Correlated response to selection for increased body weight on fecundity in <i>Hermetia illucens</i>

Abstract Genetic improvement through artificial selection holds potential for improving production of the black soldier fly, Hermetia illucens L. (Diptera: Stratiomyidae). A long‐term artificial selection for increased larval body weight is in place for the black soldier fly. To investigate the impact of body weight selection on egg production in this species, four tests were conducted, assessing the phenotypic relationship between pupal body weight, egg clutch weight, number of eggs, and egg size. To measure fecundity, egg clutches were collected from individual females. The egg clutches from the body weight (BW) line, selected for 14, 21, and 32 generations, were compared with those of the base population (BP) line to evaluate the effect of long‐term selection for body weight on the reproductive output of the black soldier fly. The maternal pupae weight showed a strong positive correlation (0.73) with egg clutch weight and a moderate positive correlation (0.47) with the number of eggs. The egg clutch weight showed a strong positive correlation (0.79) with the number of eggs and a moderate positive correlation (0.51) with the length of an egg. The BW line showed significantly higher performance over the BP line, with about an 18%–49% increase in egg clutch weight per female, a 24%–30% increase in the number of eggs per clutch, and a 3%–4% increase in the length of an egg. The linear mixed model showed that the selection had significantly increased egg clutch weight over the generations of selection in the BW line. Assessment of phenotypic relationships showed no evidence of reproductive trade‐offs with higher body weight in female black soldier flies in this study. This research provides the first empirical evidence of increased fecundity in response to artificial selection for increased larval body weight in the black soldier fly.