Assessing the impact of genetic background on homing efficiency of a CRISPR/Cas9 gene drive in spotted-wing drosophila

I will report on the performance of a suppression gene drive in Drosophila suzukii, the spotted-wing drosophila (SWD). This fruit fly is a global pest of soft-skinned fruits and is highly invasive in major fruit-growing regions of the Americas. SWD is primarily controlled with broad-spectrum insecticides, but genetic biocontrol offers a more targeted, environmentally friendly, and potentially longer-term solution. Traditional genetic pest management, namely the Sterile Insect Technique, requires massive numbers of radiation-sterilized insects. Gene drive technology, which utilizes super-Mendelian inheritance, drastically reduces the need for mass rearing and acts for a longer period. Our lab recently developed a gene drive in SWD designed to propagate a female sterility mutation over several generations. The drive uses CRISPR-Cas9 to target the doublesex gene, resulting in the accumulation of sterile females over time and subsequent population suppression. The efficiency of this system was originally demonstrated in SWD from North Carolina, with 94-99% homing observed. However, in a hypothetical release scenario, naturally occurring genetic variation could interfere with drive efficiency or facilitate the formation of resistance alleles. Considering the 2021 report from Lewald et. al. on genomic diversity across populations of SWD in the United States, particularly between the East and West coasts, we endeavored to test the drive in flies originating from several states around the country. I will present results from crossing our gene drive constructs into five alternate state backgrounds, as well as data from molecular analysis of these lines and ongoing small-cage suppression experiments.