FUNGI PARASITIC UPON ALEYRODES GITRI
By
HOWARD S. FAWCETT
A THESIS FOR THE DEGREE OF MA.-1 -CIENCK
SUBMITTED TO THE FArUKT
THE UNIVERSITY OF THE STATE OF FLORIDA
JUNK, 1908.
FUNGI PARASITIC UPON ALEYRODES CITRI
TTt-\~'
U'NrvEK
-or
'
By
HOWARD S. FAWCETT
A THESIS FOR THE DEGREE OF MASTER OF SCIENCE
SUBMITTED TO THE FACULTY OF
THE UNIVERSITY OF THE STATE OF FLORIDA
JUNE, 1908.
UNIVERSITY OF THE STATE OF FLORIDA
SPECIAL STUDIES No. i
CONTENTS.
ENTOMOLOGY
UBfiABY
PAGE.
I. INTRODUCTION 5
Statement of Work on Which the Thesis is Based 777 . . . ,-rv . . , 5
Historical Review of Entomogenous Fungi 5
Historical Review and Economic Status of Aleyrodes citri R. & H 8
II. ASCHERSONIA ALEYRODIS WEBBER 10
Discovery and Description 10
History 10
Methods of Introduction 11
Germination of Conidia 12
Cultures 13
Infection of Aleyrodes citri from Cultures 16
Distribution 17
III. ASCHERSONIA FLAVO-CITRINA P. HENN 11
Discovery and Description • 11
Comparison with A. aleyrodis 18
Cultures 18
Germination of Conidia 39
Super-parasite 21
List of Localities in Florida 21
IV. VERTICILLIUM HETEROCLADUM PENZ 21
Discovery and History 21
Description 22
Cultures 23
Germination of Conidia 24
Infection of Aleyrodes citri from Cultures 24
List of Insects Parasitized, with Localities 25
V. Sl'H AEROSTILBE COCCOPHILA Tui 25
Description 25
History 26
Relation to San Jose and Other Scale Insects 27
Parasitism on Aleyrodes citri 28
List of Insects Parasitized, with Localities 29
VI. M ICROCERA SP 29
Technical Description ' 29
Discovery 30
Cultures 30
Infection of Aleyrodes citri from Cultures 32
Germination of Conidia 33
Variation in size of Conidia 33
Distribution in Florida 34
VII. THE "BROWN FUNGUS" 34
Discovery 34
Description by Webber 34
Brown fungus of Parkin 35
Methods of Introduction 35
Distribution 36
SUPPLEMENTARY NOTES 36
SUMMARY ?>1
BIBLIOGRAPHY :58
EXPLANATION OF PLATES.. 41
272696
LIST OF ILLUSTRATIONS.
PACK.
Fig. 1. — Adult and egg of .llcyrodcs citri facing 8
Fig. 2. — Larvae and pupae of Alcyrodcs citri : facing 9
Fig. 3. — Conidia of Aschcrsonia alcyrodis 12
Fig. 4. — Conidium of Aschcrsonia alcyrodis germinating 13
Fig. 5. — Hyphae of Aschcrsonia flaro-citrina H»
Fig. 6. — Conidia of Aschcrsonia flaro-citrina 1 (.)
Figs. 7, 8 and 9. — Sporids of Aschcrsonia flavo-citrina 20
Fig. 10. — Conidiophores and conidia of / 'crticilliitm hctcrocladnin 23
Fig. 11. — Spore-like bodies of I 'crticillinin hctcrocladnin 23
Fig. 12. — Perithecium of Spkaerostilbe coccophila 2,~>
Fig. 13. — ASCIIS of Sphacrostilbc coccophila 2.">
Fig. 14. — Sporodochium of $j hacrostilbc coccophila 2(5
Fig. 15. — Conidia of Sphacrostilbc coccophila 26
Fig. 16. — Hypha and conidia of Microccra sp 30
Fig. 17. — Conidia of Microccra sp 30
Fie. 18. — Conidia of Microccra sp 30
Fig. 19. — Sporids of Microccra sp 33
Figs. 20. 21. 22 and 23.— Cultures of . Ischcrsonia alcyrodis Plate I
Fig. 24.— .Ischcrsonia flaro-citrina on Citrus leaf Plate II
Fig. 23.— .Ischcrsonia alcyrodis on Citrus leaf Plate II
Figs. 26 and 27. — Cultures of . Ischcrsonia flaro-citrina '. Plato 1 1 1
Figs. 28, 29 and 30.— Cultures of Aschcrsonia flaro-citrina Plate IV
Fig. 31. — / 'crticillinin hctcrocladnin on Citrus leaf Plate IV
Figs. 32, 33 and 34. — Cultures of / 'crticillinin hctcrocladnin Plate V
Fig. 33. — / 'crticiliinin hctcrocladnin on leaf Plate V
Fig. 36. — Sphacrostilbc coccophila on . Ispidiotns hcdcrac Plate VI
Figs. 37 and 38.—Sphacrostilhc coccophila on Mytilasfiis citricola Plate VI
Figs. 39 and 40. — Cultures of Microccra sp Plate VI
Fig. 41.— Microccra sp. on Citrus leaf Platc yj
Fig. 42.— Brown Fungus on Citrus K-af Plate yjj
HH. 43. — Super-parasite on Aschcrsonia flaro-citrina Plate VI I
FUNGI PARASITIC UPON ALEYRODES GITRI.
BY
HOWARD S. FAWCETT,
Plant Pathologist, Florida Agricultural Experiment Station.
I. INTRODUCTION.
Since taking up the investigation of Citrus diseases in the fall of 1905,
in connection with work in the Florida Experiment Station, the author has
given considerable attention to the study of the fungi parasitic on Aleyrodes
citri R. & H., and on scale insects. Since the beginning of the work three
species of fungi have been discovered to be parasitic upon the larvae and
pupae of Aleyrodes citri; two of these, Aschcrsonia flavo-citrina, and an
undetermined species of Microcera, were first noticed by Prof. P. H. Rolfs,
and the third, Vcrticillium hctcrocladum, by the author. With the addition
of these three, the number of known fungus parasites of this insect is in-
creased to six, namely:
1. Aschcrsonia alcyrodis Webber,
'2. Aschcrsonia flavo-citrina P. Henn.,
3. J^crticilliuni hctcrodadnin Penz.,
4. Spkaerostilbe coccophila Tul.,
.">. Microcera sp.,
(>. The sterile Brown fungus of Webber.
Cultures of all these fungi except the Brown fungus have been grown in
the laboratory by the author. One of these, Sphaerostilbe coccophila., had
been previously studied in pure cultures by P. H. Rolfs, who published his
results in Bulletin 41 of the Florida Experiment Station under the title of
"A Fungus Disease of the San Jose Scale". For this reason a further study
of this fungus in cultures was not undertaken, and it is, moreover, only
rarely parasitic upon Aleyrodes citri.
It is the purpose of this thesis, after a brief review of previous investiga-
tions of the fungus parasites of insects, to describe the results of recent study
of the fungi that are parasitic upon Aleyrodes citri in Florida. With the
description of each fungus there is given its distribution and the names of
its insect hosts. A bibliography of the six fungi is added. The illustrations,
except Figs. 1, 2, and 42, are original. Technical descriptions and a general
review of previous literature, when any such has been published, are in-
cluded with the account of each fungus.
ENTOMOGENOUS FUNGI.
The fact that certain low forms of plant growth, such as fungi and
bacteria, are at times the cause of the destruction of great numbers of
insects, has created much popular as well as scientific interest for many
G l-r.\V.l PARASITIC UPON ALKYRODKS CITRI.
years. As early as 1T54, according to M. C. Cooke,1 a popular description
was written by Father Torrubia of a fungus growing out from the bodies
of wasps. Father Torrubia had collected specimens of this at Havana,
Cuba, as early as 1749. Cooke thinks that this fungus was Cordyceps
specocephala. lie quotes Torrubia's account from Edwards' "Gleanings
in Xatural History," published in 1<5S, and says that this species represents
the rather celebrated vegetable wasp which had a romantic history a century
l.efore. Cooke also gives an account of a species of Isaria, which had been
known as early as 1782 on the Sphinx moth.1 He mentions as many as
1!»7 species, representing 39 genera of fungi, that have been found growing
upon various insects. The majority of these species are included by Cooke
under ."i genera: Cordyceps, with 48 species; Laboulbenia, with 34 species;
Isaria, with 2\ species; Entomophthora, with 22 species; and Empusa, with
13 species. Since then main new genera have been added to the ento-
inngencms fungi. Species of Cordyceps found on wasps, bees, ants, cater-
pillars, and scale insects, have been mentioned by many scientists and
popular writers from the last-mentioned date down to the present time.
Cooke refers to the "History of Insects" by Murray, published in 1838. as
containing interesting accounts of fungi growing upon insects.
The Tulasne brothers were probably among the first to study the para-
sitism of these fungi. They published descriptions of some of them in
L857,a and of others in isii.").-' Among those described in 1865 was Sphaer-
ostilbc cticcophila Tul.. which is one of the species treated of in this thesis
as sometimes parasitic on Alcyrodcs citri. The work of Pasteur on the
flacherie of the silkworm, marked a great advance in our knowledge of
insect diseases. This disease was due to a species of bacterium. Pasteur's
work was taken up with the view of protecting the insect from parasitic
growth, while most subsequent work has been carried on with the view of
destroying insect pests by means of their parasites. A work of much scien-
tific importance was that of Roland Thaxtcr,:: "The Entomophthoraceae of
the I'nited States", published in 1888. The genera which he studied attack
flies, beetles, moths, caterpillars, grasshoppers, and plant lice.
Since the institution of Experiment Stations in the United States, ex-
periments have been made with several species of fungi, with a view of
using them in combating insect pests. l"p to this time the greatest degree
of Miccess has l;een attained in Florida, where the conditions of temperature
and moisture are conducive io the spread of fungi. The use of fungi to
combat insect peMs has met with only limited success in the Northern States.
A number <>f years agn the employment of a species of Sporotrichum for
spreading disease among chinch-bugs received much attention. Tn 1895.
'Vegetable Wa>p> and Plant Worm-. pp. U-48, London. ls«.»:.».
2Cookr. M. C' \Ym-ialili- Waspv and IMant Worms. ,,],. ;,, :;;; n 73 <,<; j |-» ]s-. , n(>
881.
'Mi-moil-* of tin- P,.,MOH Soi-irtv of Natural History. Vol. IV. Xo. 6.
INTRODUCTION. 7
S. A. Forbes4 of the Illinois Experiment Station gave a detailed account of
cultures and infection experiments carried on with this fungus. A few
sentences from his discussion of the results are here quoted:
The white muscadine will not spread among vigorous chinch-bugs in the field in
very clrv weather to an extent to give this disease any practical value as a means of
promptly arresting serious chinch-hug injury under such conditions. :
It is most likely to catch in low spots, where the soil is kept somewhat moist by
dense vegetation, a mat of fallen herbage, or the like. * * *
If decidedly wet weather follows upon its introduction, even after an interval of
several weeks, it is likely to start up and take visible effect ; but continuous rains,
depressing the vital energies of the insect, seem commonly requisite to its efficient
action.
Some investigation has been carried on with a number of other ento-
mogenous fungi grown in pure cultures. G. F. Atkinson5 and R. H. Pettit6
studied cultures of Cordyceps, Isaria and Sporotrichuin. R. H. Pettit in
his bulletin issued in 1895 included a long bibliography of the literature on
entomogenous fungi, to which any one interested in the history of this
subject is referred.
In 1897, P. H. Rolfs,7 in his bulletin "A Disease of the San Jose Scale,"
demonstrated that the fungus Sphaerostilbc coccophila could be used in a
practical way in combating the San Jose scale in Florida. In 1906, a valu-
able paper by J. Parkin,8 "Fungi Parasitic on Scale Insects," gave a general
review and the distribution of the fungus parasites of Coccidae and Aley-
rodidae which had been described in all countries up to that time. He
referred to a recent publication by Gueguen9 in France, which is said to be
an exhaustive work on the fungus parasites of man and animals. A recent
contribution by Dop1" on a new fungus parasite in Martinique that has
saved the cocoanut industry of that island is also briefly mentioned.
In Florida, insects belonging to the orders Coccidae and Aleyrodidae
are very subject to attacks of fungi. In addition to the six fungus parasites
of Alcyrodcs citri here treated of, there are two other fungi which are not
found on this insect, although they are quite common on scale insects of
Citrus. These are Ophioucctria coccicola E. & E., and Myriangiuw duriaci
Mont, both of which are illustrated in Bulletin 94 of the Florida Experi-
ment Station. Webber also found on the wax scale Ceroplastcs florldcns'is,
the fungus Aschcrsoma turbinata; and he mentions finding on various in-
4 Experiments with the Muscadine Disease of the Chinch-bug, etc., 111. Agr. Exp. Sta.,
Ikil. :;s, 1S95.
5 Artificial cultures of an Entomogenous Fungus. Bot. Gaz., Vol. XIX, pp. 129-145, 1894.
h Studies in Artificial Cultures of Entomogenous Fungi. Cornell Univ. Agr. Exp. Sta.
Bui. 97, 1S95.
7 A Fungus Disease of the San Jose Scale. Fla. Agr. Exp. Sta. Bui. 41, 1897.
8 Annals of Roy. Bot. Card. Peradeniya, Vol. 3, Part 1.
9 Gueguen, F. Les Champignons parasites de I'homme et des animaux, pp. 252, Paris,
1904. Bot. Centralbl., XCVI, p. 044.
" Dop, P. Bull. Sci. France et Belgique. XXXIX, p. 1P>5, 1905. Bot. Centralbl., XCIX,
p. 50.*).
> I-l'Ni'.I PARASITIC UPON ALEYRODES CITRI.
sects other Aschersonias, which, as far as we know, he has not identified.
I'mf. II. II. Hume sent to the author in 1906 a species of Aschcrsonia found
mi what appeared to he an Alcyrodcs on the leaves of Hc.v Dahoon. It is
(|iiite probable that further observation will reveal a number of other species
»>f fungi parasitic u])nn insects of these two orders in Florida and the ad-
joining S:au--.
