Comparative fine structural analysis of the male reproductive accessory glands in Bactrocera oleae and Ceratitis capitata (Diptera, Tephritidae)

The morphology and ultrastructure of the male reproductive accessory glands from Bactrocera oleae and Ceratitis capitata were comparatively investigated. In both insects, there are two types of glands, mesoderm- and ectoderm-derived, which open in the ejaculatory duct. The mesoderm-derived glands are sac-like in B. oleae and very long tubules in C. capitata, whereas the ectodermic glands, generally branched finger-like structures, are longer in B. oleae than in C. capitata. Despite their different morphology, the ultrastructure of the two types of glands is quite similar in both Tephritids. The epithelium of the mesoderm-derived glands consists of binucleate and microvillate secretory cells. In C. capitata, but not in B. oleae, the secretory cells contain smooth endoplasmic reticulum and, in the sexually mature males, enlarged polymorphic mitochondria. The gland lumen is filled with a dense or sometimes granulated secretion. The ectoderm-derived glands undergo a cycle of maturation, by which their epithelial cells form a large subcuticular cavity filled with an electrontransparent secretion. Electrophoretic analysis of accessory gland secretion reveals in both species the presence of low molecular weight protein bands. A major band of about 29 kDa or 30 kDa in B. oleae and C. capitata, respectively, is revealed.