| Evolution of resistance to the Bacillus sphaericus Bin toxin is phenotypically masked by combination with the mosquitocidal proteins of Bacillus thuringiensis subspecies israelensis. | |
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MedLine Citation:
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PMID: 20141526 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Two insecticidal bacteria are used as larvicides to control larvae of nuisance and vector mosquitoes in many countries, Bacillus thuringiensis ssp. israelensis and B. sphaericus. Field studies show both are effective, but serious resistance, as high as 50 000-fold, has evolved where B. sphaericus is used against Culex mosquitoes. To improve efficacy and deal with even greater potential problems of resistance, we previously developed several recombinant larvicidal bacteria that combine the best mosquitocidal proteins of these bacteria. In the present study, we report laboratory selection studies using our best recombinant strain against larvae of Culex quinquefasciatus. This recombinant, Bti/BsBin, is a strain of B. thuringiensis ssp. israelensis engineered to produce a large amount of the B. sphaericus binary (Bin) toxin, which makes it more than 10-fold as mosquitocidal as the its parental strains. Here we show that larvae exposed to Bti/BsBin failed to develop significant resistance after 30 successive generations of heavy selection pressure. The highest level of resistance obtained at the LC(95) level was 5.2-fold, but declined to less than two-fold at the 35th generation. Testing the selected populations against B. sphaericus alone showed resistance to Bin evolved, but was masked by combination with B. thuringiensis ssp. israelensis. These results suggest that recombinant bacterial strains have improved mosquito and vector management properties compared with the wild-type strains used in current commercial formulations, and should prove useful in controlling important human diseases such as malaria and filariasis on a long-term basis, even when used intensively under field conditions. |
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Authors:
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Margaret C Wirth; William E Walton; Brian A Federici |
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Publication Detail:
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Type: Journal Article; Research Support, N.I.H., Extramural Date: 2010-02-07 |
Journal Detail:
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Title: Environmental microbiology Volume: 12 ISSN: 1462-2920 ISO Abbreviation: Environ. Microbiol. Publication Date: 2010 May |
Date Detail:
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Created Date: 2010-06-11 Completed Date: 2010-10-21 Revised Date: - |
Medline Journal Info:
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Nlm Unique ID: 100883692 Medline TA: Environ Microbiol Country: England |
Other Details:
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Languages: eng Pagination: 1154-60 Citation Subset: IM |
Affiliation:
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Department of Entomology, University of California, Riverside, CA 92521, USA. |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Bacillus / classification, genetics, metabolism Bacillus thuringiensis / classification, genetics, metabolism* Bacterial Proteins / genetics, metabolism, pharmacology* Bacterial Toxins / genetics, metabolism, pharmacology* Culex / drug effects*, genetics Evolution, Molecular Insecticide Resistance / genetics* Insecticides / pharmacology* Larva / growth & development Pest Control, Biological Phenotype Protein Subunits / metabolism Recombinant Proteins / genetics, metabolism, pharmacology |
| Grant Support | |
ID/Acronym/Agency:
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R01 AI 45817/AI/NIAID NIH HHS; U01 AI 54778/AI/NIAID NIH HHS |
| Chemical | |
Reg. No./Substance:
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0/Bacterial Proteins; 0/Bacterial Toxins; 0/Insecticides; 0/Protein Subunits; 0/Recombinant Proteins; 0/binB protein, Bacillus sphaericus |
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