Tobacco is one of the major industrial crops cultivated worldwide. Chemical control is the main method employed to reduce damage by insect pests. The use of entomopathogenic fungi represents an alternative to replace insecticides. The search for effective strains in the field constitutes a first step when developing a formulation. The objective of this work was to study genetic differences among isolates of entomopathogenic fungi obtained from tobacco grown soils using ISSR markers. The pathogenicity of the strains towards Helicoverpa gelotopoeon and Diabrotica speciosa was also assessed in order to search for a relationship between virulence and genetic diversity. Nineteen isolates were identified according to morphological features and molecular techniques as Beauveria bassiana (11) and Purpureocillium lilacinum (8). The diversity tree generated by ISSR analysis showed a high diversity among the strains. The pathogenicity towards H. gelotopoeon and D. speciosa was assessed and the logistic models generated showed that B. bassiana isolates LPSc1215 and LPSc1364 were the most pathogenic against both insect pests tested. In the diversity tree, these strains were grouped in a same cluster with a similarity level of approximately 85%, indicating a possible relationship between virulence and the band pattern generated.

中文翻译：

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探索昆虫病原真菌遗传多样性的 ISSR 标记：对烟草害虫生物防治的意义

烟草是世界范围内种植的主要经济作物之一。化学防治是减少害虫危害的主要方法。昆虫病原真菌的使用代表了替代杀虫剂的替代方法。在现场寻找有效菌株是开发配方的第一步。这项工作的目的是使用 ISSR 标记研究从烟草种植土壤中获得的昆虫病原真菌分离株之间的遗传差异。还评估了菌株对 Helicoverpa gelotopoeon 和 Diabrotica speciosa 的致病性，以寻找毒力与遗传多样性之间的关系。根据形态特征和分子技术鉴定出 19 个分离株为球孢白僵菌 (11) 和紫花紫薇 (8)。ISSR 分析生成的多样性树显示菌株之间具有高度的多样性。对 H. gelotopoeon 和 D. speciosa 的致病性进行了评估，生成的逻辑模型表明 B. bassiana 分离株 LPSc1215 和 LPSc1364 对测试的两种害虫的致病性最强。在多样性树中，这些菌株以大约 85% 的相似度分组在同一簇中，表明毒力与产生的条带模式之间可能存在关系。