Gene duplication in the major insecticide target site, Rdl, in Drosophila melanogaster

Emily J. Remnant, Robert T. Good, Joshua M. Schmidt, Christopher Lumb, Charles Robin, Phillip J. Daborn, Philip Batterham

Research output: Contribution to journalArticlepeer-review

55 Citations (Scopus)


The Resistance to Dieldrin gene, Rdl, encodes a GABA-gated chloride channel subunit that is targeted by cyclodiene and phenylpyrazole insecticides. The gene was first characterized in Drosophila melanogaster by genetic mapping of resistance to the cyclodiene dieldrin. The 4,000-fold resistance observed was due to a single amino acid replacement, Ala301 to Ser. The equivalent change was subsequently identified in Rdl orthologs of a large range of resistant insect species. Here, we report identification of a duplication at the Rdl locus in D. melanogaster. The 113-kb duplication contains one WT copy of Rdl and a second copy with two point mutations: an Ala301 to Ser resistance mutation and Met360 to Ile replacement. Individuals with this duplication exhibit intermediate dieldrin resistance compared with single copy Ser301 homozygotes, reduced temperature sensitivity, and altered RNA editing associated with the resistant allele. Ectopic recombination between Roo transposable elements is involved in generating this genomic rearrangement. The duplication phenotypes were confirmed by construction of a transgenic, artificial duplication integrating the 55.7-kb Rdl locus with a Ser301 change into an Ala301 background. Gene duplications can contribute significantly to the evolution of insecticide resistance, most commonly by increasing the amount of gene product produced. Here however, duplication of the Rdl target site creates permanent heterozygosity, providing unique potential for adaptive mutations to accrue in one copy, without abolishing the endogenous role of an essential gene.
Original languageEnglish
Pages (from-to)14705-14710
Number of pages6
JournalProceedings of the National Academy of Sciences
Issue number36
Publication statusPublished - 3 Sept 2013
Externally publishedYes


  • Dieldrin gene
  • Drosophila melanogaster
  • insecticide
  • Gene duplication
  • Rdl
  • GABA-gated chloride channel
  • cyclodiene
  • phenylpyrazole
  • cyclodiene dieldrin
  • RNA
  • Ectopic
  • Roo transposable elements


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