Point mutations in the Drosophila sodium channel gene para associated with resistance to DDT and pyrethroid insecticides

B. Pittendrigh, R. Reenan, R. H. Ffrench-Constant, B. Ganetzky

Research output: Contribution to journalArticlepeer-review


The gene para in Drosophila melanogaster encodes an α subunit of voltage-activated sodium channels, the presumed site of action of DDT and pyrethroid insecticides. We used an existing collection of Drosophila para mutants to examine the molecular basis of target-site resistance to pyrethroids and DDT. Six out of thirteen mutants rested were associated with a largely dominant, 10- to 30-fold increase in DDT resistance. The amino acid lesions associated with these alleles defined four sites in the sodium channel polypeptide where a mutational change can cause resistance: within the intracellular loop between S4 and S5 in homology domains I and III, within the pore region of homology domain III, and within S6 in homology domain III. Some of these sites are analogous with those defined by knockdown resistance (kdr) and super-kdr resistance-associated mutations in houseflies and other insects, but are located in different homologous units of the channel polypeptide. We find a striking synergism in resistance levels with particular heterozygous combinations of para alleles that appears to mimic the super-kdr double mutant housefly phenotype. Our results indicate that the alleles analyzed from natural populations represent only a subset of mutations that can confer resistance. The implications for the binding site of pyrethroids and mechanisms of target-site insensitivity are discussed.

Original languageEnglish (US)
Pages (from-to)602-610
Number of pages9
JournalMolecular and General Genetics
Issue number6
StatePublished - 1997


  • DDT/pyrethroids
  • Drosophila melanogaster
  • Insecticide resistance
  • Voltage-gated sodium channel
  • para

ASJC Scopus subject areas

  • Genetics


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