Electroantennogram and behavioral responses of Cotesia plutellae to plant volatiles

Abstract Plant volatiles have been demonstrated to play an important role in regulating the behavior of Cotesia plutellae , a major larval parasitoid of the diamondback moth (DBM), Plutella xylostella , but little is currently known about the function of each volatile and their mixtures. We selected 13 volatiles of the DBM host plant, a cruciferous vegetable, to study the electroantennogram (EAG) and behavioral responses of C. plutellae . EAG responses to each of the compounds generally increased with concentration. Strong EAG responses were to 100 μL/mL of trans ‐2‐hexenal, benzaldehyde, nonanal and cis ‐3‐hexenol, and 10 μL/mL of trans ‐2‐hexenal and benzaldehyde with the strongest response provoked by trans ‐2‐hexenal at 100 μL/mL. In the Y‐tube olfactometer, C. plutellae , was significantly attracted by 1 μL/mL of trans ‐2‐hexenal and benzaldehyde. β‐caryophyllene, cis ‐3‐hexenol or trans ‐2‐hexenal significantly attracted C. plutellae at 10 μL/mL, while nonanal, benzyl alcohol, cis ‐3‐hexenol or benzyl cyanide at 100 μL/mL significantly attracted C. plutellae . Trans ‐2‐hexenal significantly repelled C. plutellae at 100 μL/mL. EAG of C. plutellae showed strong responses to all mixtures made of five various compounds with mixtures 3 ( trans ‐2‐hexenal, benzaldehyde, nonanal, cis ‐3‐hexenol, benzyl cyanide, farnesene, eucalyptol) and 4 ( trans ‐2‐hexenal, benzaldehyde, benzyl alcohol, ( R )‐(+)‐limonene, β‐ionone, farnesene, eucalyptol) significantly attracting C. plutellae . These findings demonstrate that the behavior of C. plutellae can be affected either by individual compounds or mixtures of plant volatiles, suggesting a potential of using plant volatiles to improve the efficiency of this parasitoid for biocontrol of P. xylostella .