Standardised bioassays reveal that mosquitoes learn to avoid compounds used in chemical vector control after a single sub-lethal exposure
Seynabou Sougoufara, Hanna Yorkston-Dives, Nurul Masyirah Aklee, Adanan Che Rus, Jaal Zairi & Frederic Tripet
英国基尔大学的Frederic Tripet和同事发现，雌性蚊子能在单次杀虫剂暴露后学会避开杀虫剂。他们表示，这也许会影响杀虫剂的灭蚊功效。
杀虫剂被用来遏制蚊媒疾病的传播。近几十年里，蚊子对杀虫剂的抗性有增无减，但之前尚不清楚这在多大程度上是由蚊子行为导致的。
雌性埃及伊蚊和致倦库蚊都能传播登革热、寨卡、西尼罗热等病毒，Tripet与同事将这两种蚊虫暴露在灭蚊常用的杀虫剂中，如马拉硫磷、残杀威、溴氰菊酯、二氯苯醚菊酯和高效氯氟氰菊酯。
随后，他们研究了对同种杀虫剂的再次暴露是否会阻止蚊子的摄食和休息，并评估了这是否会影响蚊子的存活率。
研究团队发现，相比没有在某个杀虫剂中预暴露过的蚊子，更高比例的预暴露蚊子不会穿过一个经杀虫剂处理的网来获得食物。相关研究2月18日发表于《科学报告》。
在这项研究中，只有15.4%的预暴露埃及伊蚊和12.1%的预暴露致倦库蚊会为了摄食而穿过这个网——没有预暴露蚊子的相应比例分别是57.7%和54.4%。预暴露蚊子的存活率也是没有预暴露蚊子的两倍以上。38.3%的预暴露埃及伊蚊和32.1%的预暴露致倦库蚊以及11.5%的没有预暴露的埃及伊蚊和12.9%的没有预暴露的致倦库蚊在穿过经杀虫剂处理的网后存活了下来。
研究团队还发现，预暴露蚊子比没有预暴露的蚊子更容易在一个有对照物质气味的容器中休息，而不是在一个有杀虫剂气味的容器中休息。75.7%的预暴露埃及伊蚊和83.1%的预暴露致倦库蚊会在没有杀虫剂的容器中休息——没有预暴露蚊子的相应比例分别是50.2%和50.4%。
研究还显示，在非致命杀虫剂剂量中暴露过的蚊子学会了避开这些杀虫剂，因此可能会寻找更安全的食物来源和休息点，让自己有机会繁衍下去。
来源：中国科学报 晋楠
Abstract
Vector-borne diseases are worldwide public health issues. Despite research focused on vectorial capacity determinants in pathogen transmitting mosquitoes, their behavioural plasticity remains poorly understood. Memory and associative learning have been linked to behavioural changes in several insect species, but their relevance in behavioural responses to pesticide vector control has been largely overlooked. In this study, female Aedes aegypti and Culex quinquefasciastus were exposed to sub-lethal doses of 5 pesticide compounds using modified World Health Organization (WHO) tube bioassays. Conditioned females, subsequently exposed to the same pesticides in WHO tunnel assays, exhibited behavioural avoidance by forgoing blood-feeding to ensure survival. Standardized resting site choice tests showed that pre-exposed females avoided the pesticides smell and choose to rest in a pesticide-free compartment. These results showed that, following a single exposure, mosquitoes can associate the olfactory stimulus of pesticides with their detrimental effects and subsequently avoid pesticide contact. Findings highlight the importance of mosquito cognition as determinants of pesticide resistance in mosquito populations targeted by chemical control.
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