Department of Entomology and Acarology, Luiz de Queiroz College of Agriculture (ESALQ), University of São Paulo (USP), Avenue Pádua Dias 11, Piracicaba, São Paulo, Brazil.
J Econ Entomol. 2021 Apr 13;114(2):903-913. doi: 10.1093/jee/toab011.
Spodoptera frugiperda (J.E. Smith) is one of the key cross-crop pests in Brazilian agroecosystems. Field-evolved resistance of S. frugiperda to some conventional insecticides and Bt proteins has already been reported. Thus, the use of insecticides with new mode of action such as sodium channel blockers (indoxacarb and metaflumizone) could be an important tool in insecticide resistance management (IRM) programs. To implement a proactive IRM, we conducted baseline response and monitoring to indoxacarb and metaflumizone in 87 field populations of S. frugiperda collected from major maize-growing regions of Brazil from 2017 to 2020, estimated the frequency of resistance alleles to indoxacarb, and evaluated cross-resistance of indoxacarb and metaflumizone to some selected insecticides and Bt proteins. Low variation in susceptibility to indoxacarb (4.6-fold) and metaflumizone (2.6-fold) was detected in populations of S. frugiperda in 2017. The frequency of the resistance allele to indoxacarb was 0.0452 (0.0382-0.0527 CI 95%), by using F2 screen method. The mean survival at diagnostic concentration, based on CL99, varied from 0.2 to 12.2% for indoxacarb and from 0.0 to 12.7% for metaflumizone, confirming high susceptibility of S. frugiperda to these insecticides in Brazil. No cross-resistance was detected between sodium channel blocker insecticides and other insecticides (organophosphate, pyrethroid, benzoylurea, spinosyn, and diamide) and Bt proteins. These findings showed that sodium channel blocker insecticides are important candidates to be exploited in IRM strategies of S. frugiperda in Brazil.
草地贪夜蛾（Spodoptera frugiperda）是巴西农业生态系统中跨作物的关键害虫之一。已经有报道称，草地贪夜蛾对一些常规杀虫剂和 Bt 蛋白产生了田间进化抗性。因此，使用具有新作用模式的杀虫剂，如钠离子通道阻断剂（茚虫威和氟苯虫酰胺），可能是害虫综合治理（IRM）计划中的一个重要工具。为了实施积极的 IRM，我们从 2017 年到 2020 年，在巴西主要玉米种植区采集了 87 个草地贪夜蛾田间种群，对茚虫威和氟苯虫酰胺进行了基线反应和监测，估计了对茚虫威的抗性等位基因频率，并评估了茚虫威和氟苯虫酰胺对一些选定杀虫剂和 Bt 蛋白的交叉抗性。2017 年，草地贪夜蛾种群对茚虫威（4.6 倍）和氟苯虫酰胺（2.6 倍）的敏感性变化很小。使用 F2 筛选法，对茚虫威的抗性等位基因频率为 0.0452（0.0382-0.0527 CI 95%）。基于 CL99 的诊断浓度下的平均存活率，茚虫威为 0.2%至 12.2%，氟苯虫酰胺为 0.0%至 12.7%，这证实了巴西草地贪夜蛾对这些杀虫剂的高度敏感性。钠离子通道阻断剂杀虫剂与其他杀虫剂（有机磷、拟除虫菊酯、苯甲酰脲、多杀菌素和双酰胺）和 Bt 蛋白之间未检测到交叉抗性。这些发现表明，钠离子通道阻断剂杀虫剂是巴西草地贪夜蛾 IRM 策略中的重要候选药剂。
