Feeding responses of four phytophagous lady beetle species (Coleoptera: Coccinellidae) to cucurbitacins and alkaloids

Abstract

Feeding responses of adults and larvae of Epilachna admirabilis, E. boisduvali, E. vigintioctomaculata, and E. vigintioctopunctata to four cucurbitacins (B, E, I and E-glucoside) were investigated. Both adults and larvae of E. admirabilis, which mainly feeds on the genus Trichosanthes (Cucurbitaceae), were strongly stimulated to feed by these cucurbitacins, especially by cucurbitacin E-glucoside. E. boisduvali feeds on Diplocyclos palmatus (Cucurbitaceae). Larvae of this species were stimulated to feed by all four cucurbitacins, especially by cucurbitacin I, and adults were stimulated to feed by cucurbitacin B only. E. vigintioctomaculata and E. vigintioctopunctata, which usually feed on solanaceous plants, were also stimulated to feed by cucurbitacins. They were not stimulated to feed by solanine and tomatine, which are usually contained in solanaceous host plants.