Department of Entomology and Plant Pathology, Universidade Estadual do Norte Fluminense Darcy Ribeiro, Campos dos Goytacazes RJ CEP 28013-602 Brazil.
Parasit Vectors. 2011 Jan 25;4:8. doi: 10.1186/1756-3305-4-8.
Dengue fever transmitted by the mosquito Aedes aegypti, is one of the most rapidly spreading insect borne diseases, stimulating the search for alternatives to current control measures. The dengue vector A. aegypti has received less attention than anophelene species, although more than 2.5 billion people are at risk of infection worldwide. Entomopathogenic fungi are emerging as potential candidates for the control of mosquitoes. Here we continue our studies on the pathogenicity of the entomopathogenic fungus Metarhizium anisopliae against adult A. aegypti females. With the aim of further reducing mean survival times of A. aegypti exposed to fungus impregnated surfaces, a sub-lethal concentration of the neonicotinoid insecticide Imidacloprid (IMI) was added to fungal suspensions.
A sub-lethal concentration of IMI that did not significantly alter the daily survival rates or mean survival percentages of mosquitoes was identified to be 0.1 ppm. This sub-lethal concentration was combined with M. anisopliae conidia (1 × 10(9) conidia mL(-1)). Both the combined treatment and the conidia alone were able to reduce the survival of A. aegypti compared with untreated or IMI treated mosquitoes. Importantly, mosquito survival following exposure to the combined treatment for 6 and 12 hrs was significantly reduced when compared with mosquitoes exposed to conidia alone.
This is the first time that a combination of an insecticide and an entomopathogenic fungus has been tested against A. aegypti. Firstly, the study showed the potential of IMI as an alternative to the currently employed pyrethroid adulticides. Secondly, as an alternative to applications of high concentrations of chemical insecticides, we suggest that adult A. aegypti could be controlled by surface application of entomopathogenic fungi and that the efficiency of these fungi could be increased by combining the fungi with ultra-low concentrations of insecticides, resulting in higher mortality following relatively short exposure times.
登革热由埃及伊蚊传播，是传播最快的虫媒病之一，这刺激了人们寻找替代当前控制措施的方法。登革热媒介埃及伊蚊比疟蚊属物种受到的关注较少，尽管全世界有超过 25 亿人面临感染风险。昆虫病原真菌作为控制蚊子的潜在候选者而出现。在这里，我们继续研究昆虫病原真菌绿僵菌对成年埃及伊蚊雌性的致病性。为了进一步降低接触真菌浸渍表面的埃及伊蚊的平均存活时间，在真菌悬浮液中添加了新烟碱类杀虫剂吡虫啉（IMI）的亚致死浓度。
确定不会显著改变蚊子日存活率或平均存活率百分比的亚致死浓度 IMI 为 0.1 ppm。将该亚致死浓度与绿僵菌分生孢子（1×10(9)分生孢子 mL(-1))组合。单独的分生孢子和组合处理都能够降低埃及伊蚊的存活率，与未处理或用 IMI 处理的蚊子相比。重要的是，与单独接触分生孢子的蚊子相比，暴露于组合处理 6 和 12 小时后蚊子的存活率显著降低。
这是第一次测试杀虫剂和昆虫病原真菌对埃及伊蚊的联合作用。首先，该研究显示了 IMI 作为目前使用的拟除虫菊酯类杀虫剂替代品的潜力。其次，作为替代高浓度化学杀虫剂的应用方法，我们建议通过表面应用昆虫病原真菌来控制成年埃及伊蚊，并且可以通过将真菌与超低浓度的杀虫剂结合使用来提高这些真菌的效率，从而在相对较短的暴露时间后实现更高的死亡率。
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