Plant chemicals affect trade-offs between adult preference and larval performance of the rice water weevil, Lissorhoptrus oryzophilus

Herbivores use plant chemicals for host-plant selection to maximize their own and/or offspring performance. Since host plants that are optimal for mother and offspring are often different and spatially/temporally separated, how plant chemicals affect trade-offs between adult preference and larval performance remains unclear. We found that adults of the rice water weevil (Lissorhoptrus oryzophilus), one of the most important pests on rice in the world, preferred volatiles from barnyard grass over rice, tended to feed and oviposit on barnyard grass compared with rice. In contrast, larvae performed better on rice roots than on barnyard grass roots. Chemical analysis further show that rice roots had higher nitrogen and soluble sugar but lower lignin and cellhouse contents than barnyard grass. Together, these results suggest that violate, nutritive and defensive chemicals could jointly determine trade-offs of the adult preference and larval performance on these two hosts. As developing chemical-based technology is one of the main approaches for control of pest insects, our findings may also contribute to the future efforts for management of the rice water weevil.