Morphological and histological observations on the hair brush of Endoclita vietnamensis (Lepidoptera, Hepialidae).

The most prominent insect pest harming eucalyptus trees in China was Endoclita vietnamensis, which resulted in considerable losses to the environment and economy. This study examined the hair brush on the postpedes of male E. vietnamensis using transmission and scanning electron microscopy. The finding revealed that the hair brush was made up of many large, flattened, pale yellow, specialized scales that were highly elongated. These scales were firmly affixed to the epidermis at their base, and at the attachment site, there was a swollen hair follicle. The interior of the pencil was hollow with ducts, and the surface featured rows of pores and longitudinal ridges. Numerous features, including mitochondria, lipid droplets, smooth and rough endoplasmic reticulum, and microvilli, were present in the tissue cells of the tibial segment of postpedes of male moths. The tibial segment of postpedes of male moths exhibited thicker epidermis, cavities, and voids in the tissue cortex, suggesting the presence of secretory activities in the tissue cells. With the location and structure of the pheromone gland determined, a theoretical foundation for future research into the communication between the female and male E. vietnamensis as well as the development of sex-specific pheromone-based catching and killing methods will be available. RESEARCH HIGHLIGHTS: Endoclita vietnamensis Buchsbaum & Grehan, 2022 is the most prominent insect pest harming eucalyptus trees in China. With the location and structure of the pheromone gland determined, a theoretical foundation for future research into the communication between the female and male E. vietnamensis as well as the development of sex-specific pheromone-based catching and killing methods will be available.