Anatomy and histology of the male reproductive tract of the parasitoid wasp Hymenoepimecis bicolor (Brullé, 1846) (Hymenoptera: Ichneumonidae)

Abstract

Hymenoepimecis wasps (Hymenoptera: Ichneumonidae) are ectoparasitoids of spiders that modify the hosts’ behaviour by inducing changes in webs. Variations in the male reproductive tract contribute to enhancing our understanding of the reproductive behaviour of these insects. This study describes the morphology of the male reproductive tract of Hymenoepimecis bicolor (Brullé, 1846) using light microscope. The male reproductive tract of H. bicolor consists of a pair of testes, each containing a single follicle, two vasa deferentia, one ejaculatory duct and two accessory glands. The testis follicle has cysts at various stages of spermatogenesis, indicating ongoing sperm cell development and maturation. The vasa deferentia are elongated, with a coiled distal portion, whereas the proximal regions are laterally associated with a pair of accessory glands. The wall of the vasa deferentia has simple cuboidal epithelium. The accessory glands had a simple columnar epithelium with the lumen filled with heterogeneous content. The seminal vesicle is absent. The similarity in the anatomy and histology of the male reproductive tract of H. bicolor with other Hymenoptera suggests that the parasitoid behaviour does not result in significant alteration to their reproductive organs, indicating that the reproductive tract is conserved in Hymenoptera, regardless of their behaviours.