title: Toxicity of Bacillus thuringiensis delta-endotoxins against bean shoot borer (Epinotia aporema Wals.) larvae, a major soybean pest in Argentina.
abstract: The toxicity of seven Bacillus thuringiensis Cry protoxins was tested against neonate larvae of Epinotia aporema, a major soybean pest in Argentina and South America. The most active protoxins were Cry1Ab and Cry1Ac, with LC50 values of 0.55 and 1.39 microg/ml, respectively. Cry1Aa, Cry1Ba, Cry1Ca, and Cry9Ca protoxins were equally toxic with LC50 values about 4 microg/ml, whereas Cry1Da was not toxic. The synergistic activity of different protoxin-mixtures was also analyzed, no synergistic effect between the Cry proteins was observed, with the exception of the poorly toxic Cry1Ba/Cry1Da mixture that was slightly synergistic. The binding capacity of individual Cry1 and Cry9Ca toxins to brush border membranes of E. aporema was also determined. The non-toxic Cry1Da toxin was the only toxin unable to bind to E. aporema membranes. In addition the heterologous competition experiments showed that Cry1Ab and Cry1Ac toxins share a common binding site. Based on these data, we propose that Cry1Ab and Cry1Ac toxins could be used in the biological control of E. aporema.
authors.affiliation: Bioinsumos Microbianos, Instituto de Microbiología y Zoología Agrícola, INTA., CC. No. 25 (1712) Castelar, Buenos Aires, Argentina. dsauka@cnia.inta.gov.ar
authors.forename: Diego H
authors.initials: DH
authors.lastname: Sauka
authors.forename: Jorge
authors.initials: J
authors.lastname: Sánchez
authors.forename: Alejandra
authors.initials: A
authors.lastname: Bravo
authors.forename: Graciela B
authors.initials: GB
authors.lastname: Benintende
mesh_terms: D000818:Animals; D001118:Argentina; D001413:Bacillus thuringiensis / Q000737:chemistry*; D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins / Q000633:toxicity*; D001427:Bacterial Toxins / Q000633:toxicity*; D004731:Endotoxins / Q000633:toxicity*; D006460:Hemolysin Proteins / Q000633:toxicity*; D007306:Insecticides / Q000633:toxicity*; D007814:Larva / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D007915:Lepidoptera / Q000187:drug effects* / Q000254:growth & development / Q000382:microbiology; D010572:Pest Control, Biological; D013025:Glycine max
chemical_list: D000083722:Bacillus thuringiensis Toxins; D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004731:Endotoxins; D006460:Hemolysin Proteins; D007306:Insecticides; C030956:insecticidal crystal protein, Bacillus Thuringiensis