Laboratoire d'Ecologie Alpine, LECA-UMR 5553, Université de Grenoble 1, BP 53, 38041 Grenoble cedex 09, France.
Aquat Toxicol. 2013 Sep 15;140-141:389-97. doi: 10.1016/j.aquatox.2013.07.004. Epub 2013 Jul 16.
Mosquitoes are vectors of major human diseases, such as malaria, dengue or yellow fever. Because no efficient treatments or vaccines are available for most of these diseases, control measures rely mainly on reducing mosquito populations by the use of insecticides. Numerous biotic and abiotic factors are known to modulate the efficacy of insecticides used in mosquito control. Mosquito breeding sites vary from opened to high vegetation covered areas leading to a large ultraviolet gradient exposure. This ecological feature may affect the general physiology of the insect, including the resistance status against insecticides. In the context of their contrasted breeding sites, we assessed the impact of low-energetic ultraviolet exposure on mosquito sensitivity to biological and chemical insecticides. We show that several mosquito detoxification enzyme activities (cytochrome P450, glutathione S-transferases, esterases) were increased upon low-energy UV-A exposure. Additionally, five specific genes encoding detoxification enzymes (CYP6BB2, CYP6Z7, CYP6Z8, GSTD4, and GSTE2) previously shown to be involved in resistance to chemical insecticides were found over-transcribed in UV-A exposed mosquitoes, revealed by RT-qPCR experiments. More importantly, toxicological bioassays revealed that UV-exposed mosquitoes were more tolerant to four main chemical insecticide classes (DDT, imidacloprid, permethrin, temephos), whereas the bioinsecticide Bacillus thuringiensis subsp. israelensis (Bti) appeared more toxic. The present article provides the first experimental evidence of the capacity of low-energy UV-A to increase mosquito tolerance to major chemical insecticides. This is also the first time that a metabolic resistance to chemical insecticides is linked to a higher susceptibility to a bioinsecticide. These results support the use of Bti as an efficient alternative to chemical insecticides when a metabolic resistance to chemicals has been developed by mosquitoes.
蚊子是主要人类疾病的载体，如疟疾、登革热或黄热病。由于大多数这些疾病没有有效的治疗方法或疫苗，控制措施主要依赖于使用杀虫剂来减少蚊子数量。许多生物和非生物因素被认为可以调节用于控制蚊子的杀虫剂的效果。蚊子的滋生地从开阔地到植被茂密的地方不等，导致紫外线梯度暴露较大。这种生态特征可能会影响昆虫的一般生理机能，包括对杀虫剂的抵抗力。在它们对比鲜明的滋生地背景下，我们评估了低能量紫外线暴露对蚊子对生物和化学杀虫剂敏感性的影响。我们表明，几种蚊子解毒酶活性（细胞色素 P450、谷胱甘肽 S-转移酶、酯酶）在低能量 UV-A 暴露下增加。此外，通过 RT-qPCR 实验发现，五个先前显示与对化学杀虫剂的抗性有关的解毒酶编码基因（CYP6BB2、CYP6Z7、CYP6Z8、GSTD4 和 GSTE2）在 UV-A 暴露的蚊子中过度转录。更重要的是，毒理学生物测定表明，暴露于 UV 的蚊子对四种主要化学杀虫剂类（DDT、吡虫啉、氯菊酯、涕灭威）的耐受性更高，而生物杀虫剂苏云金芽孢杆菌亚种以色列（Bti）则更为有毒。本文首次提供了低能量 UV-A 增加蚊子对主要化学杀虫剂耐受性的实验证据。这也是首次将对化学杀虫剂的代谢抗性与对生物杀虫剂的更高敏感性联系起来。这些结果支持在蚊子产生对化学杀虫剂的代谢抗性时，使用 Bti 作为化学杀虫剂的有效替代品。
