Abstract
<jats:p>The global expansion of Black Soldier Fly (BSF), Hermetia illucens (L.), production systems for organic waste management has increased the need to better understand its reproductive biology in order to optimize mass-rearing programs. In this study, we macroscopically characterized the chronological morphological changes in the internal genitalia of adult H. illucens reared on a sustainable alternative diet based on coffee pulp and corn bran. Morphological assessments and dissections were conducted on both female and male reproductive tracts at 3, 6, and 9 days after adult emergence. Overall, the general organization of both reproductive systems was consistent with previous descriptions reported in the literature. However, one of the most notable findings was the identification of a tripartite fertilization chamber in females, composed of three distinct compartments that appear to be associated with the three spermathecae. This anatomical organization may be associated with sperm storage and post-copulatory reproductive processes, although its functional significance remains to be determined. In addition, both sexes exhibited an apparent later pattern of reproductive maturation than that reported in previous studies using conventional larval diets. Females reached full oocyte maturity, evidenced by maximum ovarian distention and the presence of localized yellowish eggs, at 9 days of age, whereas previous studies have reported maturity peaks between 5 and 7 days. Likewise, male testes reached their greatest volume, opacity, and apparent gamete accumulation on day 9. The observed delay in reproductive development is likely associated with the nutritional composition and carbohydrate-to-protein balance of the coffee pulp-based larval diet. Taken together, these results provide detailed iconographic records and chronological information that may help improve laboratory rearing protocols and support the industrial-scale bioconversion of coffee by-products using H. illucens.</jats:p>