AI.KYKDDES CITRI.
ffhis insect, the larval and pupal stages of which are parasitized by the
fungi to he discussed later, has been a serious pest of orange groves in
Florida and the adjoining States for a number of years. It had been ob-
served by C. Y. Riley in 1878 in the greenhouses at the United States De-
partment of Agriculture at Washington. In 1885, Mr. Ashmead wrote an
account of it for the "Florida Despatch", in which he gave it the name of
Alc\rodcs citri. In 1895, Riley and Howard11 first described this species
in "Insect Life". In this publication it is reported as having been received
from Mississippi. Louisiana, North Carolina and many points in Florida,
(xainesville and Crescent City are places mentioned at which it had been
studied by Jas. Yoyle and H. G. Hubbard, before 1893. It is also stated that
during the years 1892 and 189;? it had so multiplied in parts of Louisiana and
Florida as to deserve immediate attention. It is of interest here to note that
it was about this time. IS!):?, that Webber discovered the first fungus para-
site of this insect.
This insect is not a true fly, as the name might imply, but belongs to
the Order I lemiptera, which also includes the plant lice and scale insects.
Tlie following summary of the life-history of Aleyrodes citri is from Bul-
letin ss nf the Florida Agricultural Experiment Station, by E. W. Berger :
There are three well-defined broods of the whitefly, with an interval of several
da\s t.. several weeks hetweeii each brood, when few or none are seen on the wing.
The first brood generally appears some time during March, April or May; the second
during June. Jul\ or August; and the third during September and October.
Larvae and pupae of the whitelly are to be found on the under surfaces of the
leave-, and seldom elsewhere. The larvae are scale-like and closely appressed against
tile leaf. They vary in si/e from the very young, just visible to the unaided eye, to the
fully matured larvae which measure about one-sixteenth of an inch in length.
The larvae are white and translucent with a tinge of yellow, and almost invisible
upon the leal. The pupa (Fig. :». X... s) is the transformation stage from the larva
to the adult winged tly. The pupae are readily visible as yellowish-white, plump, oval
b-,di,.^with a dark reddish sp.,t on the back. From the pupa emerges the adult winged
Tin- little white cases, with a T-shaped split on the back, found on the under
; a leal, are tin- empty pupa cases from which the adults have emerged (Fig.
No, in). The eggs <Fi«. ,. N08, 3 and ft) are JUS1 visible to the unaided eye as a
upon the nndrr surface ,,f ,he leaves. An ordinary hand lens will show
them as little egf-shaped bodies iniu-h resembling grains of wheat. * * *
Fig. 1. — AlJvYRODES CITRI.*
No. 1 and 2, Adult female; No. :-i. Egg; No. 4, Egg-shell; No. 5, Claspers at tip of
abdomen of male; No. 6, Antenna; No. 7, Fore margin of front wing.
INSECTS SOMETIMES MISTAKEN FOR ALEYRODES CITRI.
No. 8, Larva of Alcyrodcs floridcnsis; Nos. <) and 10, Margin of larva; No. 11, Larva
of Lccaniuin hesperidum.
From Fla. Agr. Exp. Sta. Bui. 07, by H. A. Gossard.
Fig. 2.— ALEYRODES CITRI.*
No*. 1 and :->. Larva first stage, at different magnification* ; No. 3, Larva, second stage -
No. 4. Larva third stage; No. 5, Larva, fourth stage; No. .;. Margin of advanced
larva; No. 7, Vasiform orifice of fourth stage; Xo. s, Pupa; No. 0, Adult emenrine
tn.ni pupa-case; No. 10, Empty pupa-case.
*From Fla. Ayr. Kxp. Sta. I'.ul. c,7, by H. A. Gossard.
INTRODUCTION. 9
Twenty thousand eggs have been estimated on a large orange leaf. From observa-
tions made in the laboratory, egg-laying begins when the female is from eighteen to
thirty hours old ; and from seventeen to twenty-five eggs are deposited. These eggs
are generally all laid within twenty-four hours after the first egg has__h£en laid. Her
length of life has been estimated at from three days in warm weather to three weeks
in cool weather, and the complete length of life cycle from egg to adult is from forty
or fifty days in summer to six months in winter.
The origin of the whitefly pest in Florida is only a matter of con-
jecture. It is not definitely known whether it is a native species or was
introduced from the East. A recent report that Aleyrodes citri has been
discovered in Asia gives some weight to the latter view. H. A. Gossard,
in Bulletin (>T of the Florida Experiment Station, "The Whitefly", 1903, said
with regard to its advent in Florida :
The fly seems to have been first known in Florida throughout the region comprised
in Volusia, Marion, Lake, Alachua, and Orange counties ; from which, I have little
doubt, it was transferred to Manatee county and to local centers along the northern
borders of the State.
It had therefore become widely distributed before it attracted any consid-
erable attention. At the present time it is widely distributed in many parts
of Florida, and is spreading slowly to parts not before infested, in spite of
the work that is done by the growers to keep it out of the groves.
Several investigations are being carried on at the present time by the
Florida Experiment Station, and by the United States Department of Agri-
culture in order to work out practical methods of controlling the pest.
Spraying with insecticides, fumigation with hydrocyanic acid gas under
tents, and infection with fungus parasites have all been used. Fumigation
and fungus infection are the most promising remedies known at the present
time. The use of the fungus parasites in destroying this insect will be
briefly discussed later, when the various fungi are described.
The most serious injury caused by the whitefly is the sooty mold that
always follows the insect. This is a species of Meliola, a soot-colored
fungus that lives in the honeydew secreted by the whitefly larvae. Since
the larvae are found upon the under surfaces of the leaves, the honeydew
collects upon the upper surfaces of the leaves below and furnishes a suita-
ble medium for the growth of Meliola. The sooty mold spreads in a black
layer over the surface. The fruit is also blackened, so that it must frequently
be washed before it is shipped. The vitality of the tree is lowered, not
only by the loss of the nourishment sucked out by the insects, but also by
the shutting off of the sunlight from the surfaces of the leaves. An account
of this fungus is given by Webber in Bulletin 13 of the Division of Vegetable
Physiology and Pathology, Washington, D. C.
10 FUNGI PARASITIC 1'1'ON AI.KYKODKS CITRI.
II. ASCHERSONIA ALEYRODIS WEBBER.
This species was first discovered by H. J. Webber in August, 18913, at
Crescent City, in the grove of J. H. Harp. Mr. Webber12 published a pre-
liminary notice of the entomogenous nature of this fungus in 1894, referring
it to Aschcrsonia tahitcnsis Mont. In 189(5, under the same name, he
mentions it in the bulletin, "The Principal Diseases of Citrus Fruits in
Florida". 1:I Finding it after further study to be a distinct species, he de-
scribed it in 1897 in his bulletin, "Sooty Mold of the Orange and its Treat-
ment," as Aschcrsonia alcyrodis,'14 as follows:
.Ischcrsonia alcyrodis Webber. Stroma hypophyllous, depressed hemispherical,
pinkish buff or cream colored, coriaceous, 1 — 2V£mm. in diameter ; mycelial hypothallus
grayish white, forming a thin membrane closely adhering to the leaf and extending
about 1 mm. beyond the stroma ; perithecia membranaceons, at first superficial, later
becoming immersed, irregular, reniform or orbicular in mature specimens, and opening
by small, round, or elliptical pores or slits; basidia crowded, filiform, slender, con-
tinuous, 28 — 40 microns long, 0.94 — 1.5 in diameter; paraphyses abundant, slender,
projecting beyond the basidia, 65 — 100 microns long, y± — 1 micron in diameter; spor-
ules fusiform, continuous, mucilaginous, hyaline, sometimes obscurely 3 — 4 guttulate,
9.4 — 14.1 microns long by 0.94 — 1.88 microns wide, very abundant and erumpent, form-
ing conspicuous coral red or rufus masses. (Parasitic on Alcyrodcs citri R. & H. infest-
ing citrous leaves in Florida).
HISTORY.
Some species of Aschersonia have been reported to be conidial stages of
the genus Hypocrella, an Ascomycete. Massee13 speaks of having shown
that the ascigerous forms of species of Aschersonia were produced on fallen
leaves on which the conidial stages had grown. Parkin10 also mentions this
genus as the probable perfect stages of species of Aschersonia and refers
to a species of Hypocrella (H. Raciborskii) described by Zimmerman,17
with a conidial stage referable to Aschersonia. No ascigerous forms have
as yet been discovered in connection with the Aschersonias in Florida.
In I'.KI."), F. S. Earlels reported Aschcrsonia alcyrodis on Alc\rodes
citri in Cuba. In I'.MM;. J. Parkin10 reported finding an Aschersonia on sev-
eral undetermined species of Aleyrodes in Ceylon, which closely resembled
Aschcrsonia alcyrodis. He said, "Numerous forms of Aschersonia have
been found in Ceylon on species of Aleyrodes and Lecanium". In February,
I'.Kis. Cook and Home20 reported Aschcrsonia alcvrodis on .llcvrodcs citri
and on Ale\rodes howardi'i, in Cuba.
"Webber, H. J. Journal of Mycology, V<>1. VI, No. 4, p. :;<;:;. \
13 WeblK-r, II. J. Div. of Veg. Phys. & Path., Bui. s, p. ;_>;. Washington I) C L896
"Webber, H. J. Div. ,,f YY-. Phys. & Path.. I'.ul. L3, p. 21, Washington I") C*. ls«»7
"Massee, G. Jour. Hot. V«>1. 34, i». 151.
10 Parkin, J. Ann. Roy. Bot. Card. IVradtniya. V.>1. III. Part 1 pp »<) and 3> I'.MII,
17 Zimmerman. Central!), fiir I'.akt.. Abth. II. Vol. VII. p. 872.
18 Primer Informe Anual de la Estarion Central . \-ronoinica <lr Cuba 1WM and l')<r>
p. 169, I'.ioii.
"Annals Roy. Bot. Card. P< radnm a. Vol. III. Pan I. p. ;;«;. l<t<m.
"Cook, M. 'l\. and llornr. \\'. T. Cuban K\p. Sta. P.nl. (.i. p. :;l. 1908.
ASCHERSONIA AIvEYRODIS. 11
Previous to Webber's publication,21 the entomogenous nature of the
genus Aschersonia was not known, although up to that time__there were 19
species of this genus described, as recorded in Saccardo's "Sylloge Fun-
gorum". This species was therefore the first known parasite of Aleyrodes
citri, and was probably the first fungus that had been reported on any
species of Aleyrodes. In the course of his investigations on the sooty mold,
Webber reported that he had found three other species of Aschersonia,
parasitic on other insects in Florida ; one of which was Aschersonia tur-
binata on the Wax Scale (Ceroplastes floridensis Comst.). The others
were not determined by him. In 1897, when he wrote his bulletin on sooty
mold, Webber reported that Aschersonia aleyrodis was found in Florida
at Crescent City, Bartow, Panasoffkee and Gainesville. He also stated that
no sign of the fungus was apparent in groves infested with Aleyrodes citri
at Ocala, Orlando, Evinston and Ormond. In the same bulletin, the de-
velopment of the fungus, the probable method of spore dissemination, and
the methods of introducing the fungus on the orange trees, are discussed
at some length. The description of the development of the fungus in the
next paragraph is taken with slight changes from this bulletin.22
The first indication of the effect of the fungus on the larva of the whitefly is
the appearance of slightly opaque, yellowish spots unusually near the edge of the
larva. In the early stages of infection the larva becomes noticeably swollen, and appears
to secrete a greater abundance of honeydew than normally. As the fungus develops,
the interior organs of the larva appear to contract away from the margin, leaving a
narrow circle, which becomes rilled with hyphae. Shortly after this the hyphae burst
out around the edge, forming a dense marginal fringe. This may form all around
the larva at about the same time, or develop at one portion of the margin sooner than
the others. Death usually ensues, it is believed, before the hyphae burst out. Tne
fungus does not spread over the leaf to any extent, but grows upward in a mass,
gradually spreading over the larval scale. It is not uncommon to find the pycnidia, with
their bright coral-red masses of sporules, formed in a circle around the edge of the
larva while it is yet visible. As the Aschersonia develops, the hyphae spread over
the larva forming a dense compact stroma, which ultimately entirely envelops the
larva. The stroma in this stage is thin and disk-like, the fructification being usually
borne in a circle near the edge. The hyphae, which make up the main mass of the
stroma are from 8.5 to 7.5 micro-millimeters in diameter. Within the body of the
insect and near the pycnidia they are somewhat smaller.
METHODS OF INTRODUCTION.
Two methods of introducing the fungus into groves infested with
Aleyrodes citri were used by Webber with fair success. (1) Pinning
fungus-bearing leaves into trees infested with Ale\rodes citri, in such a
way as to cause the fungus spores to come in contact with larvae not yet
infected. (2) Planting small trees with fungus infected larvae in a grove,
so that the fungus-bearing leaves came in contact with the leaves on which
21 Webber, H. J. Div. of Veg. Phys. & Path.. Bui. 13, p. 20, Washington, D. C., 1897.
"Webber, H. J. Div. of Veg. Phys. & Path., Bui. i;$, pp. 23-24, Washington, D. C,
1 S<)7
1\! i'l'XC.I PARASITIC ri'O.N AI.K.Vkt >!>KS CITRI.
it was desired to start the fungus. Further methods of introducing this
Asclvrsmiia by spraying the trees with water containing fungus spores,
obtained either from previously infected larvae or from artificial cultures,
have been recently carried on by E. W. Berger2'5 of the Florida Experi-
ment Station. Webber24 had tried infecting larvae by spraying a mixture of
conidia in water, but had failed to reproduce the fungus in this way. E. W.
I Merger has found that to succeed with this method it is best to have a spray
pump that contains no copper parts, and that has also not been previously
used for spraying fungicides or insecticides. Fairly good infection of this
fungus has been obtained bv Merger, by the spore-spraying method, at St.
Petersburg, Leesburg. New Smyrna, Gainesville and Lake City. The fact
that infections may be made from cultures that have grown under artificial
conditions in the laboratory for long periods of time, suggests the possi-
bility of using these cultures in a practical way at the very beginning of
the rainy season, when fresh fungus on leaves is hard to obtain. Consid-
erable quantities of this fungus may be grown artificially on various media,
as will be shown in the following pages.
C.Kk.M I. NATION OF CONIDIA.
Conidia of this fungus were germinated in hanging drop cultures of dis-
tilled water, tap water, and various solutions of glucose. In all of these
cultures the germination was very slow, scarcely ever beginning in less
time than v?n hours. Germination in distilled water and tap water was very
feeble, while that in solutions of glucose was much stronger, as is explained
more fully under the germination tests for Aschcrsonia flaro-citrina.
Trials were made at various times to germinate spores in hanging drop
cultures from pustules that had dried in the atmosphere of the laboratory.
