Fitness costs of insect resistance to bacillus thuringiensis

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358 Scopus citations


Evolution of resistance by insect pests threatens the continued effectiveness of Bacillus thuringiensis (Bt) toxins in sprays and transgenic crops. Fitness costs of Bt resistance occur when, in the absence of Bt toxins, fitness is lower for resistant insects than for susceptible insects. Modeling results show that fitness costs can delay resistance by selecting against Bt-resistant genotypes in refuges where insects are not exposed to Bt toxins. In 77 studies including 18 species, fitness costs were detected in 62% of experiments testing for declines in resistance and in 34% of fitness component comparisons. Mean fitness costs were 15.5% for survival, 7.4% for development time, and 2.5% for mass. Although most fitness costs were recessive, nonrecessive costs can select more strongly against resistance. Because fitness costs vary with ecological conditions, refuges designed to increase the dominance or magnitude of fitness costs could be especially useful for delaying pest resistance.

Original languageEnglish (US)
Pages (from-to)147-163
Number of pages17
JournalAnnual review of entomology
StatePublished - Jan 2009


  • Dominance
  • Evolution
  • Refuge strategy
  • Resistance management
  • Transgenic crops

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Insect Science


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