Structural and histological observations on the male reproductive system of adult red poplar leaf beetle Chrysomela populi Linnaeus, 1758 (Coleoptera: Chrysomelidae)

Morphology of the male reproductive system and spermatozoa of Smicridea (Rhyacophylax) iguazu Flint, 1983 (Trichoptera, Hydropsychidae)

The Trichoptera, holometabolous aquatic insects found worldwide except in Antarctica, exhibit a unique feature in their sperm, which are solely nucleated (eupyrene). Current knowledge on Trichoptera sperm is limited to Old World species. To enhance our understanding of their reproductive biology and contribute to systematic discussions, we describe the male reproductive system and spermatozoa of Smicridea (Rhyacophylax) iguazu Flint, 1983 (Hydropsychidae). This species lacks seminal vesicles, possesses piriform to oval-shaped testes with spermatozoa grouped in apical bundles and dense filamentous material filling other areas. The vasa deferentia are long and a pair of elongated accessory glands displays distinct proximal and distal regions. The relatively short (∼40 μm) spermatozoa are nucleated, aflagellated, and immobile. Further research could explore variations and assess the taxonomic utility of these features for genus identification within Hydropsychidae.

Morphology of the male reproductive system and sperm ultrastructure of the green lacewing, Chrysopa pallens (Rambur, 1838) (Neuroptera: Chrysopidae)

BACKGROUND

Chrysopa pallens is one of the most beneficial and effective natural predators, and is famous for its extensive distribution, wide prey spectrum, and excellent reproductive performance. This study examined the anatomy and fine structure of the C. pallens reproductive system and spermatogenesis.

RESULTS

The male reproductive system of C. pallens comprises a pair of testes, a vas deferens, seminal vesicles, accessory glands, and short ejaculatory ducts. The testes were already mature on the day of emergence, but the accessory glands did not mature until 5 days post-emergence. In early spermatids, the flagellum had an axoneme on one side of the two mitochondrial derivatives. The nucleus was surrounded by parallel crystalline and paracrystalline materials. The spermatid envelope extends towards the paracrystalline material in a tail-shaped wing. In mature spermatids, the axoneme is located between the two accessory bodies and mitochondrial derivative sets. The parallel-crystalline and paracrystalline materials disappeared. In the testes, the wall of seminal cysts consists of a layer of epithelium, a muscular-connective sheath, and several vesicles of different sizes. The mature seminal cysts contained 128 spermatozoa. The accessory gland is composed of six parts: ventral papilla-like protuberance, anterior glandular lobe, lateral glandular lobe, seminal cyst, posterior kidney-shaped lobe, and posterior papilla-like protuberance. Muscle fibers and secretory granules are extensive.

CONCLUSIONS

This study provides information on the reproductive system of C. pallens and offers a resource for taxonomy and reproductive biology.

Insights into spermatogenesis in the migratory locust, Locusta migratoria (Linnaeus, 1758) (Orthoptera: Acrididae), following histological and ultrastructural features of the testis

The migratory locust, Locusta migratoria (Linnaeus, 1758), is one of the most destructive agricultural pests globally, and this species is particularly localized in several regions of Egypt. However, so far, very little attention has been paid to the characteristics of the testes. Furthermore, spermatogenesis requires careful analysis to characterize and track developmental episodes. We thus investigated, for the first time, the histological and ultrastructural properties of the testis in L. migratoria employing a light microscope, a scanning electron microscope (SEM), and a transmission electron microscope (TEM). Our results revealed that the testis comprises several follicles, emerging with distinct outer surface wrinkle patterns for each follicle throughout the length of the follicular wall. Furthermore, histological examination of the follicles showed that each has three developmental zones. Each zone has cysts with characteristic spermatogenic elements, beginning with the spermatogonia at the distal end of each follicle and ending with the spermatozoa at the proximal end. Moreover, spermatozoa are arranged in spermatozoa bundles called spermatodesms. Overall, this research provides novel insights into the structure of the testes of L. migratoria, which will significantly contribute to formulating effective pesticides against locusts.

Anatomical and Histological Structures of Male Reproductive System in Long-Horned Beetle Isotomus speciosus (Schneider, 1787) (Coleoptera: Cerambycidae): Light and Scanning Electron Microscopic Study

Isotomus speciosus is a polyphagous insect that damages coniferous and deciduous trees. There is no study on the male reproductive system of I. speciosus although it is an important pest. For this purpose, the male reproductive system anatomy and histology of I. speciosus were investigated using light and scanning electron microscopy. According to the results obtained, the male reproductive system of I. speciosus consists of a pair of testes (each with a pair of separate testis lobes), two pairs of vasa efferentia, a pair of vasa deferentia, an ejaculatory duct, an aedeagus, and three pairs of accessory glands. Each testis lobe has about 65 testis follicles. Testis lobe has sperm development stages (growth, maturation, and differentiation). Each testis lobe is connected to the vas deferens via the vas efferens. There are masses of mature sperm that completely fill lumen of the vas deferens. The vas efferens has cylindrical epithelium, and the vas deferens has cubic epithelium. The vas deferens then opens into the aedeagus by an ejaculatory duct. The ejaculatory duct has an intima layer with spines, monolayer of epithelium, and muscle layer. In this study, similarities and differences in anatomy and histology of male reproductive organs of I. speciosus with other coleopteran species were revealed.