The following is a record of these tests:
/7 1. On November K), l!)()(i. cultures were made from
// leaves collected on October IV. I'.HH;, which had remained
/I in the laboratory v»s days. The tests were made in glucose,
1 1 in distilled water, and in tap water. On December 11 (31
days) sporids formed in :» per cent, glucose. The growths
Fit:.:;. "i distilled water and in tap water had not proceeded far
"IIH SL - ( >» January 5, 1907, cultures were made from leaves
nonn
collected October IV, lixxi, which had remained in the
laboratory for s.~> days. The test was made in distilled water. \o germina-
tion took place.
•' Fl;i. Kxp. Sta. Bui. 88, ].p. 57-63, I'.MM;.
"Webber, II. J. Div. of Veg. Phys, \- Path., Bui. 13, p. :>«;. Washington, D. c.
ASCHERSONIA ALEYRODIS. 13
3. On April 18, 1907, cultures were made in tap water from leaves
collected October 12, 1906, which had remained in the laboratory 189 days.
No germination took place. CZlr"::'" '"•"**^
4. On April 18, 1907, cultures were made in tap "^""^^S^niX^
water from leaves collected on December 12, 1906, Fig. 4. conidiumof Ascher-
which had remained in the laboratory 128 days. No gftSSSftg^; SK
germination took place. tion at 25°c.. x 1000.
5. On April 18, 1907, germination trials were made from a culture
isolated December 7, 1906, which was transferred to potato on January 14,
1907, and had not entirely dried out. A few spores germinated.
CULTURES.
Pure cultures of Aschersonia aleyrodis were first obtained in January,
1907. On December 7, 1906, petri dishes of neutral 5 per cent, glucose agar
were poured. These were made by introducing into the melted agar a
platinum loop, that had been thrust several times into a test-tube containing
spores from several stromata shaken up in sterile water. In the first dilu-
tion, on January 5 (29 days), at a temperature of 15° to 25° C., minute
fungus mycelia appeared, yellow in the center, with a fringe of delicate
white hyphae projecting outward. On January 8 .(32 days), the largest
of these had turned red in color. They were raised, hemispherical, and
had the upper surface dotted with little white lumps. Larger stromata were
2 to 4 mm. in diameter. On January 15 (39 days) the stromata were 5
to 7 mm. broad, with a wide fringe of straight hyphae projecting outward
over the agar. The stroma by this time contained pycnidial cavities with
spores (Plate I, Fig. 20).
On April 10, 1907, this fungus was again isolated. Leaves were picked
at Orlando, on April 6. Pustules were broken up in water in a watch-glass,
and a dilution set of three petri dishes A, B and C, was poured with agar
(1 per cent, normal acid to phenolphthalein) , to which 5 per cent, glucose
sugar had been added. Petri dish A was overrun with bacteria and quick-
growing fungi. Petri dish B contained, on April 26 (16 days), about 50
centers of growth just beginning, and a few bacteria. Petri dish C, on
April 26 (16 days), contained no visible growth. On May 11 (31 days),
C contained a fine growth of 11 mycelia, which probably first showed a few
clays before. No further record was kept.
On September 23, 1907, this fungus was isolated for the third time in
petri dish cultures A, B and C. Four or five small pustules were shaken
up in 7 cc. of water until it became milky in appearance. Five loopfuls wrere
washed into A, etc. A was contaminated with other fungi, C developed one
mycelium of A. alcyrodis, and one of another fungus. Petri dish B devel-
oped a pure culture as follows: — On October 8 (15 days), one point of
growth was just appearing. On October 18, there were four mycelia, five
to six mm. in diameter, with rings of reddish pycnidia ; and seven others
just starting. On October 28 (35 days), twenty very red pustules with
abundant spores and light gray fringes of outgrowing hyphae had de-
veloped.
From these isolation tests, it appears that on 5-10 per cent, glucose agar
in the laboratory, it requires from 30-40 days for the fungus to mature a
pustule and produce pycnidia. This time corresponds somewhat closely
to the time for the fungus to develop upon larvae of Ale\rodc$ citri, as
1 t l-l NC.I I'AKASITIC fl'UN Al.KYKODKS CITRI.
shown by the infection experiments of K. \V. Uerger. (See Bulletin 88.
Florida Experiment Station, pp. .*>;. oS.) The fungus is extremely slow in
developing in the petri dishes, thus increasing the liability to contamination
with other fungi and bacteria. Its slow-growing habit demands therefore
a strictly pure culture, since the rapidly growing fungi and bacteria will
otherwise crowd it out completely.
The many previous failures of the author and of others before him to
grow this fungus in cultures, were probably due to the fact that the petri
dishes were rejected too soon, or were allowed to dry out before the spores
had time to form mycelia and stromata. This fungus was transferred from
petri dish cultures to test-tubes of sweet potato (Plate I, Fig. 22), Irish
potato, rice, white cornmeal (Plate 1. Figs. 21, <M). and bread. On all
of these media, the growth was similar in general appearance to the growth
of Aschcrsonia flat'o-citrina. except that the color of the stroma and spore-
masses was red instead of yellow. The most luxuriant growth was on sweet
potato plugs. The characteristic red color of the fungus stroma rarely ap-
peared on Irish potatoes. This would seem to indicate that sugar was
necessary for the proper development of both the red pigment of Aschcr-
sonia alcyrodis. and the yellow pigment of A. flat'o-citrina.
The growth on sweet potato plugs is given here for comparison with
the growth of Aschersonia flaVD-citrina on this same medium.
1. ( )n April <s. 1JM)?, spores were transferred from cultures made on
January 14, 1907. The spores were streaked onto the surface of the sweet
potato plug with a platinum needle. On April 17, abundant growth all
along the streak had begun. ( )n April 2(>, a large raised red mass, 40 mm.
long, had formed.
8. < )n April s. spores were transferred as in Xo. 1. On April 17, very
abundant growth had started, and on April 2(>, a very large red mass had
formed.
.">. ( )n April s. spores were transferred as in Xo. 1. On April 17, good
growth with thickened points had started. ( )n April 2<>. a very large mass
of red growth had formed.
I. ( >n April S. spores were transferred as in Xo. 1. On April 17. a
cream-colored to orange, mealy appearance was evident, spreading to each
side of the streak. ( )n April 2<>, an abundant growth, red in color, had
formed.
KXI'KKIMKNTS IN C.KOWI.XC. AsC 1 1 KKSo\ I A AI.KYRODI S IN I.AKC.I-. <J t 'A N TIT I I-S.
In April, r.ni;. experiments were begun in order to grow large quantities
of fungus for infection of Alc\rodcs citri. Ten large moist chambers, nine
wide-nKHlthed bottles of .V><> cc. capacity, and four petri dishes five inches
in diameter, wen.- prepared with sweet potato medium. The potatoes were
washed, peeled, washed again and put through a meat chopper. This
ground-up ma.ss was then washed in running water to get out tine particles.
and the moist medium was sterilized in the autoclave at 110° C. for about
20 minuu-s. After .sterili/ation. the medium appeared well cooked.
( )n April '». these were inoculated, in the transfer closet, by spraying the
>urfaiv of the medium with a hand atoini/cr with a mixture of conidia in
ASCHKRSONIA ALEYRODIS. 15
sterile water. The conidia were obtained from an old culture of the fungus
grown on sweet potato. All of the cultures, except two large petri dishes,
finally became contaminated with a growth of bacteria. This-was probably
due to insufficient sterilization of the interiors of the large masses of medium
:n the moist chambers and in the 500 cc. bottles. The fungus in the two
petri dishes which were successful, appeared in 15 days as a creamy white,
ieit-like growth over the surface of the medium, with no red color. Very
little red color appeared later, and no large spore-masses developed. It
seemed that the spores had been sown too thickly over the surface to develop
the characteristic pustules with pycnidial cavities. This experiment was
practically a failure.
On June 12, 1907, five bottles of ground-up sweet potato, and one bottle
of bread, which had been sterilized in an autoclave for about half an hour
at 120° C., were inoculated by streaking the surface with a large platinum
loop from cultures previously made on sweet potatoes. Three of these
were successful, two on sweet potato, and one on bread. The notes on
these are as follows :
1. On June 12, 1907, a culture on bread was made from a culture on
sweet potato plug, which had been transferred three times from an isolation
culture in petri dish poured December 7, 1906, and described above.
Transfers had been made on January 14, 1907, April 10, 1907, and June
3, 1907. On June 19, the fungus was growing well at one point.
On July 1, a large raised mass */2 inch in diameter was formed. On
July 20, a large area 1 inch in diameter, and red in the interior, with abund-
ant spores, had grown.
2. On June 12, 1907, a culture on sweet potato was made from another
culture with same history as above. On June 19, the fungus had started at
seven points. On July 1, masses 1-3 inch in diameter had formed on one
side of the bottle.
3. On June 12, 1907, a culture on sweet potato was made from a sweet
potato plug, which had been transferred once from a petri dish culture of
April 10, 1907, being transferred on June 3, 1907. On June 19, the fungus
was just starting at three points. On July 1, raised areas one inch in
diameter had formed on one side. On July 20, a growth l/2 inch in diam-
eter had formed.
( )n June 19, six bottles of sweet potato and one of bread were inoculated
from sweet potato test-tube cultures which had been transferred twice from
an isolation culture made not later than April 10, 1907. Four bottles de-
veloped pure cultures.
1. On June 19, 1907, the surface of a bottle of sweet potato medium
was streaked with a small needle from a culture of June 3, 1907. On July
1, three or four areas of growth had appeared. On July 20, a good white
growth had formed all around the base of the potato plug.
2. On June 19, 1907, sweet potato medium was streaked as in No. 1,
from a culture made June 3, 1907. On July 1, a good growth had formed
on the surface, white and lumpy in appearance. On July 20, the growth had
formed all over the surface of potato, and spores had grown in the pycnidia.
On August 12, spores were very abundant.
3. On June 19, 1907, sweet potato medium was inoculated by shaking
up conidia in a test-tube of water and pouring it over the plug. On July 1,
very small areas on side of glass appeared. On August 12, areas of large
size had grown, but no conidia could be found.
1C Kr.\<,l PARASITIC rroN A I.KYROl >KS ClTRI.
I. On I une 1!>, I'.HI;, bread medium was inoculated as the sweet potato
in No. :». with eonidia from a culture made on June :>, 1907. The old potato
plug from the same culture was also dropped in. ( )n July 1, a good growth
out from old plug had started. On July •><>. growth over nearly entire
surface, reddish in patches, had formed. On August 12, no eonidia could
l.e found.
INI-KCTION 01- AI.KYKODKS CITKI 1-ROM cn.Tl'KKS.
In two localities in the State, this fungus was started on larvae of
.-llcvrodcs citri, from cultures which had grown for some time on culture
media in the laboratory. This infection work was done by E. W. Berger
at Gainesville and St. Petersburg, from cultures grown by the author.
The following records are taken from E. \Y. Merger's field notes:
1. . \ugtist 1(). H»OT. Gainesville. From culture on sweet potato made June :>:\.
having been isolated not later than April 10, 1907. Culture mixed up in water and
sprayed with hand sprayer on under surface of leaves on lower branches of an orange
tree. October 6, no fungus found. On Xovemher 1(>. three pustules of fungus found.
On December :M. sprinkling of pustules evident. April ::. 1!H)S. quite a sprinkling of
fungus pustules evident.
:.'. August 10. I'.ioT. Gainesville, Florida. From old cultures in three test-tubes.
Age of cultures unknown. No start by April :;. I'.ios.
::. August 1.">, I'.ioT. St. Petersburg, Florida. From culture made June !'.», on
bread in large bottles and transferred twice before from cultures isolated not later
than April 10. The culture was washed to fine pulp in water and strained. One and
a half to two quarts of the liquid was used. Sprayed on the under side of leaves with
a compressed-air sprayer. On October :'!!, quite a sprinkling of fungus was found.
Some twigs had several leaves well covered with pustules, mainly on the newest
growth. On December ](). about the same condition. On February 8, 190S, an abund-
ance of fungus was found on northwest side of tree, and fresh pustules were appearing.
t. August 1"». I'.iOT. St. Petersburg, Florida. From culture on sweet potato,
made June 1'.i. I'.iOT. Culture washed to fine pulp and strained. Two quarts of solu-
tion were sprayed on with compressed-air hand sprayer. On October :Z3. a good
sprinkling of fungus was found with some leaves well covered. P>est catdi was on
we>t side, mainly on newer growth. On December 10, I'.IOT. pustules more mature.
but apparently not spreading. On February s I'.ios. an abundant catch of fungus was
evident.
5, August i:,. I'.MiT. St. Petersburg. Florida. From a mixture of two cultures,
one of Ascfarsonta alcyrndis made June I'.i on potato plug and transferred twice
before; the other of . Isi'licrsaiihi flai'o-citrina made May :»:;. mi sweet potatoes in a
bottle, and transferred twice before. Cultures mixed, washed and strained, making
one gallon of the solution. On October '.':;, fair sprinkling of the fungus, probably
only the red. mainly on newer growth. ( )n December 10. same, but pustules more
matured On February 8, I'.-os. all red pustules, no yellow pre-uit.
<; August 14. I'.iOT. St. Petersburg. Florida. From culture made June I'.i. I'.iOT.
and transferred twi.-e before. \o start by February 8, 1908.
\ugust M. I'.iOT. St. Petersburg. Florida. From culture made April s. I'.HMi,
which had been dried for two months. The fungus bad been transferred twice' before.
Isolated from petri dish culture made December T. I'.ioi;. \o start of fungus by Feb-
ruarv .s. itMis.
ASCHERSONIA FLAYO-CITRINA. 17
DISTRIBUTION OF ASCHERSONIA ALEYRODIS IN 1908.
In Florida it has been reported from or seen at the following places,
occurring only on Aleyrodcs citri:
Alva, Apopka, Bartow, Bradentown, Buckingham, Citra, Fort Myers,
Gainesville, Glen St. Mary, Jacksonville, Lake City, Leesburg, Manatee,
Mclntosh, New Smyrna, Oneco, Orlando, Oviedo, Palmetto, Sarasota, St.
Petersburg, St. Augustine.
Outside of Florida it was reported by Cook and Home from Cuba on
Aleyrodcs citri R. & H., and Aleyrodcs howardii. Quaintance ; from Java
by Kirkaldy & Kotinsky, doubtfully upon Aleyrodcs longicornis Zehntner;
from Brazil by the same authority, doubtfully upon Aleyrodcs horridus
Hempel; from Ceylon by Parkin on various undetermined species of Aley-
rodes; and from Jamaica by Cockerell under the name of Aschcrsonia tahit-
ensis Mont., which is probably A. alcyrodis Webber.
