Exploring the potential of crossbreeding to enhance black soldier fly (<i>Hermetia illucens</i>) production

The increasing world population leads to a growing demand for animal protein, calling for sustainable solutions. Insects, such as the black soldier fly (<i>Hermetia illucens</i>, BSF), will therefore play a crucial role due to their fast growth, high protein content, good bioconversion efficiency and their ability to thrive on diverse feed substrates. Selective breeding has proven valuable in plants and livestock and holds great potential for farmed insects. Moreover, crossbreeding is a successful strategy to improve the genetic value of progeny, for example by exploiting heterosis. Nevertheless, crossbreeding experiments in BSF remain scarce. In this exploratory study, we present the outcome of a crossbreeding experiment in BSF. Four strains (F0) were used to set up reciprocal crosses (F1). Subsequently, four second generation populations (F2) were created. All populations were reared at pilot scale on chicken feed in triplicate. Each generation (F0, F1, and F2) was evaluated for growth, feed conversion, bioconversion efficiency, mating behaviour and egg production. The mean final larval mass of the F2 generations did not significantly differ from the mean of the F0s, although the development speed of the larvae was higher, resulting in a higher percentage of prepupae at the end of the rearing phase. Interestingly, some F1 crosses showed reciprocal differences (i.e. reversing maternal and paternal lines) in maximal larval weight of 32%. Furthermore, egg production was 19% higher in the F2 generations compared to the average F0s. Taking both production and reproduction traits into account, we calculated an increase of 16.5% in total larval mass production and an increase of 19.1% dried larval mass production for the F2s compared to the F0s. These findings explore the potential for crossbreeding in future BSF rearing programmes and highlight the need for further investigation into reciprocal differences between parental lines.