title: Cross-resistance spectra of Culex quinquefasciatus resistant to mosquitocidal toxins of Bacillus thuringiensis towards recombinant Escherichia coli expressing genes from B. thuringiensis ssp. israelensis.
abstract: Sixteen Escherichia coli clones were assayed against susceptible and Bacillus thuringiensis-resistant Culex quinquefasciatus larvae. The clones expressed different combinations of four genes from Bacillus thuringiensis ssp. israelensis; three genes encoded mosquitocidal toxins (Cry11Aa, Cry4Aa and Cyt1Aa) and the fourth encoded an accessory protein (P20). The cross-resistance spectra of the mosquitoes were similar to the profiles for recombinant B. thuringiensis strains expressing B. thuringiensis toxin genes, but with varied toxicity levels. The toxicity of the recombinants towards resistant mosquito larvae was improved when p20 and cyt1Aa were expressed in combination with cry4Aa and/or cry11Aa. Recombinant pVE4-ADRC, expressing cry4Aa, cry11Aa, p20 and cyt1Aa, was the most active against the resistant Culex, and resistance levels did not exceed fourfold. These results indicate that B. thuringiensis ssp. israelensis genes expressed in a heterologous host such as E. coli can be effective against susceptible and B. thuringiensis-resistant larvae and suppress resistance.
authors.affiliation: Department of Entomology, University of California, Riverside, CA 92521, USA. mcwirth@mail.ucr.edu
authors.forename: Margaret C
authors.initials: MC
authors.lastname: Wirth
authors.forename: Arieh
authors.initials: A
authors.lastname: Zaritsky
authors.forename: Eitan
authors.initials: E
authors.lastname: Ben-Dov
authors.forename: Robert
authors.initials: R
authors.lastname: Manasherob
authors.forename: Vadim
authors.initials: V
authors.lastname: Khasdan
authors.forename: Sammy
authors.initials: S
authors.lastname: Boussiba
authors.forename: William E
authors.initials: WE
authors.lastname: Walton
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000737:chemistry* / Q000235:genetics; D001427:Bacterial Toxins / Q000235:genetics / Q000494:pharmacology*; D003465:Culex / Q000187:drug effects* / Q000382:microbiology; D004926:Escherichia coli / Q000235:genetics; D007305:Insecticide Resistance / Q000502:physiology*; D030781:Organisms, Genetically Modified; D011994:Recombinant Proteins
chemical_list: D001427:Bacterial Toxins; D011994:Recombinant Proteins