title: Lack of fitness costs and inheritance of resistance to Bacillus thuringiensis Cry1Ac toxin in a near-isogenic strain of Plutella xylostella (Lepidoptera: Plutellidae).
abstract: BACKGROUND
  Resistance to Bacillus thuringiensis (Bt) formulations in insects may be associated with fitness costs. A lack of costs enables resistance alleles to persist, which may contribute to the rapid development and spread of resistance in populations.
  
  
  RESULTS
  To assess the fitness costs associated with Bt Cry1Ac resistance in Plutella xylostella, life tables were constructed for a near-isogenic resistant strain (NIL-R) and a susceptible strain in this study. No fitness costs associated with Cry1Ac resistance in NIL-R were detected, based on the duration of egg and larval stages, the survival of eggs and larvae, adult longevity, fecundity, net reproductive rate, gross reproduction rate, finite rate of increase and mean generation time. Based on log dose-probit lines, resistance in NIL-R is incompletely recessive and results from a single, autosomal, recessive locus; the degree of dominance was estimated to be -0.74 and -0.71 for F1 (resistant ♀ × susceptible ♂) and F1 ' (susceptible ♀ × resistant ♂) progeny respectively.
  
  
  CONCLUSIONS
  Assessment of near-isogenic Cry1Ac-resistant and Cry1Ac-susceptible strains of P. xylostella indicated that resistance is not accompanied with fitness costs, and that resistance is incompletely recessive. These findings should be useful in managing the development of Bt Cry1Ac resistance.
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Xun
authors: X
authors: Zhu
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Yanjv
authors: Y
authors: Yang
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Qingjun
authors: Q
authors: Wu
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Shaoli
authors: S
authors: Wang
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Wen
authors: W
authors: Xie
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Zhaojiang
authors: Z
authors: Guo
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Shi
authors: S
authors: Kang
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Jixing
authors: J
authors: Xia
authors: Department of Plant Protection, Institute of Vegetables and Flowers, Chinese Academy of Agricultural Sciences, Beijing, China.
authors: Youjun
authors: Y
authors: Zhang
mesh_terms: D000818:Animals; D001413:Bacillus thuringiensis / Q000502:physiology*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000494:pharmacology*; D004731:Endotoxins / Q000494:pharmacology*; D005260:Female; D006460:Hemolysin Proteins / Q000494:pharmacology*; D007305:Insecticide Resistance / Q000235:genetics; D007306:Insecticides / Q000494:pharmacology*; D007814:Larva; D008297:Male; D009036:Moths / Q000187:drug effects / Q000235:genetics* / Q000382:microbiology / Q000502:physiology; D010572:Pest Control, Biological
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bacillus thuringiensis; Plutella xylostella (L.); inheritance of Cry1Ac resistance; lack of fitness costs; near-isogenic lines