The impact of oviposition-site deprivation in gravid females of Anopheles gambiae (Diptera: Culicidae) on fecundity, trophic behaviour and life expectancy

Abstract

Short and long dry spells occur throughout the year and limit the access of gravid mosquitoes to oviposition sites. Using simulations in laboratory conditions, we explored the possible consequences of a long duration of egg retention on reproductive capacity, trophic behaviour, life expectancy and gonotrophic cycle in a context of breeding-site absence. KISUMU and wild gravid females of Anopheles gambiae were subjected to a delay in egg-laying following the preset modalities as immediate egg-laying versus retention for 5, 10 and 15 days. The egg batch size and the hatching rate were measured. In addition, blood-feeding patterns and life expectancy were investigated. Our study showed that oviposition occurs much faster in the standard susceptible laboratory strain An. gambiae KISUMU with a lapse of 2.2 days than in the wild females of An. gambiae with an average of 5 days between the second blood meal and egg-laying. In this experiment, the egg-retention time did not significantly affect the number of eggs laid. In the absence of breeding sites, the rate of egg-hatching decreased in proportion as the retention time became longer. The study also showed that gravid females deprived of oviposition sites continue to take blood meals. The average longevity of non-gravid females was estimated to be lower than that of gravid females. The oviposition-site deprivation has no impact on female fecundity and blood feeding, but influences egg-hatching.