Variation in reproductive traits associated with different host plants in the subsocial bug Elasmucha putoni (Hemiptera: Acanthosomatidae)

Host plants are an important selective factor for the evolution of reproductive traits in herbivorous insects. Among different host plants, offspring will be exposed to different environmental conditions, and parents are expected to allocate reproductive resources adaptively to their offspring according to such environmental heterogeneity. Elasmucha putoni Scott (Hemiptera: Acanthosomatidae) is a bivoltine shield bug showing maternal care. We examined the variation in reproductive traits, that is, egg size, clutch size and the trade-off between them, between two generations of a population and two populations of the same (later) generation, which differ in their host plants. Controlling for female body size, a significant difference was detected in egg size, but not in clutch size between the earlier generation on Morus australis and the later one on Euptelea polyandra or Rosa multiflora. Moreover, there was no difference in the two traits between the populations (one using E. polyandra and another using R. multiflora) of the same generation. A significant trade-off between egg size and clutch size was detected in the earlier generation on M. australis but not in the later generation on E. polyandra or R. multiflora. This is the first study indicating variable reproductive allocation according to different host plants in herbivorous insects with maternal care.