BACKGROUND Resistance to pyrethroid insecticides in Aedes aegypti has become widespread after almost two decades of the frequent use of these pesticides to reduce arbovirus transmission. Despite this resistance, pyrethroids continue to be used because they are relatively inexpensive and have low human toxicity. Resistance management has been proposed as a way to retain the use of pyrethroids in natural populations. A key component of resistance management is the assumption that negative fitness is associated with resistance alleles such that resistance alleles will decline in frequency when the insecticides are removed. At least three studies in Ae. aegypti have demonstrated a decrease in pyrethroid resistance once the insecticide has been removed. METHODS/PRINCIPAL FINDINGS The present study aims to evaluate variation in the loss of pyrethroid resistance among newly established laboratory populations of Ae. aegypti from Mexico. Eight field collections were maintained for up to eight generations, and we recorded changes in the frequencies of the mutations at the V1,016I locus and at the F1,534C locus in the voltage-gated sodium channel gene (VGSC). I1,016 and C1,534 confer resistance. We also examined resistance ratios (RR) with type 1 and 2 pyrethroids. CONCLUSIONS/SIGNIFICANCE We demonstrate that, in general, the frequency of the Ae. aegypti pyrethroid-resistance alleles I1,016 and C1,534 decline when they are freed from pyrethroid pressure in the laboratory. However, the pattern of decline is strain dependent. In agreement with earlier studies, the RR was positively correlated with the frequencies of the resistance allele I1,016 and showed significant protection against permethrin, and deltamethrin, whereas F1,534C showed protection against permethrin but not against deltamethrin.

中文翻译：

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新建立的埃及伊蚊实验室菌落中的拟除虫菊酯抗性丧失。

背景技术在埃及伊蚊中对拟除虫菊酯类杀虫剂的抗药性在将近二十年来频繁使用这些杀虫剂以减少虫媒病毒传播后变得很普遍。尽管有这种抗药性，但由于拟除虫菊酯相对便宜且对人体无害，因此仍继续使用。已经提出了抗药性管理作为在自然种群中保留拟除虫菊酯使用的一种方法。耐药性管理的关键组成部分是假设负适应性与耐药性等位基因相关联，这样一来，当去除杀虫剂时，耐药性等位基因的频率就会降低。Ae至少进行了三项研究。一旦杀虫剂被清除，埃及伊蚊已经证明了拟除虫菊酯的抗药性降低。方法/主要发现本研究旨在评估新建立的Ae实验室人群中拟除虫菊酯抗性丧失的变化。来自墨西哥的埃及。八个场集合最多可维持八代，我们记录了电压门控钠通道基因（VGSC）中V1,016I基因座和F1,534C基因座的突变频率变化。I1,016和C1,534赋予电阻。我们还检查了1型和2型拟除虫菊酯的抗药性比（RR）。结论/意义通常，我们证明了Ae的频率。当它们在实验室中摆脱拟除虫菊酯的压力时，埃及拟除虫菊酯抗性等位基因I1,016和C1,534下降。但是，下降的模式取决于应变。与先前的研究一致，