Plant genotype and the preference and performance of herbivores: cultivar affects apple resistance to the florivorous weevil Anthonomus pomorum

摘要

Plant resistance strongly depends on plant characteristics that affect herbivore preference or performance. Different plant genotypes may express specific characteristics that lead to differential resistance to herbivores. Few studies have investigated these aspects for weevils, a particularly speciose taxon of insect herbivores, on fruit tree cultivars, which are vegetatively propagated. We studied the influence of apple cultivar on preference and performance of a fruit tree herbivore, the flower-feeding apple blossom weevil Anthonomus pomorum (Coleoptera: Curculionidae). We quantified field infestation of five different apple genotypes by the weevil at different collection dates as measure of preference, as well as the mass and emergence time of weevils developing on these cultivars as measures of performance. Infestation of apple flower buds by A. pomorum differed significantly between cultivars. The collection date affected the number of infested flowers in a cultivar-specific way. Weevil mass differed significantly between apple cultivars. The average mass of weevils from Ariwa, the cultivar producing the heaviest weevils, was 40% higher than the mass of weevils from Rewena, the cultivar producing the lightest weevils. Weevil emergence time from infested flowers differed significantly between cultivars. Weevils emerged earliest from cultivars Ariwa and Retina, at an intermediate time from Discovery and Florina, and latest from Rewena. The present study demonstrates that preference and performance of florivores feeding on fruit trees can strongly differ between apple cultivars representing specific tree genotypes. These differences may directly and indirectly affect herbivore and antagonist populations and can be considered for pest management.