale nymphs. Most of the 
dead pupae of A. theae in winter had been denuded by Lindorus . On the 
other hand, 2 or more larvae of Microweisea feed together. This cocci- 
nellid consumes the host nymphs individually by making an irregular hole 
in the male armor . 

The peaks of Lindorus and Microweisea populations more or less 
alternated with each other during the season (Fig. 2). This may be 
the result of competition between the 2 species. A multiple regression 
analysis indicated that variations in the populations of male tea scale 
were caused by the activity of these 2 predator species acting together 
as well as individually. 

A complex of Chrysopa spp. and 2 coccinellids, Cybocephalus sp. and 
Chilocorus stigma (Say), which feed on male nymphs, are also occasionally 
present among the tea scale colonies. But because of their extremely 
low populations and irregular occurrence during the season, these 
predators did not play any significant role in the population dynamics 
of tea scale. The combined mortality of male nymphs caused by predators 
ranged from 3.40% in September to 25.09% in May, with an annual average 
of 13.22%. 

A considerable number of male nymphs were found dead but the cause 
of death could not be ascertained. Diseases and some other physiological 
reason may be responsible for this mortality which ranged from 4.76% in 
September to 34.31% in February, with an annual average of 14.08%. The 
highest rates of mortality occurred during January - March indicating 
that cold may be the major cause of death in this category. 



60 

Female nymphs: This stage includes both unelongated and elongated 
nymphs with unsclerotized armor. A local species of parasites, 
Aspidiotiphagus sp. nr. lounsburyi (Berlese and Paoli) (Aphelinidae) , 
attacks the female nymph. It oviposits in the body of the second instar 
nymphs, and the larva feeds endoparasitically. Pupae are black and can 
be seen through the thin covering of the dead host. A round hole near 
one end of the unsclerotized armor is made by the emerging adult. A 
few hosts with fully sclerotized armor also contained emergence holes. 
This parasite is very rare with rates of parasitization ranging from 
in May to 3.93% in November with an annual average of 1.57%. 

Female nymphs were also parasitized by A. theae. Rate of parasitism 
by A. theae on female nymphs ranged from 1.37% in June to 5.06% in July, 
with an average of 1.05% during the year. Death in the majority of female 
nymphs can be attributed to diseases. Bodies of such nymphs became liqui- 
fied under the armor. In later studies, it appeared that liquif ication 
might be due to reorganization of the body tissue preliminary to pupation. 
Nevertheless, in the absence of experimental evidence to the contrary, 
these nymphs have been assumed dead due to disease. Mortality by this 
cause ranged from 11.87% in October to 31.01% in July, with an average 
of 21.46% during the year. 

Pre-reproductive . Male pre-reproductives: This is the fourth instar 
or pupal stage. Although neither A. theae nor predators were found 
attacking the pupae, many dead individuals were encountered in the field. 
Most of the dead pupae had died as pharate adults. Direct cause of 
death was desiccation caused by the denudation of pupae by the predators, 
which removed the armors while probing for food but left the pupa intact. 
Mortality in male pupae ranged from 4.05% in June to 48.39% in February, 



61 



with an annual average of 15.09%. Very high mortality in February 
indicates that cold may also be responsible for death of pupae. In 
population surveys, the pupal stage is the most appropriate index of 
population density. Duration of this stage is very short and, therefore, 
the extent of generation overlap is minimal. 

Female pre-reproductives: In this stage females have fully sclero- 
tized scales. A large number of females were found dead apparently be- 
cause of hostfeeding by Aspidio tiphagus sp. nr. lounsburyi . Some of 
the dead female nymphs may have died of this cause also. It is possible 
that Aspidio tiphagus adults may be parasitizing the nymphs but hostfeeding 
on pre-reproductives. Rate of mortality ranged from 18.80% in April to 
29.02% in January with an average of 26.21% during the year. 

Reproductive . Male reproductives : This stage was sampled by counting 
the number of empty pupal armors which indicated the successful emergence 
of male adults. Cause of death is recorded in the life tables as senility 
which, in fact, means natural death after mating. 

Female reproductives: All ovipositing females that survived to re- 
produce are included in this category. Generation mortality ranged from 
92.65% in February to 96.92% in April with an annual average of 95.15%. 

Population trend index (I) is the most practical measure of popu- 
lation changes obtained from the life tables. It was calculated as the 
ratio of number of eggs in 2 successive generations. Stable populations 
have population trend index (I) value equal to 1. A value of (I) greater 
or less than 1 indicates increasing or decreasing population trends. 

Population trend index (I) of tea scale varied from 0.70 in 
November to 1.39 in October with an annual average of 0.98. This shows 
that on an average tea scale populations were on decline during the year 



62 

1977 - 1978. This finding is in agreement with the fluctuating popu- 
lation trends reported by other workers for all species studied to date. 
This should occasion no surprise as all species have good years and bad 
years. 

To determine the relationship of variation in population trend 
index (I), and other variables such as sex-ratio, male and female densi- 
ties, and the generation mortality, data were subjected to a multiple 
regression analysis. The results of analysis showed that the generation 
mortality was the main factor responsible for fluctuations in the values 
of population trend index (I) . 

The column headings of the life tables (Table 6) are similar to those 
proposed by Morris and Miller (1954) except that the last column, labeled 
as 100d x /N 1 represents generation mortality. A brief description of 
column headings follows: 

x = The age interval 

1 = The number alive (1) at the beginning of the 
age interval (x) 

d F = The factor responsible for the death of indi- 
X viduals (d x ) within each age interval 

d = The number dying (d) within the age interval 
stated in the (x) column 

lOOq = Percentage mortality (d x as percentage of l x ) 
lOOd /N-l = The percentage of generation mortality 

The figures in l x and d x columns represent the number of individuals 
per 30 cm 2 of the infested leaves; figures in other columns were calcu- 
lated from these numbers. In d F column, parasites are mentioned in- 
dividually by name, whereas, the predators are grouped together. This 



63 

is because it is possible to distinguish deaths caused by each species 
of parasites, while it is not possible to quantify the damage caused by 
the individual species of predators. 



