Isolation and identification of floral attractants from a nectar plant for the dried bean beetle, Acanthoscelides obtectus (Coleoptera: Chrysomelidae, Bruchinae).

BACKGROUND: The response of virgin females of the legume pest Acanthoscelides obtectus (Coleoptera: Bruchidae) to headspace extracts of volatiles collected from flowers of a nectar plant, Daucus carota, was investigated using behaviour (four-arm olfactometry) and coupled gas chromatography-electroantennography (GC-EAG).

RESULTS: Odours from inflorescences were significantly more attractive to virgin female beetles than clean air. Similarly, a sample of volatile organic compounds (VOCs) collected by air entrainment (dynamic headspace collection) was more attractive to beetles than a solvent control. In coupled GC-EAG experiments with beetle antennae and the VOC extract, six components showed EAG activity. Using coupled GC-mass spectrometry (GC-MS) and GC peak enhancement with authentic standards, the components were identified as α-pinene (S:R 16:1), sabinene, myrcene, limonene (S:R 1:3), terpinolene and (S)-bornyl acetate. Females preferred the synthetic blend of D. carota EAG-active volatiles to the solvent control in bioassays. When compared directly, odours of D. carota inflorescences elicited stronger positive behaviour than the synthetic blend.

CONCLUSION: This is the first report of behaviourally active volatiles linked to pollen location for A. obtectus, and development of the six-component blend is being pursued, which could underpin the design of semiochemical-based field management approaches against this major pest of stored products. © 2018 Society of Chemical Industry.