Alkhaibari A M, Carolino A T, Bull J C, Samuels R I, Butt T M
Department of Biosciences College of Science, Swansea University Singleton Park, Swansea SA2 8PP, UK (
Department of Entomology and Plant Pathology, State University of North Fluminense, Campos dos Goytacazes, Rio de Janeiro 28016-602, Brazil (
J Med Entomol. 2017 May 1;54(3):696-704. doi: 10.1093/jme/tjw223.
Biorational insecticides are being increasingly used in integrated pest management programs. In laboratory bioassays, the pathogenicity of blastospores and conidia of the entomopathogenic fungus Metarhizium brunneum ARSEF 4556 was evaluated against larvae of three mosquito species. Three propagule concentrations (1 × 106, 1 × 107, and 1 × 108 spores ml - 1) were used in the bioassays. Results showed that Aedes aegypti had lower survival rates when exposed to blastospores than when exposed to conidia, whereas the converse was true for Culex quinquefasciatus larvae. Anopheles stephensi larvae survival rates were similar when exposed to blastospores and conidia, except at the higher doses, where blastospores were more virulent. Several assays showed little difference in mortalities when using either 1 × 107 or 1 × 108 spores ml - 1, suggesting a threshold above which no higher control levels or economic benefit would be achieved. When tested at the lowest dose, the LT50 of Cx. quinquefasciatus using blastospores, wet conidia, and dry conidia was 3.2, 1.9, and 4.4 d, respectively. The LT50 of Ae. aegypti using blastospores, wet conidia, and dry conidia was 1.3, 3.3, and 6.2 d, respectively. The LT50 of An. stephensi using blastospores, wet conidia, and dry conidia was 2.0, 1.9, and 2.1 d, respectively. These observations suggest that for optimized control, two different formulations of the fungus may be needed when treating areas where there are mixed populations of Aedes, Anopheles, and Culex.
生物合理杀虫剂在害虫综合管理计划中的使用越来越广泛。在实验室生物测定中，评估了昆虫病原真菌球孢白僵菌ARSEF 4556的芽生孢子和分生孢子对三种蚊虫幼虫的致病性。生物测定中使用了三种繁殖体浓度（1×10⁶、1×10⁷和1×10⁸孢子毫升⁻¹）。结果表明，埃及伊蚊暴露于芽生孢子时的存活率低于暴露于分生孢子时，而致倦库蚊幼虫的情况则相反。斯氏按蚊幼虫暴露于芽生孢子和分生孢子时的存活率相似，但在较高剂量下，芽生孢子的毒性更强。几项试验表明，使用1×10⁷或1×10⁸孢子毫升⁻¹时死亡率差异不大，这表明存在一个阈值，超过该阈值将无法实现更高的防治水平或经济效益。在最低剂量下进行测试时，致倦库蚊使用芽生孢子、湿分生孢子和干分生孢子的半数致死时间（LT50）分别为3.2天、1.9天和4.4天。埃及伊蚊使用芽生孢子、湿分生孢子和干分生孢子的LT50分别为1.3天、3.3天和6.2天。斯氏按蚊使用芽生孢子、湿分生孢子和干分生孢子的LT50分别为2.0天、1.9天和2.1天。这些观察结果表明，为了实现优化防治，在处理同时存在埃及伊蚊、按蚊和库蚊混合种群的地区时，可能需要两种不同的真菌制剂。