64 



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77 

K-Factor Analysis of Life Tables 
Varley and Gradwell (1960) described a method of analyzing life 
table data that reveals factors responsible for changes in population 
density. By this method, the killing power, or k-value, of each mortal- 
ity factor is measured by taking the difference between the logarithm of 
population numbers before and after its action (Appendix 3) . Since a 
series of mortality factors act successively in a population, their total 
killing power, or K-value, equals the total killing power of the indi- 
vidual factors. Its application to tea scale is as follows: 
k-L = mortality of crawlers during dispersal 
k2 = mortality of settlers due to predators 

ko = mortality of nymphs due to parasites, predators, 
diseases and unknown causes 

koa = mortality of male nymphs due to A. theae , (contained 
in k 3 ) 

kA = mortality of the pre-reproductives due to parasite, 
host feeding, and desiccation 

Using these k-values, generation mortality (K) can be expressed as 
follows: K = kj_ + k 2 + k 3 + k4 

The k-values for different age intervals and K-value for each month 
(Appendix 3) were plotted in Fig. 7, where the contribution of each 
mortality factor to variation in K can be seen by visual inspection. 
From the figures it is quite apparent that there are two main types of 
mortality factors; the first is for dispersion loss of crawlers (k^ and 
the second is the action of natural enemies on nymphs (k 3 ) . Both k-values 
followed, more or less, the same pattern as did the generation mortality 
(K) . Action of A. theae is shown separately as k^a, which is similar to 
k 3 but somewhat lower in magnitude. Since A. theae failed to become 



78 



1.6 r 

1.4 

1.2 

I 

0.8 

0.6 

0.4 




( = kl + k2+k3 + k4) 





k3a 



Figure 7. Key Factor Analysis. The Recognition of Key Factors in 
the Life Tables for Tea Scale, Fiorinia theae, by Visual 
Correlation of Various Mortality Factors (ks) with the 
Generation Mortality (K) . 



79 

permanently established, it is no longer operating as a mortality 
factor affecting tea scale populations in Gainesville. 



80 

Survivorship Curves 

A survivorship curve is the simplest graphical description of a 
life table and is obtained by plotting the number in the l x column on 
the ordinate against age on the abscissa (Fig. 8) . Lotka (1925) pointed 
out that survivorship curves become more informative if 1 is plotted on 
a logarithmic scale. A straight line would indicate a constant mortali- 
ty throughout life, while other shapes would measure the different "force 
of mortality" at different age intervals. Pearl and Miner (1935) and 
Deevey (1947) recognized 3 general types of survivorship curves: 
Type I, "the negatively skew rectangular" or convex curve is shown by 
members of a cohort which, having been born at the same time, die more 
or less simultaneously after a life span characteristic of the species. 
In other words, mortality acts heavily on old individuals. Type II is 
the "diagonal" curve and represents a constant mortality rate at all age 
intervals. That is, there is no greater probability of death at one stage 
than at another. Type III, "the positively skew rectangular" or concave 
curve indicates very high mortality in the young stages, but the few in- 
dividuals which survive to advanced ages have a relatively high probability 
of further life. This is the most common type of survivorship curve met 
with in animals. Most invertebrates and lower vertebrates exhibit this 
trend of mortality. In the higher vertebrates, the survivorship curve 
is of Type I because of greater parental care to their offspring. 

Most survivorship curves known so far tend to be rather intermediate, 
in varying degree, between Type I and Type II. Price (1975) analyzed 
the survivorship curves of 22 insect species and found that there were 
2 basic types of curves, although intermediates also occurred. In insects, 
mortality occurs in distinct stages; therefore, their survivorsip curves 
show a number of distinct steps (Ito, 1961). 



81 



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TYPE III 



AGE 



Figure 8. General Types of Survivorship Curves. 



82 



In tea scale, the eggs are retained under the female armor until 
hatching. This is a sort of parental care comparable to the higher 
vertebrates with Type 1 curves. The shape of the tea scale survivorship 
curve (Fig. 9) is somewhat convex in the beginning because of the high 
survival of eggs. The latter portion of the curve conforms to the typical 
stepped appearance of insect survivorship curves. Survivorship curve for 
females shows a consistent pattern throughout the year, while that for 
the males indicates variation in the survival which is directly affected 
by absence or presence of A. theae . Data for the survivorship curves 
are presented in Appendix 4. In the preparation of survivorship curves, 
actual numbers were converted to begin at 1000. 

The shape of survivorship curves of insect pests helps in determining 
the vulnerable stage of each species and may lead to the emphasis of 
control efforts on that stage. For instance, in the case of tea scale, 
the most vulnerable stage is the female nymph. If a species of natural 
enemy can be found that attacks this stage, the tea scale population 
can be reduced to non-economic levels. 



83 






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87 

Fertility Tables 

Knowledge of sex-ratio is a pre-requisite for species fertility 
tables. Tanner (1978) stated that sex-ratio can be categorized into 
the specific sex- ratio and the crude sex-ratio. The former relates to 
the ratio of the numbers of each sex within a particular age group; the 
latter is the ratio of the number of each sex in the entire population. 

The specific sex-ratio in tea scale varied greatly during different 
months because of the differential activity of natural enemies. Aphytis 
theae was the major mortality factor acting on the second instar male 
nymphs. Populations of A. theae also fluctuated during the season. 
During summer months it killed a major portion of male nymphs, but during 
the winter period, A. theae was wiped out by prolonged cold. Absence of 
A. theae released the pressure on the male nymphs of tea scale, and the 
sex-ratio swung further in favor of male sex. For instance, during 
March through September, when A. theae was active, the sex-ratio at 
nymphal stage ranged from 2.75:1 to 4.87:1, while during October through 
February, when Aphytis was inactive or absent, the sex-ratio at nymphal 
stage ranged from 6.02:1 to 8.43:1 (Table 7). Data are presented in 
Appendix 5 . 

The effect of fluctuations in A. theae populations was also reflect- 
ed by the varying sex-ratio in the subsequent stages of tea scale. Al- 
though the specific sex-ratios at the pre-reproductive and reproductive 
stages were in favor of females (except during March - May in the case 
of pre-reproductives, and May and June in the case of reproductives) , the 
crude sex-ratio consistently remained in favor of males (Fig. 10) . A 
delayed effect of A. theae on sex-ratio is also depicted by Fig. 10. 
The highest proportion of males occurred in February at the nymphal stage, 
in April at pre-reproductive stage, and in May at reproductive stage. 



88 



TABLE 7 
Specific and Crude Sex-Ratios of Tea Scale, Fiorinia theae 









Sex-ratio (male 


female) 




Month 


Nymph 


Pre-Reprod. 


Reproductive 


Crude 


Sep. 


77 


3.53:1 


0.12:1 


0.17:1 


1.03:1 


Oct. 