III. ASCHERSONIA FLAVO-CITRINA P. HENN.
The discovery that Aschcrsonia flai'o-citrina P. Henn. was parasitic
upon Aleyrodcs citri R. & H., was made by P. H. Rolfs25 by means of
specimens sent to him from J. F. Adams, Winter Park, Fla., in September,
1906 (Plate II, Fig. 24). Later in the same year E. W. Berger found this
fungus effectively parasitizing Aleyrodcs citri in several other localities in
the eastern part of Florida, and since that time he has succeeded in intro-
ducing it into still other localities. This fungus was first described by P.
Hennings in 1902, as occurring on leaves of Psidium from the botanical
gardens of Sao Paulo, Brazil. No mention is made by him of any insect
associated with its presence on the guava leaf. This species is described by
Hennings26 as follows :
Aschcrsonia flai'o-citrina P. Henn. Stromatibus carnosis, hypophyllis, subdis-
coideo-pulvinatis vel hemisphaerico-depressis, citrinis, 2 — 2.5 mm. diameter, pruinosis,
superne ptmctulato-pertusis, intus subaurantiis, subiculo membranaceo, flavo ; pycnidiis
immersis oblongis, paraphysibus filiformibus, flexuosis, hyalinis 140-180X1—1.5 micr.,
continuis; conidiis fusoideis, utrinque acutis, continuis, hyalinis, 12-18X2 micr.; con-
idiopboris brevibus, hyalinis, fasciculatis.
It was found in the botanical garden of Sao Paulo on a leaf of Psidium
sp., October, 1901.
That Aschcrsonia flai'o-citrina may be able to attack other Aleyrodidae
besides A. citri is shown by the fact that in June, 1907, Stene of the Rhode
Island College of Agriculture, was able to infect larvae of Aleyrodcs raf>or-
arionnn, on cucumber leaves in the greenhouse, from material sent from
Florida by E. W. Berger.27 These are the only two species of Aleyrodes on
which it has yet been observed. It is probable, however, that further ob-
25 Rolfs, P. H. Fla. Exp. Sta. Kept., p. xvi, 1907.
'Hennings. P. Hedwigia, Vol. 41, p. HOT, 1902.
21 Berger, E. W. Fla. Agr. Exp. Sta. Kept., p. xxxiv, 1907.
18 FUNGI PARASITIC UPON AI.EYRODES CITRI.
servations will reveal its presence on other Aleyrodidae native to the woods
of Florida.
COMPARISON OF ASCHERSONIA FLAVO-CITRINA WITH A. ALEYRODIS.
The two species are very much alike in their general appearance, and
also approach each other closely in the measurements of their structural
parts. The most evident distinction is in the color. A. aleyrodis is usually
red or pink, while A. flavo-citrina is yellow and never contains any reddish
pigment. The stromata of A. aleyrodis, under similar conditions, average
less in diameter, and the pycnidial cavities are usually more sunken than
in A. flavo-citrina. The spores of A. aleyrodis also average a little smaller
than those of A. flavo-citrina. Measurements of Florida specimens show
that the spores of A. aleyrodis are about 9 — 14X2 — 3 microns, while those
of A. flavo-citrina measure about 12 — 15X2 — 3 microns. Cultures of these
two Aschersonias on similar culture media, under similar conditions, showed
them to be distinct forms.
CULTURES.
Soon after the discovery of A. flavo-citrina on Aleyrodcs citri, attempts
were made by the writer to produce cultures of this fungus on ordinary
culture media. Attempts to isolate Aschersonia aleyrodis on neutral pep-
tonized agar had been made without success. The beneficial effect of the
addition of sugar on the germination of the spores in hanging drops had
been noticed. On the addition of 10 per cent, glucose to the agar, petri dish
cultures of A. flavo-citrina were successfully grown. The growth on 10
per cent, glucose agar, poured on September 14, 190f>, at a temperature of
about 28° to 30° C., was as follows:
On October 2 (18 days) small, whitish delicate-fringed colonies ap-
peared, just visible to the unaided eye. On October 11 (25 days), a distinct
elevated stroma had formed, waxy and pale, with a yellow center contain-
ing pycnidia with spores. Surrounding this was a white fringe of outgrow-
ing mycelium. These stromata became 2 to (> millimeters in diameter, and
closely resembled the stromata growing naturally on leaves bearing larvae
(Plate III, Fig. 2G). Later cultures grown on the same medium bore
stromata 2~> millimeters in diameter, indicating that the size of any individual
stroma depends on the amount of the medium taken, and the length of time
before it is dried out (Plate III, Fig. 27). The fungus was then transferred
to test-tubes containing other media. Cultures were obtained on sterilized
SWeel potato. Irish potato, hread and Her. The most luxuriant growth was
obtained on sweet potato plugs, this being probably due to the presence of
BUgar in that medium ( I 'late IV. Figs. 88, -.".' and 30).
The progress of the fungus on the various media was as follows:
On sweet potato pings, transferred from petri dish culture by inserting a
platinum needle into a spore mass, tin-re was no evident growth in three
days. In six days, numerous small white points appeared along the scratch
made- by the needle. In fourteen days, stromata •> mm. in diameter, and
turning yellow, were formed. In twenty days these had heroine typical
ASCHERSONIA FLAVO-ClTRINA. 19
stromata with spores. In forty-seven days, these separate points had grown
together into one waxy, yellow mass, fringed and tipped with a white
velvety growth of vegetative hyphae, as shown in the photograph (Plate IV,
Figs. 28, 29, 30). Numerous pycnidial masses were also present. On
Irish potato plugs, the growth of the fungus, for the first fourteen days,
was about the same as on sweet potato plugs. From that time on, the
growth was more feeble, and the yellow color rarely
appeared. Typical spore-masses were not so abund-
ant. On sterilized rice there appeared in ten days a
slightly yellow growth, not much raised above the
surface. In eighteen days, the growth had spread
out considerably over the surface of the rice, and the
color had become a decided yellow, without present-
ing any raised mass as described for sweet and Irish
potatoes. In thirty-four days, there appeared small
whitish patches over the surface of the yellow
growth. On white cornmeal, the growth of the
Fig. 5. fungus was the same as on rice. On bread, the
Hyphae ofjtroma. fungus grew well and formed yellowish masses in
a few weeks.
GERMINATION OF CONIDIA.
The germination of the conidia of this fungus was very
slow as compared with that of many fungi. In September,
190(3, germination tests were made of conidia placed in
hanging drops of distilled water, tap water, agar, and
various solutions of glucose in water. These were pre-
i 1 1 • r • f i • Fig. 6. Conidia from
pared by placing a number of minute drops of the solution dried pustules of
. , . , . Aschersonia flavo-
on each sterilized cover glass, and putting in them by atrina, x 1000.
means of a sterile needle a few conidia from fresh pustules of the fungus.
These were then placed in a moist chamber to keep them from drying out.
In all of these solutions some germination took place. In distilled water and
tap water, the germination was slow and feeble, the hyphal tube not advanc-
ing far. The addition of sugar appeared to increase germination up to 10
per cent, of sugar. Above 10 per cent, germination was retarded, and at 30
per cent, only a few spores were seen to germinate. In October, 1907, part
of the same test was repeated with the same general results ; except that in
this case the conidia in 5 per cent, glucose solution appeared to germinate
a little more readily than in 10 per cent, and the conidia in 30 per cent, solu-
tion refused to germinate at all. Parallel tests in part were made with
conidia of Aschersonia aleyrodis with similar results.
The table below gives the result of the tests for Aschersonia flavo-citrina.
In germinating, the first hyphal tube usually pushed out just behind one of
the acute ends of the boat-shaped spore (Figs. 7, 8 and 9). The acute end,
l-TNC.I I'.'.RASITIC ri'ON AI.KYRODES CITRI.
which seemed to lack protoplasm, was bent back in the opposite direction.
The hyphal tube then grew very slowly,
and in four days, in 10 per cent, glu-
cose solution, began to form sporids
at the distal ends (Figs. 8 and 9).
Fig. 7. ronidium of A*rhi'i:*»ni<i ,/fmo-cftrftM
germinal 'ng in ::o per cent glucose solution
after 27 dats. (a) Original conidium, (!>}
spore like bodies. X 1000.
Fig. 8. Fig. 9.
Figs. 8-9. Conidia germinating, (n) conidium. (b)
hyphal tube, (c) sporid, X 1000.
ASCHERSOXIA FLAYO-CITRINA GERMINATION OF CONIDIA.
MEDIUM.
'.' I TO 28 HOURS.
44 TO 48 HOURS.
Distilled water.. .
No germination.
Germination just be-
ginning.
Tap water ....
X«> germination.
Germination just be-
In 6 days good germ-
ination, some hyphae
ginning.
2 or 3 times longer
than the conidia.
Glucose 1 per cent.
Germination just be-
ginning.
Fairly good germina-
tion.
Glucose 2 per cent.
Germination just be-
ginning.
.(Dried out.)
Glucose 3 per cent.
Germination advanced
farther than in 2 per
Very good germination
of many conidia.
Glucose 5 per cent Good germination in :>*
hours, hyphal tubes as
long as conidia.
Good germination, hy-
phae growing slowly.
GlucoM- in per cent.
Very good germination,
hyphal tubes 2 to 3 times
length of conidia.
Very good germination,
hyphae growing slowly.
In 4 days sporids form-
ing on ends of hyphal
tubes.
Glucose 20 per cent.
Only a few just begin-
ning to germinate.
1 lyphal tubes as long as
conidia.
GlucnM- :;n ,,,-r rent.
No germination.
No germination.
A very few finally
germinated. S p o r ids
formed in 27 days.
( M-rminatinn tests of conidia fn.ni dried pustules made at various times
showed the following results:
1. ( )n November 1". iwii. lian^in^ drop cultures were made from
specimens sent in from Winter I 'ark on September -'S, 1 !HX;, which had
remained in the laboratory exposed to the atmosphere for 1C. (lavs. Tests
VKRTICILUUM HETEROCIvADUM. 21
were made in distilled water, in tap water and in 5 per cent, glucose at a
temperature of 15° to 20° C. No germination occurred up to December
11, 1906, when the slides were discarded.
'2. On January 5, 1907, hanging drop cultures of conidia in distilled
water were made from leaves picked September 28, 1906, which had re-
mained in the laboratory exposed to the atmosphere for 68 days. No germ-
ination was noticed up to January 9, 1907, when the slides were discarded.
3. On January 5, 1907, hanging drop cultures in tap water were made
from leaves collected by E. W. Berger on December 18, 1906, and kept in
the laboratory 18 days. On January 7, many conidia had germinated, and
on January I), some hyphal tubes were twice as long as the conidia.
4. ( )n April 18, hanging drop cultures were made from leaves collected
on September 28, 1906, at Orlando, and kept in the laboratory 203 days.
No germination had occurred by April 29, 1907, when the slides were dis-
carded.
A SUPER-PARASITIC OF ASCHERSONIA FLAYO-ClTRINA.
A super-parasite belonging to the genus Cladosporium has been noticed
as of common occurrence on Aschcrsonia flaio-citrina. Attention was first
called to it by A. W. Morrill, who afterwards observed it at Orlando over-
running this Aschersonia, in the summer of 1906. Later on a brief report
was given by E. W. Berger. Plate VII, Fig. 4.3, shows a leaf from Or-
lando with pustules of Aschcrsonia flavo-citrina covered over with the
dark brown Cladosporium. This same fungus has also been observed by
the writer associated with sooty mold (Meliola) in secretions of honeydew
from Alcyrodes citri, and it appears to aid at times in smothering the white-
fly larvae, as does also the Meliola. Cultures of this fungus were readily
obtained in 5 per cent, glucose agar, and the fungus was transferred to
potato plugs. The growth was rapid and the color was the same as on
the leaves.
DISTRIBUTION OF ASCHKRSONIA Kr.AYO-ClTRINA IN FLORIDA IN 1908'.
Altamonte Springs,
Gainesville (introduced) ,
Largo (introduced),
Maithmd,
New Smyrna (introduced),
( )rlando,
Oviedo,
St. Petersburg (introduced),
Winter Park.
IV. YERTICILLIUM HETEROCLADUM PENZ.
The attention of the writer was first called to this fungus in November,
1!)()5, b\ E. H. Sellards, Entomologist of the Florida Experiment Station,
who brought in specimens of Brown fungus from Palmetto, Florida, with
which was associated a cinnamon-colored fungus. At the time of its dis-
FUXC.I I'.'KASITIC UPON ALEYRODES CITRI.
coveiv on .-llcyrodcs citri, it was thought that this fungus might possibly
be the spore-bearing stage of the sterile "Brown fungus" described by
Webber, because of its close association with the stroma of the Brown
fungus, and since it also resembled the Brown fungus somewhat in color.
Cultures of the I'crticUlium hctcrochuium, however, together with inocula-
tions oi larvae of Aleyrodcs citri in the greenhouse, showed that this fungus
was distinct from the Brown fungus found by Webber in 1890. Further
evidence of its distinct character was subsequently obtained when it was
found in other localities on Aleyrodcs citri and on other insects, in no way
associated with the Brown fungus. At Palmetto, where it was first dis-
covered, it was seen to be attacking the long scale, Mytilaspis citric ola, that
occurred on the same leaves with larvae of Aleyrodcs citri. In 1907 it was
found on Mytilaspis glorcrii at Gainesville, quite independent of the Brown
fungus. During the same year, it was found on a species of Diaspis on the
leaves of Euonymus Amcricanns in the woods near Gainesville. Later on
it was observed unaccompanied by Brown fungus on Aleyrodcs citri at St.
Petersburg, Fla. It was introduced by the writer on larvae of Aleyrodes
citri on a privet hedge at Gainesville in the fall of 1907. It was also intro-
duced by Mr. Gaitskill along with the Brown fungus on larvae of Alevrodes
citri at Mclntosh, during the summer of 1907. Specimens of the same
fungus on Aleyrodes citri were sent in from Apopka and Citra, Florida,
early in 1908. In a few cases only has it been found in large quantities,
and as yet its efficiency as a parasite of Aleyrodes citri is not fully de-
termined. In its parasitism it differs from the three fungi previously de-
scribed, by attacking other insects not belonging to the genus Aleyrodes.
