JOURNAL OF THE EAST AFRICA NATURAL HISTORY SOCIETY AND NATIONAL MUSEUM QH 1 E11X NK 25 November, 1976 Vol. 31 No* 160 BREEDING SITES OF SOME SPECIES OF ZAPRIONUS (DIPTERA) IN UGANDA By J. H. Buruga Botany Department , Maker ere University , P.O, Box 7062 , Kampala , Uganda INTRODUCTION Zaprionus Coquillett belongs to the family Drosophilidae (Diptera). A large family with many genera, mostly tropical, it contains many common species which tend to be fruit “pests”. Because the most widespread genus within the family is Drosophila , much information has been collected on the breeding and feeding habits within the genus. The principal breeding sites for the Drosophila are various materials containing naturally occurring carbohydrate substrates. These vary from fruits, barks, exudates and rotting leaves to fleshy fungi. It has been shown (Carson & Stalker 1951) that yeasts, associated bacteria and related micro-organisms, which thrive on these materials, form the main food supply for both adults and larvae of many species of the genus. Cosmopolitan species such as D. melanogaster Meigen, D. simulans Sturtevant, D. immigrans Sturtevant, and D. busckii Coquillett have been bred from garbage, rotting fruits and other habitats usually associated with domestication. Most of the wild species of Drosophila require specialised breeding sites, but some can breed in ‘domestic’ breeding sites. Examples of truly wild species of Drosophila which have been found in fleshy fruits are D. affinis Sturtevant and D. tripunctata Loew. These have been reared from rotting fruits of the May Apple Podophyllum peltatum. D. athabasca Sturtevant & Dobzhansky was bred from rotting persimmons Diospyros virginiana together with D. melanogaster Meigen and D. simulans Sturtevant (Carson & Stalker 1951). D. americana Spencer was found breeding in the bark of Salix interior (Blight & Romano 1953); D. laciola Patterson bred on rotting phloem of Populus tremuloides Michx (Spieth 1951), Exudates from trees have also been used as breeding sites for Drosophila. Gordon (1942) bred D. obscura Fallen from the exudate of elm trees. D. persimilis Dobzhansky & Epling and D. pseudoobscura Frolova were found breeding in the fluxes of Quercus kellogii together with D, victoria Sturtevant and D. California Sturtevant (Carson 1951). Fleshy fungi, especially the larger agarics, have yielded such Drosophilidae as D. tripunctata Loew and D. transversa Fallen (Carson & Stalker 1951). Preliminary work in Uganda (Buruga & Olembo 1971 ; Tallantire & Buruga 1971), confirmed that many wild species of Drosophila have similar breeding sites. In addition, Aubertin (1937), found the larvae of D. gibbinsi Aubertin living together with Simulium larvae in an aquatic situation at Jinja. The gut contents of these larvae showed that they were carnivorous. Other genera of Drosophilidae were found breeding in very specialised sites. For example, Odhiambo (1958) found Leucophanga sp. indet. near Serna Burla breeding in the frothy fluid secreted by nymphs of Ptyleus davescens F. (Homoptera, Cercodae). Carson (1965) has discussed the importance of a full understanding of the ecological niches of the Drosophilidae to appreciate the evolutionary trend of the species. Since Sturtevant (1921), this has been a much neglected area. Sturtevant (1918) also pointed out the possibility of medical significance in such studies. In the Ivory Coast of West Africa Lachaise and Tsacas (1974) and Lachaise (1974) have done much work on the ecology of Drosophilidae, including that of Zaprionus. Page 2 J. H. BURUGA No. 160 Much of the ecological genetics of African Drosophilidae, however, remains to be worked out. This work on Zaprionus represents an initial effort in understanding the ecology of locally occurring Drosophilidae. ZAPRIONUS COQUILLETT Over 15 species of Zaprionus have already been described from Africa and southern Asia. Z. vittiger Coq. and Z. ghesqurerei Collart have been recorded from various parts of Africa, together with a number of other species. Okada (1964) records Z. obscuricornis (de Moijere) from Borneo, Sumatra, Java and the Phillipine Islands in Southeast Asia. The Zaprionids can be readily recognised by the characteristic white stripes on the head, the mesonotum, and the scutellum. Ecological work has, however, been scanty and more information is required on the breeding and feeding habits of Zaprionus. This work in Uganda hopes to contribute to this body of knowledge. Breeding and feeding sites investigated followed closely the pattern studied in Drosophila and also included nectar-containing flowers. METHODS