77 


6.44:1 


0.51:1 


0.20:1 


1.62:1 


Nov. 


77 


6.46:1 


0.07:1 


0.47:1 


2.00:1 


Dec. 


77 


6.32:1 


0.16:1 


0.26:1 


2.22:1 


Jan. 


78 


6.02:1 


0.73:1 


0.13:1 


1.92:1 


Feb. 


78 


8.43:1 


0.76:1 


0.13:1 


2.07:1 


Mar. 


78 


4.87:1 


1.31:1 


0.56:1 


1.97:1 


Apr. 


78 


3.35:1 


1.63:1 


0.98:1 


1.89:1 


May 


78 


2.75:1 


1.27:1 


1.13:1 


1.87:1 


Jun. 


78 


2.78:1 


0.07:1 


1.10:1 


1.67:1 


Jul. 


78 


3.44:1 


0.09:1 


0.24:1 


1.99:1 


Aug. 


78 


3.03:1 


0.22:1 


0.13:1 


1.41:1 



Average 4.52:1 0.55:1 0.42:1 1.83:1 



89 



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90 

Females of a species are capable of reproducing only during a 
certain age span. Much of their life is spent as either immature 
(pre-oviposition) or too old (post-oviposition) . To estimate the growth 
of populations with overlapping generations, it is essential to know the 
number of female individuals that are present at each age interval (Table 8) 
and the number of female offspring produced by an average female at dif- 
ferent intervals in her reproductive life. Once these parameters are 
known, the calculation of fertility rate (m^) becomes an easy process. 
Fertility rate (n^) and sex-ratio are used in preparing the fertility 
tables. 

A fertility table describes, in a summarized fashion, the net re- 
placement rate (Rq) f an average female. R Q is defined as the number 
of daughters that replace an average female in the course of a generation. 
The usual method of calculating Rq is from tables of age survivorship 
(l x ) and fecundity (n^) . The sum of all products of l x and m^. denotes 
R . A value of R Q equal to 1, indicates a stable population; greater 
than 1 indicates an increasing population; and less than 1 indicates 
a decreasing population. 

R is used in the calculation of reproduction or instantaneous 
rate of population growth (r) . Here r = log R Q /T, where T is the gen- 
eration time. According to Price (1975), in the case of populations 
with overlapping generations, each month can be considered as a breeding 
season. Therefore, for purposes of generation time T of the tea scale 
assumed as one month is used. Then r = log R Q /1 or r = log R Q . 

A stable population will have r = 0, while a value more than 
will indicate an increasing population, and a minus value of r will 



91 



TABLE 8 
Number of Female Tea Scale, Fiorlnia theae, per 30 cm 2 area of leaves 





h 


of Camellia 


japonica 


at Wilmot Garden, 

nber of Females 
Pre-reproductives 
survived died 


Gainesville 

Rep 
survive 




Mont 


Nym 
survived 


phs 
died 


Nu 


roductives 

d to reproduce 


Sep. 


77 


172 




36 




136 


38 




98 


Oct. 


77 


219 




31 




188 


51 




137 


Nov. 


77 


178 




40 




138 


41 




97 


Dec. 


77 


229 




67 




162 


41 




121 


Jan. 


78 


287 




59 




228 


68 




160 


Feb. 


78 


214 




38 




176 


50 




126 


Mar. 


78 


180 




37 




143 


30 




113 


Apr. 


78 


190 




41 




149 


28 




121 


May 


78 


147 




42 




105 


19 




86 


Jun. 


78 


146 




52 




94 


28 




66 


Jul. 


78 


158 




62 




96 


25 




71 


Aug. 


78 


172 




51 




121 


36 




85 


Total 


2292 








1736 






1281 


Mean 




191 








141 






107 


Std. 


Dev. 


40. 


5 






39.7 






27.9 



92 



represent a decreasing population. Values of R Q and r for tea scale 
during September 1977 - August 1978 are presented in Table 9. 



