Evolution of Resistance in Culex quinquefasciatus (Say) Selected With a Recombinant Bacillus thuringiensis Strain-Producing Cyt1Aa and Cry11Ba, and the Binary Toxin, Bin, From Lysinibacillus sphaericus.
Fourth instars of Culex quinquefasciatus (Say) (Diptera: Culicidae) were selected with a recombinant bacterial strain synthesizing the mosquitocidal proteins from Lysinibacillus sphaericus (Bin) and Cry11Ba and Cyt1Aa from Bacillus thuringiensis. Selection was initiated in Generation 1 with a concentration of 0.04 μg/ml, which rose to a maximum selection concentration of 8.0 μg/ml in Generation 14, followed by an unexpected, rapid increase in mortality in Generation 15. Subsequently, a selection concentration of 0.8 μg/ml was determined to be survivable. During this same period, resistance rose to nearly 1,000-fold (by Generation 12) and declined to 18.8-fold in Generation 19. Resistance remained low and fluctuated between 5.3 and 7.3 up to Generation 66. The cross-resistance patterns and interactions among the component proteins were analyzed to identify possible causes of this unusual pattern of evolution. Poor activity in the mid-range concentrations and lower-than-expected synergistic interactions were identified as potential sources of the early resistance. These findings should be considered in the development of genetically engineered strains intended to control nuisance and vector mosquitoes.
Department of Entomology, University of California, Riverside, CA 92521. mcwirth@ucr.edu.
Margaret C
MC
Wirth
Department of Entomology, University of California, Riverside, CA 92521.
William E
WE
Walton
Department of Entomology, University of California, Riverside, CA 92521. Interdepartmental Graduate Programs in Microbiology, and Cell, Molecular and Developmental Biology, University of California, Riverside, CA 92521.
Brian A
BA
Federici
D000818:Animals; D001407:Bacillus / Q000235:genetics; D001413:Bacillus thuringiensis / Q000235:genetics; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D003465:Culex / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development; D004731:Endotoxins / Q000494:pharmacology*; D019143:Evolution, Molecular; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007305:Insecticide Resistance; D007814:Larva / Q000187:drug effects / Q000235:genetics / Q000254:growth & development; D010572:Pest Control, Biological
D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C046134:binB protein, Bacillus sphaericus; C030956:insecticidal crystal protein, Bacillus Thuringiensis
mosquito; recombinant Bacillus thuringiensis; resistance