Inheritance of resistance to Bt toxin crylac in a field-derived strain of pink bollworm (Lepidoptera: Gelechiidae).

Bruce E. Tabashnik, Yong Biao Liu, Timothy J. Dennehy, Maria A. Sims, Mark S. Sisterson, Robert W. Biggs, Yves Carrière

Research output: Contribution to journalArticle

115 Scopus citations

Abstract

Laboratory selection with Cry1Ac, the Bacillus thuringiensis (Bt) toxin in transgenic cotton, initially produced 300-fold resistance in a field-derived strain of pink bollworm, Pectinophora gossypiella (Saunders), a major cotton pest. After additional selection increased resistance to 3,100-fold, we tested the offspring of various crosses to determine the mode of inheritance of resistance to Cry1Ac. The progeny of reciprocal F1 crosses (resistant male x susceptible female and vice versa) responded alike in bioassays, indicating autosomal inheritance. Consistent with earlier findings, resistance was recessive at a high concentration of Cry1Ac. However, the dominance of resistance increased as the concentration of Cry1Ac decreased. Analysis of survival and growth of progeny from backcrosses (F1 x resistant strain) suggest that resistance was controlled primarily by one or a few major loci. The progression of resistance from 300- to 3,100-fold rules out the simplest model with one locus and two alleles. Overall the patterns observed can be explained by either a single resistance gene with three or more alleles or by more than one resistance gene. The pink bollworm resistance to Cry1Ac described here fits "mode 1" resistance, the most common type of resistance to Cry1A toxins in Lepidoptera.

Original languageEnglish (US)
Pages (from-to)1018-1026
Number of pages9
JournalJournal of economic entomology
Volume95
Issue number5
DOIs
StatePublished - Oct 2002

ASJC Scopus subject areas

  • Ecology
  • Insect Science

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