93 



TABLE 9 
Monthly and Annual Fertility Tables for Tea Scale, F. theae 



September 1977 
Sex-ratio - 3.53:1 



1 m 1 m 

x m x XX 



Nymphs 1.00 

Pre-reproductives- 0.79 

Reproductives 0.57 28.82/4.53 = 6.36 3.63 

R = 3.63 
° _ .56 



October 1977 
Sex-ratio - 6.44:1 



lx 
Nymphs 1 . 00 

Pre-reproductives 0.85 
Reproductives 0.62 



^ 


1 x m x 














28.82/7.44 = 3.87 


2.40 


«o = 


= 2.40 


r = 


.38 



November 1977 
Sex-ratio - 6.46:1 



X 


lx 


m x 








1 x m x 


Nymphs 


1.00 














Pre-reproductives 


0.77 














Reproductives 


0.52 


28 


82/746 = 


= 3 


86 
R o 


2.01 
= 2.01 



.30 



94 



TABLE 9-continued 



December 1977 
Sex-ratio - 6.32:1 



Nymphs 1.00 

Pre-reproductives 0.71 
Reproductives 0.53 



mx 1 x m x 





28.82/7.32 = 3.94 



R o = 

r = 



2.08 

2.08 
.32 



January 1978 
Sex-ratio - 6.02:1 



x 
Nymphs 1 . 00 

Pre-reproductives 0.79 
Reproductives 0.56 





28.82/7.02 = 4.10 



R_ = 



1 m 
x x 







2.29 

2.29 
.36 



February 1978 
Sex-ratio - 8.43:1 



Nymphs 1.00 

Pre-reproductives 0.82 
Reproductives 0.59 



m x 


Vx 














28.82/9.43 = 3.06 


1.80 


% = 


1.80 


r = 


.26 



95 
TABLE 9-continued 



March 1978 
Sex-ratio - 4.87:1 



1 m 1 m 

XX XX 



Nmyphs 1.00 

Pre-reproductives 0.79 

Reproductlves 0.63 28.82/5.87 = 4.91 3.09 

R D = 3.09 
r = .49 



April 1798 
Sex-ratio - 3.35:1 



x 1 x "Sc 1 x m x 

Nymphs 1.00 

Pre-reproductives 0.78 

Reproductives 0.64 28.82/4.35 - 6.62 4.24 

R D = 4.24 

r = .62 



May 1978 
Sex-ratio - 2.75:1 



x l x mx ix"^ 

Nymphs 1.00 

Pre-reproductives 0.71 

Reproductives 0.58 28.82/3.75 = 7.68 4.45 

Ro = 4.45 
r = .65 



96 



TABLE 9-continued 



June 1978 
Sex-ratio - 2.78:1 



Nymphs 



July 1978 
Sex-ratio - 3.44:1 



1* 

1.00 



Pre-reproductives 0.64 
Reproductives 0.45 



x 1 

x 

Nymphs 1.00 

Pre-reproductives 0.61 
Reproductives 0.45 



m x l xmx 





28.82/3.78 = 7.62 3.43 

% = 3.43 
r = .53 





28.82/4.44 = 6.49 



1 m 
x x 





2.92 



*o = 2.92 
r = .46 



August 1978 
Sex-ratio - 3.03:1 



x l x 

Nymphs 1.00 

Pre-reproductives 0.70 

Reproductives 0.49 



"be 




1 x m x 


















28.82/4.03 = 


7.15 


3.50 




R = 


3.50 



,54 



97 



TABLE 9-continued 



Average: September 1977 - August 1978 
Sex-ratio - 4.53:1 



x l x mx l^ 

Nymphs 1.00 

Pre-reproductives 0.76 

Reproductives 0.55 28.82/5.53 = 5.21 2.86 

R = 2.86 
? = .45 



98 

Age Composition 

The age pyramids are constructed in order to determine whether 
populations are increasing, decreasing, or stable in time. It is 
therefore essential to know the age distribution in the population. In 
the natural populations with overlapping generations, at each interval 
dead members are being replaced by the addition of new members. Because 
of this, the populations with overlapping generations are a complex of 
individuals representing all possible age groups. Difference in the 
age composition of populations at different intervals becomes quite 
apparent from the shape of the age pyramids. By following a series of 
age pyramids, changes in the age structure of a population can be acer- 
tained with reasonable accuracy. 

Age composition of tea scale is presented in Fig. 11. As in 
survivorship curves, female populations are more or less stable. Male 
populations show variations through the season. Adult males were in 
the lower proportions during July - September and December - February. 
The first reduction was caused by A. theae , while the second reduction 
was caused by cold, as low temperatures prevented the pupae from becoming 
adults. Data for Fig. 11 are presented in Appendix 6. 



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102 





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104 



Methodology to Calculate Survival Rates of Female and Male 
Tea Scale Populations 

Females . Male and female armors remain attached to the leaf even 
after the death of tea scale. Accumulation of the females of successive 
generations gives the impression of heavy infestations. In reality, how- 
ever, only a proportion of the female population is alive. Since pest 
management strategies require a precise estimation of potential damage, 
it becomes necessary to determine the proportion of gravid females in the 
total population. A procedure to derive the reproductive value of tea 
scale females present on leaves is described below: 

1) A sample of 60 field collected leaves of Camellia japonica was 
examined to determine the number of dead and live females in pre-oviposi- 
tion, oviposition, and post-oviposition stages. The following data were 
obtained: 

Total number of females 6269 

number of live females in 
pre-oviposition stage 889 

number of dead females in 
pre-oviposition stage 1161 

number of females in 

oviposition stage (live) 3546 

number of females in 
post-oviposition stage (dead) 673 

2) A 40-leaf sample was examined to determine the number of females 

in oviposition stage and to record the following information: 

Total number of females in 

oviposition stage 2469 

number of females (ovipo- 
sition stage) with no 
hatched eggs (i.e., eggs 
were present but none had 
yet hatched) 482 



105 



number of females (ovipo- 

sition stage) with some 

hatched eggs 1987 

3) Average fecundity of 40 females was determined by counting the 
number of eggshells, unhatched eggs, and eggs still present inside the 
ovaries (Table 2) . 

4) A sample of 40 ovipositing females was examined to determine the 
reproductive value (average number of remaining eggs) by counting the 
number of eggshells and deducting this number from the average fecundity 
(28.82) of females (Appendix 7) • The average number of remaining unlaid 
and unhatched eggs per female was 12.45 

5) Expected progeny of ovipositing females 

with no hatched eggs = 482 x 28.82 = 13891 

Expected progeny of ovipositing females 

with some hatched eggs = 1987 x 12.45 = 24738 

Total expected progeny of ovipositing females = 38629 

Average expected progeny of ovipositing 

females = 39629/2469 = 15.65 

6) There were 6269 females on 60 leaves, and if all were alive would 

deposit (6269 x 28.82) 180,673 eggs. But there are only 889 (pre-ovipo- 

sition stage) and 3546 (oviposition stage) live females. 

Expected progeny of live females in 
pre-oviposition stage = 889 x 28.82 = 25621 

Expected progeny of live females in 

oviposition stage = 3546 x 15.65 = 55495 

Total progeny of live females = 81116 

Average progeny of live females = 81116/4435 = 18.29 

Average progeny of all (dead and live) = 12.94 
females = 81116/6269 

This is the reproductive value of each female present on the leaf. Total 

number of eggs on a leaf can be calculated by multiplying the number of 



106 

females present on a leaf by 12.94. This also means that for every 
100 females present on a leaf, only 44.9 (12.94/28.82 x 100) are poten- 
tial producers. 

Two simple methods to determine the total number of females on 
infested leaves were developed and are described below. 

The area of randomly selected uninfested leaves of Camellia japonica 
was measured with a leaf -area measuring machine. The average of 100 
leaves was 21.7 cm 2 - 6.7. Then 50 infested leaves were procured from 
the field and cleaned with a soft brush to remove scales. On each leaf 
an area of 3 cm 2 was delineated in the center with a circular corer. The 
number of mature females was counted in the 3 cm 2 area first, and then the 
number of females present on the whole leaf was counted (Appendix 8) . 

One method to calculate the total number of females on a leaf is to 
multiply the number of females in 3 cm 2 by a factor of 7.23 (21.7/3). 

o 

The second method would be to multiply the number of females in 3 cnr- 
by factor ( number on whole leaf /number in 3 cm 2 ) . This factor obtained 
from a 50-leaf count was 8647/1596 = 5.42 (see Appendix 8). A comparison 
of the two methods indicates that only the second method is accurate and 
should be employed in sampling future populations. The difference between 
the two methods is due to the fact that distribution of tea scale on leaves 
is clumped. If distributions were random, both methods would conform. 

Males . Sex-ratio in tea scale can be used in estimation of the total 
population and the survival rate of the males. During September - December 
1979, the number of males emerging from a 50-leaf sample per month was 
recorded. The number of females present on the leaves was also counted. 



