A PCR diagnostic for cyclodiene insecticide resistance in the red flour beetle Tribolium castaneum

A molecular diagnostic was used to examine the conservation of cyclodiene resistance associated mutations between different strains of Tribolium castaneum (Herbst.). An improved insecticide bioassay for discrimination between resistant genotypes was developed and seven resistant strains were established from five different continents. In order to develop a molecular diagnostic a partial cDNA of the cyclodiene insecticide resistance gene Rdl, a γ‐aminobutyric‐acid‐gated chloride‐ion channel, was cloned and sequenced. This cDNA spans exon 7, the region containing the resistance‐associated mutation, and part of exon 8. An ‘allele‐specific’ oligonucleotide primer, carrying the resistance‐associated mutation at its 3′ end, was used in combination with a flanking ‘allele‐independent’ primer in the polymerase chain reaction to selectively amplify a single resistance‐associated mutation from all seven strains collected worldwide. The implications of these findings for the population genetics of insecticide resistance and its management in pest insects via quarantine are discussed.