Ultrastructural Study of the Midgut and Hindgut in Eight Species of the Genus <I>Dendroctonus</I> Erichson (Coleoptera: Scolytidae)

Abstract

Chemical communication mediated by pheromones is a crucial aspect in the life cycle of beetles in the genus Dendroctonus. This communication plays an important role in mate location and in the colonization of host conifers. The study of the alimentary canal of these species is of importance not only because this organ is involved in the processes of digestion, detoxification, nutrient absorption, and transport, but also in the production of semiochemical compounds, such as pheromones. To better understand these functions and where they occur, the ultrastructural differences between the anterior and posterior midgut and the hindgut and their different cellular types were characterized. Adult specimens of both sexes from eight species were dissected and the alimentary canal was removed. It was sectioned into three parts: anterior midgut, posterior midgut, and hindgut, and analyzed by transmission electron microscopy. Results show that the epithelial tissue of the midgut possesses ultrastructural characteristics that permit differentiation of the anterior and posterior midgut. There are no ultrastructural differences within sexes of the same species, but differences exist among species. The ultrastructural characteristics of the hindgut do not differ between sexes or among species, but they do differ from those of the midgut.