Differences in Male Mate Recognition between the Invasive Anoplophora glabripennis (Coleoptera: Cerambycidae) and Japanese Native A. malasiaca

SIMPLE SUMMARY: The invasive Asian longicorn beetle Anoplophora glabripennis and native Japanese white-spotted longicorn beetle A. malasiaca show an extensive overlap with host plants, niches, and emergence season. Hybridization between these two species is suspected. The surface of the female body is covered with contact sex pheromones that elicit male mating behavior within species. We evaluated the contact pheromonal activity of crude extract and fractions of female A. glabripennis and revealed a hydrocarbon fraction to show activity; however, it was relatively weak. There might be other, as yet unidentified active compounds in the extract. Only a small number of male A. glabripennis showed mating behavior when they were exposed to the crude extract of female A. malasiaca, whereas a considerable number of male A. malasiaca showed mating behavior when exposed to both female A. glabripennis and A. malasiaca extracts. Gomadalactones are essential contact pheromone components that elicit mating behavior in male A. malasiaca. We, therefore, attempted to detect gomadalactones in female A. glabripennis extract, but without success. We investigated the possible reasons for this phenomenon and the difference in male mate recognition systems between A. glabripennis and A. malasiaca. ABSTRACT: The Asian longicorn beetle Anoplophora glabripennis is a recently arrived invasive species to Japan. The Japanese native A. malasiaca shows an extensive overlap with A. glabripennis with host plants, niches, and emergence season. Hybridization between these two species is suspected in Japan. The surface of the female is covered with contact sex pheromones that elicit male mating behavior within species. We evaluated the contact pheromonal activity of crude extract and fractions of female A. glabripennis coated on a black glass model and revealed a hydrocarbon fraction and a blend of fractions to show activity but relatively weak, suggesting the presence of other unknown active compounds. Few male A. glabripennis showed mating behavior when they were exposed to a crude extract of female A. malasiaca. However, a considerable number of A. malasiaca males mounted and showed abdominal bending behavior when presented with glass models that were coated with each extract of female A. glabripennis and A. malasiaca. Gomadalactones are essential contact pheromone components that elicit mating behavior in male A. malasiaca; however, we could not detect them in female A. glabripennis extract. Here, we investigated the possible reasons for this phenomenon and the difference in male mate recognition systems between these two species.