Suppression of female fertility in <i>Aedes aegypti</i> with a CRISPR-targeted male-sterile mutation.

Abstract

<i>Aedes aegypti</i> spread devastating viruses such as dengue, which causes disease among 100 to 400 million people annually. A potential approach to control mosquito disease vectors is the sterile insect technique (SIT). The strategy involves repeated release of large numbers of sterile males, which reduces insect populations because the sterile males mate and thereby suppress the fertility of females that would otherwise mate with fertile males. While SIT has been successful in suppressing certain agricultural pests, it has been less effective in depressing populations of <i>Ae. aegypti</i> This limitation is in part because of the fitness effects resulting from mutagenizing the mosquitoes nonspecifically. Here, we introduced and characterized the impact on female fertility of an <i>Ae. aegypti</i> mutation that disrupts a gene that is specifically expressed in testes. We used CRISPR/Cas9 to generate a null mutation in the <i>Ae. aegypti β2-tubulin</i> (<i>B2t</i>) gene, which eliminates male fertility. When we allowed wild-type females to first mate with <i>B2t</i> mutant males, most of the females did not produce progeny even after being subsequently exposed to wild-type males. We also introduced <i>B2t</i> mutant and wild-type males simultaneously with wild-type females and found that a larger number of <i>B2t</i> mutant males relative to the wild-type males was effective in significantly suppressing female fertility. These results raise the possibility of employing <i>B2t</i> sterile males to improve the efficacy of SIT in suppressing populations of <i>Ae. aegypti</i> through repeated releases and thereby reduce the transmission of viruses by these invasive mosquitoes.