Materials collected in the field were brought into the laboratory and kept in clean glass containers stoppered with heat-sterilised cotton wool. The containers were examined daily for several weeks for Drosophilidae. Sometimes larvae found in the material were transferred to corn meal-agar media. Also traps were set, of bananas, pawpaws, pineapples and tomatoes. COLLECTION AREAS Sites investigated for Drosophilidae included cultivated, forest and savannah areas. Cultivated areas Material was collected from the Botany Garden at Makerere where both indigenous and introduced plants are cultivated. It is constantly weeded and thinned and being easily accessible was found suitable for the study of Drosophilidae. Forests Several forests were sampled. Mpanga forest, 37 km west of Kampala at an altitude of between 1143 m and 1204 m is a moist evergreen forest. Mabira forest, 22 km east of Kampala, is a semi- deciduous forest at an altitude of 1216 m. Budongo forest, also semi-deciduous, lies at about the same altitude; it is situated approximately 200 km north of Kampala. These forests receive an annual rainfall of between 143 cm and 175 cm. A large number of plant species, most of them indi- genous, are found in them. Because of the moist atmosphere and the canopy, many types of fungi and other soil macroflora are present. Savannah Two savannah areas were studied. Kaazi, at an altitude of about 1240 m, is situated on Lake Victoria and receives an annual rainfall of 70 cm- 100 cm. Arua, in northern Uganda, rises up to 1204 m and receives a maximum rainfall of 700 mm. RESULTS The total number of Zaprionus species obtained, is shown in Table 1. At least eight different species have so far been identified. These were obtained by trapping or by breeding them out of various organic materials. Zaprionus species breeding in flowers Flowers from several plant families were examined (Table 2). At least four species of Zaprionus were obtained, the commonest being Z. tuberculatus. Although the species Z. vrydaghi has been observed feeding on the flowers of C. afer in Budongo and Mabira forests, it has never been found breeding in flowers of Costus afer from the Botany Garden, Makerere. No. 160 BREEDING SITES OF ZAPRIONUS Page 3 Table i Zaprionus species in Uganda Species Origin Locality Z. ghesquierei Collart Fruits Flowers Traps Botany Garden Nabugabo Camp Ziika Forest Z. inermis Collart Traps Botany Garden Ziika Forest Z. koroleu Burla Traps Botany Garden Zaprionus sp, near koroleu but with tuberculate femur Traps Botany Garden Zaprionus sp. c.f. spinosus Collart (possibly a new species) Traps Ziika Forest Arua Z. tuberculatus Malloch Fruits Flowers Traps Botany Garden Nabugabo Camp Ziika Forest Z, vittiger Coq Fruits Flowers Traps Arua Botany Garden Nabugabo Camp Ziika Forest Z. vrydaghi Collart Flowers Budongo Forest Mabira Forest Zaprionus species (Unidentified) Feeding on exudates Mpanga Forest Table 2 Representative species of plant families from whose flowers Drosophilidae were reared Family Species Zaprionus species Locality Apocynaceae Tabernaemontana holstii K. Schum. Z. tuberculatus Makerere Bignoniaceae Spathodea nilotica P. Beauv. Z. tuberculatus Makerere Convolvulaceae Ipomoea tricolor Cav. Z. vittiger Makerere Leguminosae Erythrina abyssinica Lam. Z. tuberculatus Makerere Kigezi Malvaceae Gossypium hirsutum L. Z. tuberculatus Kawanda Moraceae Treculia africana Decne. Z . tuberculatus Ziika Forest Passifloraceae Fassiflora sp. Z. vittiger Makerere Zingiberaceae Costus afer Ker-Gawl. Costus spectabilis (Fenzl) K. Schum. Z. vrydaghi Z. tuberculatus Z. vittiger an unnamed Zaprionus sp. Mabira Forest Botany Garden Makerere Zapriopus species breeding in fruits A large number of ripe and decaying fruits were collected. Fruits were of indigenous plants* particularly of families Moraceae and Solanaceae, and of introduced plants. Most of the fruits collected from indigenous plants were from the forest and savannah areas. These fruits were usually collected because Drosophilidae were seen to feed on them. The results are presented in Table 3. Page 4 ]. H. BURUGA No. 160 Table 3 Plant species from whose fruit Zaprionus were obtained Zaprionus species Plant species Locality Z. ghesquierei Averrhoa carambola L. Botany Garden, Makerere Carica papaya L. 5) Cyphomandra betacea Sendth. M Ficus brachypoda Hutch. 33 Mangifera indica L. Araa Musa sp. (Banana) Botany Department Persea arnericana Mill (Avocado) Botany Garden, Makerere Solanum gilo Raddi 33 Nabugabo Z. tuberculatus Aframomum sanguineum K. Schum. Botany Garden, Makerere Averrhoa carambola L. 33 Coffea canephora Frochner. Kawanda Cyphomandra betacea Sendtn. Botany Garden, Makerere Eriobotrya japonica Lindl. 