107 



The absolute population of tea scale and male mortality was estimated 

as follows: 

Number of females on 200 leaves 

(50 leaves per month) = 32356 

Crude sex-ratio (Table 7) 

males: females = 1.83:1 

Therefore, the potential number of 

males on 200 leaves = 32356 x 1.83 = 59212 

Total population of tea scale 
on 200 leaves = 32356 + 59212 
or, 32356 x 2.83 = 91568 

Number of males actually emerged 

from 200 leaves = 6499 

Survial rate of males = 

6499/91568 x 100 = 7.097% 



SUMMARY AND CONCLUSIONS 

Tea scale is the most serious pest of camellias and hollies in the 
eastern United States. In Florida it breeds continuously with several 
overlapping generations throughout the year. Both immature and mature 
stages exhibit well marked sexual dimorphism. Males molt 4 times and 
complete development in about 34 days. Their armors are soft in texture 
and white in color. Females are neotenic and molt twice before commenc- 
ing oviposition in about 65 days. They have well sclerotized armors of 
brown color. Effective protection is provided to eggs by the female 
armor during incubation periods. Asynchronous maturation of males and 
females effectively prevents mating between individuals of the same 
brood. Unfertilized females cannot lay fertile eggs, but male biased 
sex-ratio and polygamous nature of males ensure fertilization. Compari- 
son of rates of development of tea scale in different areas indicates 
that higher temperatures expedite the development of different stages. 

A complex of native predators feeds on male nymphs, while a local 
parasite attacks female nymphs. These native natural enemies, however, 
are ineffective in keeping the host populations below economic levels. 
Because chemical control is costly and otherwise less satisfactory, two 
species of parasites from India were introduced into Florida. Both para- 
sites proved to be specific to male tea scale. One species, Aphytis theae , 
could not become permanently established because of prolonged cold periods 
during winter, but was an important mortality factor during the period of 



108 



109 



study; the other parasite, Aspidiotip hagus sp., has become established. 
In spite of very high rates of parasitism, these sex-specific parasites 
failed to reduce tea scale populations, thus confirming a long held view 
of biological control workers regarding efficacy of male-specific natural 
enemies. 

Field collected data are utilized to construct 12 monthly and 1 
annual life tables. These life tables are the first of their kind for 
a sexually dimorphic, multivoltine species with overlapping generations. 
The methods developed for tea scale life tables will prove suitable for 
constructing the life tables for species with characteristics similar 
to tea scale. According to tea scale life table analysis, the major 
mortality factors were dispersion loss at crawler stage and parasitiza- 
tion of male nymphs by A. theae . Analysis of survivorship curves for 
males and females indicates that tea scale populations can be reduced 
if a natural enemy attacking female nymphs is introduced. 

Specific sex-ratio in the tea scale varied at all stages; there 
were more males at nymphal stages but females were more abundant as 
adults. Crude sex-ratio indicated a constant preponderance of males. 
Major cause of variation in sex-ratio was mortality of the male nymphs 
by A. theae . Variations in the relative populations of males and fe- 
males in all stages are presented in the form of 12 monthly and 1 annual 
age pyramids. Methods to calculate the survival rates of males and fe- 
males are developed and will provide useful guidelines in future popu- 
lation surveys of the tea scale. Data generated by field and laboratory 
studies will provide valuable basic information for comparison of results 
of future attempts on the biological control of tea scale. 



REFERENCES CITED 

Atkinson, P. R. 1977. Preliminary analysis of a field population 
of citrus red scale, Aon idiella aurantii (Maksell) , and the 
measurement and expression of stage duration and reproduction 
for life tables. Bull. Ent. Res. 67:65-87. 

Beardsley, J. W. , and R. H. Gonzalez. 1975. The biology and ecology 
of armored scales. Ann. Rev. Entomol. 20:47-73. 

Beshear, R. J., H. H. Tippins, and J. 0. Howell. 1973. The armored 

scale insects (Homoptera: Diaspididae) of Georgia and their hosts. 
Univ. Georgia, College of Agric. Res. Bull. 146:10. 

Bodenheimer, F. S. 1951. Citrus entomology in the Middle East. 
W. Junk, Publishers, The Hague. 663 p. 

Borchsenius, N. S. 1966. A catalog of the armored scale insects 
(Diaspididae) of the world. Academy of Sciences of the USSR, 
Zoological institute, Moscow. 449 p. 

Cameron, P. 1891. Hymenopterological notes. Memoirs and Proceedings 
of the Manchester Literary and Philosophical Society 6(4): 183. 

Chiu, C, and C. A. Kouskolekas. 1978. Laboratory rearing of tea scale. 
Ann. Entomol. Soc. Amer. 71:850-851. 

Collins, F. A. 1978. Importation of Aphytis theae into Florida for 
control of tea scale, Fiorinia theae . Unpublished manuscript. 

Collins, F. A., and W. H. Whitcomb. 1976. A Florida survey for natural 
enemies of tea scale, Fiorinia theae (Homoptera: Diaspididae). 
Unpublished manuscript. 

Compere, H. 1955. A systematic study of the genus Aphytis Howard 
(Hymenoptera: Aphelinidae) with descriptions of new species. 
Univ. Calif. Publ . Ent. Berkeley, 10:271-320. 

Das, G. M. , and S. C. Das. 1962. On the biology of Fiorinia theae Green 
(Coccoidea: Diaspididae) occurring on tea in North-east India. 
Indian J. Entomol. 24:27-35. 

Deevey, E. S. , Jr. 1947. Life tables for natural populations of 
animals. Quart. Rev. Biol. 22:283-314. 

Dekle, G. W. 1965. Florida armored scale insects: Arthropods of 

Florida and neighboring land areas. Fla. Dept . Agric. Div. Plant 
Indust. 3:64. 



110 



Ill 



English, L. L. , and G. F. Turnipseed. 1940. Insect pests of azaleas 
and camellias and their control. Ala. Agric. Exp. Sta. Circ. 
84:1-18. 

Fernald, M. E. 1903. A catalogue of the Coccidae of the world. 
Carpenter and Morehouse, Massachusetts. 250 p. 

Ferris, G. F. 1942. Atlas of the scale insects of North America. 
4th Series, Stanford Univ. Press, Calif. 253 p. 

Green, E. E. 1900. Remarks on Indian scale insects (Coccidae) with 
descriptions of new species. Indian Museum Notes, 5(l):3-4. 

