Epidermis associated with wax secretion in the Harpactor angulosus (Hemiptera: Reduviidae).

摘要

Beginning at the third instar, the generalist predator Harpactor angulosus (Lepeletier & Serville) (Reduviidae: Harpactorinae) appears gray in color because of the presence of a whitish particulate wax-like material covering all body segments. In this study, we tested the hypothesis that epidermal cells are responsible for the secretion of the wax-like substance onto the cuticle of H. angulosus. The integument of third instar to the adults of H. angulosus have no external structures specialized in wax secretion, as the wax particles are deposited in a filamentous manner. Third to fourth instars and adult stages have a single-layered epidermis composed of columnar cells. In contrast, lack of wax deposit on the body surface of first and second instars is associated with flattened epidermal cells. The columnar epidermal cells are characterized by a well-developed nucleus, basal cell surface with large infoldings, and a cytoplasm rich in vacuoles. These vacuoles are negative for the presence of carbohydrates and proteins, but strongly positive for the presence of lipids. The structural features of the epidermis and the presence of lipid droplets suggest that lipid metabolism is active within the epidermis from the third instar to the adult of H. angulosus. This is the first record of a glandular epidermis associated with wax secretions in Reduviidae.