Effects of density dependent larval competition on the life history traits of Aedes aegypti and Aedes albopictus (Diptera: Culicidae)

Consequences of larval competition at the population level provide explanation for the differences in relative abundance of Aedes aegypti and Aedes albopictus in different geographical regions. The outcome of competition is assessed through the estimates of the life history traits as a response to varying density and resource available for larval development. In the present study, variations in the life history traits due to density-dependent intra- and inter- specific competition involving A. aegypti and A. albopictus were assessed following the minimalist model. The instar-I larvae (0-day old F2 generation) of both Aedes species were reared to the adult stages using the initial rearing density of 1, 2, 4 and 6 (individuals/10ml) in multiple replicates. The age at pupation, pupal weight, adult weight and adult wing length of the individuals were considered as the response variables and surrogates of estimating the competitive interactions. Density dependent variations in the competitive interactions were evident for both the mosquitoes with reference to the selected life history traits. In A. aegypti, the life history traits varied with the levels of competition, which was not observed for A. albopictus . Although the density levels considered in the present instance were lower than in earlier studies, the observations were similar, with A. albopictus being competitively superior. It appears that irrespective of the density levels, interspecific competition affects A. aegypti and thus may bear population level consequences and overall abundance in the areas where both species are present.