Journal of Economic Entomology (2008) 101, 1691-1696

L.Z. Han, P.L. Liu, M.L. Hou and Y.F. Peng (2008)
Baseline susceptibility of Cnaphalocrocis medinalis (Lepidoptera: Pyralidae) to Bacillus thuringiensis toxins in China
Journal of Economic Entomology 101 (5), 1691-1696
Abstract: Geographic variability in susceptibility of field-collected Cnaphalocrocis medinalis (Guenée) (Lepidoptera: Pyralidae) to Bacillus thuringiensis (Berliner) was studied to establish a geographic baseline for comparison of future population responses to the increased use of B. thuringiensis-based insect control products. Colonies of C. medinalis were established from 10 populations collected from 10 different provinces in the major rice (Oryza savita L.)-growing regions of China. Populations were evaluated for their susceptibility to Cry1Ac and Cry1Ab endotoxin proteins with the leaf-dip bioassay. The LC₅₀ values to Cry1Ac and Cry1Ab were estimated for the 10 populations. Bioassay results indicated that the ranges of LC₅₀ in the second instars of C. medinalis to Cry1Ac and Cry1Ab were from 3.77 to 208.22 mg ([AI])/liter and 0.22-7.05 mg ([AI])/liter, respectively. The relative ratios in susceptibility between the most susceptible and the most tolerant populations were beyond 50-fold for Cry1Ac and 30-fold for Cry1Ab. Moreover, there was a significant positive correlation between susceptibilities to the two toxins tested, suggesting that insect populations that are relatively tolerant to one protein are also relatively tolerant to the other.
(The abstract is excluded from the Creative Commons licence and has been copied with permission by the publisher.)
Link to article at publishers website
Database assignments for author(s): Mao-Lin Hou

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Cnaphalocrocis medinalis	Rice (Oryza)	China (south)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Cnaphalocrocis medinalis	Rice (Oryza)	China (south)