Oxidase-Based DDT-Pyrethroid CrossResistance in Guatemalan Anopheles albimanus

An oxidase resistance mechanism producing DDT-pyrethroid cross-resistance has been identified in an isofemale line of Guatemalan Anopheles albimanus Wiedemann through application of bottle bioassays and biochemical analysis. The resistance is fully synergized by piperonyl butoxide. Oxidase resistance in individuals may be detected and levels measured using a microplate assay. Only adult female mosquitoes express the oxidase mechanism. In the parent strain, an additional pyrethroid resistance mechanism, an elevated esterase, coexists with the oxidase. Mosquitoes with the oxidase resistance show induction by phenobarbital and sublethal pyrethroid exposure.