Attraction of Callosobruchus chinensis Linnaeus (Coleoptera: Bruchidae) to Volatiles Emitted by Various Leguminous Seeds

Callosobruchus chinensis (L.) (Coleoptera: Bruchidae) is a destructive storage pest, causing serious losses to stored legume seeds. The olfactory system of these insects plays an important part in assisting them locate host plants. Olfactory responses of female C. chinensis adults to volatiles of disparate bean seeds (Vigna radiata, Pisum sativum, Vigna unguiculata, Glycine max, and Phaseolus vulgaris) were evaluated using electroantennography (EAG) and various olfactometer bioassays. In behavioral bioassays, C. chinensis was mostly attracted to the volatiles of V. radiata. We detected 37 components in the volatile profile of V. radiata. Among these, nonanal (11.83%), 1-hexanol (7.35%), hexanal (5.71%), tetradecane (3.83%), and 2-ethyl-1-hexanol (3.70%) were present in relatively high contents. EAG recordings indicated that the antennae of C. chinensis can detect these five compounds, and that adult C. chinensis exhibited significant positive behavioral responses to them across various concentrations. No significant differences in the olfactory preference of C. chinensis for nonanal were observed among different concentrations, while attraction was greatest for 1 µg/µL 1-hexanol, 25 and 10 µg/µL hexanal, 25 µg/µL tetradecane, and 1 µg/µL and 10 µg/µL 2-ethyl-1-hexanol. Based on comparisons of these compounds at their most attractive concentrations, C. chinensis exhibited the greatest olfactory preference for 1-hexanol. Adult female C. chinensis can keenly perceive volatile compounds emitted by the preferred legume V. radiata via their peripheral olfactory systems, and they showed positive chemotactic responses to these volatile semiochemicals. These results provide new insight into mechanisms underlying host preference in this stored-product pest. Among the compounds tested, 1-hexanol represents a potential attractant for C. chinensis monitoring and control.