Electrophysiological Responses of Curculio elephas (Coleoptera: Curculionidae) to Chestnut Plant Volatiles

Curculio elephas is an oligophagous insect, attacking fruits of chestnut ( Castanea spp.) and oak ( Quercus spp.). It is considered one of the most important pests of European chestnut ( Castanea sativa ) in Europe and it occurs in a continuous range throughout Greece. The aim of this study was to identify the potential volatile organic compounds (VOCs) from chestnut reproductive plant tissues (catkin, nut, and bur) acting as attractants for C. elephas adults to be used for the development of a monitoring system integrating pest management tools. VOCs were sampled in situ during spring and autumn of 2021 and 2022 in different areas of Greece. For the collection and identification of VOCs, the dynamic-headspace technique combined with gas chromatography–mass spectrometry (GC–MS), was employed. In total, 122 compounds from these tissues were detected, with most of them being terpenes (>80%). Further analysis showed that chestnut trees release different VOCs depending on their developmental stage. Antennae of both male and female chestnut weevil adults responded to terpenes, green leaf volatiles, and methyl salicylate. Identification of semiochemicals for manipulating weevils’ behavior will contribute to the development of efficient monitoring tools for the detection and management of this pest.