Optimization of the irradiation dose for Anopheles coluzzii for implementation of the sterile insect technique

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Résumé

Background: The Sterile Insect Technique (SIT) is a population suppression strategy that
involves releasing sterile male insects, which mate with wild females, thereby inducing sterility
in the target population. Although SIT represents a promising complementary approach for
malaria vector control, its success depends on identifying an irradiation dose that ensures high
sterility while preserving the biological performance of males. This study aimed to determine
the optimal irradiation dose for sterilizing Anopheles coluzzii, a major malaria vector in West
Africa, under laboratory conditions in Burkina Faso.
Methods: Experiments were conducted using the 13th generation (G13) of the laboratory strain
of Anopheles coluzzii. Pupae were irradiated with doses ranging from 40 to 120 Gy. Key
biological parameters, including adult emergence rate, insemination rate, fertility (egg hatching
rate), and survival, were evaluated under controlled laboratory conditions.
Results: Irradiation did not affect adult emergence at any of the tested doses. Though
insemination rates declined at higher doses, they were not significantly impacted by doses
between 40 and 70 Gy. All irradiation doses negatively affected mosquito survival, with more
pronounced effects observed at higher doses. Egg hatching rates remained unaffected at 40 and
50 Gy, were significantly reduced at 60 Gy, and were completely suppressed at 70 Gy.
Conclusions: An irradiation dose of 70 Gy appears optimal for Anopheles coluzzii, because it
induces complete sterility (0% hatching) while maintaining insemination and emergence rates
similar to those of the control group, despite a dose-dependent reduction in survival. Further
studies are needed to evaluate the mating competitiveness of males irradiated at this dose under
semi-field and field conditions in order to support the implementation of the sterile insect
technique (SIT) in Burkina Faso.

Mots-clés

Malaria, Anopheles coluzzii, Sterile Insect Technique, irradiation dose, biological traits