Exploitation of Fabaceae plants by the Mexican bean beetle Epilachna varivestis (Coleoptera: Coccinellidae) in Japan.

Abstract

The host plant preference of the Japanese population of Epilachna varivestis Mulsant (Coleoptera: Coccinellidae) as well as the host suitability for the beetle were studied at 25°C, under a 15L:9D photoregime. Three Fabaceae crops: Vigna angularis (L.), Phaseolus vulgaris L. and Vicia faba L., and two Fabaceae weeds: Pueraria lobata (Willd.) and Lespedeza bicolor Turcz., were examined. None of the 1st stadium larvae of E. varivestis fed on L. bicolor. The survivorship of larvae was low on P. lobata, but some adults fed on this plant. Thus, P. lobata may be used as a temporary resource by E. varivestis before this beetle colonizes more suitable plants. Neither adults nor 1st stadium larvae of E. varivestis fed on V. faba, but almost all the beetles examined completed development and reproduced on V. angularis and P. vulgaris. Therefore, E. varivestis has the potential to become an economic pest of V. angularis, although this bean, at present, is not as suitable as P. vulgaris for larval development and reproduction.