Expression of chemosensory proteins in hairs on wings of Locusta migratoria (Orthoptera: Acrididae)

The hairs on the wings of Locusta migratoria were observed and mapped using light microscopy, as well as by scanning and transmission electron microscopy. Based on their ultrastructure, we can distinguish four main types of hairs on the wings of adult L. migratoria, viz, short, medium and long hairs, and sensilla chaetica. The long hairs are located only on the ventral surface of the hindwing, whereas the other three types are present both on the dorsal and ventral surfaces of forewing and hindwing in both sexes. Medium hairs and sensilla chaetica are significantly more abundant on the dorsal surface of forewings in both females and males, than on the ventral surface, whereas the opposite was observed for short hairs (P < 0.01). No significant difference between males and females was observed in the density of any type of hairs (P > 0.1). Several dendritic branches, enveloped by a dendrite sheath, are situated in the lymph cavity of sensilla chaetica. Instead, no dendritic structure was observed in the cavity of the other three types of hairs. Immunocytochemical localization of chemosensory proteins (CSPs) was performed on ultrathin sections of hairs on wings. The antiserum against chemosensory proteins from L. migratoria (LmigCSP-II) strongly labelled sensilla chaetica, with gold granules only found in the outer sensillum lymph. In addition, the epidermal cell membrane of the wing was stained by the antiserum against LmigCSP-II. The other three types of hairs were never labelled. The results indicate that the wings might involve in contact chemoreception process.