Assessment of optimal blood exposure time at 37 °C during in vitro tsetse flies feeding for quality production in mass-rearing colonies.

Abstract

Control of African animal trypanosomosis is implemented through an integrated control strategy, with the sterile insect technique (SIT) as one of its components. The SIT requires mass rearing of tsetse fly colonies using an in vitro feeding system. The exposure of blood at 37 °C on heating plates over time can have an impact on the quality of fly productivity. In this study, we investigated the survival and fecundity of adult tsetse flies fed at 37 °C on 8 blood exposure times ranging from 30min to 4h with increments of 30min (treatment 1, flies were fed 30min after exposure to blood at 37 °C; treatment 2, 1h and so on until treatment 8 [4h after]) in order to determine the optimal exposure time. In addition, bacterial growth in blood from each treatment was assessed by agar culture at 37 °C for 72h. The results showed that the adult female survival rates were similar regardless of the treatment. For males, only those of treatment 1 (30min) showed a marginal lower survival than those of treatments 7 and 8 fed after 3h 30min and 4h of blood exposure, respectively. Over the 4-h interval of blood exposure at 37 °C, the results showed that the number of pupae produced per initial female and pupal weight tended to increase with exposure time, but the differences were not significant. We discuss the implications of these results on tsetse mass rearing for the SIT program.