CRISPR-Ready Mosquito Strain Informs Vector Control

Insecticide resistance threatens the effectiveness of chemical interventions used against Aedes aegypti, a major vector of dengue, Zika, chikungunya and yellow fever. To isolate genetic mechanisms underlying resistance, the authors generated a pyrethroid-resistant Cas9 strain (PRCas9) by repeatedly backcrossing a susceptible Cas9-modified Liverpool line with a highly permethrin-resistant Puerto Rico strain. The resulting mosquitoes retained extremely high resistance—over 18,000-fold relative to a susceptible reference—while maintaining a genetically tractable background suitable for genome editing.

RNA sequencing comparing susceptible and resistant populations identified more than 70 differentially expressed genes associated with resistance. These were dominated by metabolic detoxification enzymes, including the cytochrome P450 genes CYP6BB2, CYP9J19, and CYP9J23, as well as venom carboxylesterase-6, all of which were strongly overexpressed in resistant mosquitoes. Variant analysis revealed numerous fixed SNPs within detoxification genes and regulatory regions, including promoter variants in NOX4-art, an NADPH oxidase involved in reactive oxygen species (ROS) production. Elevated NOX4-art expression suggests that ROS-linked signalling pathways may regulate detoxification gene activation. Gene ontology enrichment further supported a central role for P450-mediated metabolic detoxification.

By creating a resistant mosquito line that already expresses Cas9, the study establishes a platform for rapid CRISPR-based validation of candidate resistance genes and regulatory elements. Functional testing of these targets could identify molecular markers for resistance monitoring or reveal vulnerabilities in detoxification pathways, supporting the design of insecticides, synergists, or management strategies that remain effective against resistant mosquito populations.

The study was conducted by Dylan Brown, Reese Houck and Nannan Liu at Auburn University, USA. It was published in Archives of Toxicology on 16 March 2026.