title: Increased toxicity of Bacillus thuringiensis Cry3Aa against Crioceris quatuordecimpunctata, Phaedon brassicae and Colaphellus bowringi by a Tenebrio molitor cadherin fragment.
abstract: BACKGROUND
  Biopesticides containing Cry insecticidal proteins from the bacterium Bacillus thuringiensis (Bt) are effective against many lepidopteran pests, but there is a lack of Bt-based pesticides for efficient control of important coleopteran pests. Based on the reported increase in Bt toxin oligomerization by a polypeptide from the Cry3Aa receptor cadherin in Tenebrio molitor (Coleoptera: Tenebrionidae), it was hypothesized that this cadherin peptide, rTmCad1p, would enhance Cry3Aa toxicity towards coleopteran larvae. To test this hypothesis, the relative toxicity of Cry3Aa, with or without rTmCad1p, against damaging chrysomelid vegetable pests of China was evaluated.
  
  
  RESULTS
  Cry3Aa toxicity was evaluated in the spotted asparagus beetle (Crioceris quatuordecimpunctata), cabbage leaf beetle (Colaphellus bowringi) and daikon leaf beetle (Phaedon brassicae). To assess the effect of rTmCad1p on Cry3Aa toxicity, neonate larvae were fed Cry3Aa toxin alone or in combination with increasing amounts of rTmCad1p. The data demonstrated that Cry3Aa toxicity was significantly increased in all three vegetable pests, resulting in as much as a 15.3-fold increase in larval mortality.
  
  
  CONCLUSIONS
  The application of rTmCad1p to enhance Cry3Aa insecticidal activity has potential for use in increasing range and activity levels against coleopteran pests displaying low susceptibility to Bt-based biopesticides.
authors.affiliation: State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, PR China.
authors.forename: Yulin
authors.initials: Y
authors.lastname: Gao
authors.forename: Juan Luis
authors.initials: JL
authors.lastname: Jurat-Fuentes
authors.forename: Brenda
authors.initials: B
authors.lastname: Oppert
authors.forename: Jeffrey A
authors.initials: JA
authors.lastname: Fabrick
authors.forename: Chenxi
authors.initials: C
authors.lastname: Liu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Gao
authors.forename: Zhongren
authors.initials: Z
authors.lastname: Lei
mesh_terms: D000818:Animals; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D015820:Cadherins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D001517:Coleoptera / Q000187:drug effects* / Q000254:growth & development; D004731:Endotoxins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D019476:Insect Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D007814:Larva / Q000187:drug effects / Q000254:growth & development; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity; D013712:Tenebrio / Q000235:genetics*
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D015820:Cadherins; D004731:Endotoxins; D006460:Hemolysin Proteins; D019476:Insect Proteins; D011993:Recombinant Fusion Proteins; C030956:insecticidal crystal protein, Bacillus Thuringiensis