Aedes aegypti Mosquitoes Use Their Legs to Sense DEET on Contact
Aedes aegypti Mosquitoes Use Their Legs to Sense DEET on Contact
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DOI：
10.1016/j.cub.2019.04.004
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发表时间：
2019-05-06
期刊：
影响因子：
9.2
通讯作者：
Vosshall, Leslie B.
中科院分区：
文献类型：
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作者：
Dennis, Emily J.;Goldman, Olivia V.;Vosshall, Leslie B.
DEET（N，N-二乙基间甲苯酰胺）是最有效和最广泛使用的驱虫剂，但其作用机制既复杂又有争议[1]。避蚊胺作用于昆虫的嗅觉[2-6]和味觉[7-11]，其嗅觉作用模式需要气味辅助受体orco [2，3，6]。我们之前观察到，orco突变的雌性埃及伊蚊即使在DEET存在下也会强烈吸引人类，但在接触DEET处理的皮肤后，它们会迅速被排斥[6]。避蚊胺抑制果蝇的食物摄取，这种驱避作用是由长鼻中的苦味神经元介导的[9]。在蚊子的喙中发现了类似的神经元，这导致了DEET通过激活令人厌恶的苦味通路来排斥接触的假设[10]。为了了解避蚊胺接触化学排斥的基础，我们进行了行为实验，发现避蚊胺通过三种不同的机制起作用：气味，摄入和接触。与苦味促味剂一样，避蚊胺在摄入时是一种摄食抑制剂，但其苦味本身并不能完全解释避蚊胺接触化学排斥。蚊子的血液喂养的人手臂处理高浓度的苦味，但迅速避免避蚊胺处理的皮肤，并没有血饲料。昆虫通过它们的长鼻和腿来探测味剂。我们表明，避蚊胺接触化学排斥反应完全由腿的跗骨节介导，而不是长鼻。这项工作确立了蚊子腿作为DEET的行为相关接触传感器。这些结果将为寻找介导避蚊胺接触化学排斥的分子机制和新型接触型驱虫剂提供信息。
DEET (N, N-diethyl-meta-toluamide) is the most effective and widely used insect repellent, but its mechanism of action is both complex and controversial [1]. DEET acts on insect smell [2-6] and taste [7-11], and its olfactory mode of action requires the odorant coreceptor orco [2, 3, 6]. We previously observed that orco mutant female Aedes aegypti mosquitoes are strongly attracted to humans even in the presence of DEET, but they are rapidly repelled after contacting DEET-treated skin [6]. DEET inhibits food ingestion by Drosophila melanogaster flies, and this repellency is mediated by bitter taste neurons in the proboscis [9]. Similar neurons were identified in the mosquito proboscis, leading to the hypothesis that DEET repels on contact by activating an aversive bitter taste pathway [10]. To understand the basis of DEET contact chemorepellency, we carried out behavioral experiments and discovered that DEET acts by three distinct mechanisms: smell, ingestion, and contact. Like bitter tastants, DEET is a feeding deterrent when ingested, but its bitterness per se does not fully explain DEET contact chemorepellency. Mosquitoes blood fed on human arms treated with high concentrations of bitters, but rapidly avoided DEET-treated skin and did not blood feed. Insects detect tastants both through their proboscis and legs. We show that DEET contact chemorepellency is mediated exclusively by the tarsal segments of the legs and not the proboscis. This work establishes mosquito legs as the behaviorally relevant contact sensors of DEET. These results will inform the search for molecular mechanisms mediating DEET contact chemorepellency and novel contact-based insect repellents.