Direct and correlated responses to artificial selection on flight activity in the oriental fruit moth (Lepidoptera: Tortricidae)
The ability of a sufficient number of individuals to disperse is crucial for long-term survival of populations. However, dispersal is often energetically costly, and thus is expected to trade-off against other life-history traits. In insect pest species, the occurrence of individuals with high flight activity challenges management practices. We performed artificial selection on flight activity and measured correlated responses to selection in the oriental fruit moth, Grapholita (= Cydia) molesta, a widely distributed and expanding lepidopteran pest of fruit crops. Both sexes rapidly responded to the imposed regime of divergent selection, indicating an adaptive potential of flight activity in this species. Upward-selected moths died sooner than downward-selected ones, providing evidence for a cost of flight activity to adult survival, reputedly associated with enhanced metabolic rates. Oppositely-selected females had similar total reproductive output, disproving a trade-off between dispersal and reproduction, although females with higher flight activity laid their eggs sooner. The ratio of body weight to forewing surface (forewing loading) did not significantly differ between selected lines. The present study contributes to the understanding of dispersal evolution, and also provides new insights into life-history theory as well as important baseline data for the improvement of pest management practices. © 2010 The Linnean Society of London, Biological Journal of the Linnean Society, 2010, 100, 879–889.