Fine structure and chemical analysis of the metathoracic scent gland of Eurygaster maura (Linnaeus, 1758) (Heteroptera: Scutelleridae).

The morphology and ultrastructure of the metathoracic scent glands (MTG) of Eurygaster maura were studied by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Also, extracts of the volatile fraction of the MTG secretion from males and females were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). In SEM investigations, MTG are composed of a reservoir and a pair of lateral glands connected to the reservoir by a duct. MTG are open in between the meso- and the metacoxae. These areas, called evaporation areas, are composed of mushroom-like elements. In TEM investigations, the reservoir walls contained two types of cells. Generally, a reservoir is lined by a single layer of epithelial cells, type I cells, which have numerous organelles. Type II cells are found only in a certain area of the reservoir wall. These cells have large secretory ducts lined by a cuticular intima layer. The lateral glands are lined by secretory cells and a secretory duct found in their cytoplasm. Nuclei of secretory cells are closed to the basal region of the cells and circular-shaped. In GC-MS investigations, the MTG exhibited a typical scutellerid composition. In general, (E)-2-hexanal, (E)-2-hexenyl acetate, n-tridecane, n-hexanoic acid, octadecanoic acid, and n-dodecane compounds were present, while diisooctyl acetate and 14-Beta-H-Pregna were detected only in the male extracts of Eurygaster maura.