Antennal fine structure of two rapeseed pests, Xenostrongylus variegatus and Brassicogethes aeneus (Coleoptera: Nitidulidae), revealed by scanning electron microscopy

Xenostrongylus variegatus (Nitidulidae: Nitidulinae) and Brassicogethes aeneus (Nitidulidae: Meligethinae) are wide- spread in China and are major pests of rapeseed. Insect antennae play an important role in foraging, communication, mating, and other behaviors. In this study, we analyzed and compared the antennal sensilla of male and female adults of X. variegatus and B. aeneus using scanning electron microscopy (SEM). The results showed that both species have club-shaped antennae consisting of the scape, pedicel, and nine flagellomeres. Both species shared the same five main morphological types (sensilla trichodea (ST), sensilla basiconica (SB), sensilla styloconica (SS), sensilla chaetica (SC), Böhm sensilla (BS)), but differed in the number and composition of subtypes: X. variegatus possessed nine subtypes, while B. aeneus possessed eleven, with ST3 and SB4 being unique to the latter. However, no sexual dimorphism was observed in either species. We also inferred the functions of the sensilla based on the comparative morphology, thereby establishing a foundation for research on chemical communication in nitidulid beetles.