Effect of larval nutrition on the reproductive success of male Anopheles gambiae s.l. mosquitoes

Background/Question/Methods The success of genetically modified mosquitoes for malaria control depends on manipulation of the factors that enhances their reproductive success within wild populations. We studied the effect of three levels of larval food on development time, adult body size, emergence, insemination and oviposition success, survival and average life expectancy of Anopheles gambiae s.l. mosquitoes. The colony used to generate eggs for the experiment was first identified morphologically and molecularly using PCR-based methods. We used three food levels: high (200 mg), medium (100 mg) and low (50 mg) amounts of Tetrafin Godfish food. Larvae were reared in plastic trays with larval density of 200 individuals per tray. After emergence, 10 females were mated with 20 males (per food level) in three separate plastic bucket cages for one hour. Females were subsequently dissected after death and mating confirmed by examining the spermathecae for the presence of sperm. Survival and average life expectancy experiments were conducted over a 22-day period for two groups of unmated males: Starved (water only) and Fed (10% sugar solution). Five replicates were performed of each set of comparisons. Results/Conclusions   Mean adult male body size was significantly influenced by (F-value = 51.847; P < 0.01) and correlated with larval nutrition (r = 0.946; P < 0.01). Oviposition success was significantly correlated with insemination success (r = 0.698; P < 0.01) but not with male larval nutrition. Survival and mean life expectancy experiments showed significant variation in the distribution of survival trends, with males fed the high food amount having the lowest survival (F-value = 4.491, P = 0.012) with mean survival of 11 days. Although adult male body size and survival/mean life expectancy were significantly influenced by larval nutrition, other components of male reproductive success were not. Nevertheless, a careful manipulation of larval food level could be useful in the mass-rearing of transgenic Anopheles gambiae mosquitoes with large optimal body sizes and long life spans. This work points to a need to understand the effect of quantity and quality of different larval food sources on the reproductive success of transgenic mosquitoes.