Harcourt, D. G. 1969. The development and use of life tables in the 

study of natural insect populations. Ann. Rev. Entomol. 14:175-196. 

Ito, Y. 1961. Factors that affect the fluctuation of animal numbers, 

with special reference to insect outbreaks. Bull. Nat. Inst. Agric. 
Sci. 13:57-89. 

Kouskolekas, C. A. 1971. The tea scale and its control in the camellia 
garden. Amer. Camellia Yearbook, 1971:30-38. 

Kouskolekas, C. A. 1973. Tea scale control on camellias in the land- 
scape. J. Econ. Entomol. 66(2) :533-534. 

Kouskolekas, C. A., and R. L. Self. 1973. Control of tea scale on con- 
tainer grown camellias with granular systematic insecticides. 
J. Econ. Entomol. 66(5) : 1163-1166. 

Krebs, C. J. 1972. Ecology: The experimental analysis of distribution 
and abundance. Harper and Row, New York. 374 p. 

Kuitert, L. C. 1949. Control of insect pests of camellias. American 
Camellia Yearbook, 1949:147. 

Kuitert, L. C. , and G. W. Dekle. 1972. Tea scale, Fiorinia theae Green 
(Homoptera: Diaspididae) . Fla. Dept. Agric. Consumer Serv. Div. 
Plant Ind. Entomol. Circ. 120:1-2. 

Kuwana, I. 1925. The diaspine Coccidae of Japan. iii. The Genus 
Fiorinia . Dept. Finance, Japan, Imp. Plant Quar. Serv. Tech. 
Bull. 3:1-20. 

Lawson, P. B. 1917. The Coccidae of Kansas. Univ. Kansas, Lawrence, 
Biol. Ser. Bull. 18(1) : 161-275. 

Leopold, A. 9133. Game management. Charles Scribner's Sons, 
New York. 481 p. 

Lobdel, G. H. 1937. Two segmented tarsi in coccids: Other notes 
(Homoptera). Ann. Entomol. Soc. Amer. 30:75-80. 



112 



Lotka, A. 1925. Elements of physical biology. Williams and Wilkins, 
Baltimore. 465 p. 

MacGillivary, A. D. 1921. The Coccidae. Scarab Co. Urbana, Illinois. 
502 p. 

Merrill, G. B. 1953. A revision of the scale insects of Florida. 
State Plant Board, Fla. Bull. 1:48. 

Merrill, G. B., and J. Chaffin. 1923. Scale insects of Florida. 
Quar. Bull. S.P.B. Fla. 7 (4) :177-298. 

Moreno, D. S., G. E. Carman, R. E. Rice, J. G. Shaw, and H. S. Bain. 
1972. Demonstration of a sex pheromone of the yellow scale, 
Aonidiella citrina . Ann. Entomol. Soc. Amer . 65:443-446. 

Morris, R. F. 1963. The dynamics of epidemic spruce budworm popula- 
tions. Mem. Entomol. Soc. Canad. 31:1-332. 

Morris, R. F., and C. A. Miller. 1954. The development of life tables 
for the spruce budworm. Canad. J. Zool . 32:283-301. 

Murakami, Y. 1970. A review of the biology and ecology of diaspine 
scales in Japan (Homoptera, Coccoidea) . Mushi, 43:1-114. 

Nagarkatti, S. 1977. Personal communication. 

Pearl, R. , and J. R. Miner. 1935. Experimental studies on the duration 
of life. XIV. The comparative mortality of certain lower organisms. 
Qtr. Rev. Biol. 10:60-79. 

Pearl, R. , and S. L. Parker. 1921. Experimental studies on the duration 
of life: An introductory discussion of the duration of life in 
Drosophila . Am. Naturalist, 55:481-509. 

Price, P. W. 1975. Insect ecology. John Wiley & Sons, New York. 
514 p. 

Rice, R. E., and D. S. Moreno. 1969. Marking and recapture of 

California red scale for field condition studies. Ann. Entomol. 
Soc. Amer. 62:558-560. 

Rice, R. E. , and D. S. Moreno. 1970. Flight of male California red 
scale. Ann. Entomol. Soc. Amer. 63:91-96. 

Riddick, E. 1955. Check list of hosts of scale insects of Florida. 
State Plant Board of Fla. Bull. 7. 78 p. 

Rosen, D. 1973. Methodology for biological control of armored scale 
insects. Phytoparasitica l(l):47-54. 



113 



Rosen, D. , and P. DeBach. 1977. Resurrection of Aphytis theae 

(Hymenoptera: Aphelinidae) , a parasite of tea scale, with notes 
on a new group of species. Fla. Entomologist, 60(1) :1-10. 

Samarasinghe, S., and E. J. LeRoux. 1966. The biology and dynamics 

of the oystershell scale, Lepidosaphes ulmi (L.) (Homoptera: Cocci- 
dae) on apple in Quebec. Ann. Entomol. Soc. Quebec, 11:206-259. 

Sasscer, E. R. 1912. The genus Fiorinia in the United States. 
U. S. Dept. Agric, Bureau of Entomol. Tech. Ser. 5:75-82. 

Sasscer, E. R. 1914. Notes on entomological inspection in the District 
of Columbia. J. Econ. Entomol. Cncord, 7 (2) :240-244. 

Schoener, T. W. 1974. Resource partitioning in ecological communities. 
Science, 185:27-39. 

Southward, T. R. E. 1966. Ecological methods with particular reference 
to the study of insect populations. Methuen, London. 391 p. 

Stickney, F. S. 1934. The external anatomy of the Parlatoria date 
scale, Parlatoria blanchardi Targioni - Tozzetti, with studies of 
the head skeleton and associated parts. U. S. Dept. Agr . Tech. 
Bull. 421:1-67. 

Stoetzel, M. B., and J. A. Davidson. 1974. Sexual dimorphism in all 
stages of the Aspidiotini (Homoptera: Diaspididae). Ann. Ent . Soc. 
Amer. 67(1) :138-140. 

Takagi, S. 1970. Diaspididae of Taiwan based on material collected 
with the Japan - U.S. Cooperative Science Programme. Insecta 
Matsumurana 33:1-146. 

Tanner, J. E. 1978. Guide to the study of animal populations. Univ. 
Tennessee Press, Knoxville. 186 p. 

Tapia, E. A. 1968. A diaspid new to our country. Hofa inf. Inst. 
Patol. Veg. 24:2. 

