Food utilization of aphidophagous hoverfly larvae (Diptera: Syrphidae, Chamaemyiidae) on herbaceous plants in an urban habitat

Abstract

AbstractWe examined food utilization in a community of aphidophagous hoverfly larvae (Diptera: Syrphidae and Chamaemyiidae) in open lands in an urban habitat in central Japan for 3 years. The community consisted of 17 hoverfly species feeding on 20 aphid species occurring on 14 species of dominant herbaceous plants. In terms of larval prey preference, the dominant eight species of hoverfly were categorized into three groups: a polyphagous ‘generalist’ group consisting of four species, Episyrphus balteatus, Betasyrphus serarius, Syrphus vitripennis and Sphaerophoria sp.; an oligophagous ‘specialist’ group consisting of three species, Metasyrphus hakiensis, Dideoides latus and Paragus hemorrhous; and Leucopis puncticornis, which showed a preference for two aphid species on the plant Torilis scabra. The prey aphids of the second group have behavioral or morphological defense mechanisms that are effective for preventing attacks by generalist hoverflies; two prey aphids are aggressive toward generalist predators and the others are protected by ant‐attendance. The specialist hoverflies seem to be adapted to overcome these defense mechanisms. The prey ranges overlapped little between the generalist and the specialist groups, while those within the generalist group overlapped greatly.