评价来自巴西最北部罗赖马州的埃及伊蚊种群对拟除虫菊酯和有机磷杀成虫剂的抗药性和 kdr 基因分型。
Evaluation of resistance to pyrethroid and organophosphate adulticides and kdr genotyping in Aedes aegypti populations from Roraima, the northernmost Brazilian State.
机构信息
Laboratório de Parasitologia e Monitoramento de Artrópodes Vetores da Amazônia, Universidade Federal de Roraima, Boa Vista, RR, Brazil.
Laboratório de Fisiologia e Controle de Artrópodes Vetores, Instituto Oswaldo Cruz, FIOCRUZ, Av Brasil 4365, Manguinhos, Rio de Janeiro, RJ, Brazil.
出版信息
Parasit Vectors. 2020 May 20;13(1):264. doi: 10.1186/s13071-020-04127-w.
BACKGROUND
Roraima, the northernmost State in Brazil, borders Venezuela and Guyana. Although mostly covered by the tropical forests, the urban centers of this state are highly infested with Ae. aegypti and are endemic for dengue, Zika and chikungunya. We accessed the insecticide resistance status of Ae. aegypti populations from the capital Boa Vista, two cities on international borders (Pacaraima and Bonfim) and Rorainópolis bordering Amazonas State, in order to evaluate the chemical control efficacy in these localities.
METHODS
Tests with World Health Organization (WHO)-like tubes impregnated with the pyrethroid deltamethrin (0.05% and 0.12%) and the organophosphate malathion (0.7%) were conducted with Ae. aegypti from Boa Vista, Pacaraima, Bonfim and Rorainópolis, collected in 2016 and 2018. Genotyping of kdr mutations, related to resistance to pyrethroids, was performed for the SNP variations at sites 1016 and 1534 of the voltage gated sodium channel gene (Na) with a TaqMan qPCR approach.
RESULTS
Aedes albopictus was absent in our collections, and therefore only Ae. aegypti was tested. All Ae. aegypti populations were susceptible to 0.7% malathion in 2016; however, mortality dropped to under 90% in Bonfim and Pacaraima populations in 2018. All populations were resistant to 0.05% deltamethrin in both years. The time that 50% of females suffered knockdown (KdT) under exposure to 0.05% deltamethrin was 3.3-5.9-fold longer in mosquitoes from the natural populations compared to the susceptible Rockefeller strain. Only the Pacaraima population (2018) remained resistant to 0.12% deltamethrin. Kdr genotyping revealed the absence of the wild-type NaS haplotype (1016Val + 1534Phe) in the populations from Roraima, indicating that all tested insects had a genetic background for pyrethroid resistance. The double kdr NaR2 haplotype (1016Ile + 15434Cys) was present in higher frequencies in all populations except for Rorainópolis, where this haplotype seems to have arrived recently.
CONCLUSIONS
These results are important for the knowledge about insecticide resistance status of Ae. aegypti populations from Roraima and will help improve vector control strategies that may be applied to diverse localities under similar geographical and urban conditions.
背景
巴西最北部的罗赖马州与委内瑞拉和圭亚那接壤。尽管该州大部分地区被热带雨林覆盖，但该州的城市中心仍有大量埃及伊蚊滋生，并流行登革热、寨卡和基孔肯雅热。我们评估了罗赖马州首府博阿维斯塔、两个与国际接壤的城市（帕拉赖马和博芬姆）以及与亚马逊州接壤的罗赖诺波利斯的埃及伊蚊种群的杀虫剂抗药性状况，以评估这些地方的化学控制效果。
方法
2016 年和 2018 年，我们使用世界卫生组织（世卫组织）类似管，对从博阿维斯塔、帕拉赖马、博芬姆和罗赖诺波利斯采集的埃及伊蚊进行了测试，这些管中浸渍有拟除虫菊酯溴氰菊酯（0.05%和 0.12%）和有机磷马拉硫磷（0.7%）。利用 TaqMan qPCR 方法，对电压门控钠离子通道基因（Na）的 1016 和 1534 位的 SNP 变异，对 kdr 突变（与拟除虫菊酯抗性相关）进行基因分型。
结果
在我们的采集物中没有发现白纹伊蚊，因此只测试了埃及伊蚊。所有埃及伊蚊种群在 2016 年均对 0.7%马拉硫磷敏感；然而，2018 年博芬姆和帕拉赖马种群的死亡率降至 90%以下。所有种群在两年中均对 0.05%溴氰菊酯产生抗药性。与敏感的洛克菲勒品系相比，在自然种群中，50%雌性遭受击倒（KdT）的时间在接触 0.05%溴氰菊酯时延长了 3.3-5.9 倍。只有帕拉赖马种群（2018 年）对 0.12%溴氰菊酯仍有抗性。Kdr 基因分型显示，罗赖马州种群中不存在野生型 NaS 单倍型（1016Val + 1534Phe），这表明所有测试的昆虫都具有对拟除虫菊酯的遗传抗性背景。除了罗赖诺波利斯，在所有种群中都存在双 kdr NaR2 单倍型（1016Ile + 15434Cys），而在罗赖诺波利斯，这种单倍型似乎是最近才出现的。
结论
这些结果对于了解罗赖马州埃及伊蚊种群的杀虫剂抗药性状况非常重要，并将有助于改进可能在类似地理和城市条件下应用于不同地点的病媒控制策略。
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