Electroantennographic responses and field attraction to peach fruit odors in the fruit-piercing moth, Oraesia excavata (Butler) (Lepidoptera: Noctuidae)

Abstract

The olfactory responses of adult males and females of the fruit-piercing moth, Oraesia excavata, to lactones as specific components among ripe peach fruit odors were recorded by electroantennogram (EAG) techniques and trap captures in the field. Six lactones (γ-hexalactone, γ-octalactone, δ-octalactone, γ-decalactone, δ-decalactone and γ-dodecalactone) and a green leaf volatile compound (cis-3-hexen-1-ol) as the reference compound for normalization were used to measure EAG responses. The EAG response to γ-hexalactone, shown to be the highest among the six lactones tested, did not reach as high as that to a mixture of five lactones when 10% concentrations (v/v) of the lactones were used. There was no significant difference between males and females in EAG responses to those compounds. In the field experiment, the number of moths captured by traps baited with a mixture of the five lactones (γ-hexalactone, γ-octalactone, γ-decalactone, δ-decalactone and γ-dodecalactone=142 : 7 : 145 : 70 : 28, v/v) was about half that captured with ripe peach fruit; however, the moths were not captured by traps with individual lactones. These results show that O. excavata is attracted by a mixture of lactones, but not by individual lactones, although individual lactones are recognized by antennal receptors.