Wingless strain created using binary transgenic CRISPR/Cas9 alleviates concerns about mass rearing of Hermetia illucens.

Larvae of the black soldier fly Hermetia illucens have potential as a natural waste recycler and subsequent use as protein-rich feed for livestock. A common question about the insect-farming processes is, what about the concerns of mass escape of insects from large populations? Here, we present a binary transgenic CRISPR/Cas9 system to generate wingless strain with the potential to address this issue. We identified gonad-specific promoters in vivo and evaluated use of the two strongest promoters, nanos and exuperantia, to drive Cas9 expression. We found that crossing the Hiexu-Cas9 with transgenic sgRNA-expressing insects resulted in higher knockout efficiency of the marker gene white. The Hiexu-Cas9 strain exhibited a maternal deposition of Cas9 that caused more effective knockout in the progeny of female Cas9-expressing individuals. Using this system, we generated wingless mutants lacking mating ability, which can be maintained in colony through a genetic cross of two single strain. These insects are less likely to escape and would be unable to successfully mate if they did escape. Taken together, this study validates effective genetic tools that can be used for gene function studies and industrial applications in black soldier fly and provides an approach to alleviate the concern about massive rearing.