Reproduction Remix: the effect of adult’s sex ratio on the reproductive output of Tenebrio molitor

Abstract In the sector of insect farming, large-scale production systems aim to maximize their profitability and sustainability. For Tenebrio molitor farming, a crucial factor influencing production efficiency is the reproductive performance. Yet the effect of sex ratio and adult density on reproductive outcomes has not been investigated thoroughly. Thus, for this study, fifteen combinations of different sex ratios and densities were designed in order to examine the effects of sex ratio and density on egg production and hatchability of T. molitor , under controlled conditions over a period of 28 days. The results revealed that while survival rates of adults were unaffected by sex ratio and density, egg production and hatchability varied significantly across treatments particularly at later time points. Among all treatments, the 4:16 female-to-male (F:M) sex ratio consistently resulted in the highest egg production and hatchability at days 21 and 28, suggesting that this ratio optimizes the reproductive output. Within density groups, sex ratios such as 2:8 F:M and 6:24 F:M also demonstrated superior performance in terms of cumulative egg production. These findings underscore the role of polyandry in enhancing reproductive success for T. molitor , as females benefit from mating with multiple males. Interestingly, no adverse effects on female survival were observed despite increased reproductive activity.