In vitro feeding in the rearing of tsetse flies (Glossina m. morsitans and G.p. palpalis, Diptera: Glossinidae).

The increasing demand for laboratory reared tsetse flies for research and biological control makes it necessary to develop effective and standardized tsetse fly feeding methods without using live animals for the daily blood uptake. The in vitro feeding technique, described in this paper, has been used for rearing G. m. morsitans by feeding them defibrinated equine blood through a silicone membrane. The results obtained for female longevity and productivity and mean weight of puparia are satisfactory. However, feeding defibrinated bovine blood results in significantly lighter puparia. A colony of G. p. palpalis feeding on defibrinated bovine blood is the only colony of this species that has been successfully maintained by in vitro feeding over several years. The survival rate of the females being fed defibrinated bovine, equine or porcine blood is equal. The number of larvae produced by females being fed defibrinated equine blood is significantly lower. Females younger than 50 days produce larvae which form a heavier puparia than females aged between 51 to 80 or 100 days, irrespective of blood source. Bovine blood used within the first 3 days after its collection leads to significantly higher mean weights of puparia than bovine blood used therafter. The increasing degree of haemolysis is most probably not the reason for this observation. A colony production model based on the performance of both species, G. m. morsitans and G. p. palpalis, fed in vitro, shows the importance of the first five age group periods (i.e. 45 to 50 days after emergence) for the overall performance of the flies. According to the results obtained, about 2,3 puparia per female are needed to maintain the same number of females in the colony. This level of production is reached in the fifth age group period. All larvae produced thereafter are available for colony expansion or experimental purposes. Rearing of both species with in vitro feeding is now a matter of routine.