Journal of Applied Entomology (2005) 129, 407-412

K. He, Z. Wang, L. Wen, S. Bai, X. Ma and Z. Yao (2005)
Determination of baseline susceptibility to Cry1Ab protein for Asian corn borer (Lep., Crambidae)
Journal of Applied Entomology 129 (8), 407-412
Abstract: Although transgenic Bacillus thuringiensis (Bt) corn can provide a new tool for control of the Asian corn borer (ACB), Ostrinia furnacalis (Guenée), concern has been raised regarding the possibility of the target insect evolving resistance to the Bt protein under intensive selection pressure from Bt corn. Therefore, it is necessary to establish baseline data to enable detection of changes in susceptibility in field populations after prolonged exposure to Bt corn. Susceptibility to purified Cry1Ab protein from Bt was determined for 10 populations of ACB from the major corn-growing regions of China, ranging geographically from Heilongjiang Province in the northeast to Shaanxi Province in the east-central part. Neonate ACB were exposed to semi-artificial diet incorporated with increasing Cry1Ab protein concentrations, and mortality and growth inhibition were evaluated after 7 days. The range of LC₅₀ (50% lethal concentration) among the populations was 0.10 to 0.81 µg/g (Cry1Ab protein/diet). Differences (P < 0.05) in susceptibility among the populations were significant. LC₅₀s generated from the Huanghuaihai Summer Corn Region were higher than those from the Spring Corn Regions. Bt was one of the significant natural biomortality factors of overwintering generation ACB. There was a significant correlation between percentage of the larvae infected with Bt and their LC₅₀ values to Cry1Ab protein in geographic distinct populations (r = 0.7350*, d.f. = 8, _r0.05 = 0.632). Based on the background of Bt formulations used for corn insect pests control in these areas, these differences were not caused by prior exposure to Bt insecticides. Instead, the small differences likely reflect natural Bt selection pressure. Because the variation in susceptibility to Cry1Ab was small (<10-fold), the ACB apparently is susceptible to Cry1Ab across its range within China.
(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): Kanglai He

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

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Pest and/or beneficial records:

Beneficial	Pest/Disease/Weed	Crop/Product	Country	Quarant.
	Ostrinia furnacalis	Maize/corn (Zea mays)	China (NE)
Bacillus thuringiensis genes in crops (entomopathogen)	Ostrinia furnacalis	Maize/corn (Zea mays)	China (NE)
Bacillus thuringiensis Cry1A-toxin (entomopathogen)	Ostrinia furnacalis	Maize/corn (Zea mays)