Particularities of the Hermetia illucens (L.) (Diptera: Stratiomyidae) Ovipositing Behavior: Practical Applications

SIMPLE SUMMARY: The industrial rearing of Hermetia illucens is based on knowledge of the reproductive particularities and reproductive behavior, which are important for increasing the efficiency of the rearing technology. Therefore, this study aimed to evaluate the particularities of the ovipositing behavior of females from the perspective of their affinity towards the size of the ovipositing slots, the correlations between this and the resulting egg mass, as well as the effect of the humidity of attractive substrate on the oviposition particularities. Over 90% of H. illucens females oviposited with predilection for ovipositing devices with slots of 1–3 mm. The differentiated affinity for oviposition in 1-, 2- and 3-mm slots, depending on the size of the females, is positively correlated with the size of the resulting clutches. The optimum humidity of the attractive substrate for ovipositing is obtained by the mixing equal parts of the dry substrate and water (1:1). ABSTRACT: The industrial rearing of Hermetia illucens offers sustainable solutions to the acute challenges of modern society associated with the accumulation of increasing amounts of organic waste, the substantial reduction of natural ocean fish stocks, and the imminent food crisis. Detailed knowledge of the reproductive particularities and reproductive behavior of the species is essential for increasing the efficiency of the breeding technology. This study aimed to identify the affinity shown by females regarding the size of the oviposition slots (1, 2, 3, 4 and 5 mm), the vertical distribution of the ovipositing rate, and the influence of the substrate’s moisture on ovipositing behavior (dry matter/water: 1:0.5; 1:1; 1:1.5; 1:2). Over 90% of females oviposited in the 1-, 2- and 3-mm slots, with most of the eggs (58.57%) being oviposited in the 1-mm slots. There was a positive correlation between the size of the oviposition slots and the average weight of the clutches (r = 0.985). The vertical distribution of ovipositing followed a fluctuating trend, with a tendency to oviposit closer to the attractive substrate. The females avoided ovipositing close to substrates with low humidity (1:0.5); indeed, only 6.8% oviposited under these conditions, the differences being significant compared to substrates with higher humidity (p < 0.001). The vast majority of females (43.2%) oviposited on substrates with an average humidity of 1:1 (p < 0.001). These results provide new insights into the ovipositing behavior of H. illucens, which allow for a differentiated harvest of large-sized clutches, providing practical applications with significant impact on the economic efficiency of the species’ industrial growth technology.