Electrophysiological and Behavioral Responses of Adult Vine Weevil, Otiorhynchus sulcatus (Coleoptera: Curculionidae), to Host Plant Odors

Vine weevil, Otiorhynchus sulcatus F. (Coleoptera: Curculionidae), is an economically important pest species in many soft-fruit and ornamental crops. Economic losses arise from damage to the roots, caused by larvae, and to the leaves, caused by adults. As adults are nocturnal and larvae feed below ground, infestations can be missed initially, with controls applied too late. In the absence of a vine weevil sex or aggregation pheromone, the development of an effective semiochemical lure for better management of this pest is likely to focus on host-plant volatiles. Here, we investigate the electrophysiological and behavioral responses of adult vine weevils to volatile organic compounds (VOCs) originating from their preferred host plant Euonymus fortunei, and synthetic VOCs associated with this host when presented individually or as blends. Consistent electroantennographic responses were observed to a range of generalist VOCs. Behavioral responses of weevils to VOCs, when presented individually, were influenced by concentration. Vine weevil adults showed directional movement toward a mixture of seven plant volatiles, methyl salicylate, 1-octen-3-ol, (E)-2-hexenol, (Z)-3-hexenol, 1-hexanol, (E)-2-pentenol, and linalool, even though no, or negative, responses were recorded to each of these compounds presented individually. Similarly, vine weevils showed directional movement toward a 1:1 ratio mixture of (Z)-2-pentenol and methyl eugenol. Results presented here point to the importance of blends of generalist compounds and their concentrations in the optimization of a lure.