Strong potential for selection for larger larval size in the black soldier fly (Hermetia illucens)

Using selective breeding to increase the size of larvae is a potential strategy to make insect production more efficient. Based on observations in other insect species, we hypothesized that larval size in black soldier flies (Hermetia illucens L.; Diptera: Stratiomyidae) is moderately heritable and should, therefore, respond to selection. We estimated the additive genetic variation for larval size assessed in three ways: individual larval surface area (ISA), group surface area (GSA), and group weight (GW). A full-/half-sib design was used, and a total of 92 sires mated successfully with 169 females (1.84 females per male). For each female, on the day of egg-hatching, two cups were prepared with a sufficient amount of feed, and fifty larvae were transferred to each cup. On day 12 after egg hatching, from each cup thirty larvae were selected randomly, and ISA was recorded (9 486 larvae from 317 full-sib groups). For each full-sib group, the GW was recorded as the collective weight of the thirty larvae (317 records), and the GSA was the aggregated ISA of the thirty larvae (317 records). The data were analyzed using sire-dam models including the population average and batch (3 batches) as fixed effects, and sire, dam and cup as random effects. The results showed a high heritability for ISA (0.40), with a moderate effect of the common environment (0.21). For GSA and GW, moderate-to-high heritabilities were observed (0.30 and –0.39). The results show that there is great potential for black soldier fly breeders to select for bigger larval size.