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Transposon-mediated resistance to Bacillus sphaericus in a field-evolved population of Culex pipiens (Diptera:

Isabelle Darboux1, Jean-François Charles, Yannick Pauchet

  • 1UMR1112 Réponses des Organismes aux Stress Environnementaux, INRA-UNSA, 400 Route des Chappes, BP 167, F-06903 Sophia-Antipolis, France. Isabelle.Darboux@sophia.inra.fr

Cellular Microbiology
|March 31, 2007
PubMed

Insights

A novel resistance mechanism in Culex pipiens mosquitoes involves transposable element DNA insertion. This insertion alters mRNA splicing, creating a modified receptor that prevents the Bacillus sphaericus binary toxin from binding, thus conferring resistance.

Area of Science:

  • Molecular Biology
  • Entomology
  • Genetics

Background:

  • Bacillus sphaericus binary toxin is a key larvicide for controlling disease-carrying mosquitoes.
  • Increasing resistance to B. sphaericus poses a threat to the efficacy of this biopesticide.

Purpose of the Study:

  • To characterize a new mechanism of resistance to the binary toxin in Culex pipiens.
  • To investigate the role of transposable elements in insecticide resistance.

Main Methods:

  • Analysis of gene sequences in a natural population of Culex pipiens.
  • Investigation of mRNA splicing events induced by DNA insertion.
  • Characterization of altered membrane proteins and their interaction with the toxin.

Main Results:

  • A transposable element-like DNA insertion was identified in the midgut toxin receptor gene.
  • This insertion triggered aberrant mRNA splicing, creating a new intron.
  • The resulting altered membrane protein could not bind the binary toxin, conferring resistance.

Conclusions:

  • A novel resistance mechanism mediated by transposable element insertion and altered splicing is described.
  • This mechanism provides a significant survival advantage to Culex pipiens.
  • Transposable elements may play a broader role in insect resistance to microbial insecticides.

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