UTILIZATION OF PRIMARY NUTRIENTS BY THE POLYPHAGOUS XYLOPHAGE, HOMALODISCA-COAGULATA, REARED ON SINGLE HOST SPECIES

Feeding experiments were conducted to assess development of the polyph agous leafhopper, Homalodisca coagulata, on single host species. Insec ts were reared from eggs on two cultivars of Euonymus japonica, two cu ltivars of Lagerstroemia indica, and two species of Prunus. Only insec ts on nonvariegated E. japonica and L. indica cv. Osage survived to ma turity, although a substantial proportion of those on P. salicinia dev eloped to the fourth instar. Chemical profiles of food source (xylem f luid), insect excreta and body composition, and consumption rates were used to estimate assimilation efficiencies, daily assimilation rates, and efficiency of conversion of food into biomass for all primary nut rients identified in the xylem fluid. Rates of successful maturation w ere greatest on the highest nitrogen and carbon source (nonvariegated E. japonica) and were associated with low consumption rates, high assi milation efficiencies, and prolonged instar durations. Developmental p eriod on L. indica was shorter and consumption rates were higher, yet assimilation efficiencies were reduced and young nymphs had lower surv ivorship. Low consumption rates, coupled with the low nutritional valu e of P. salicinia precluded sufficient accumulation of nutrients to co mplete development. Insects fed on hosts with xylem fluid containing h igh ratios of amides to total organic compounds (indicative of low car bon to nitrogen ratios) had higher consumption rates but less efficien t assimilation of primary nutrients. Carcass analyses of newly eclosed adults suggest that regulation of consumption rates and assimilation efficiencies to provide adequate accumulation of essential amino acids may be pivotal for successful development. (C) 1996 Wiley-Liss, Inc.