Antennal morphology and sensillar ultrastructure of Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae)

Abstract

The parasitoid beetle Dastarcus helophoroides (Fairmaire) (Coleoptera: Bothrideridae) is an important parasite of longicorn beetles (Cerambycidae), and has been used in China for the biological control of the Asian longicorn beetle and the Japanese pine sawyer. In this study the antennal morphology and sensillar ultrastructure of D. helophoroides were observed using scanning electron microscopy and transmission electron microscopy. Two types of sensilla trichodea (Tr. 1 and Tr. 2), two types of sensilla basiconica (Ba. 1 and Ba. 2), three types of sensilla chaetica (Ch. 1, Ch. 2 and Ch. 3), and Bohm's bristles were identified according to the morphology and fine structure of each type of sensilla in both sexes. Ultrastructural studies revealed porous structures on the cuticle wall and dendritic branches in the inner lumen of Tr. 1, Tr. 2, Ba. 1, and Ba. 2, thereby suggesting chemoreceptor functions. No difference in shape, structure, sensilla distribution and typology was observed between the sexes. These structures likely have roles in the host locating and habitat searching behavior of adult D. helophoroides, and suggest future studies on the olfaction and host location behavior of D. helophoroides and other coleopteran parasitoids.