Genetic mapping of a major locus controlling pyrethroid resistance in Tribolium castaneum (Coleoptera: Tenebrionidae).

Tribolium castaneum (Herbst) strain QTC279 is highly resistant to deltamethrin and other synthetic pyrethroids. This strain was shown to carry at least 1 resistance gene, PyR-1, on linkage group 9, approximately 20 map units from the visible mutant marker, pearl. Three-point mapping involving pearl and another visible mutant marker, cola, indicated a gene order of pearl-cola-PyR-1. Evidence of a 2nd LG9-linked resistance factor (R) mapping in the gene order R-p-co was also observed. Other resistance factors were clearly present in QTC279, but were not genetically mapped. Piperonyl butoxide, an inhibitor of cytochrome P450-mediated oxidative metabolism, significantly increased the toxicity of deltamethrin to a strain derived from QTC279 that carries PyR-1, strain pR. Compared to susceptible beetles, QTC279 and pR had elevated and comparable levels of cytochrome P450 protein. The significance of pyrethroid resistance in T. castaneum is discussed.