Management of the banana root borer (BRB), Cosmopolites sordidus (Germar; Coleoptera: Curculionidae), remains a challenge in banana and plantain production worldwide. Synthetic pesticides remain the most widely used solution while mycoinsecticides are increasingly being recommended. In this study, we selected indigenous isolates of Beauveria bassiana and Metarhizium anisopliae collected from plantain fields in Cameroon, and tested them in the laboratory for their viability, pathogenicity and virulence against all C. sordidus life stages. Of 13 isolates initially screened for spore germination and pathogenicity to adult weevils in conidial suspension of 3.2 × 108 conidia/ml, eight isolates with high to moderate germination and highest weevil mortality were selected for dose–response bioassays with four concentrations per isolate: 3.2 × 102, 3.2 × 104, 3.2 × 106 and 3.2 × 108 conidia/ml. The virulent isolates from adult bioassays were tested with eggs, larva and pupae in conidial suspension of 3.2 × 108 conidia/ml. Isolates performance depended on insect life stage with significantly high pathogenicity and virulence against larval, pupa and adult stages. The Beauveria isolate BIITAC6.2.2 caused the highest mortality rates followed by MIITAC1.1.5. Lethal times and lethal concentrations were relatively low for the three M. anisopliae isolates and three B. bassiana isolates which were the best isolates in almost all insect life stages. Apart from being effective in multiple life stages, these isolates were transmitted horizontally from one stage to another when eggs and pupae were treated. The implication of these findings for integrated management of the BRB, and potential biopesticides development and commercialization are discussed.

中文翻译：

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Cosmopolites sordidus (Germar) 对土著喀麦隆白僵菌 (Bals.) Vuill 的敏感性。和绿僵菌 (Metsch.) 分离株

香蕉根蛀虫 (BRB) Cosmopolites sordidus (Germar; Coleoptera: Curculionidae) 的管理仍然是全球香蕉和大蕉生产的一个挑战。合成杀虫剂仍然是最广泛使用的解决方案，而越来越多地推荐使用杀真菌剂。在这项研究中，我们选择了从喀麦隆车前草田收集的白僵菌和绿僵菌的本地分离株，并在实验室中测试了它们对 C. sordidus 生命阶段的所有生命阶段的活力、致病性和毒力。在 3.2 × 108 分生孢子/ml 的分生孢子悬浮液中最初筛选了孢子萌发和对成年象鼻虫的致病性的 13 个分离株中，选择了 8 个具有高至中等萌发和最高象鼻虫死亡率的分离株进行剂量反应生物测定，每个分离株有四个浓度：3.2 × 102、3。2 × 104、3.2 × 106 和 3.2 × 108 分生孢子/ml。用 3.2 × 108 分生孢子/ml 的分生孢子悬浮液中的卵、幼虫和蛹测试来自成虫生物测定的毒力分离株。分离株的性能取决于昆虫的生命阶段，对幼虫、蛹和成虫阶段具有显着高的致病性和毒力。白僵菌分离株 BIITAC6.2.2 引起的死亡率最高，其次是 MIITAC1.1.5。三种 M. anisopliae 分离物和三种 B. bassiana 分离物的致死时间和致死浓度相对较低，它们是几乎所有昆虫生命阶段中最好的分离物。除了在多个生命阶段都有效之外，这些分离物在处理卵和蛹时会从一个阶段水平传播到另一个阶段。这些发现对 BRB 综合管理的意义，