Several other species of the genus Verticillium have been reported as
occurring on insects. 1'crlicilliiim aphidis Bauml.28 on plant lice, and Verti-
cillium minutissimum Corda29 on larvae of a small insect, were described
from Europe. An undetermined species of Verticillium is reported by J.
Parkin30 on a scale insect Asterolccanium miliaris which was infesting the
leaves of a bamboo bush in Ceylon. Parkin also refers to Gueguen as
authority for the statement that 1'crticiUium hctcrochuium had been found
in Africa and the Antilles. It would therefore appear to be a widely
distributed species.
DESCRIPTION.
This fungus was first described and figured by O. Penzig/51 in 1882,
occurring on Lecanium hcsperidum on lemon leaves in Italy. His descrip-
tion is as follows:
/'••/•/ /V/7/iMwi hctcrocladum Penzig (Fung. Agrumic. N. 108, Fig. 1193). Hyphis
* Saccardo, P. A. Sylloge Fungorum, X, p. 546, 1892.
9 Ibid. IV. p. 152, 1886.
'•"Annuls Roy. Bot. Card., Peradeniya, Vol. Ill, Part T, p. •}."•, 1906.
<ii I'.otanici sugle Agrumi c sullc Planti Aflini, p. 398, Tavola XU Fig 3 Roma
1887.
VERTICIUJUM HF/TEROCLADUM.
23
repentibus, elongatis, paulltim ramosis, continuis; ramis fertilibus adscendentibus,
ramnlosis ; ramulis ternis vel quaternis, oppositis vel alternis, patentibus, rectis, apice
attenuatis ; conidiis in ramulorum apice solitariis, geminatis vel ternis, saepius pedi-
cellis brevissimis stiff ultis, oblongis, hyalinis, 5.5-6 micr. long., 2-3 micrTcfassis.
Verticillium heterocladum, in general
appearance, resembles the Brown fungus
of Webber (Plate IV, Fig. 31). On close
examination, however, it is found to be
strikingly different. The pustules, which
are cinnamon colored, are powdery on
the surface. Under the hand lens, they ap-
pear brushlike in form, bristling with
hyphae. From the edge of the pustules
there grows out a creeping layer of white,
delicate, interwoven hyphae. From these
colorless hyphae, as well as from the top
of the pustules, there arise upright con-
idiophores. These may have eithet a
simple series of whorls, 2 to 4 branches
in each, or the branches of the whorls
may again be whorled. The conidia are
borne on the ends of the ultimate
branches (Fig. 10).
The conidiophores are quite delicate,
slender, hyaline, 150 to 240 microns by
times septate. The conidia are oblong, hyaline,
The main body of the cinnamon-
in
Fig. 10. Verticillium hetei-ocladum. («) Conidio-
phore with conidia forming, X 450. (b)
Conidiophorewith mature conidia. X 450.
(c) Conidia, X 1000.
o to 4 microns, several
4 to 6 microns long by 1.5 to 2.5 thick,
colored stroma when mature becomes powdery
appearance, and under the microscope it is found
that the hyphae have broken up into short pieces
irregular in shape and length with rounded ends,
some of them quite closely imitating spores (Fig.
11). These have thicker walls than the conidia,
and probably act as reproductive bodies in carry-
ing the fungus through a period of dry weather.
Fig. 11. Short hyphal bodies
into which the central por-
tion of a mature pustule
breaks up, X 450.
CULTURES.
Pure cultures of this fungus were made in November, 1905, soon after
the fungus was discovered on Aleyrodes citri. The next year other cultures
were made and spores of the fungus transferred from cultures to larvae
of Aleyrodes citri in the greenhouse. The fungus was readily grown in 5
per cent, glucose agar by drawing a moistened platinum needle over the
top of the upright conidiophores and then washing it off into the melted
agar.
On November 12, 1906, two petri dishes (A and B) of 5 per cent, glu-
21 l-r.\(,i I'AKASITIC UPON ALEYRODES CITRI.
cose agar were poured. A moistened needle was drawn over the upright
brush of conidiophores and washed into a little bouillon in a test-tube. In-
oculations were made from this with a platinum loop, nine loops being
transferred to A, and nine from A to B.
On November 20 (8 days), 120 pure white mycelia appeared in A and 4
in 1>. :> to 4 mm. in diameter, with reddish brown center and a brush of up-
ward growing white conidiophores. On December 5 (23 days), the mycelia
in B were 25 mm. in diameter and reddish brown. On December 12 (32
days), the mycelia in B were 30 to 35 mm., and cinnamon-colored almost
to the edges. By this time a pustule was formed composed of closely inter-
woven hyphae and closely resembling the pustules upon larvae of Ale\rodes
citri (Plate V, Fig. 34)."
The fungus was transferred to test-tubes of sterilized Irish potato,
sweet potato, rice, white cornmeal, stems of canna and of caladium, and
bread ; on all of which the fungus grew to some extent. It grew best, how-
ever, on sweet potato and bread, over the entire surface of which it formed
a felted cinnamon-colored stroma (Plate V, Figs, 32, 33). On rice the
color was that of ocher, and on caladium stems it was brick-red. On the
other media the color was nearly that of the growth on 5 per cent, glucose
agar.
The growth on sweet potato plugs was recorded as follows : On Novem-
ber 22. 1 !><•<;, conidia from cultures made November 12, were rubbed on the
surface of the potato. On December 5 (13 days), a brown colored growth
had formed over the surface of potato. By December 12 (20 days), the
entire surface was yellowish brown. On January 15, 1907 (39 days), the
entire surface was covered over with a thick cinnamon-colored mat of
fungus.
(.KR MI. NATION OF CONIDIA.
Conidia were placed in distilled water in hanging drops. It was found
that they germinated much more rapidly than did the conidia of Ascher-
sonia. In distilled water, in 24 hours, conidia had just begun to elongate;
in 18 hours a few spores were found with short hyphal tubes. In bouillon,
in 24 hours a slight germination took place, the hyphal tubes becoming as
long as the spore: in :> days, the hyphae were 120 to 200 microns long and
1 to \l/2 microns wide, and branched once or twice.
In ~> per cent, glucose, in 24 hours, the tube had extended one to two
times the length of the spore, and in three days, the growth had proceeded
farther than those in distilled water.
When germinating, the spores first swelled, elongated, and then sent out
a hyphal tube from one or both ends.
IM IATION OF LARVAE OF ALEYRODES CITRI.
( )n December (\, llinii. small badly infested orange trees which had pre-
viously been in the greenhouse, were covered wiih large belljars. Conidia
from a petri dish culture poured Xovember 12, I'.MM; \->\ days old), were
shaken up in sterile water, and this was spraved on to the plants with a
small atomizer. In :>:> days several leaves were found with stromata in a
spore-bearing condition, identical with those from which the culture had
originally been obtained. These had evidently developed sooner than 35
• lays, and had been overlooked. Thev became powdery in appearance and
in all particulars were like the natural pustules.
SPHAEROSTILBE COCCOPHIIA.
On September 19, 1907, leaves containing VerticiUiuni hctcrocladum
were tied to a twig of privet (Lignstrnm ovalifolium) bearing abundant
larvae of Alc\rodcs citri. The weather was moist for two weeks^ after.
On October 5 (16 days), pustules were very evident on inany larvae
on leaves adjacent to those tied in. Under the microscope a mycelium was
to be seen inside the larvae. On October 25 (36 days), the fungus with
conidia was well established on a few neighboring leaves, but was not
spreading rapidly (Plate V, Fig. 35).
On November 16, leaves of Enonymns Ainericanus bearing a species
of Diaspis attacked by Verticillium hctcrocladum were pinned on to an
orange tree at Gainesville by E. W. Berger. On December 31, 1907, three
pustules of freshly grown Verticillium were found (one on a scale insect,
probably Lecanium, and the others apparently on larvae of Aleyrodcs citri),.
on a tree next to the one in which the fungus had been pinned.
INSECTS PARASITIZED, WITH LOCALITIES.
Aleyrodcs citri: Palmetto, Manatee, St. Petersburg, Gainesville, Apopka,
Citra, Mclntosh.
Mytilaspis ghverii : Gainesville.
Diaspis sp. on leaves of Buonyimis Ainericanus \ Gainesville.
Lecanium sp. on orange leaves: Gainesville.
Lecanium hcspcridnm on lemon leaves: Italy.
Mytilaspis citricola: Palmetto, Citra.
In Africa and the Antilles the host insect is not known.
V. SPHAEROSTILRE COCCOPHILA TUL.
This fungus, which has a world-wide distribution, and has been re-
ported as a parasite on no less than fifteen different species of scale insects,
has been found in a few instances attacking larvae of Aleyrodcs citri.
The conidial stage of this fungus (Figs. 14
and 15) was discovered by Desmazieres:}2 on §
scales of a coccid on young willow-stems in
France, as early as 1848. It was described un-
der the name Microccra coccophiia. The per-
ithecia (Figs. 12 and 13) were discovered by
Tulasne33 and described by him in 1865 as oc-
curring on scale insects on species of Laurus,
Salix and Fraxinus in France, Italy and Amer- AFig:fly>
A „
X75.1D! ica- Desmazieres' description is as follows: Ci^ritxh2eoo
Microccra, Desmaz. Velum externum persistens, membranaceo-floccostim, dein
supra in lacinias plures rumpens ; receptaculum clavatum carnosttm e fibris sub-
simplicibus sporidiiferis formatum ; sporidia fusiformia, acuata.
Microcera coccophiia Desmaz. M. minutissima, subcaespitosa cornuto-conica,
simplex, lateritio-rosea, basi membrana tenuissima albida vaginato-connata. Sporidiis-
paucis, hyalinis, elongatis, utrinque acutis. Hab. in coccis. Hieme.
" Desmazieres. Ann. des Sc. Nat., Tome X, p. 359, 1848.
Tulasne. Carpologia, Vol. Ill, 105, 1865.
26 FUNC.I PARASITIC UPON ALEYRODES CITRI.
The ascus stage is described in Saccardo's Sylloge Fungorum34 thus :
Sphacrostilbc coccophila Tul. Carp. III., 105.— Peritheciis permultis supra et prope
stromata conidiophora nascentibus, minimis globosis, obtusis, brevissime papillatis,
glaberrimis, nitide rubris, saepe 4-5 sociatis, senio collabentibus; ascis linearibus,
60-80X6J/2; sporidiis oblique monostichis, ovatis, 10X5, 1-septatis, subhyalinis, leniter
constrictis. — Stat. conid. Microccra coccophila Desm. Stromate e crusta coccornm
solitarie oriundo, crasse teretiusculo, obtuso. rnbro 2 mill, alt.; conidiis lineari-
lanceolatis 4-6 locularibus, 65X6 subhyalinis.
In 1892, Ellis and Everhart-'55 in "Xorth American Pyrenomycetes" gave
nearly the same description in English, and reported this fungus on a speci-
men of Alnus scrrulata collected in Pennsylvania, adding:
The conidial stage (Microccra coccophila Dcsm.) which has been sent from
Florida by Dr. Martin and collected in Carolina by Ravenel (F. Am. 286), has stroma
arising from various species of dead bark-lice. It is red, obtuse and about 2 mm.
high. The conidia are linear lanceolate, 5-7 septate and 56-65X5-6 microns, nearly
hyaline.
D. McAlpine36 in describing the con-
/ft'''Vf\ idial stage of this species in Australia
/i la 1ft gives the measurements of the conidia
as 75—103X5^—8^ microns. Meas-
urements made of a number of Florida
specimens from different localities gave
Fig. 15. Conidia.
70—112X3.5—6 microns. Measurements x 200.
of the perfect stage from Florida specimens were as
follows: — Perithecia 350 — 390 long by 300 microns
thick. Divisions of perithecial wall 6 — 10 microns.
Asci, 70—98X8—12 microns. Spores 12—18X7—9
microns.
HISTORY.
!•'!•_'. 11. >i>orodochinm, or
°*2K2S2±S^°f This fungus has been found in nearly every coun-
try in the world. In 1892, M. C. Cooke37 spoke of it
as common in Europe and as a well-known parasite on dead Coccus. In
the same year it was reported from Jamaica by T. D. A. Cockerell.38 In
1894, Henry Tryon39 reported it on the long scale, the red scale and the
circular black scale in Queensland, Australia. In 1897, it was reported
by P. H. Rolfs40 as a parasite of the San Jose Scale, Aspidiotns pcrniciosus
Comst In 1899, it was reported by I). McAlpine41 on Aspidiotns anrantii
**Saccardo. Sylloge Fungorum, II. p. :.!.;. 1S83.
Ellis, J. B. and Everhart, .M. I'.. North Aim-rioau Pyrenomycetes, p. 111. ]s«i:.'.
"Fungus diseases of Citric Tn-rs in Australia. Drpt. of Agr., Victoria, p. 113, 1899.
"Vegetable Wasps and Plant Worm-, p. :;:J:j. I.i>r.<l<m, 1S92.
"*Bul. Botanical Dept. of Jamaica, No. :;•'.. p. r», i
"Queensland Dept. of Agr., Hul. l. p. i.v
"A Disease of San Jose Scale, Fla. Exp. Sta. Bui. 41.
41 Fungus Diseases of Citrus Tn-i-s in Australia. Drpt. of Agr., Queensland, np 27 and
28, 1899.
SPHAEROSTILBE COCCOPHILA. 27
Mask, in Australia. In 1900, P. H. Rolfs42 reported that Mytilaspis citri-
cola Pack., Mytilaspis gloverii Pack., and Parlatoria pergandii Comst. were
all attacked by this fungus in Florida. The same year F. B.~ iBafle43 found
it common on Aspidiotus ob scums Comst. on water oaks in Alabama. It
also occurs naturally in Georgia, and has been found as far north as Phila-
delphia, Pa. In 1901, Fuller44 reported finding the same fungus in Natal,
South Africa. In 1903, H. A. Gossard45 first reported its occurrence on Al-
eyrodes citri. In 1903, F. S. Earle46 found it in Porto Rico, and in 190447
in Cuba ; in both places on Mytilaspis citricola. In 1904, S. I. Kuwana48
reported the fungus as present upon Aspidiotus peruiciosus Comst. and on
Diaspis pcntagona Targ. in Japan. He spoke of finding it on the last-
named insect in the mountain districts. In 1906, it was reported by J.
