Effects of Age and Size on Anopheles gambiae s.s. Male Mosquito Mating Success

Before the release of genetically-modiÞed or sterile male mosquitoes in an attempt to control local populations of malaria vectors, it is crucial to determine male traits involved in mating success. The effects of male size and age as determinants of male mating success in Anopheles gambiae s.s. were measured in the Þeld and under laboratory conditions in Burkina Faso. First, the body sizes (estimated by wing length) of mating, swarming, and indoor-resting male mosquitoes were compared over a 3-yr period (2006Ð2009) from July to October in Soumousso and Valle´e du Kou, two villages in western Burkina Faso. Second, the age structure of swarming and resting male mosquitoes were characterized based on the number of spermatocysts and the proportion of sperm in the reservoir of wild-caught male testis. Third, male age effects on the insemination rate of female An. gambiae were investigated in the laboratory. The mean size of males collected in copula was signiÞcantly larger than the mean for swarming males and indoor-resting males. The optimum male age for successful insemination of females was 4Ð8 d. These results suggest that male size is an important trait in determining male mating competitiveness in the Þeld. Although age was not found to be a signiÞcant factor in mating competitiveness, it was signiÞcantly correlated with swarming behaviors in the Þeld and insemination success in the laboratory.Theimplications of these results in terms of sexual selection in An. gambiae and vector control programs are further discussed. (Résumé d'auteur