The Chemical Basis of the Host Selection in the Mexican Bean Beetle, Epilachna varivestis (Coleoptera, Coccinellidae)1

Abstract

Fractions containing phaseolunatin and/or related cyanogenetic glycosides were isolated from leaves of bush and lima beans, and were shown to elicit strong biting response from the Mexican bean beetle, when present at low concentrations in combination with glucose. After acid hydrolysis these fractions elicit a negligible response. At higher concentrations they act as inhibitors. It has been suggested that phaseolunatin in high concentrations is responsible for the resistance of certain varieties of bush beans and lima beans to the Mexican bean beetle.