Parkin49 as occurring upon Mytilaspis citricola Pack, and Aspidiotus aur-
autii Mask, in Ceylon. In 1908, it was reported by C. W. Howard50 from
the Transvaal. It has also been found by E. W. Berger on Aspidiotus
hcdcrac (Vail) and Aspidiotus ancylus Putnam, in Florida.
Both the conidial and ascus stage of this fungus (Plate VI, Figs. 36,
37, 38) are found commonly in Florida, although the latter is not at all
common in other parts of the world. In Ceylon, the perithecia have not
been found by Parkin ; and one would infer, from the name Microcera,
which is used by D. McAlpine, that the perfect stage is not common in
Australia.
RELATION OF S. COCCOPHILA TO THE} SAN JOSE AND OTHER SCAI^E INSECTS.
The use of this fungus as a practical remedy in combating the San Jose
scale was first brought out by P. H. Rolfs in 1897, in Bulletin 41 of the
Florida Experiment Station. This fungus was discovered by him upon the
San Jose scale in northern Florida during the previous year. By means of
pure cultures and infection experiments, Rolfs demonstrated that the San
Jose scale could be readily infected with spores of this fungus grown upon
sterilized bread or other media. The results of these experiments are given
in the bulletin referred to.
This fungus was also discovered to be a common parasite of the obscure
scale, Aspidiotus obscurus Comst., on the twigs of water oaks (Quercus
aquatica). A simple method of infection has been developed in Florida by
one of the peach-growers, Mr. F. P. Henderson, by tying into the top of
42 Proc. Fla. Sta. Hort. Soc.. p. 63, 1900.
43 Ala. Exp. Sta. Bui. 106, p. 198, 1900.
4" First Rept. of Govt. Entomologist, Dept. of Agr., Natal, p. 99, 1901.
43 Fla. Exp. Sta. Bui. 67, p. 623, 1903.
* Annual Rept. Office of Exp. Sta., Washington, D. C., p. 457, 1903.
4T Primer Informe Annual de la Estacion Central Agronomica de Cuba (1904-05),
p. 162, 1906.
48 Japan Imperial Agr. Exp. Sta. Rept., p. 26, 1904.
10 Annals Roy. Bot. Card., Peradeniya. Vol. Ill, Part I, p. 50.
50 Dept. of Agr., Transvaal, Agr. Journal, p. 6, 1908.
l-T.M.I PARASITIC l'P().\ A I.K YK< >I>KS CITRI.
an 'nfested tree a short piece of .wood whose bark bears a good supply of
the fungus. This has proved to be a very effective way of distributing this
fungus, and has already saved thousands of dollars to the peach and orange
growers of the State. In addition to attacking Aspidiotns perniciosus and
. Ispidiotus ohscurus, this fungus is effective in checking a number of other
scale insects in Florida. It is, under favorable moisture conditions, an
effectual parasite of Mytilaspis citricola, Mytilaspis gloi'erii, Aspidiotus
ficus, .Ispidiotirs hciicrac and Parlatoria pergandii. There are times, in dry
weather, when these scale insects get ahead of the fungus ; but a moist
period of a few days will quite often enable the fungus ro kill them off
almost completely. (Plate VI, Figs. 3(5, 37 and 38.)
The effective work of this fungus, and two others, Ophionectria coc-
cicola E. & E.. and Myriangwm dttriaei Mont, upon the orange scales, is
readily shown by spraying an orange tree very thoroughly with Bordeaux
mixture. During the summer and fall of 1907, the author sprayed a num-
ber of orange trees with Bordeaux mixture for another purpose. The trees
were sprayed very thoroughly, once in May, once in July, and once in
September. Before the first spraying, the trees were practically unhurt by
Mytihispis citricola, only a few individuals of this scale being found on any
part of the trees. After the first spraying this scale insect began to spread,
and increased slowly in numbers until November, when the trees were badly
attacked by the scale. Other trees near by, that had received no spray, were
as free from scale as at the first. The fungicide had evidently destroyed,
on the sprayed trees, the fungi that had been all along working upon the
unspraved trees.
Soon after the discover}- of this fungus in Florida by P. H. Rolfs, ex-
periments were made by S. A. Forbes51 of the Illinois Experiment Station,
Ii. Smith-"1- of the Xe\v Jersey Experiment Station, J. Craig5-'5 of the
Canadian Experiment Station, and F. A I. Webster"'1 of the Ohio Experi-
ment Station, to introduce Sphacrostilbc coccophila on San Jose scale in
the Xorth. hut the climate of these States did not prove to be conducive
to its spread, and the work was abandoned.
I'll II, A AS A PA HAS IT K o|- AI.I-VK )1)|-S CITKI.
As was stated previously. Spluicrostilhc coccophila seems to have been
first reported as parasitic on .llcyrodcs citri in 1!M)3 by H. A. Gossard. It
was f<»und on larvae of .llcymdcs citri on orange leaves received from Or-
lando. In 1!Hi:,. K. II. Sellanls"1"1 al.so reported having received it from
" 111. Kxp. Sta. I'.ul. :,('.. pp. 270 280
J. Kxp St.-.. Kept, is. ,,p. IT., 179, 1897. Kept. P.I. pp. 145-446. l.s'.is. Rept 24 n
"Canada Kxp. I-V.nn Ki-pt.. p. 11'.'. Lfi
1 ( )iii.. Kxp. Sta. I'.ul. in:;, p. p.is. [898,
" Kla. Kxp. Sta. Rt-pt . p. 87, L905.
MI GROCER A.
29
Orlando. In 1906, E. W. Berger found it on a few whitefly larvae at
Leesburg, Florida.
The effect of this parasite upon Aleyrodes citri seems-to—be of little
practical value. It has only rarely been observed attacking this insect, and
then does not occur in quantity, as do the other fungi before spoken of. It
is not uncommon to find a large amount of this fungus upon Mytilaspis
citricola in trees that are at the same time infested with larvae of Aleyrodes
citri on which no fungus can be found.
LIST OF INSECTS PARASITIZED.
A list of insects reported to be attacked by this fungus is here given,
together with the authority for the report and the localities in which they
were found parasitized :
NAME OE INSECT.
LOCALITY.
AUTHORITY.
Alcvrodcs citri R & H !
Florida
H A Gossard
Aspidiotus cinc\lus Putnam
Florida
E W Berger
Aspidiotus articulatus Morgan
Jamaica ....
T D A. Cockerell.
Aspidiotus articulatus Morgan .
West Africa
J Parkin
Aspidiotus articulatus Morgan
West Indies
J Parkin.
Aspidiotus aurantii Mask
Australia ...
D McAlpine
Aspidiotus aurantii Mask
Natal
Fuller
Aspidiotus aurantii Mask
Ceylon
J Parkin
(Chfysompfutlus) aurantii Mask
Transvaal
C W Howard
Aspidiotus ficus Comst
Florida
(Cl:i'\soniphalus cioniduin) Linn
Transvaal
C W Howard.
Aspidiotus licdcrac (Vail)
Florida
E W Berger
Aspidiotus obscurus Conist
Florida
P H Rolfs.
Aspidiotus pcrniciosus Conist
Florida
P H Rolfs
Aspidiotus pcrniciosus Comst
Taoan
S I Kuwana.
Chionaspis citri Comst
Cuba
Cook and Home.
Diaspis pcnta^ona Tar°" ...
Tapan
S I Kuwana.
l^ionnia fiornnac Tar0"
Mauritius
J Parkin
Ischnaspis filifonnis
West Indies . .
J Parkin
Mytilaspis citricola Pack .
Cevlon
J Parkin
M\iilaspis citricola Pack
Cuba
F S E'arle
Mytilaspis citricola Pack
Porto Rico
F S E'arle
Mytilaspis ctti'icola Pack . .
Florida
P H Rolfs
Mytilaspis sloi'crii Pack . . .
Florida
(L,cpidosophcs} gloi'crii Pack
Transvaal
C W Howard
Parlatoria bereandii Comstock. .
Florida .
P. H. Rolfs.
VI. MICROCERA SP.
Microccra sp. : Mycelium pure white; hyphae delicate, septate, loosely
branching, hyaline, 4 — 5 microns thick ; conidia at first borne on the ends
of the branches, one and two-celled, oval to oblong, 7 — 12X3 microns;
conidial tubercules various in size, cushion-shaped, pink, made up of a
compact mass of conidia ; conidia lunate, acute at both ends, 3 to 5 septate,
mostly 28 — 1-0X3.5 — 5 microns. A few conidia reach 52 microns. On
Alcvrodcs citri R. £ H.. on citrus trees in Florida, U. S. A.
30
PARASITIC I'l'OX ALEYRODES CITRI.
DISCOVERY.
In September, 1907, Prof. P. H. Rolfs, when visiting the orange grove
of Mr. F. Wills at Sutherland, Florida, noticed that a great many larvae
of Aleyrodcs citri were dead or dying. None of the known parasitic fungi
were to be seen, but by the use of the hand lens a whitish fringe could be
noticed growing from the edges of the larvae. Specimen leaves were
brought back to the laboratory on September 13, and on microscopic ex-
amination, the larvae upon these leaves were found to be diseased by a
species of Microcera. Leaves sent in by Mr. Wills on September 26, were
found to have even more abundant fungus, and nearly all the larvae were
dead. Orange leaves sent in from Manatee a few days later were also
found to bear larvae infected with the same fungus. This Microcera has
since been found at Largo, Bayview, and Safety Harbor by the author, and
has been brought in from Orlando, DeLand and Leesburg by E. W. Berger.
A preliminary notice of this fungus was published by
the author in Press Bulletin 68 of the Florida Experiment
Station, "A Xew \Yhitefly Fungus". This fungus presents
a fringe of delicate white hyphae growing outward from
/j the edges of the larvae (Plate VI, Fig. 41). These hyphae
at first bear one-, two-, or three-celled conidia, which are
oval to fusiform in shape (Fig. 16). Afterwards there are
formed on the edge of the larvae
pinkish spore-masses, which are
Kiir. I'1., llyj-liii «»f
Microeera from
"f cltn" x m'
edge of larva
showing branch-
ing and forma-
no., of one- and made up of a compact mass of lunate
two-celled coni- , __». ,_.,
dia. x 1000. spores (Fig. 17). These are 3- to
5-septate, and -jS to i<> microns long, by :>.."> to 5
microns thick, in fresh specimens. When the larvae
are placed in distilled water on a microscope slide,
the fungus spores are seen to float apart and spread ^om
out in the water.
CULTURES.
Culture- i»f this Microcera were grown much more easily and quickly
than those of any of the previously described fungi. This" fungus grew
rapidly on nearly all kinds of media which were tried.
On September II. I'.in;, the day after the fungus had
been examined and recogni/ed as a new parasite on Alc\-
rodes citri. three- sets of petri dish cultures of three each,
A. U. and C, were prepared according to the usual method
For isolation. The first Se1 was made by touching an in-
fected larva with a moist platinum needle, and washing
the needle off in test-tube A. I', received three loops from
A. and T three loops f n .in I'. In three days on petri dish
A. two mycelia and a number of bacterial colonies were
evident. In nine days, the fungus had overrun almost tin-
entire dish, in spite- of the bacteria present, and was pro-
ducing an abundance of conidia. \\ and C developed no fungus.
Fijf. IK. Cr.Ili.1iK
I-., 111 i, .-i tube '-ul-
on broiil. X I.Vi.
< Cullur.- hud <1ri«-«l
MICROCERA. 31
The second set was inoculated with spores from a test-tube in which
an infected larva had been shaken up in water. In both A and B, a good
growth of fungus appeared. The fungus just showed after ~24~Iiours. In
A, in three days, there were about 50 mycelia. In B, in three days, the
mycelia, three in number, had become 10 to 12 mm. in diameter, loosely
tufted, with numerous conidia on the upwardly projecting, irregularly
branching hyphae. In nine days, the growth had covered the entire surface
of the medium.
The third set was inoculated from a test-tube containing a little sterile
water, in which two infected larvae had been placed. Only the first petri
dish A developed a growth of Microcera, which grew as described for the
second set.
The fungus in all cases was of a pure white color. It grew in loose
tufts, with upwardly growing, very delicate hyphae, forming a loose, fluffy
mass, which soon collapsed when the cover of the petri dish was removed.
A microscopic examination of this growth showed that it was made up of
irregularly branching hyphae bearing conidia.
All intermediate shapes of spores from the oval one-celled conidium,
to the septate lunate conidium, could be found in. the same culture. (Figs.
1G, 17, 18). It may be remarked in this connection, that in the cultures of
Sphaerostilbc coccophila made by P. H. Rolfs in 1897, the conidial stage
of which has been referred to Microcera, these one- and two-celled conidia
appeared, and are figured by him in Bulletin 41 of the Florida Experiment
Station, Plate II. Judging from the growth of Microcera sp. in cultures,
it would probably fit into the genus Fusarium, but since the distinction be-
tween Microcera and Fusarium is rather vague, we prefer to hold to the
name Microcera until the perfect stage is worked out. Perithecia of this
fungus appear to be developing at the present time on culture media.
On September 18, two test-tubes of standard agar, one of Irish potato,
and one of rice, were inoculated by drawing a moist needle over the top
of culture P> of the second set poured on September 14. On agar tubes
there seemed to be some evidence of growth in three or four hours. On
September 21 (3 days), tufts of white mycelium were formed over the
entire surface. On November 20, the agar had begun to shrink away from
the sides of the tube, and the fungus had grown down over the sides of
the medium. On Irish potato, September 28, almost the entire surface was
covered with a snowy white growth of fungus. On rice in a 50 cc. flask,
by November 11 (54 days) the entire surface was covered with growth,
and the spaces between the rice grains were packed with a fungus mycelium.
The mycelium was very thick, matted, and pink on the sides near the glass
(Plate" VI, Figs. 39 and 40).
On September 25, a test-tube and a flask of rice, and two tubes of bread,
were inoculated from the same culture as before. On rice, September 28
(3 days), a delicate growth 10 mm. high was formed in the test-tube. The
rice had turned pinkish from the top to ^4 inch down on the sides. In the
flask almost the entire surface was covered, and was pinkish at the base on
the sides of the rice. By October 18 (23 days) the fungus had grown
through all the available spaces in the medium, forming a pinkish matted
FUNGI PARASITIC UPON AI.KYRODES CITRI.
-rnwtli. ( )n November 11, numerous conidia were present in pink masses
on tin- sides of the rice. ( )n the bread, on September 28 (5 days), a delicate
white growth was formed over the upper surface. On October 10 (15
days), the growth had taken up every available space in the pores of the
bread. giving it a pinkish matted appearance.
