Morphology and ultrastructure of integumentary glands of Semiadalia undecimnotata schn. (Coleoptera : Coccinellidae)

Abstract The ultrastructure of integumentary glands of the adult ladybird, Semiadalia undecimnotata (Coleoptera : Coccinellidae) is described. Two types of glands can be found distributed over the head, thorax, and abdomen: glands without ducts and glands with secretory ducts. Glands without ducts consist of a single cell and a secretory apparatus located within the thickness of the cuticle and equipped with a cuticular cribriform plate; this cribriform plate separates 2 superimposed cavities, and epicuticular filaments fill the lower cavity. Glands without ducts are thought to release volatile pheromones. Glands with a duct appear to be made of 2 kinds of cells: one cell forms the receiving duct and later synthesizes the secretory products, one (or more) cell makes the evacuating duct. Their secretions are abundant and released on the surface of the cuticle in the shape of tortuous cylinders, which are resistant to acetone treatment. Glands without ducts and glands with secretory ducts correspond, respectively, to classes 1 and 3 gland cells according to the nomenclature of Noirot and Quennedey (1974, Annu. Rev. Entomol. 19 : 61–80).