title: Resistance monitoring of Helicoverpa armigera (Lepidoptera Noctuidae) to Bacillus thuringiensis insecticidal protein in China.
abstract: Sensitivities of Helicoverpa armigera (Hübner) field populations to Bacillus thuringiensis (Bt) insecticidal protein CrylAc were monitored during 1998-2000 in China. A total of 41 strains was sampled, and most of them were collected from Bt cotton planting regions. The range of IC50 values (concentration producing 50% inhibition of larval development to third instar) among different populations in 1998,1999, and 2000 were 0.020-0.105 microg/ml, 0.016-0.099 microg/ml, and 0.016-0.080 microg/ml, respectively. Diagnostic concentration studies (IC99) showed that the percentage of individuals reaching third instar ranged from 0 to 4.35%, with only eight of the 41 tested populations showing values above 0%. Also interesting was a trend over successive years in which fewer populations contained individuals that survived the diagnostic concentration by reaching third instar. Considering these data, it was determined that the field populations sampled during the 3-yr study were susceptible to CrylAc protein, and that movement toward resistance among H. armigera populations was not apparent.
authors.affiliation: Institute of Plant Protection, Chinese Acad of Agricultural Sciences, Beijing, PR China. wkm@caascose.net.cn
authors.forename: Kongming
authors.initials: K
authors.lastname: Wu
authors.forename: Yuyuan
authors.initials: Y
authors.lastname: Guo
authors.forename: Nan
authors.initials: N
authors.lastname: Lv
authors.forename: John T
authors.initials: JT
authors.lastname: Greenplate
authors.forename: Randy
authors.initials: R
authors.lastname: Deaton
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D001427:Bacterial Toxins / Q000494:pharmacology*; D001681:Biological Assay; D002681:China; D004731:Endotoxins / Q000494:pharmacology*; D006460:Hemolysin Proteins; D007305:Insecticide Resistance; D007814:Larva / Q000187:drug effects; D009036:Moths / Q000187:drug effects*; D010572:Pest Control, Biological / Q000379:methods
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis