Morphology and ultrastructure of the male reproductive system of the jewel wasp, Nasonia vitripennis (Walker) (Hymenoptera: Pteromalidae)

Abstract

The genital systems of insects are undoubtedly of great key for the success of mating and population reproduction. In the meantime, morphological and ultrastructural characteristics of the reproductive systems also provide valuable evidences for the studies of taxonomy, reproductive biology and evolutionary biology. More previously, the reproductive system of female Nasonia vitripennis was already described. To complement the information of reproductive systems from this species, the male reproductive system was here dissected and characterized by light microscopy and transmission electron microscopy. Results showed that the system follows the pattern of most Hymenoptera species: paired testes with one follicle, deferent ducts, seminal vesicles, accessory glands and a fused ejaculatory duct ultimately connected to the external aedeagus. Histologically, the testes, seminal vesicles and accessory glands are all composed of three portions, all of which include epithelial and luminal regions. In addition, both lipidic inclusions and nuclei are presented in the three organs with variable sizes and shapes. Spermatozoa are observed in the testes and seminal vesicles, and also vary considerably in size and shape, suggesting different phases of spermatogenesis. Mitochondria are abundant in seminal vesicles and accessory glands. Notably, membranous inclusions and Golgi complexes are found only in seminal vesicles, whereas secretory granules are presented only in accessory glands, being indicative of organ or age specificity. Together, this study complements the information of the reproductive systems from N. vitripennis, and provides an extensive resource for taxonomy, reproductive biology and evolutionary biology.