Validation of a feeding disruption bioassay for the detection of resistance to Bacillus thuringiensis toxin and species identification is reported using field strains of Heliothis virescens and Helicoverpa zea collected from the southern United States in 1998. Feeding disruption is measured by a lack of fecal production from larvae exposed to a diagnostic concentration of CryIAc in a blue indicator diet. The bioassay provided rapid (24 h) diagnosis of the species composition of larvae tested and also monitored for the presence of resistance in H. virescens. An additional diagnostic concentration was established for monitoring resistance in H. zea. A probit model was used to compare the fecal production responses of insect strains over a range of CryIAc doses. Probability calculations, derived from our assay results, are also presented to aid in the interpretation of future results from field trials. Integration of the feeding disruption bioassay into integrated pest management programs is discussed.
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1 February 2001
Species Diagnosis and Bacillus thuringiensis Resistance Monitoring of Heliothis virescens and Helicoverpa zea (Lepidoptera: Noctuidae) Field Strains from the Southern United States Using Feeding Disruption Bioassays
Woodward D. Bailey,
CAVELL BROWNIE,
Jack S. Bacheler,
Fred Gould,
George G. Kennedy,
Clyde E. Sorenson,
R. Michael Roe
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Journal of Economic Entomology
Vol. 94 • No. 1
February 2001
Vol. 94 • No. 1
February 2001
Bacillus thuringiensis
Bollworm
cotton integrated pest management
Helicoverpa zea
Heliothis virescens
insecticide resistance
tobacco budworm