Electrophysiological and Behavioral Responses of Orchestes steppensis (Coleoptera: Curculionidae) to Ulmus Plant Volatiles

The flea-weevil <i>Orchestes steppensis</i> Korotyaev (Coleoptera: Curculionidae) is an Eastern Palaearctic Steppe species, and a serious pest of elm trees (<i>Ulmus</i> spp., Ulmaceae) by feeding on the leaves (adults) or mining them heavily (larvae) in Xinjiang, China. In order to search for chemical and ecological pest management practices, the olfactory preferences of <i>O. steppensis</i> for leaves of three elm species were investigated. The results revealed that <i>O. steppensis</i> has different host preferences for the three elm species: <i>U. pumila</i> L. first, followed by <i>Ulmus laevis</i> Pall. and <i>Ulmus densa</i> Litw. last. Volatile organic compounds from the leaves of the three <i>Ulmus</i> species were collected using dynamic headspace adsorption and analyzed through gas chromatography-mass spectrometry (GC-MS). A total of 94 volatile components in the healthy leaves and the infested leaves by <i>O. steppensis</i> of the three elm species were identified and analyzed, and 13 active compounds were identified using coupled gas chromatography-electroantennographic (GC-EAD) recording and GC-MS analysis. The response of <i>O. steppensis</i> to different concentrations of active compounds was determined using EAG, and the behavioral response to the highest EAG concentration of each active compound was determined. The results demonstrated that 3-hexen-1-ol, 3,7-dimethyl-1,3,6-Octatriene, methyl salicylate, 1-hexanol, and 3-hexen-1-ol, acetate were attractive to <i>O. steppensis</i>, while nonanal and 2-hexenal were repellent.