The molecular impacts of chronic pesticide exposure on bee learning and memory

背景：最近，人们开始关注一类被称为新烟碱类杀虫剂对蜜蜂和本地蜜蜂传粉者的影响。这些新烟碱类被广泛用于农业种子处理。然而，目前尚不清楚新烟碱类杀虫剂在实际的田间水平上对蜜蜂是否具有显著的致死或亚致死作用。越来越多的人担心，通过蜜蜂采集的花蜜、花粉和水，将新烟碱类物质长期暴露在蜂巢中。长期暴露会破坏蜜蜂的繁殖、移动、导航、喂养、觅食、记忆、学习和整个蜂巢的活动。这些化学物质也被怀疑会影响蜜蜂的免疫系统，使它们更容易受到寄生虫和病原体的攻击。最近蜜蜂种群数量下降的另一个主要原因是寄生螨瓦螨的破坏。它已经成为欧洲蜜蜂最严重的害虫，因为欧洲蜜蜂缺乏对付这种螨虫的天然防御能力。螨虫也是许多病毒的载体，这些病毒可以极大地影响蜂群的健康，现在被认为是蜜蜂数量下降的主要原因之一。为了控制瓦螨，养蜂人对受感染的蜂箱施用化学杀瓦螨剂。在英国注册的几种产品包括草酸、百里香酚、甲酸、两种拟除虫菊酯杀虫剂——氟戊酸酯和氟甲菊酯，以及一种由樟脑外消旋、桉树油、薄荷醇左旋、百里香酚组成的专有混合物。此外，Coumaphos和Amitraz已在美国注册使用。有证据表明，其中一些化学物质对蜜蜂有害，导致蜜蜂数量下降，而且新烟碱类杀虫剂可能对蜜蜂的归巢能力和觅食率产生重大影响。阿米特拉兹也被认为是一种增效剂，可以放大拟除虫菊酯和新烟碱类杀虫剂的毒性作用。实验方法：该项目将研究蜂箱化学物质对蜜蜂的移动、导航、记忆和学习的亚致死效应。这些实验将使用一种新的热视觉竞技场场所学习分析平台进行，蜜蜂必须在一个不吸引人的温暖环境中找到一个隐藏的“安全”目标（即一块凉爽的瓷砖），利用竞技场墙壁上可用的空间线索。使用专有跟踪软件评估低剂量农药对蜜蜂学习和返回安全区能力的影响，而农药对短期和长期记忆的亚致死效应将通过研究对蜜蜂记忆途径的直接影响来评估，这些途径在生物化学和分子水平上具有相对较好的特征。培训：开展这项研究的技术和设施可以在洛桑研究所获得，学生将与其他研究生和博士后一起工作。学生将发展与蜜蜂基因组相关的生物信息学技能，熟悉广泛适用的标准分子技术（PCR，凝胶电泳等），并将从学习更专业的技术（如昆虫行为分析，农药应用技术等）中受益。该学生还将参加该研究所广泛的研究生培训计划。

Background: Recently, concern has been raised regarding the impact of a common class of pesticide known as neonicotinoids on honey bees and native bee pollinators. These neonicotinoids are widely used as seed treatments in agriculture. However, it is unclear whether neonicotinoids have a significant lethal or sub-lethal effect on bees at realistic field levels. There is a growing concern regarding chronic exposure to neonicotinoids through nectar, pollen, and water picked up by foraging bees and carried back to the hive. Chronic exposure can disrupt bees' reproduction, mobility, navigation, feeding, foraging, memory, learning, and overall hive activity. These chemicals are also suspected of affecting the honey bees' immune systems, making them more vulnerable to parasites and pathogens. Another key suspect in the recent decline of honey bee colonies is the parasitic mite Varroa destructor. It has become the most serious pest for the European honey bee Apis mellifera, which lacks natural defences to be able to deal with the mite. The mite also vectors of a number of viruses which can dramatically affect colony health, and is now recognised as one of the primary causes of honey bee decline. In order to control varroa, beekeepers apply chemical varroacides to infected hives. Several products are registered in the UK including Oxalic acid, Thymol, formic acid, two pyrethroid insecticides - tau-fluvalinate and flumethrin, and a proprietary blend consisting of Camphor Racemic, Eucalyptus Oil, Menthol Levo, Thymol. Additionally, Coumaphos and Amitraz are registered for use in the USA. There is evidence that some of these chemicals are hazardous to bees and contribute to bee decline, and as with the neonicotinoids may have significant impact on the bees homing ability and foraging rates. Amitraz has also been cited as a synergist that amplifies the toxic effects of pyrethroids and neonicotinoids. Experimental approaches: This project will examine the sub-lethal effects of bee hive chemicals on bee mobility, navigation, memory and learning. These experiments will be conducted using a novel thermal-visual arena place learning assay platform, where bees must find a hidden 'safe' target (that is a cool tile) in an otherwise unappealing warm environment, using available spatial cues on the walls of the arena. The effects of low dose pesticide application on the ability to learn and return to the safe zone will be assessed using proprietary tracking software, whereas the sub-lethal effects of pesticides on short and long term memory will be assessed by studying the direct effects on the bees memory pathways, which are relatively well characterised at the biochemical and molecular level. Training: The techniques and facilities for carrying out this research are available at Rothamsted and the student will work alongside other graduate students and post-docs. The student will develop bioinformatics skills relating to bee genomes, will become conversant with standard molecular techniques (PCR, gel electrophoresis etc) that are widely applicable and will also benefit from learning more specialised techniques e.g, insect behaviour assays, pesticide application techniques etc). The student will also participate in the Institutes extensive postgraduate training programme.