Simple Summary
Longhorn beetles are known to infest a variety of plants, such as trees, flowers, and crops. These insects frequently move on vertical trunks and on the undersides of leaves, aided by specialized microscopic setae that are adhesive and located on the ventral sides of their tarsi. This study used scanning electron microscopy to examine and compare the attachment structures of three species of Cerambycidae beetles and one Vesperidae beetle species. The results revealed that the first three segments of their tarsi are broadened and covered with different forms of adhesive setae. The variation in these adhesive structures appears to be influenced by phylogenetic, ecological, and gender-related factors.
Abstract
Longhorn beetles mainly harm trees, flowers, and certain crops. They are closely associated with their host plants and often climb on vertical trunks, branches, and the underside of leaves. Their tarsi have numerous micro-scale adhesive setae on the ventral side. These setae provide sufficient force to enable the beetles to adhere firmly to smooth or slightly micro-structured surfaces. This study observed and analyzed the ultrastructures of the adhesive setae of three species from different subfamilies of Cerambycidae and one species from Vesperidae using a scanning electron microscope. The comparative analysis focused on characterizing the types, morphology, distribution patterns and adhesion mechanisms of the adhesive ultrastructures in four longhorn beetle species. The results showed that the longhorn beetles generally had pseudotetramerous tarsi (except An. chinensis, which had tetramerous tarsi), and that tarsomeres I–III were expanded and widened to increase the contact area between the tarsi and the substrate. Furthermore, a large number of micro-scale adhesive setae were present on the ventral surface of these tarsomeres. In total, five types of adhesive setae were found in the four species studied. The three species belonging to the Cerambycidae family exhibited adhesive setae with numerous short setules, while in the species Mantitheus pekinensis belonging to Vesperidae, there are two types of adhesive setae without any short setules. The differentiation of the adhesive structures in longhorn beetles is shaped by the combined effects of phylogeny, sexual dimorphism, and host-plant adaptations.