Frequency of alleles conferring major resistance to bacillus thuringiensis toxin upon a philippine population of the stripped stemborer, Chilo Suppressalis

Issue Date

10-2002

Abstract

The F2 screen methodology entails sib-mating within isofemale lines todetect any resistance allele that was intially present in the fertilized eggs of field collected females. We applied the F2 screen methodology to the stripped stemborer, Chilo suppressalis (Walker) (Lepidoptera: Pyralidae), using IR72 rice plants transformed with a cry1Ab/cry1Ac hybrid gene. When all 151 isofemale lines were included in the analysis, the frequency of alleles encoding major resistance to the Cry1Ab/Cry1Ac toxin was <1.6 X 10-3 with a 96% detection probability. The upper 95% Credibility Intervals of the frequency of such allele was 4.8 X 10-3. By analyzing the subsets of data consisting of 151 isofemale lines that produced = 1, 2, 3, 4, and 5 F, families per isofemale line, a conservative estimate of allele frequency would rely on data with = 3 F1 families per isofemale line with a high value (99%) of detection probability. Our results suggest that the frequency of allele conferring resistance to the Cry1Ab/Cry1Ac hybrid toxin in the population of C. suppressalis sampled approaches 10-3, which had been suggested as the maximum initial resistance allele frequency that would enable the high does/refuge resistance management strategy to be successfully applied.

Source or Periodical Title

Philippine Entomologist

ISSN

0048-3753

Volume

16

Issue

2

Page

156

Document Type

Article

Frequency

semi-annually

Language

English

En – AGROVOC descriptors

CHILO SUPPRESSALIS; LEPIDOPTERA; INSECTA; PLANT PESTS; BACILLUS THURINGIENSIS; PHILIPPINES

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