Evolution of insecticide resistance via parallel amino acid substitutions in insect pests and their parasitoid wasps

Insecticides have become the primary selective force in many insect species; however, whether beneficial insects developed resistance remains unknown. We analyzed the sequences of hymenopteran GABAA receptor subunit gene Rdl (resistance to dieldrin), which encodes the target of cyclodiene and phenylpyrazole insecticides. The resistance-conferring A2 S mutations were found in seven parasitoid wasps and similar amino acid replacements at homologous sites have been identified in four of their resistant hosts. Our findings indicate how parallel molecular evolution at a single amino acid site confers adaptation in both insects and their natural enemies, which may shape species interactions and community structure.