The effect of host plant cultivar on the fitness of aphids

Plant susceptibility to insect attack under field conditions can differ from host suitability when tested in the laboratory under controlled conditions. In the laboratory, we tested seven crape myrtle (Lagerstroemia spp.) cultivars from two parentages, two height classes and four pedigrees for their suitability as hosts for the crapemyrtle aphid (Sarucallis kahawaluokalani). We recorded aphid daily fecundity and longevity by rearing four aphid clonal lines on excised leaf tissue. Daily fecundity did not differ between cultivars or clones, but total fecundity was different among parentage, mature plant height and pedigree. Our results are not completely congruent with those found for field susceptibility, which could be different due to environmental or tritrophic interactions.