( )n ( October 11 the following- cultures were made by transferring spores
from the bread cultures of September 25, which had been transferred once
before. Three tubes of agar, one of sweet potato, one of Irish potato, one
of rice in a .">() cc. flask, and one of bread were used. Notes were taken on
( >ctoher 1!' only. In the three agar tubes, which reacted 1.0, 1.5 and 2.0
respectively to phenolphthalein. the growth was about one inch high with
abundance of conidia. There was no noticeable difference in the growth.
( )n sweet potatoes, a pure white, delicate growth appeared ; on Irish po-
tatoes, a very abundant growth; on rice, an abundant growth with a -pink-
ish color on the surface, and thick mycelium between the rice grains.
INKKCT10N OK AUCYROPKS CITRI.
On September 1!>, 1!M)7, infection experiments were made on healthy
whiten*}- larvae from cultures of this fungus. The larvae were on the leaves
of a privet hedge (Ligustnuii ovali folium) in Gainesville. The following
is taken from notes made at the time of the experiments :
Healthy larvae were very abundant on the privet leaves. The weather
was damp after a rain. Inoculations were made from 3 to 5 p. M.
\o. 1. Inoculation was made from culture of September 14; conidia
were penciled on the under side of the leaves on one branch with a moist
camel s-hair brush ; a piece of cheese cloth was tied around the inoculated
branch. On September 21 no conidia were found; the cheese cloth was
removed. On September 2<S, no conidia were found. On October 5, abund-
ant conidia of Microcera were present. On October 25, about 50 per cent,
of the larvae were dead.
\o. 'I. Inoculation was made from same culture, penciled on as in No.
1, but not covered with cheese cloth. On September 28, no spores were,
found. On October 1, spores of Microcera were present. On October 5,
pink spore-masses were developed on the edges of larvae. P>y October 25,
about -V> per rent, of larvae were dead.
\o. 3. Conidia were penciled on as above, and not covered with cheese
cloth. On September 21. no spores were found. On September 28, no
spores were found. On October 1. Microcera spores were present. ' On
•nk spore masses were present on the edges of the larvae. ( )n
( )cto],er 2~>. about ."in per cent, of the larvae were dead.
Xo. I. Inoculation was made from larvae on citrus leaves from Mana-
\o cheese cloth was tied around. ( )n September 21. larvae seemed to
be attacked by a small fungus, which looked like the Microcera of the
cultures. The conidia were one- and two-celled. ( )n September 2«, abund-
ant spores of .Microcera « >n .lead larvae were found, and live larvae with
filaments ,,f fnngns within. About (in per cent estimated dead. On Octo-
ber "). pink conidial masses were evident on edge's of larvae.
No. 5, A branch as a check was not inoculated. l,nt tied up with cheese
cloth. On September 21, no COnidia of Microcera were to be found. On
September 2s. n«> conidia of .Microcera to be found.
MICROCERA. 33
Xo. 6. A branch near Xo. 5 was neither inoculated, nor tied with cheese
cloth. On September 21, no spores of Microcera were to be found. On
September 28, no spores of Microcera were found.
X"o. 7. A branch above Xo. 4 was neither inoculated, nor tied with
cheese cloth. When examined on September 28, no Microcera could be
found.
During the first two weeks after these infection experiments were made
there were frequent rains, and the weather was quite moist. This was fol-
lowed by two weeks of drier weather during which the fungus apparently
ceased to grow. These inoculation experiments show that under favorable
climatic conditions like those under which they were carried on, the larvae
of Ale yr odes citri may readily be infected either directly from previously
infected larvae, or from pure cultures.
GERMINATION OF CONIDIA.
The conidia of Microcera germinated quite readily in water. On Octo-
ber 3, a hanging drop culture was made with conidia from a potato culture.
In 24 hours, one of the cells of the conidia, usually the end cell, sent out
hyphal tubes to a distance of one to four times the length of the conidia.
On the end of a number of these were seen small oval sporids (Fig. 19).
In 48 hours the hyphae were 6 to 7 times the length of the conidia, some
of them branched as in Fig. 19, and many sporids had formed. In six
days the branching hyphae were j\ ^r-^Z^ ^!k*" ' ' ' '-^^j-^
prominent, with many sporids. The /V^^"*^J> ^^v "*"^^?\
segments of the conidia had become if ^\
swollen, thus causing constrictions G?3 °
Fig. 19. Conidium of Microcera germinating
at the septa. and forming sporids. (a) Conidium. (?>) hyphal
tube, (c) sporid, X 450.
VARIATION IN SIZE OF CONIDIA.
The measurements of conidia at various times and under various con-
ditions indicated a considerable variation in size. The greatest variation
was in the length. As has been said, the conidia varied from oval one-
celled spores to long lunate spores. Measurements of lunate spores on
larvae were as follows :
On September 23, the first specimen from Sutherland after drying bore
conidia measuring 28 — 40 by 3.5 — 5 microns. On September 26, the second
lot of specimens from Sutherland, while still fresh, contained conidia meas-
uring 36 — 45X3.5 — 4.5 microns. On October 5, privet leaves from inocu-
lation experiment X^o. 4, at Gainesville, while still fresh, bore conidia meas-
uring 31—52X3.5 — 4.5.
Measurements of lunate spores in cultures were as follows:
On September 17, conidia from cultures made September 14 measured
21 — 32X3.5 — 4.5 microns. On XTovember 21, conidia from culture on
potato, measured 12 to 30 microns long; two-celled conidia were 12 microns,
the others longer. On February 2, 1908, from cultures 101 days old, made
October 26, 1907, on white cornmeal cultures not dried out; conidia in pink
34 FUNGI PARASITIC UPON ALEYRODES CITRI.
cushion-shaped masses, 5-septate, 40—60 microns long; most of them 40
microns, few 60 microns. On June 2, 1908, from culture on bread made
September 25, 1906, dried out; conidia 15—30X3—4.5 microns.
DISTRIBUTION OF MICROCERA SP. IN FLORIDA.
Sutherland September 13, 1907.
Manatee September 18, 1907.
Gainesville September 21, 1907. (Introduced.)
Leesburg October 11, 1907.
Orlando November 25, 1907.
Largo November 1907.
Titusville December 3, 1907.
Safety Harbor March, 1908.
VII. THE BROWN FUNGUS OF ALEYRODES CITRI.
In March, 1896, H. J. Webber56 discovered this fungus on whitefly
larvae in the grove of J. H. Viser, Manatee, Florida. During the summer
of that year the fungus spread rapidly through the Viser grove, and was
observed to be a very effective parasite of Aleyrodes citri. As no fructifica-
tion of any kind has been found in connection with this fungus, it has not
been classified. It has been known since its discovery as the "Brown
Fungus" of the whitefly (Plate VII, Fig. 42).
INSCRIPTION.
Webber57 gave a general description of this fungus in Bulletin 13 of
the Division of Vegetable Physiology and Pathology, as follows :
The mature stroma is compressed hemispherical, frequently having a slight de-
pression in the apex over the center of the insect, where the hyphae come together as
they spread from the edges of the scale in their development. The size varies greatly,
according to the stage of development of the insect attacked. In very young larvae
it is from l/4 to l/2 a millimeter in diameter. In mature larvae and pupae it frequently
reaches 2 millimeters in diameter. The thickness, or height, also varies in like manner,
specimens on mature larvae or pupae being usually from 175 to 260 microns, while
those on young larvae are much thinner. * * * The stroma is commonly seal
brown, with a shade of chestnut, but becomes slightly darker with age. * * * The
hyphae, which make up the body of the stroma, are light brown, very tortuous, and
but slightly branched. Those in the body of the insect are of similar character, but a
much darker brown. From the base of the stroma a ground mycelium, or hypothallus,
spreads out in all directions on the surface of the leaf, forming a compact membrane
near the stroma, but becoming gradually dispersed into separate filaments. * * *
The hyphae of the hypothallus are colorless, sparingly branched, mostly continuous,
having only an occasional septum, and are from 5 to 7 microns in diameter. In some
places in the hypothallus. where the hyphae are apparently somewhat massed and
knotted, tlu-y become light brown, similar in color to the isolated hyphae of the
stroma.
Div. of Veg. Phys. & Path., Washington, 1). C.. I',ul \\\ p. "7 is«»7
Ibid. pp. 28-30.
THE BROWN FUNGUS. 35
BROWN FUNGUS OF PARKIN.
J. Parkin58 in writing of the Ceylon forms of fungi parasitic on Aley-
rodes, mentions having found on three different kinds of teav^s a brown
sterile fungus, which he thinks is similar to the one described by Webber
on Aleyrodes citri. He also states that these brown pustules were in many
cases closely associated with Aschersonia aleyrodis of Webber, and suggests
the possibility of one being a form of the other. In regard to this point he
writes :
Intermingled with the brightly colored Aschersonia stromata on the leaf of
Flemingia strobilifera were other brown ones. Many of these latter were evidently
old or arrested Aschersonia stromata, as sections of them revealed closed pycnidia.
Others again were flatter, more nearly resembling Webber's brown fungus, thus sug-
gesting the possibility of all these sterile pustules being really connected with Ascher-
sonia. The two fungi often appear in association on the same scale and even on the
same leaf. Webber mentions that A. aleyrodis was present on those orange bushes
containing also the "brown mealy wing fungus". In the Ceylon specimen on Meme-
cylon the two were intimately associated. Atmospheric conditions such as dryness
may also influence the development of the Aschersonia as to induce it to assume a
sterile resting form. This, when conditions are again favorable, might send out in-
fecting hyphae over the leaf surface. Webber's account of how this brown fungus
develops and spreads hardly favors such a view. However, its close association with
Aschersonia is a point to be kept in mind. By cultures perhaps this sterile form might
be induced to form some fructifications, and so a clue to its nature and relationship
might be obtained.
The cultures of Aschersonia aleyrodis and Aschersonia flavo-citrina made
by the author on various media and at different times of year with varying
amounts of water, never showed any tendency to develop the brown sterile
form of the Brown fungus. In Florida there seems to be no evidence to
indicate any connection between this sterile Brown fungus and the Ascher-
sonias parasitic upon Aleyrodes citri.
METHODS OF INTRODUCTION.
Webber, in the bulletin previously referred to, describes in some detail
the method of introducing this fungus into trees infested with Aleyrodes
citri by pinning in leaves, or by planting young fungus-bearing trees in
such a way that their leaves would come in contact with the larvae-bearing
leaves to be infected with fungus. E. W. Berger59 has recently produced
some infection by grinding up the brown stromata, stirring with water, and
spraying this water upon infested leaves.
A number of attempts have been made by the writer to grow cultures of
this fungus in the laboratory, but so far he has been unsuccessful. In one
case where stromata of the brown fungus were placed close to a drop of
agar in a hanging drop culture, short tortuous hyphae were seen to grow
158 Annals Roy. Bot. Card. Peradeniya, Vol. Ill, Part I, p. 52, 1906.
C9Fla. Exp. Sta. Bui. 88, p. 64, 1906.
:;r, „ i-r.\(,i PARASITIC UPON ALEYRODES CITRI.
out from the edge. This is the only growth that lias so far been observed
under artificial conditions.
niSTKII'.r H<>.\ OF THE BROWN FUNGUS.
Florida. — Alva. Bartow, Buckingham, Bradentown, Fort Myers, Largo,
Leesburg, Manatee, Oneco, Orlando, Palmetto, St. Augustine and St..
Petersburg, on Ale yr odes citri.
Ceylon, as reported by J. Parkin, on various species of Aleyrodes.
SUPPLEMENTARY NOTES.
1. Since the above has been written, what appear to be the spores of
the Brown fungus of Aleyrodes citri have been discovered. These spores
are germinating in hanging drop cultures of sugar solutions, and are pro-
ducing hyphae that seem to be identical with those of the Brown fungus.
Further studv is needed to prove the relationship of these spores to the
Brown fungus.
V. A species of Sporotrichuin has been discovered upon the adult and
larva of Aleyrodes citri. This fungus seems to be responsible, during damp
weather, for the premature death of great numbers of adults. Cultures and
inoculation experiments are being carried on, the results of which will be
published later.
3. Since the writing of this thesis it has been shown by Dr. E. W. Berger,
Entomologist of the Florida Experiment Station, that the insects hitherto
designated as Ale\rodes citri comprise two distinct species of Aleyrodes;
one with smooth eggs and clear wings, and the other with rough eggs
covered with a delicate net of five- and six-sided meshes, and wings with
a smoky-colored area at the end of each fore wing. Specific differences
have also been observed in the first and fourth stage larvae. (See Press.
Bulletin t)T, Fla. Agri. E\p. Sta., and Proc. Fla.'Sta. Ho'rt. Soc., p. 86, 1908.)
Dr. Berger's observations and also those of the writer seem to show that
these two species of Aleyrodes are differently attacked by the Aschersonias
(A. oleyrodis and .•/. flavo-citrina}, and also by the Brown fungus and
Microccra sp. Aschersonia flaz'O-citrina attacks readily onlv the smoky-
winged Aleyrodes. but will attack the clear-winged species. Aschersonia
ulcyrodis and the Brown fungus attack both species of Aleyrodes in an equal
degree, but the greater number of the specimens so far observed have been
found upon the clear-winded species. The Microceni has been found on
both species of Aleyrodes, although it is more effective upon the smoky-
winged .species. The infection experiments described in the foregoing pages
with cultures of Microccni sp. (page :;•>) and / V/7/V/7/////// hetcrochuinm
(pag€ &4) were made up. .11 the clear-winged species. The infection ex-
periments also made by E. \Y. Berger at St. Petersburg and ('.ainesville--
i page 1'i) weft aNo upon the clear-winged Aleyrodes.
October 1, 1908.
SUMMARY. 37
SUMMARY.
1. Entomogenous species of fungi representing many different genera
have been described in the past hundred or more years.
2. These have not, until recent times, been studied from an economic
standpoint. The greatest success in the use of fungi to combat insect
pests seems to have been attained in Florida, where proper conditions of
temperature and moisture are present.
3. Aleyrodes citri R. & H., known since 1885 as a pest to citrus trees in
Florida, has spread to many citrus districts since that time, doing much
damage chiefly by creating conditions favorable to the growth of Meliola.
4. A study of the fungi parasitic upon Aleyrodes citri shows that there
are at least six species, five of which have been grown upon culture media
in the laboratory.
5. Aschersonia ale\rodis Webber is the most widely distributed fungus
parasite of Aleyrodes citri. It is easily isolated and grown in pure cultures
in 5 to 10 per cent, glucose agar medium, maturing a stroma in 30 to 40
days.
