title: Cadherin mutation linked to resistance to Cry1Ac affects male paternity and sperm competition in Helicoverpa armigera.
abstract: Several lepidopteran pests of cotton have cadherin-based resistance to the Bacillus thuringiensis (Bt) toxin Cry1Ac. Cadherins are transmembrane proteins that mediate cell-cell adhesion and tissue morphogenesis, suggesting that fitness costs associated with cadherin mutations may be present in many aspects of life history. To evaluate whether cadherin-based resistance is associated with fitness costs reducing male paternity in Helicoverpa armigera, we examined the effects of a major cadherin resistance allele on sperm competition within and between male ejaculates. When homozygous resistant and susceptible males competed for fertilization of a homozygous resistant or susceptible female, fertilization success was high in males with a different cadherin genotype than females, and low in males with the same cadherin genotype as females. Single matings between heterozygous males and susceptible females produced offspring within typical Mendelian ratios. Heterozygous males mated to resistant females, however, resulted in a disproportionate number of heterozygous offspring. While these results show that cadherin-based resistance to Cry1Ac has significant impacts on paternity in H. armigera, there was no evidence that costs associated with resistance consistently reduced male paternity. Rather, effects of cadherin-based resistance on paternity depended on interactions between male and female genotypes and differed when males or sperm competed for fertilization of females, which complicates assessment of impacts of cadherin resistance alleles on resistance evolution.
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Haonan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Bing
authors.initials: B
authors.lastname: Du
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yihua
authors.initials: Y
authors.lastname: Yang
authors.affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, USA; Center for Insect Science, University of Arizona, Tucson, USA.
authors.forename: Dawn M
authors.initials: DM
authors.lastname: Higginson
authors.affiliation: Center for Insect Science, University of Arizona, Tucson, USA; Department of Entomology, University of Arizona, Tucson, AZ, USA.
authors.forename: Yves
authors.initials: Y
authors.lastname: Carrière
authors.affiliation: College of Plant Protection, Nanjing Agricultural University, Nanjing 210095, China.
authors.forename: Yidong
authors.initials: Y
authors.lastname: Wu
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics*; D015820:Cadherins / Q000235:genetics*; D004731:Endotoxins / Q000235:genetics*; D005260:Female; D005306:Fertilization / Q000235:genetics* / Q000502:physiology; D005838:Genotype; D006460:Hemolysin Proteins / Q000235:genetics*; D007814:Larva / Q000502:physiology; D008297:Male; D009036:Moths / Q000235:genetics* / Q000502:physiology; D030821:Plants, Genetically Modified / Q000235:genetics; D016133:Polymerase Chain Reaction; D013094:Spermatozoa / Q000502:physiology*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis
keywords: Bt resistance; Cadherin; Fitness costs; Non-Mendelian inheritance; Sperm competition