Frequency of alleles conferring major resistance to Bacillus thuringiensis toxin upon a Philippine population of the striped stemborer Chilo suppressalis (Lepidoptera: Pyralidae)
2002
Cuong, N.L. (Cui Long Delta Rice Research Inst., Cantho (Vietnam)) Andow, D.A. | Leeb, D. | Adalla, C.B. | Cohen, M.B.
The F2 screen methodology entails sibmating within isofemale lines to detect any resistance allele that was initially present in the fertilized eggs of field collected females. The authors applied the F2 screen methodology to the striped stem borer, Chilo suppressalis (Walker) Lepidoptera: Pyralidae, using IR 72 rice plants transformed with a cryl Ab/cryl Ac hybrid gene. When all 151 isofemale lines were included in the analysis, the frequency of alleles encoding major resistance to the Cryl Ab/Cryl Ac toxin was 1.6 x 10 E-3 with a 96% detection probability. The upper 95% Credibility Intervals of the frequency of such allele was 4.8 x 10 E-3. By analyzing the subsets of data consisting of 151 isofemale lines that produced greater than or equal to 1, 2, 3, 4, and 5 F1 families per isofemale line. A conservative estimate of allele frequency would rely on data with greater than or equal to F1 families per isofemale line with a high value (99%) of detection probability. Results suggest that the frequency of allele conferring resistance to the Cryl Ab/Cryl Ac hybrid toxin in the population of C. suppressalis sampled approaches 10 E-3, which has been suggested as the maximum initial resistance allele frequency that would enable the high dose/refuge resistance management strategy to be successfully applied
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