6. Healthy larvae of Aleyrodes citri may be infected from cultures of
this fungus by spraying a mixture of conidia in water on trees infested with
Aleyrodes citri.
7. Aschersonia flai'o-citrina P. Henn., which was recently found in
eastern Florida, is also an important parasite of Aleyrodes citri. Its growth
on culture media is the same as that of A. aleyrodis.
8. Conidia of both of the Aschersonias germinated best in a 5 to 10 per
cent, solution of glucose in water. Percentages of sugar above or below
this retarded germination. Conidia from stromata dried in the laboratory
for more than 28 days failed to germinate.
9. Verticillinni heterocladnni Penz. has been recently shown to occur
parasitically upon Aleyrodes citri. It has also been observed on a number
of other insects. Cultures and inoculation experiments show that this
fungus is distinct from the "Brown fungus", which it somewhat resembles in
general appearance, and with which it is frequently found associated.
10. The growth of this fungus in cultures is much more rapid than that
of the two species of Aschersonia described.
11. Sphaerostilbe coccophila, known since 1848, is world-wide in dis-
tribution, and has been reported on no less than fifteen species of scale
insects, in addition to being found on Aleyrodes citri.
12. Sphaerostilbe coccophila has been used in Florida as an effective
parasite in controlling the San Jose scale and other scale insects. In more
northern States it has not proved to be effective. It is possibly a weak
parasite of Aleyrodes citri.
13. Microcera sp., recently discovered, has been found in a number of
places in Florida attacking larvae of Aleyrodes citri. Abundant cultures of
38 Kr.xr.I I'ARASITIC UPON ALEYRODES CITRI.
this fungus may be grown in a few days, and larvae of Aleyrodcs citri may
be infected from these cultures. Conidia of this fungus vary greatly in size
under different conditions of growth.
1 1. The Brown fungus, known in Florida since 1896, has never been
observed to produce spores and is therefore unclassified. Its growth and
development on Aleyrodcs citri were described by Webber. All attempts to
grow this fungus in pure cultures have failed. (See, however, Supplement-
ary Note 1.)
BIBLIOGRAPHY.
The literature referred to in this bibliography is grouped under seven heads, corre-
sponding to the seven divisions under which the subject is discussed. The references
in each division are arranged in chronological order. All but three of the papers
have been seen by the author. These three are designated by an (*) asterisk.
GENERAL, LITERATURE.
('88) Forbes, S. A. On our present knowledge concerning Insect Diseases. Psyche,
Vol. V, pp. 3-12, 1888-90. (Bibliography, pp. 15-22.)
('88) Thaxter, Roland. The E'ntomophthoraceae of the United States. Memoirs
of the Boston Soc. of Nat. History, Vol. IV, No. 6, 1888. (With bibliography.)
('88) Lugger, Otto. Fungi Which Kill Insects. Univ. of Minn. Ann. Kept. Agr.,
pp. 380-392, 1888.
('92) Cooke, M. C. Vegetable Wasps and Plant Worms, London, 1892
('93) Riley, C. V. and Howard, L- O. Insect Life, Div. of Ento., Wash., D. C.,
Vol. V, No. 4, p. 220, 1893.
('95) Pettit, R. H. Studies in Artificial Cultures of Entomogenous Fungi. Cor-
nell Univ. Agr. Exp. Sta. Bui. 97, 1895 (with bibliography).
('95) Forbes, S. A. Experiments With the Muscadine Disease of the Chinch-
bug, etc. 111. Agr. Exp. Sta. Bui. 38, is-.i:,
('97) Rolfs, P. H. A Disease of the San Jose Scale. Fla. Agr. Exp. Sta Bui 41
1897.
('98) Forbes, S. A. 111. Agr. Exp. Sta. Bui. 56, pp. 270-280, 1898.
('06) Parkin, J. Fungi Parasitic Upon Scale Insects (Coccidae and Aleyrodidae),
etc. Ann. Roy. Bot. Gardens Peradcniya, Vol. Ill, Part I. (With bibliography.)
ASCHERSONIA AI.KVKODIS \YEHBER.
('94) Webber, H. J. Preliminary Notice of a Fungus Parasite on Aleyrodes
citri. Journ. of Mycol., Vol. VII, No. 4, p. 363, 1894.
('96) Webber, H. J. Proc. Fla. State Hort. Soc., p. 73, 1896.
('96) Webber, H. J. The Principal Diseases of Citrus Fruits in Florida. Div.
of Veg. Phys. and Path., Bui. 8, Washington, D. C., p. 27, 1896.
('97) Webber. H. J. Sooty Mold of the Orange. Div. of Veg. Phys and Path
Bui. 13, p. 20, Washington, D. C., 1897.
('99) Saccardo, P. A. Sylloge Fungorum, XIV. p. 991, 1899.
('00) Hume, H. H. Some Citrus Troubles. Fla. Agr. Exp. Sta. Bui. 53, p. 164,
('03) Gossard, H. A. Fla. Agr. Exp. Sta. Bui. 67, pp. 622-623, 190.:
('04) Hume, H. H. Citrus Fruits and Their Culture, pp. 547-550 Jacksonville
Florida, 1'.»<u.
('05) Sellards. E. II. Fla. Agr. Exp. Sta. Rept., pp. 26-27, 1905
('06) Earle, F. S. Primer Informe Anual de la Estacion Central Agronomica de
Cuba, 1904-1905, p. K.'.>. L906,
('06) Parkin, J. Fungi Parasitic Upon ScaK- Insects. Annals of Royal Bot Card
Peradeniya, Vol. Ill, Part I. ,,. :;r,, i<>06.
('06) Berger, E. W. Fla. Agr. Exp. Sta. Rept.. p. xix, v.MMi.
('07) Berger, E. W. Fla. Agr. Exp. Sta. Bui. 88, pp. 54-c.:,, 1907
('07) Berger, E. W. Fla. Agr. Exp. Sta. Rept., p. xxxi. 11107
('07) Fawcett, H. S. Fla. Agr. Exp. Sta. Rept., p. xlviii, 1907
BIBLIOGRAPHY. 39
('07) Kirkaldy, G. W. and Kotinsky, J. Board of Commissioners of Agr. and
Forestry, Div. of Entomology, Hawaiian Sugar Planters' Exp. Sta., Bui. 2, pp. 57 and
60, 1907.
('08) Berger, E. W. Fla. Agr. Exp. Sta. Press Bui. 80, 1908^__ ___
('08) Cook, M. T. and Home, W. T. Insects and Diseases of Orange. Cuba
Agr. Exp. Sta. Bui. 9, p. 31, 1908.
('08) Rolfs, P. H. and Fawcett, H. S. Fungus Diseases of Scale Insects and
Winterly. Fla. Agr. Exp. Sta. Bui. 94, 1908.
ASCHERSONIA FT.AVO-CITR1NA P. HENN.
('02) Hennings, P. Hedwigia, Vol. 41, p. 307, 1902.
('04) Hennings. Festschrift fur P. Ascherson, p. 68, 1904.
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1907.
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Soc. Rept., pp. 73-78, 1907.
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VERTICILUUM HETEROCLADUM PENZ.
('82) Penzig, O. Flora Italica, t. 1193, Mich. II, p. 462, 1882.*
('86) Saccardo. Sylloge Fungorum, IV, p. 151, 1886.
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Tavola xli, Fig. 3, Roma, 1887.
('04) Gueguen, L,es Champignons parasites de 1'homme et des animaux, p. 252,
Paris, 1904.*
('06) Parkin, J. Ann. Roy. Bot. Gard. Peradeniya, Vol. Ill, Part I, p. 45, 1906.
('07) Fawcett, H. S. The Cinnamon Fungus of the Whitefly. Fla. Agr. Exp.
Sta. Press Bulletin 76, 1907.
SPHAEROSTILBE COCCOPHILA
('48) Desmazieres. Ann. des Sc. Nat., Tome x, p. 359, 1848.
('65) Tulasne. Carpologia, Vol. Ill, p. 105, 1865.*
('S3) Saccardo. Sylloge Fungorum, II, p. 513, 1883.
('92) Cooke, M. C. Vegetable Wasps and Plant Worms, p. 322, Plate 2, Fig. 22,
London, 1892.
('92) Cockerell, T. D. A. Bui. Bot. Dept. Jamaica, No. 36, p. 6, 1892.
('92) Ellis and Everhart. North American Pyrenomycetes, p. Ill, 1892.
('94) Tryon, H. Queensland Dept. of Agr., Bui. 4, p. 15, 1894.
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1897.
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('98 ) Webster, F. M. Ohio Agr. Exp. Sta. Bui. 103, p. 198,. 1898.
('99) McAlpine, D. Fungus Diseases of Citrus Trees in Australia. Dept. of Agr.
Queensland, p. 113. Figs. 181-182, pp. 27 and 28, 1899.
('00) Rolfs, P. H. Proc. Fla. State Hort. Soc., p. 65, 1900.
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('04) Rolfs, P. H. Proc. Fla. State Hort. Soc., p. 63, 1904.
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ida, 1904.
40 FUXf.I PARASITIC UPON ALEYRODES CITRI.
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('05) Sellards, E. H. Fla. Agr. Exp. Sta. Kept, p 27, 1905.
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de Cuba, l'.n>4-l «.»(»:•. p. ]<•>:>. i<>06.
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1>. :>4. 1907.
:) Griffing. Fla. State Hort. Soc. Rept, pp. 54-55, 1907.
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MICROCERA SP.
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WKI'.r.Kk's I'.KOWX FUNGUS.
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( '97 ) Webber, H. J. Proc. Fla. State Hort. Soc., pp. 55-56, 1897.
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ida, I'.HM
) Sellards. E. H. Fla. Agr. Exp. Sta. Rept., p. 26, 1905.
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Whitefly. Fla. A-r. Kxp. Sta. liul. <)4. 1908.
i-Xl'l. \.\.\TIO.\ oi? PLATES.
PLATE I.
Fig. 20. — . Isclicrsnnid tilcyi'<)dis. Culture in petri dish of 5 per cent, glucose agar
pourc-d December 7. 1900; showing mature stroma 36 ..days old. The central
raised portion was red, and contained the pycnidial cavities with spores.
Fig. 21. — Aschcrsonia aleyrodis. Culture on rice after 5 weeks, grown at room-
temperature.
Fig. 22. — Asclicrsotiiu aleyrodis. Culture on sweet potato plug, after 5 weeks-
Grown in refrigerator after first few days
Fig. 23.— . Isclicrsonia ali-ynniis. Culture on white corn meal after 5 weeks. Grown,
at room temperature.
PLATE II.
Fig. 24.— . Ischt'i-stnini fltirn-citrina. Citrus leaf showing stromata of the fungus
in the position originally assumed by larvae of .-llcynnics citri. The hemi-
spherical raided center was yellow with a fringe of outgrowing hyphae.
.':> .--.Jsclicrsitnia dlcynxlis. Citrus leaf showing stromata. The raised center
was red instead of yellow, as in the previous figure.
111.
•M.—.tsc/u'rs<niia t'laro-cifrimi. Culture on petri dish of 5 per cent glucose
agar made -fO.5 to plienolphthnlein. after :;:; days. Culture poured September
14. ]'.»<><;; showing the mature stromata one and a half times natural size.
Fig. ZT.—Aschtrsonia flavo-citrnta. Culture on petri dish of 5 to 10 per cent
glucose agar, after in days showing how stromata will spread when given:
room to grow.
EXPLANATION OF PLATES. 41
PLATE IV.
Figs. 28-30. — Aschersonia flavo-citrina. Cultures on sweet potato plugs, inoculated
November 1, 1906, after 60 days.
Fig. 31. — Verticillium heterocladum. Citrus leaf showing fungus pustules on
larvae of Aleyrodes citri.
PLATE V.
Fig 32. — rcrticillium heterocladum. Culture in test-tube on bread.
Fig. 33.— Verticillium heterocladum. Culture in test-tube on Irish potato plug.
Fig. 34. — Verticillium heterocladum. Culture on glucose agar, showing brown
pustules.
Fig. 35. — Verticillium heterocladum. Leaf of privet bearing larvae of Aleyrodes
citri infected with the fungus by means of a citrus leaf containing pustules.
PLATE VI.
Fig. 36. — Sphaerostilbe coccophila. Sporodochia of the fungus on bodies of
Aspidiotus hederae, on Chinaberry twig.
Fig. 37. — Sphaerostilbe coccophila. Sporodochia of fungus on bodies of Mytilaspis
citri co la on citrus twig.
Fig. 38. — Sphaerostilbe coccophila. Perithecia of fungus on Mytilaspis citricola
on bark of citrus. Twice natural size.
Fig. 39 and 40. — Microcera sp. Cultures on rice showing loose fluffy growth on
top of medium. Natural size.
Fig. 41. — Microcera sp. Citrus leaf with larvae of Aleyrodes citri infected with
the fungus. The fungus is shown by white fringes on the edges of a number
of the larvae.
PLATE VII.
Fig. 42. — The Brown Fungus of Webber. Citrus leaf with brown pustules that
have formed on larvae of Aleyrodes citri. (Photographed by H. H. Hume.)
Fig. 43. — Cladosporium sp. A super-parasite found growing over Aschersonia,
flavo-citrina on leaf of citrus.
Plate I
Figs. 20-23. Cultures of Aschersonia aleyrodis.
Plate II
Fig. 24. Aschersonia flavo-citrina on citrus leaf.
Fig. 25. Aschersonia aleyrodis on citrus* leaf.
Plate III
Fig. 20. Cultures of Aschersonia flavo-cilrina.
Plate III— Continued
Fig. 27. Cultures of Aschersonia flavo-citrina.
Plate IV
Figs. 28-30. Cultures of Aschersonia flavo-citrina.
35
Figs. 32-34. Cultures of Verticillium heterocladum .
Fig. 35. Verticillium heterocladum on Aleyrodes citri on privet leaf.
Plate VI
i-l
Figs. 36-37. Sporodochia of Sphaerostilbe coccophila.
Fig. 38. Perithecia of Sphaerostilbe coccophila.
Figs. 39-40. Cultures of Microcera sp.
Fig. 41. Microcera sp. on Aleyrodes citri on citrus leaf.
Plate VII
Fig. 42. Brown fungus on Aleyrodes citri.
1-3
Fig. 43. A super-parasite (Cladosporium sp.) upon Aschersonia flavo-citrina.
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