Development of the Endo-Reproductive System and the Effect of Mating Status on Egg Development in Adult Hermetia...

Hermetia illucens L. (Diptera: Stratiomyidae), a well-known decomposer of organic wastes, is widely applied to treat food, livestock, and poultry wastes to reduce environmental pollution. It is also used to produce high-protein feed, organic fertilizers, and biomedicine as well as biodiesel. The development of the endo-reproductive system in insects plays a crucial role in their reproduction, which is key in economic insect culture. In this study, we investigate the developmental process of the endo-reproductive system and the effect of mating status on the development of the female reproductive system in adult H. illucens. The results show that the morphological characteristics of the internal reproductive system of adult H. illucens differed with age and mating status. Males exhibited a higher testicular dimension at 2-5 days old, with testicular length and width reaching their maximum at 3 days old, displaying significant differences across ages (p < 0.05). The developmental period of the ovaries varied with time and was classified into five distinct stages. The morphological characteristics of the endo-reproductive system of adult females at different mating status showed differences. The spermatheca of the unmated female was translucent, while that of the mated female exhibited cloudiness and became lighter in color with age. The length and width of the spermatheca of the mated female were larger than that of unmated females (p < 0.05). However, the length and width of the spermathecae of the mated and unmated females reached their maximum at 5 days old. Mating status affected the development of eggs; mated females oviposited matured eggs at 5 days old, while unmated females oviposited matured eggs at 9 days old. The results suggest that mating status can promote the development of eggs in H. illucens. Additionally, the maturity level or mating status can be determined based on the morphology of the endo-reproductive system and its contents.