Behavioural and electrophysiological responses of the small avocado seed borer, Conotrachelus perseae to avocado leaf, flower and fruit volatile extracts

The small avocado seed borer, Conotrachelus perseae Barber (Coleoptera Curculionidae), is an important insect pest of avocado (Persea americana Miller, Lauraceae) in Mexico. In this study, we showed that both sexes of C. perseae were attracted to flower, fruit, and leaf avocado (cv. Hass) volatile extracts, compared to a solvent control, in a Y-tube olfactometer. Among extracts, females were more attracted to flower and fruit extracts than to leaf extract, while males did not show preference for any of the extracts. In addition, females also showed stronger electroantennogram (EAG) responses to flower than to leaf extracts, while their EAG re-sponses to fruit extracts were intermediate between their responses to flower and leaf extracts. In contrast, males did not show any differences in their EAG responses to the three extracts. Gas chromatography-mass spectrometry analyses showed that flower ex-tracts contained a mixture of compounds including hydrocarbons, monoterpenes (hydrocarbons and oxygenated), and sesquiter-penes. Monoterpenes were the main components in flower extract, while sesquiterpenes were the main components in fruit and leaf extracts. We demonstrated that C. perseae females and males responded behaviourally and electrophysically to leaf, flower and fruit volatiles of P. americana (cv. Hass). These results can help to formulate an attractant for C. perseae. However, further work is needed to elucidate the crucial compounds involved in weevil attraction.