Keele Research Repository

Anopheles gambiae is a major vector of malaria in sub-Saharan Africa. Given the widespread emergence of pesticide resistance in Anopheles gambiae populations, vector control programs involving the release of sterile males or genetically-modified male mosquitoes designed to diminish malaria transmission are eliciting renewed interest.
The success of such mosquito release projects depends on the ability of released males to effectively mate and transfer sperm to wild females. Here, firstly we investigated the interactive effect of the environmental factor hydric stress and adult mosquito phenotypic quality on male and female reproductive success. Secondly, we studied the impact of colonization and genetic modification on potential correlates of reproductive success by comparing sperm quality and sexual organs in the wild strains with transgenic and colonized strains. We then experimentally tested for the potential effects of inbreeding depression on reproductive traits by creating hybrid males from inbred colonized strains. The quality of these 'Super males' was assessed by comparing sperm quality, testes and accessory gland sizes, and estimating the quantity of Plugin and Transglutaminase proteins in their accessory glands. Finally, we assessed the reproductive performance of Super males by estimating the amount of accessory gland protein transferred to females after overnight mating and estimating female fecundity and number of larvae produced.
The results underline the importance of female phenotypic quality as determinant of mosquito reproductive success. Inbreeding associated with the colonization and/or genetic modification processes strongly affects sperm length. In contrast, offspring of field-collected females strain have smaller testes and larger accessory glands than older colonized strains. Super males had a good sperm quality. Importantly, the present study suggests that Super males could represent a way to improve male’s reproductive quality under laboratory conditions.