| Abstrakt: |
The citrus fruit borer, Ecdytolopha aurantiana(Lima, 1927) (Lepidoptera: Tortricidae), is responsible for major losses to the citrus industry because it causes rot and drop of fruits. The current study aimed to select and characterize Bacillus thuringiensis(Berliner, 1911) strains toxic to E. aurantiana. For this purpose, 47 B. thuringiensisstrains were evaluated in selective bioassays using first instar larvae of E. aurantiana. The lethal concentration (LC50) of the most toxic strains was estimated, and the strains were characterized by morphological, biochemical, and molecular methods. Of the 47 strains tested, 10 caused mortality above 85% and showed mean lethal concentrations between 1.05E+7 and 1.54E+8 spores mL−1. The lowest LC50values were obtained for the HD-1 standard strain and the BR145, BR83, BR52, and BR09 strains. The protein profile showed the presence of Cry proteins of 60, 65, 70, 80, and 130 kDa. The molecular characterization showed the presence of cry1, cry2, cry3, and cry11genes. The morphological analysis identified three different crystalline inclusions: bipyramidal, round, and cuboidal. The cry1and cry2genes were the most frequent among the B. thuringiensisstrains evaluated and encode Cry proteins toxic to insects of the order Lepidoptera, which agree with the toxicity results obtained by the selective bioassays against E. aurantiana. The results showed four different B. thuringiensisstrains toxic to E. aurantianaat the same level as the HD-1 standard strain, and these strains have biotechnological potential for E. aurantianacontrol through the production of transgenic plants or the formulation of biopesticides. |
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