Insects allocate eggs adaptively across their native host plants

Abstract

Finding plants for their eggs is the only parental care shown by many winged insects. Hatched juveniles often feed on one individual plant until gaining the power of flight as adults. Females are therefore predicted to lay more eggs on plants supporting high offspring survival. Many experiments comparing egg-laying and offspring survival across plant species refute this, leading to alternative concepts including ‘enemy free space’, ‘optimal bad motherhood’ and ‘neural constraints’. Whether tested plants have the same geographic origin as the insect is often overlooked. Using 178 oviposition–performance studies, we found when insects and plants share a native range, 83% of insect species associated their eggs with plants conferring highest offspring survival. This was broadly true across insect taxa and for generalists and specialists. Only 57% did so with non-native plants. That females are attracted to hosts with high offspring survival is a well-supported theory that does not necessarily apply to exotic host plants.