33 Ficus mucuso Ficalho 33 Mangifera indica L. (Mango) Makerere, Budongo Phytolacca dodecandra L’Herit. Buto Forest Psidium guajava L. (Guava) Botany Garden, Makerere Solatium gilo Raddi 33 Solanum verbascifolium L. Kyambogo Solanum sp. Budongo Forest Unidentified (Rosaceae) Mulago Z. vittiger Anona sp. Arua Aframomum sanguineum K. Schum. Nabugabo Ananas sativus (Pineapple) 33 Artocarpus communis Forst. Entebbe Averrhoa carambola L. Botany Garden, Makerere Carica papaya L. (Pawpaw) 33 Coffea canephora Froehner (Coffee) Nabugabo Kawanda Cyphomandra betacea Sendtn. Botany Garden, Makerere Eriobotrya japonica Lindl. 33 Ficus brachypoda Hutch. Botany Garden/Entebbe Ficus mucuso Ficalho. Budongo & Mabira Forests Ficus urceolaris Hiern. Mpanga Forest Lantana camara L. Kyambogo Mangifera indica L. (Mango) Arua ; Budongo ; Makerere Psidium guajava L. (Guava) Botany Garden. Makerere Rubus steudneri Schweinf. 33 Solanum gilo Raddi 33 Solanum campylacanthum Hochst. 33 Solanum verbascifolium L. Kyambogo Solanum sp. Budongo Unidentified (Rosaceae) Mulago Stems and barks of trees Although a large collection of bark and stems of various plants was made., no Zaprionus species was seen to feed on or breed out of them. Fluxes Forest trees were examined for exudates. In Albizia gutmrdfera (Gmel) exudate flow that had been caused by slicing the bark, Drosophilid-like larvae were found crawling about. Adults of a Zaprionus species were seen to swarm around and feed on the flux. It was assumed that this pecies of Zapnonus bred on the fluxes of A. gummifera . Adult Zaprionus species were captured from these fluxes in Mpanga forest. Attempts to raise them on cornmea 1-agar media were un- successful. The larvae from these exudate flows were brought into the laboratory but could not be made to develop further on artificial media. It has so far been impossible to show whether these Zaprionus species were just feeders on the flux of A. gummifera or whether they bred in it too. No. 160 BREEDING SITES OF ZAP R I ONUS Page 5 Fleshy fungi A number of Drosophilids were bred from fleshy fungi, but no Zaprioniis species were found. Many larvae were found infesting some of the agaric collections from Mpanga forest; attempts to raise these larvae on commeal-agar or banana-agar media were unsuccessful. Rotting leaves Collections of rotting leaves yielded some species of Leucephanga together with other Drosophilidae, but no Zaprionus was found. CULTURING ZAPRIONUS IN THE LABORATORY Not all species of Zaprionus collected from the field could be bred on artificial media. Z, ghequierei , Z. inermis , Z. tuberculatus and Z. vittiger have, however, been cultured on commeal-agar media. Whereas the other species of Zaprionus have a life cycle of about two weeks at room tem- perature (25°G-27°C), Z. vittiger has a life cycle of between nine and eleven days. Zaprionus species that bred in flowers and those that bred in exudates would not breed in commeal-agar media nor in banana-agar media. They have, however, been maintained on these media for about two weeks, at the end of which they all died. Zaprionids such as Z. vittiger , Z. ghesquierei , and Z. tuberculatus which bred on both wild and cultivated fruits are easily cultured in the laboratory, whereas those that only breed in wild flowers are not. DISCUSSION Like Drosophila , Zaprionus has been found to breed in various carbohydrate substrates. However, the main breeding sites for the commoner species of Zaprionus appear to be fleshy fruits. Large fleshy fruits yielded the greatest number of Zaprionids. This may be because such fruits have adequate moisture and take a long time to dry out and disintegrate, giving the Zaprionids ample time to undergo their life-cycles. Fruits from which no Zaprionids were bred tended to be small and often dried out quickly. Some of the Zaprionus species such as Z. vittiger and Z. tuberculatus were found over a wide area from which collections were made. Some Zaprionids tended to be restricted to certain ecological areas : Z. vrydagi was taken from all the forests from which collections were made and was never collected from other ecological areas. Some of the fruit collections were interesting in that in some areas they yielded Zaprionus species, while in others they did not. Zaprionus was found in Lantana camara from Kyambogo but not found in this plant collected from Arua and Makerere. Likewise Ficus urceolaris Welwo was collected from Budongo forest, Makerere and Mpanga forest, but Zaprionus vittiger