Tashiro, H., and D. L. Chambers. 1967. Reproduction in California 
red scale, Aonidiella aurantii (Homoptera: Diaspididae). I. 
Discovery and extraction of a female sex pheromone. Ann. Entomol. 
Soc. Amer. 60:1166-70. 

Tashiro, H., and C. Moffitt. 1968. Reproduction in California red 

scale, Aonidiella aurantii . II. Mating behavior and post insemina- 
tion female changes. Ann. Entomol. Soc. Amer. 61:1014-1020. 

Tippins, H. H. 1969. Tea scale control with trunk application of sys- 
tematic insecticidies. J. Georgia Entomol. Soc. 4(3): 90-92. 



114 



Tippins, H. H. 1970. The second instar males of three species of 
Fiorinia (Homoptera: Diaspididae) . J. Georgia Entomol. Soc. 
5(2):94-99. 

Tippins, H. H. , and M. Dupree. 1973. Comparison of three types of 

sprayers for tea scale control. J. Georgia Entomol. Soc. 8(4):310- 
311. 

Varley, G. C. , and G. R. Gradwell. 1960. Key factors in population 
studies. J. Anim. Ecol. 29:399-401. 

Vaughan, A. W. 1975. Field evaluation of insecticides for controlling 
tea scale, Fiorinia theae Green, on camellia, with observations on 
biology, parasites, and predators. M.S. Thesis, University of 
Florida. 

Vaughan, A. W. , D. E. Short, and D. B. McConnell. 1976. Field evalua- 
tion of insecticides for controlling tea scale on camellia. J. Econ. 
Entomol. 69(1) : 125-216 . 

Watt, G. 1898. The pests and blights of the tea plant. Govt. Printing 
Press, Calcutta. 344 p. 

Watt, G,, and J. H. Mann. 1903. The pests and blights of the tea plant. 
Second Edit. Govt. Printing Press, Calcutta. 344 p. 

Watt, K. E. F. 1963. The analysis of the survival of large larvae in 
the unsprayed area. Morris, R. F. ed. The dynamics of epidemic 
spruce budworm populations. Mem. Entomol. Soc. Canada 31:52-63. 



APPENDIX 1 

Number of Male and Female Tea Scale, Florlnia theae, survived 

on Camellia japonica at different temperatures 

Plant No. 

& Temp. // scales 1 2 3 4 5 Total 

1 males 
15 °C females 

Total 

1-A males 

15 °C females 
Total 

2 males 
20° C females 

Total 

2-A males 
20 °C females 
Total 

3 males 
25 °C females 

Total 

3-A males 

25 °C females 
Total 

4 males 
30°C females 

Total 

4-A males 
30°C females 
Total 

5 males 
35 °C females 

Total 

5-A not used. 



71 


2 


24 


28 


32 


157 


9 


7 


15 


11 


21 


63 


80 


9 


39 


39 


53 


220 


43 


27 


14 


39 


25 


148 


4 


57 


4 


22 


9 


96 


47 


84 


18 


61 


34 


244 


32 


12 


36 


54 


27 


161 


19 


14 


18 


42 


9 


102 


51 


28 


54 


96 


36 


263 


28 


101 


37 


1 


15 


182 


6 


35 


32 


12 


3 


88 


34 


136 


69 


13 


18 


270 


36 


70 


6 


59 


64 


235 


58 


17 


22 


13 


44 


154 


94 


87 


28 


72 


108 


389 


16 


27 


34 


98 


82 


257 


13 


18 


18 


40 


28 


117 


29 


45 


52 


138 


110 


374 


15 


24 


9 


60 


10 


118 


7 


5 


4 


32 


10 


58 


22 


29 


13 


92 


20 


176 


22 


2 


10 


40 


16 


90 


46 


15 


6 


8 


20 


95 


68 


17 


16 


48 


36 


185 



115 



APPENDIX 2 
Side Preference of Tea Scale, Fiorinia theae 

Leaf # Number of Crawlers Settled 

upper side lower side Total 

17 3 10 

2 7 12 19 

3 1 4 5 

4 5 7 12 

5 3 3 

6 2 2 

7 5 16 

8 6 6 

9 1 1 

10 2 3 5 

11 6 8 14 

12 2 2 4 

13 2 3 5 

14 15 60 75 

15 18 29 47 

16 44 49 93 

17 30 39 69 

18 2 2 

19 7 4 11 

20 2 13 

21 11 

22 11 

23 1 5 6 
24-5 5 

25 5 5 

26 11 

27 36 42 78 

28 19 32 51 

29 13 37 50 

30 14 39 53 

31 3 3 

32 6 33 39 

33 7 30 37 

34 13 32 45 

35 33 54 87 

36 6 5 11 

Total 315 550 865 



116 



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117 



APPENDIX 4 
Data for the Survivorship Curves. 

Number of Tea Scale, Fiorinia theae , per 30 cm2 area of leaves 

of Camellia japonica at Wilmot Garden, Gainesville 

Number Survived 

tenth Eggs Crawlers Settlers Nymphs Pre-reproduccives Reproductives 

Male Female Comb. Hale Female Comb. Kale Female Comb. 

