Differential utilization of nutrients during development by the xylophagous leafhopper, <i>Homalodisca coagulata</i>

Abstract

Abstract Utilization of nutrients at different stages of development was examined for the xylophage, Homalodisca coagulata (Say). Survivorship and consumption rates of second‐instar, fourth‐instar and adult leafhoppers were measured daily on the hosts Lagerstroemia indica L. and Euonymus japonica Thumb. Rates of consumption, assimilation efficiencies and daily assimilation of nitrogen, carbon, and individual organic compounds were calculated based on chemical analyses of xylem fluid and insect excreta. Gross growth efficiencies of diet utilization were also estimated by comparing biomass of young adults to estimates of nutrient utilization of the two host species. Different instars survived and utilized nutrients at varying rates on the two hosts. Second‐instar leafhoppers survived at higher rates and utilized nitrogen more efficiently on E. japonica than on L. indica. However, assimilated nitrogen was much less as a result of lower consumption rates. In contrast, adults on L. indica had increased longevity, utilized carbon more efficiently, and assimilated higher quantities of both carbon and nitrogen than those on E. japonica. Efficiencies of nutrient utilization were high for H. coagulata compared to folivores or phloem feeders, particularly in the conversion of ingested nutrients to assimilated compounds. Variations in diet utilization during development are discussed in terms of polyphagy.