was found only from the Mpanga material. Z. vittiger and Z. tuberculatus have been bred from fruits of Coffea canephora Pierre collected from Kawanda but not from Makerere. Most of the fruits collected are seasonal. However, there is usually a long period in the fruiting of members of the same species. Different plants tend to have different fruiting seasons in some cases. This means that there is always some food and a breeding site for Zaprionus . These Drosophilidae can therefore breed throughout the year with peak periods when fruits are more plentiful. The peak of the breeding season for Z. vittiger and Z. tuberculatus appears to be in the May- June- July period when many plants are in fruit. In all the species, the period of least breeding activity is the November-December- January period, when very few plants are fruiting. Some of the Zaprionus species have been found to breed in flowers of various plants, but this may not be a very important breeding site. The smell of the flowers that have opened out appear to attract the Zaprionus together with other flies. The flowers collected, however, were not highly perfumed, although all of them contained nectar. Female Zaprionids appear to lay eggs in the flower during the course of feeding. These eggs develop in a few days to form larvae which are then active feeders by the time the flower withers and rots. It is possible that yeast and other micro-organisms, thriving on the rotting corolla of the flowers, provide enough food for the growth and development of the larvae. By the time the flower dries, the larvae have pupated. When the Zaprionus merge from the pupa, they then fly away in search of food. In the laboratory, the average period of development of the larvae of three Zaprionus species studied is five days. Flowers of Costus spectabiliss and presumably those of the other species of Costus , take over two weeks to dry up. Page 6 J. H. BURUGA No. i6q Fluxes of trees have so far not been shown to provide breeding sites for Zaprionus although they appear to be used for feeding by one species of Zaprionus. It was shown that this species of Zaprionus tended to frequent fresh exudates of Albizia gummifera , while My codrosophila bombax Burla tended to frequent the older exudates of the same tree. Carson (1951) has suggested that micro-biological flora of exudates offers breeding and feeding sites with differential qualities of attraction for the different species of Drosophila. It may be that the Zaprionus species prefers the micro-flora and fauna that inhabit the fresh exudates of A. gummifera to those that inhabit the older exudates of the same tree species. From the foregoing discussion, Zaprionus species can be grouped arbitrarily into “domestic” and “wild” types. The former, represented by Z. vittiger and Z. tuberculatus feed on and breed in a wide variety of sites. They are widespread and occur in man-made habitats as well as in the wild. On the other hand, Z. vrydagi and two unnamed species of Zaprionus appear to be more specific in their choice of breeding and feeding sites. They are the “wild” species of Zaprionus. SUMMARY Work done on Zaprionus in Uganda shows that many of the species bred in ripe fruits, which would therefore seem to be the principal breeding sites. They also bred in flowers. None have so far been shown to breed in the stem and barks of trees, fluxes, rotting leaves or fleshy fungi. As in Drosophila , Zaprionus species seem to have both “domestic” and “wild” types. ACKNOWLEDGEMENT I wish to thank Dr L. Tsacas for his help in identification of some of the Zaprionus species. REFERENCES Aubertin, D. (1937). A new species of Drosophila D. gihbinsi sp. n. from Uganda (Diptera). Proceedings of the Royal Entomological Society of London, (B) 6: 169. Blight, W. C. & Romano, A. (1953). Notes on a breeding site of Drosophila americana near St. Louis, Missouri. American Naturalist , 87; 112-118. Buruga, J. H. & Olembo, R. (1971). Plant food preferences of some sympatric Drosophilidae of Tropical Africa. Biotropica 3(2), 151-158. Carson, H. L. 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Sturtevant, A. H. (1918). Flies of the genus Drosophilia as possible disease carriers .Journal of Parasitology 5i 84-85. Tallantire, A. C. & Buruga, J. H. (1971). A study of some Drosophilidae of Uganda. Drosophila Information Service 46: 101-102, {Received 5 December 1975 ) Published by The East Africa Natural History Society , Box 44486 , Nairobi, Kenya and printed by Kenya Litho Ltd., Box 40775 , Changamwe Road, Nairobi. S3 \mm SMITHSONIAN INSTITUTION LIBRARIES 3 9088 01313 7302