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Elucidating the regulation of reproduction in Varroa mites: uncovering potential control strategies.

阐明瓦螨的繁殖调节：揭示潜在的控制策略。

基本信息

批准号：
BB/S008705/1
负责人：
Alan Bowman
金额：
$ 59.1万
依托单位：
University of Aberdeen
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2019
资助国家：
英国
起止时间：
2019 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=BB%2FS008705%2F1
关键词：
Elucidating regulation reproduction Varroa mites

项目摘要

Insect pollination of crops is absolutely critical to food production with an estimated annual global value of $361 billion. Honey bees (Apis mellifera) are undergoing a serious bee health crisis threatening global food security. Huge annual losses of bee colonies in the US (45%, 34%, 40% in 2012/13, 2013/14 and 2015/16) are now being matched by similar losses in Europe. The status of bee health is recognised as critical with unsustainable losses of bees. Though the cause of the bee health crisis is multifactorial, it is generally accepted that the external parasite varroa mite (Varroa destructor) and its transmission of viral pathogens is one of, if not the, major cause of honey bee colony loss. Because of the impact on global food production, varroosis is arguably the most serious disease of livestock in any species.Despite varroa's unquestionable significance, our understanding of its physiology could be considered rudimentary relative to its importance. Progress in varroa research is substantially hampered by the lack an artificial feeding and rearing system which would supply researchers with adequate numbers of consistent varroa year round and provide an ideal experimental system for studying varroa physiology, reproduction, disease transmission and the development and testing of new control strategies. We have recently developed an artificial feeding system for varroa that far exceeds any currently available. Subsequently, we succeeded in inducing varroa in the artificial feeding system to lay eggs by exposing them to the odour cues from either bee larvae or hormone-treated pupae, but not from standard pupae. These eggs hatched and developed through to adult varroa. We now need to capitalize on these initial findings and better understand the fundamentals of varroa reproduction to allow our artificial feeding system to fully evolve into an artificial rearing system.To this end, the overall aim of the project is to understand the control of reproduction in varroa and assess if this information could be utilised as a control measure. By analysing the volatile compounds emanating from cohorts of larvae, pupae and juvenile hormone-treated pupae and applying a differential chemometrics approach, we will chemically characterize components(s) of the "Oviposition Kairomone" (OK). The effect of the larval volatiles or OK on induction of oviposition, the gender of the egg and cessation of egg laying in varroa will be studied by a combination of bioassay and chemical analysis. The role of juvenile hormone in the production of these bioactive volatiles or OK by bee larvae will be elucidated. We will investigate if the varroa detects this odour cue from the bee larvae with its legs and if this signal causes egg laying in varroa through induced sex hormone production (ecdysteroids) via a neuroendocrine factor. The optimum concentration of larval volatiles or OK required to induce varroa egg laying in the artificial rearing system will be determined by chemical analysis and bioassay and then a suitable method for delivery of that concentration range developed.There are strains of bees in France, Sweden and Germany exhibiting a trait termed "Suppressed Mite Reproduction" by which varroa have reduced reproduction. By performing the oviposition bioassay and chemical analysis, we will test the hypothesis that altered levels of larval volatiles or OK are the basis for the reduced varroa reproduction on these bee strains. Finally, we will assess if larval volatiles or OK can induce varroa to lay eggs even when in an inappropriate scenario such as while on adult bees.

作物的昆虫授粉对粮食生产绝对至关重要，全球每年的价值估计为3610亿美元。蜜蜂（Apis mellifera）正经历一场严重的蜜蜂健康危机，威胁着全球粮食安全。美国每年蜂群的大量损失（2012/13、2013/14和2015/16年度分别为45%、34%和40%），现在欧洲也出现了类似的损失。蜜蜂的健康状况被认为是不可持续的蜜蜂损失的关键。虽然蜜蜂健康危机的原因是多因素的，但人们普遍认为，外部寄生虫瓦螨（Varroa destructor）及其病毒病原体的传播是蜜蜂群体损失的主要原因之一。由于对全球粮食生产的影响，Varroosis可以说是任何物种中最严重的牲畜疾病。尽管Varroa的重要性毋庸置疑，但相对于其重要性，我们对其生理学的理解可以被认为是基本的。瓦螨研究的进展受到了严重阻碍，缺乏一个人工饲养和饲养系统，这将为研究人员提供足够数量的一致瓦螨全年，并提供一个理想的实验系统，研究瓦螨生理，繁殖，疾病传播和新的控制策略的开发和测试。我们最近开发了一种瓦螨的人工喂养系统，远远超过目前可用的任何系统。随后，我们成功地诱导varroa在人工饲养系统中产卵，通过将它们暴露于蜜蜂幼虫或蜜蜂处理的蛹的气味线索，但不是从标准蛹。这些卵孵化并发育成成年瓦罗阿。我们现在需要利用这些初步发现，更好地了解瓦螨繁殖的基本原理，使我们的人工饲养系统完全发展成为人工饲养系统。为此，该项目的总体目标是了解瓦螨的繁殖控制，并评估这些信息是否可以用作控制措施。通过分析从幼虫、蛹和幼蛙处理的蛹的队列中散发的挥发性化合物，并应用差分化学计量学方法，我们将化学表征“产卵利它素”（OK）的组分。采用生物测定和化学分析相结合的方法，研究了挥发性物质对瓦螨产卵诱导、卵性别和产卵停止的影响。保幼激素在蜜蜂幼虫产生这些生物活性挥发物或OK中的作用将被阐明。我们将调查如果varroa检测到这种气味线索从蜜蜂幼虫与它的腿，如果这个信号导致产卵varroa通过诱导性激素的生产（蜕皮激素）通过神经内分泌因子。在人工饲养系统中诱导瓦螨产卵所需的幼虫挥发物或OK的最佳浓度将通过化学分析和生物测定来确定，然后开发出用于递送该浓度范围的合适方法。通过进行产卵生物测定和化学分析，我们将测试的假设，改变幼虫挥发物或OK水平的基础上减少varroa繁殖这些蜜蜂品系。最后，我们将评估幼虫挥发物或OK是否可以诱导瓦螨产卵，即使在一个不适当的情况下，如在成年蜜蜂。