Observation of antennal sensilla in <i>Xylotrechus grayii</i> (Coleoptera: Cerambycidae) with scanning electron microscopy

Abstract

The longicorn beetle Xylotrechus grayii (White, 1855) has been spreading rapidly in China, causing mass mortality of honeysuckle which is economically and medicinally important. In order to elucidate the mechanisms of mate and host location and to advance efficient control methods, antennal sensilla features were investigated in both sexes of X. grayii using scanning electron microscopy (SEM). The filiform antennae of both sexes consist of scape, pedicel, and nine flagellomeres (f1-9). Five types of sensilla were observed: sensilla chaetica (5 subtypes, SC1-5), sensilla basiconica (4 subtypes, SB1-4), Böhm bristles (Bm), grooved peg sensilla (Gp), and sensilla campaniformia (Ca). SC were most common on the antennae, followed by SB and Bm. No significant sexual differences in the type, amounts, and distribution of antennal sensilla were found except for the distribution of SB clusters and Ca. SB clusters and Ca occurred on f1-8 of male antennae but were absent on those segments in females, suggesting a potential function as receptors for female sex pheromones. The putative functions of other sensilla are discussed based on their characteristics in related species. This study provides an important foundation for further research on sensory mechanisms and control measures of X. grayii.