Sexually dimorphic body size and development time plasticity in Aedes mosquitoes (Diptera: Culicidae).

Abstract

Background: Sexual size dimorphism (SSD) in insects often accompanies a sexual difference in development time, sexual bimaturism (SBM).

Goal: To determine whether three Aedes mosquito species have similar plasticity in SSD, attain sexual dimorphism through similar strategies, and whether SSD and SBM are associated.

Organisms: Aedes albopictus, Aedes aegypti, and Aedes triseriatus (Diptera: Culicidae).

Methods: In four different food availability environments, we quantified plastic responses of relative growth rate (RGR), development time, and adult body size in individually reared males and females.

Results: Food availability affected RGR differently for the sexes for all three species. The RGR of males and females differed significantly in the 0.1 g/L food treatment. This difference did not account for observed SSD. Food levels over which the largest changes in RGR were observed differed among the species. Male and female adult mass and development time were jointly affected by food availability in a pattern that differed among the three species, so that degree of SSD and SBM changed differentially with food availability for all three species. Development time was generally less sexually dimorphic than mass, particularly in A. albopictus. At lower food levels, A. aegypti and A. triseriatus had accentuated dimorphism in development time. These results, combined with our knowledge of mosquito life history, suggest that a direct benefit of SBM is improbable for mosquitoes and that the observed intersexual differences in development time are more likely byproducts of selection for SSD.