Individual variation in oviposition preference, and its interaction with larval performance in an insect predator.

Individual female Episyrphus balteatus (DeGeer) (Diptera: Syrphidae) show different oviposition preferences when presented with two aphid prey species, Aphis sambuci L. and A. fabae (Scop). After larvae were reared on those aphids, some fitness components indicated that individual females were adapted to different host-use strategies, with preference for one aphid prey species entailing a trade-off in poorer performance on another. We interpret the pattern of significant interactions as suggesting that natural selection has responded to the nutritional value of prey.