Wing length plasticity in Eristalis arbustorum (Diptera : Syrphidae)

In Eristalis arbustorum wing length relative to overall body size is influe nced by the rearing temperature during the first half of the pupal stage. A t lower temperatures the wing length is relatively longer than at higher te mperatures. The wings of males are shorter than those of females. The respo nse to temperature is nonlinear and the sexes respond in a similar way. Sig nificant genotype-environment interactions were found, demonstrating geneti c variation among families in response to temperature. This plasticity is a lso observed in the field where relative wing length correlates well with t he average daily temperature two weeks preceeding the date the fly was coll ected. The adaptive value and the ecological consequences of this plasticit y are discussed.