Electrophysiological and behavioral responses of Helicoverpa assulta (Lepidoptera: Noctuidae) to tobacco volatiles

Abstract

The Oriental tobacco budworm moth, Helicoverpa assulta (Guenee) (Lepidoptera: Noctuidae), is a serious pest on tobacco in China. The flowering stage of the host plant is one of the most attractive stages to H. assulta for feeding and oviposition. Nine electrophysiologically active compounds in tobacco headspace at flower stage were detected by gas chromatography–electroantennographic detection (GC–EAD). These compounds were subsequently identified by gas chromatography-mass spectrometry (GC–MS) as (E)-β-ocimene, octanal, (Z)-3-hexenyl acetate, (Z)-3-hexen-1-ol, nonanal, (Z)-3-hexenyl-2-methyl butyrate, decanal, linalool, and (E)-β-caryophyllene. The synthetic blend containing nine of the above compounds attracted mated H. assulta females from a distance by upwind oriented flight. Selected subtraction assays showed that the 4-component mixture of (E)-β-ocimene, (Z)-3-hexenyl acetate, nonanal, and (E)-β-caryophyllene elicited equivalent levels of attraction as the 9-component mixture. The removal of any of the four compounds from the 4-component blend resulted in a significant decrease in female upwind flight behavior.