Medical and Veterinary Entomology (1988) 2 , 201-202

SHORT COMMUNICATION

Large-scale rearing of Glossina brevipalpis in the laboratory

S . K. MOLOO and S. B. KUTUZA International Laboratory for Research on Animal Diseases (ILRAD), Nairobi, Kenya

Glossina brevipalpis Newstead has a wide geographical distribution (Ford & Katondo, 1977). It is a vector of African trypanosomiasis (Harley, 1966) and it feeds on a range of verte- brate hosts including cattle (Weitz, 1963). However, very little research has been carried out on G. brevipalpis compared with some other tsetse species since it has not been previously colonized. This communication reports on the successful large-scale rearing of this Fusca group tsetse species.

In mid-1982, 181 wild females of G. brevipal- pis were caught in Kibwezi Forest (lat. 2"23'S, long. 37"58'E), Kenya, using the moving- landrover catching method (Bursell, 1961). These females were put in Geigy-25 cages, kept in a sealed box and transported to the ILRAD Tsetse Vector Laboratory. They were kept in a climate controlled room at a temperature of 25+0.5"C and, relative humidity of 80-85%. The tsetse were fed on the ears of lop-eared rabbits daily except Sundays. A total of 531 pupae, mean weight 67.0k2.1 mg, were pro- duced by these field-caught tsetse. Tsetse which emerged from these pupae formed the parental stock of the colony. The number of mated females in the colony increased and reached 1000 in mid-1983, 4000 in mid-1984 and the target of 5000 breeding females in December 1984.

The current rearing techniques follow. Adults and pupae are kept in a climate controlled room as above. Pupae are kept in 10X40x40cm emergence cages, up to 2000 pupaelcage. The newly emerged tsetse are immobilized at 2-3°C and sexed. The sexes are put separately into Geigy cages, fifteen per cage. Each cage,

Correspondence: Dr S. K. Moloo, ILRAD, P.O. Box 30709, Nairobi, Kenya.

1 5 ~ 8 . 5 ~ 5 cm, consists of a stainless steel wire frame having a closed end fitted with a corked hole. The cage is covered with black Terylene netting, 4 x 4 mm mesh, which enables the lar- vae to crawl through into a tray. Teneral females, fifteen in each cage, are fed on the rabbits' ears and then eighteen recently fed 7-day-old males are introduced into each cage for mating. Initial experiments mating 3-day-old females with 7-day-old males for 24 h gave a poor insemination rate. After about 48 h, fifteen males are removed from each cage using a 35 cm long, 1.5 cm diameter glass tube. The cages of mated females are kept on a rack (Nash et af., 1971). Each rack of ten cages forms a unit of 150 mated females and is given a code number. The flies are offered food for 5 days each week, Mon- day to Friday. Pupae are also collected from the trays of all the racks on these days, and the number of pupae from each unit code is recorded; pupae from one of the unit codes are weighed in bulk. Dead flies are removed on Mondays, Wednesdays and Fridays. Female flies are maintained for 80 days, and on day 81 post-emergence the surviving flies are killed.

In 1985, the mean female stock of the G . brevipalpis colony was 5238. The insemination rate was 299%. The colony produced 125,456 pupae, i.e. 0.46 pupaelfemalelweek, with a mean pupal weight of 73.10k0.57 mg. Mean daily female mortality was 1.06%. Mean sur- vival by day 80 post-emergency was 34.4% in the first half and 52.5% in the second half of the year. This improvement of the female survival resulted in better fecundity. The emergence rate from the pupae was >95%. The overall perfor- mance was thus good and the colony has since provided adequate surplus for research workers at ILRAD and elsewhere.

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202 S. K . Moloo and S. B. Kutuza

Acknowledgments

We thank Mr C. 0. Machika and Mr F. K. Masasi for excellent technical assistance. We are most grateful to Dr Ole Mpere, Chief Zoologist in the Kenya Veterinary Services, for allowing us the use of facilities at the Kiboko Field Station and to his field staff for their assistance to catch tsetse in the nearby Kibwezi Forest. This is ILRAD Publication No. 474.

References

Bursell, E. (1961) The behaviour of tsetse flies (Glossina swynnertoni Austen) in relation to pro- blems of sampling. Proceedings of the Royal Entomological Society, London, (A), 36, %20.

Ford, J. & Katondo, K.M. (1977) Maps of tsetse flies (Glossina) distribution in Africa, 1973, according to sub-generic groups on Scale of 1:5,000,000 (plus a set of 9 maps in colour). Bulletin of Animal Health and Production in Africa, 25, 187-193.

Harley. J.M.B. (1966) Studies on age and trypano- some infection rate in females of Glossina pallidipes Aust., G.palpalis fuscipes Newst. and G.brevipalpis Newst. in Uganda. Bulletin of Entomological Research, 57, 23-37.

Nash, T.A.M., Jordan, A.M. & Trewern, M.A. (1971) Mass rearing of tsetse flies (Glossina ssp.): recent advances. Sterility Principles for Insect Con- trol or Eradication, IAEA-SM-138146, pp. 99-1 10.

Weitz, B. (1963) The feeding habits of Glossina. Bulletin of the World Health Organization, 28,711- 729.

Accepted 14 September 1987