Journal of Economic Entomology (2005) 98, 1320-1324

Blair D. Siegfried, Ty T. Vaughn and Terence Spencer (2005)
Baseline susceptibility of western corn rootworm (Coleoptera: Crysomelidae) to Cry3Bb1 Bacillus thuringiensis toxin
Journal of Economic Entomology 98 (4), 1320-1324
Abstract: Susceptibility to Cry3Bb1 toxin from Bacillus thuringiensis (Bt) was determined for western corn rootworm, Diabrotica virgifera virgifera LeConte, neonates from both laboratory and field populations collected from across the Corn Belt. Rootworm larvae were exposed to artificial diet treated with increasing Cry3Bb1 concentrations, and mortality and growth inhibition were evaluated after 4-7 d. The range of variation in Bt susceptibility indicated by growth inhibition was similar to that indicated by mortality. Although interpopulation variation in susceptibility was observed, the magnitude of the differences was comparable with the variability observed between generations of the same population. In general, the toxin was not highly toxic to larvae and estimated LC₅₀ and EC₅₀ values were several times higher than those reported for lepidopteran-specific Cry toxins by using similar bioassay techniques. These results suggest that the observed susceptibility differences reflect natural variation in Bt susceptibility among rootworm populations and provide a baseline for estimating potential shifts in susceptibility that might result from selection and exposure to Cry3Bb1-expressing corn hybrids.
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Database assignments for author(s): Blair D. Siegfried

Research topic(s) for pests/diseases/weeds:
biocontrol - natural enemies
Research topic(s) for beneficials or antagonists:
general biology - morphology - evolution
resistance/tolerance/defence of host

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Diabrotica virgifera	Maize/corn (Zea mays)
Bacillus thuringiensis Cry3B-toxin (entomopathogen)	Diabrotica virgifera	Maize/corn (Zea mays)