Methyl salicylate and trans‐anethole affect the pheromonal activity of homofarnesal,the female sex pheromone of azuki bean beetle

Plant essential oils (EOs) exhibit an array of biological activities against insect pests. However, their negative influences on the pheromonal activity of azuki bean beetle (ABB), Callosobruchus chinensis L. have not received research attentions. ABB is a field‐to‐storage pest of legumes, and its female produces the sex pheromone known as homofarnesal with two isomeric components: 2E‐ and 2Z–homofarnesal, (2E,6E)‐7‐ethyl‐3,11‐dimethyl‐2,6,10‐dodecatrienals and (2Z,6E)‐7‐ethyl‐3,11‐dimethyl‐2,6,10‐dodecatrienals. We evaluated the effects of three EOs and their two major components on the attractiveness of male ABBs to synthetic homofarnesal (2E‐:2Z–homofarnesal = 6:4) using Y‐tube olfactometry in laboratory and rocket traps in the semi‐open polyhouse. Y‐tube olfactometry showed the significant negative effect of EOs of Illicium verum, Croton anisatum at 10 and 100 ng, and Gaultheria fragrantissima at 100 ng against homofarnesal (100 ng) in attracting male ABBs. Similarly trans‐anethole (at 10 and 100 ng) and methyl salicylate (at 100 ng) also ascertained significant negative effect against homofarnesal (100 ng) in Y‐tube olfactometry. When 10 mg of each of trans‐anethole and methyl salicylate was released at the downstream of 30 mg homofarnesal lure in rocket traps, highly significant effect was achieved against attractiveness of homofarnesal to ABB males. This study ascertained significant level of negative effect of the tested EOs and their major components to homofarnesal, tracing out a new opportunity of integrating them in ABB management programs both in field and storage.