Garzo Elisa, Moreno Aranzazu, Hernando Sara, Mariño Vera, Torne María, Santamaria Estrella, Díaz Isabel, Fereres Alberto
Institute of Agricultural Sciences, ICA, CSIC, Madrid, Spain.
Dow Agrosciences Iberica S.A., Madrid, Spain.
Pest Manag Sci. 2016 Apr;72(4):707-18. doi: 10.1002/ps.4041. Epub 2015 Jun 12.
Sulfoxaflor, a new insecticide from the sulfoximine chemical family, and imidacloprid, a widely used neonicotinoid insecticide, were tested to assess the susceptibility and feeding behaviour of two populations of Myzus persicae: Mp61, which exhibited target-site R81T resistance to neonicotinoids, and Mp1989, a laboratory clone maintained since 1989 as a susceptible reference.
The imidacloprid LC50 value for Mp61 was 16 times higher than for Mp1989, showing a moderate level of resistance. Sulfoxaflor LC50 values for Mp61 and Mp1989 were much closer. The probing behaviour, as assessed by electrical penetration graphs (EPGs), of both populations was clearly altered by sulfoxaflor, which reduced the ability of aphids to find and feed from the phloem. The feeding behaviour of the susceptible Mp1989 population was much more severely affected than the moderately resistant Mp61 population on imidacloprid-treated plants. PCR assays of both aphid populations followed by DNA sequencing identified differences between populations in the point mutation in the β-subunit of the nicotinic acetylcholine receptor linked to the resistant gene against the neonicotinoid insecticide.
Sulfoxaflor provoked feeding cessation more rapidly than imidacloprid in both aphid populations. Sharp differences in feeding behaviour were detected between the susceptible and the moderately resistant neonicotinoid-resistant aphid populations. The EPG technique can be used as a useful tool to give new insights into the functional effects of new chemical compounds and for early detection of low to moderate levels of resistance of sap-feeding insects to insecticides. The potential of this technique was validated by molecular analysis of the R81T mutation target site.
新型杀虫剂氟啶虫胺腈属于砜亚胺化学家族，而吡虫啉是一种广泛使用的新烟碱类杀虫剂。本研究对这两种杀虫剂进行了测试，以评估桃蚜两个种群的敏感性和取食行为：Mp61种群对新烟碱类杀虫剂表现出靶位点R81T抗性；Mp1989种群自1989年以来作为敏感对照在实验室中克隆培养。
Mp61种群对吡虫啉的LC50值比Mp1989种群高16倍，表明其具有中等水平的抗性。Mp61和Mp1989种群对氟啶虫胺腈的LC50值更为接近。通过刺探电位图谱（EPG）评估发现，氟啶虫胺腈显著改变了两个种群的刺探行为，降低了蚜虫寻找韧皮部并从中取食的能力。在吡虫啉处理的植株上，敏感的Mp1989种群的取食行为受到的影响比中等抗性的Mp61种群更为严重。对两个蚜虫种群进行PCR检测并测序后发现，与新烟碱类杀虫剂抗性基因相关的烟碱型乙酰胆碱受体β亚基的点突变在两个种群之间存在差异。
在两个蚜虫种群中，氟啶虫胺腈比吡虫啉更快地引发取食停止。在敏感和中等抗性的新烟碱类抗性蚜虫种群之间检测到了取食行为的显著差异。EPG技术可作为一种有用的工具，用于深入了解新化合物的功能效应，以及早期检测吸食汁液昆虫对杀虫剂的低至中等水平抗性。通过对R81T突变靶位点的分子分析验证了该技术的潜力。
