Evaluating the impact on F1 sterility of tsetse pupae <i>Glossina morsitans morsitans</i> irradiated following short‐term hypoxic conditioning

The sterile insect technique (SIT) for tsetse involves releasing sterilized males to outcompete wild males in mating, resulting in nonviable progeny. Balancing optimum sterility and male quality is crucial. While irradiation in hypoxia or anoxia is routine for tephritid flies, its effect on tsetse, especially postrelease, is not well understood. We conducted experiments to understand the impact of irradiation in hypoxia on the sterility of the F1 generation of Glossina morsitans morsitans (Gmm). Initially, we tested the impact of 1-h preconditioning in hypoxia before irradiation and continued hypoxia up to 24, 48, and 72 h postirradiation on the emergence and flight propensity of treated males. We then assessed mating ability, survival, pupae per initial female (PPIF) and residual fertility of flies following irradiation at various doses after 1-h hypoxia conditioning. Finally, we determined the PPIF and residual fertility of the F1generation and the emergence of treated flies to the F2 generation. Results show that short-term conditioning (1 h) in hypoxia maintains or improves the qualities of the irradiated Gmm pupae. Regardless of irradiation in normoxia or hypoxia, higher residual fertility was observed in females than males in the F0 generation, and higher residual fertility in the F1 than the F0 generation for both sexes. However, the emergence rates of males decreased in the F2 generation compared with the F1 generation, a noteworthy finding for SIT programs for tsetse, implying diminishing populations of sterile flies.