Sep. 77 3142 3142 426 147 172 319 22 136 158 17 98 115 

Oct. 77 2825 . 2825 778 273 219 492 31 188 219 28 137 165 

Nov. 77 3948 3948 816 470 178 648 50 138 188 46 97 143 

Dec. 77 2796 2796 993 593 229 822 34 162 196 32 121 153 

Jan. 78 3487 3487 954 464 287 751 25 228 253 21 160 181 

Feb. 78 4611 4611 730 341 214 555 31 176 207 16 126 142 

Har. 78 3631 3631 593 238 180 418 77 143 220 63 113 176 

Apr. 78 3256 3256 657 296 190 486 136 149 285 118 121 239 

May 78 3487 3487 545 263 147 410 117 105 222 97 86 183 

June 78 2479 2479 681 341 146 487 74 94 168 71 66 137 

July 78 1902 1902 715 439 158 597 20 96 116 17 71 83 

Aug. 78 2046 2046 626 303 172 475 12 121 133 11 85 96 



AVERAGE 3134 



313A 710 348 191 539 53 145 198 45 107 152 



118 



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120 



APPENDIX 7 

Reproductive Value of the Ovipositing Females of the Tea Scale, 

Fiorinia theae, at Wilmot Garden, Gainesville 

- Remaining Eggs 



Female # 


# Eggshells 


Avg. # Eggs 


1 


14 


28.82 


2 


13 


ii 


3 


9 


n 


4 


24 


ii 


5 


21 


ii 


6 


22 


ii 


7 


41 


M 


8 


13 


ii 


9 


14 


M 


10 


32 


ii 


11 


32 


M 


12 


2 


ii 


13 


20 


ii 


14 


30 


M 


15 


36 


n 


16 


37 


ii 


17 


14 


ii 


18 


32 


ii 


19 


15 


ii 


20 


36 


ii 


21 


30 


ii 


22 


9 


ii 


23 


9 


ii 


24 


6 


ii 



+ 14.82 
+ 15.82 
+ 19.82 
+ 4.82 
+ 7.82 
+ 6.82 

- 12.18 
+ 15.82 
+ 14.82 

- 3.18 

- 3.18 
+ 26.82 
+ 8.82 

- 1.18 

- 7.18 

- 8.18 
+ 14.82 

- 3.18 
+ 13.82 

- 7.18 

- 1.18 
+ 19.82 
+ 19.82 
+ 22.82 



121 



122 



APPENDIX 7-continued 

Females // Eggshells Avg. // Eggs - Remaining Eggs 

25 11 28.82 + 17.82 

26 9 + 19.82 

27 11 " + 17.82 

28 24 " + 4.82 

29 10 " + 18.82 

30 22 " + 6.82 

31 1 + 27.82 

32 3 + 25.82 

33 11 " + 17.82 

34 12 " + 16.82 

35 4 + 24.82 

36 22 " + 6.82 

37 24 " +4.82 

38 22 " + 6.82 

39 11 " + 17.82 

40 12 " + 16.82 

41 22 " + 6.82 

42 16 " + 12.82 

43 23 " + 5.82 

44 40 " - 11.18 

45 15 " - 13.82 

46 30 " - 1.18 

47 34 " - 5.18 

48 10 " + 18.82 

49 19 " + 9.82 

50 14 " + 14.82 

Reproductive Value: Mean = 12.45 



APPENDIX 8 
Number of Female Tea Scale, Fiorinia theae , in 3 cm area, and on 
Whole Leaves of Camellia japonica at Wilmot Garden, Gainesville 

Leaf # Females/ 3 cm 2 # Females /whole leaf Ratio 

1 27 182 6.74 

2 16 114 7.13 

3 13 68 5.23 

4 33 210 6.36 

5 78 287 3.68 

6 11 73 6.64 

7 23 136 5.91 

8 26 166 6.38 

9 43 221 5.14 

10 52 290 5.58 

11 29 72 2.48 

12 20 86 4.30 

13 46 234 5.09 

14 37 186 5.03 

15 37 251 6.78 

16 31 170 5.48 

17 7 37 5.29 

18 5 22 4.40 

19 36 257 7.14 

20 33 269 8.15 

21 5 34 6.80 

22 22 61 2.77 

23 49 407 8.31 

24 54 360 6.67 

25 18 93 5.12 

26 78 200 2.56 

27 70 357 5.10 

28 29 130 4.48 

29 22 193 8.77 

30 35 232 6.63 



123 



124 



Leaf 

31 
32 
33 
34 
35 
36 
37 
38 
39 
40 
41 
42 
43 
44 
45 
46 
47 
48 
49 
50 

Total 

Mean = 31.92 

Std.Dev. = 18.05 



// Females/ 3 cm 

13 
18 
52 
25 
41 
28 
20 
23 
25 
33 
40 
15 
42 
24 

7 
63 
56 
49 

9 
28 



1596 



APPENDIX 8-continued 

# Females /whole leaf 

108 
138 
342 
231 
191 
103 
189 

97 

80 
117 
238 

86 
230 
149 

47 
366 
255 
227 

30 
114 



Ratio 



8647 



31 
67 
67 
24 
66 
68 
9.45 
4.22 
3.20 
3.55 
5.95 
5.73 
5.48 
6.21 
6.71 
5.81 
4.55 
4.63 
4.44 
4.10 

5.42 



Mean = 172.94 
Std.Dev. = 95.43 



Mean = 5.65 
Std.Dev. = 1.67 



BIOGRAPHICAL SKETCH 
Badar Munir was born on April 7, 1938, at Rawalpindi, Pakistan. He 
completed his high school education at the Islamia High School, Rawalpindi, 
in 1955, and then joined the Gordon College, Rawalpindi, whence he ob- 
tained his B.S. degree in biology in 1961. He received his M.Sc. degree 
in Zoology from the University of Punjab in 1963. He joined the Pakistan 
Station of the Commonwealth Institute of Biological Control in 1963 as 
Junior Emtomologist and worked on the ecology of high altitude forest 
pests and their natural enemies in Pakistan. In 1968 he was promoted to 
Senior Entomologist and in that capacity studied the ecology of fruit 
flies. In 1971 he proceeded to Barbados, West Indies, to take up an 
appointment as Government Entomologist. There he worked on the biologi- 
cal control of vegetable pests. He left Barbados in 1976 to join the 
University of Florida as a graduate student. He is presently working 
for his Ph.D. degree in entomology. Mr. Munir has published 4 technical 
papers and has presented papers at various entomological meetings. He is 
a member of the International Organization of Biological Control, Entomo- 
logical Society of America, Florida Entomological Society, Caribbean Food 
Crops Society, and the International Organization for Ecology. 

He is married to Rafia Sultana and has a daughter, Saliha, and a 
son, Hummayum. 



125 



I certify that I have read this study and that in my 
opinion it conforms to acceptable standards of scholarly 
presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 



A AjA 



R. I. Sailer, Chairman 
Graduate Research Professor 
of Entomology and Nematology 



I certify that I have read this study and that in my 
opinion it conforms to acceptable standards of scholarly 
presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 



r 



T. E. Freeman 

Professor of Plant Pathology 



I certify that I have read this study and that in my 
opinion it conforms to acceptable standards of scholarly 
presentation and is fully adequate, in scope and quality, 
as a dissertation for the degree of Doctor of Philosophy. 



Wm^ B> rJoAntHj 



n 

AV^'B . Hamon 

Adjunct Assistant Professor 
of Entomology and Nematology 



This dissertation was submitted to the Graduate Faculty of 
the College of Agriculture and to the Graduate Council, and 
was accepted as partial fulfillment of the requirements for 
the degree of Doctor of Philosophy. 



March 1980 



kU 



Or~' 



Dean// College of Agriculture 



Dean, Graduate School 



UNIVERSITY OF FLORIDA 



3 1262 08553 1795