瓦螨(Varroa destructor)寄生密度与蜜蜂卷翅病毒动态复制相关性研究

病毒复制动态变化对揭示病毒病致病的机理具有重要意义。本研究以蜜蜂卷翅病毒(deformed wing virus,简写为DWV)为模型,使用荧光反转录定量PCR方法检测DWV病毒隐性感染蜂群在体壁寄生螨侵袭压力下工蜂体内病毒基因表达量的变化动态,以揭示外界生物压力与隐性感染蜜蜂体内病毒动态复制的相关性。结果显示:弱群势蜜蜂体内DWV基因表达量与引入瓦螨密度呈显著正相关(第3天:R2=0.82;第7天:R2=0.99;双向方差分析F=5.059,P=0.0171);在瓦螨密度增至30%,处理后第7天时DWV浓度达最大值;强群势的蜜蜂群体引入瓦螨后,蜜蜂体内DWV基因表达量在处理后第3天表现出与弱群相似的变化规律(R2=0.88;双向方差分析F=11.74,P=0.001 3),但在处理后第7天时,供试蜜蜂体内DWV浓度整体下降,且不同瓦螨处理水平试验组间的DWV浓度差异不明显(R2=0.66)。结果显示,强群势蜂群的工蜂可有效抑制病毒拷贝量的持续增长,从而表现较强抗病性,而弱群势蜜蜂因病毒动态复制的不可逆激增而导致病毒病暴发。该研究结果在一定程度上解释了弱群势蜜蜂高病毒病易感性和年周损失的原因。

狄氏瓦螨(Varroa destructor)的研究进展

狄氏瓦螨(Varroa destructor)是严重危害西方蜜蜂(Apismellifera)的一种寄生螨,近几年对狄氏瓦螨的研究有了新的进展,本文就血统进化、生理机制、携带病原菌和最新的防治方法等领域作一综述。

Preliminary Researches Regarding the Effectiveness of the Formic Acid Treatment on Varroa(Varroa destructor) Found in the Artificially Decapped Bee Brood

The objective of the study was to establish the effect of formic acid on varroa(Varroa destructor),inside the capped brood cells,artificially decapped.The experiments were carried out in 2017-2018 on honeybee colonies infested with varroa(V.destructor),in a research apiary belonging to the Institute for Beekeeping Research and Development in Bucharest.The decapping method in the present researches used the decapping fork to scrape the capped comb,without affecting the brood,in order to open it for an effective treatment.The combined treatment method was applied on honeybee colonies as a whole,as well as on brood combs,without bees,put in a special treatment box.The researches were focused on establishing the mortality level of various stages of varroa in artificially decapped brood,in normal colony and separately,as well as to make observations on the effect of formic acid on viability of capped bee brood,artificially decapped.The results show a high mortality of varroa,especially the protonymphs and deutonymphs stages(over 80%).The main conclusion is that the brood decapping method combined with formic acid treatment could be a useful technique to control varroa infestation,both in brood and honeybees,shortening strongly the treatment duration as compared to the usual treatments,increasing the efficacy of treatment by cutting the life cycle of varroa in brood.

Genes important for survival or reproduction in Varroa destructor identified by RNAi

The Varroa mite,(Varroa destructor),is the worst threat to honey bee health worldwide.To explore the possibility of using RNA interference to control this pest, we determined the effects of knocking down various genes on Varroa mite survival and reproduction.Double-stranded RNA (dsRNA)of six candidate genes (Da,Pros26S,RpL8, RpL11,RpPO and RpS13)were synthesized and each injected into Varroa mites,then mite survival and reproduction were assessed.Injection of dsRNA for Da (Daughterless)and Pros26S (Gene for proteasome 26S subunit adenosine triphosphatase)caused a significant reduction in mite survival,with 3.57%±1.94% and 30.03%±11.43% mites surviving at 72 h post-inj ection (hpi),respectively.Control mites injected with green fluorescent protein (GFP)-dsRNA showed survival rates of 81.95%±5.03% and 82.36 ±2.81%,respectively. Injections of dsRNA for four other genes (RpL8,RpL11,RpPO and RpS13)did not affect survival significantly,enabling us to assess their effect on Varroa mite reproduction.The number of female offspring per mite was significantly reduced for mites injected with dsRNA of each of these four genes compared to their GFP-dsRNA controls.Knockdown of the target genes was verified by real-time polymerase chain reaction for two genes important for reproduction (RpL8,RpL11)and one gene important for survival (Pros26S). In conclusion,through RNA interference,we have discovered two genes important for mite survival and four genes important for mite reproduction.These genes could be explored as possible targets for the control of Varroa destructor in the future.

Effects of Imidacloprid and Varroa destructor on survival and health of European honey bees, Apis mellifera

There has been growing concern over declines in populations of honey bees and other pollinators which are a vital part to our food security. It is imperative to identify factors responsible for accelerated declines in bee populations and develop solutions for reversing bee losses. While exact causes of colony losses remain elusive, risk factors thought to play key roles are ectoparasitic mites Varroa destructor and neonicotinoid pesticides. The present study aims to investigate effects of a neonicotinoid pesticide Imidacloprid and Varroa mites individually on survivorship, growth, physiology, virus dynamics and immunity of honey bee workers. Our study provides clear evidence that the exposure to sublethal doses of Imidacloprid could exert a significantly negative effect on health and survival of honey bees. We observed a significant reduction in the titer ofvitellogenin （Vg）, an egg yolk precursor that regulates the honey bees development and behavior and often are linked to energy homeostasis, in bees exposed to lmidacloprid. This result indicates that sublethal exposure to neonicotinoid could lead to increased energy usage in honey bees as detoxification is a energy-consuming metabolic process and suggests that Vg could be a useful biomarker for measuring levels of energy stress and sublethal effects of pesticides on honey bees. Measurement of the quantitative effects of different levels of Varroa mite infestation on the replication dynamic of Deformed wing virus （DWV）, an RNA virus associated with Varroa infestation, and expression level of immune genes yields unique insights into how honey bees respond to stressors under laboratory conditions.

Next generation sequencing of Apis mellifera syriaca identifies genes for Varroa resistance and beneficial bee keeping traits

Apis mellifera syriaca exhibits a high degree of tolerance to pests and pathogens including varroa mites. This native honey bee subspecies of Jordan expresses behavioral adaptations to high temperature and dry seasons typical of the region. However, persistent honey bee imports of commercial breeder lines are endangering local honey bee population. This study reports the use of next-generation sequencing （NGS） technology to study the A. m. syriaca genome and to identify genetic factors possibly contributing toward mite resistance and other favorable traits. We obtained a total of 46.2 million raw reads by applying the NGS to sequence A. m. syriaca and used extensive bioinformatics approach to identify several candidate genes for Varroa mite resistance, behavioral and immune responses char- acteristic for these bees. As a part of characterizing the functional regulation of molecular genetic pathway, we have mapped the pathway genes potentially involved using information from Drosophila melanogaster and present possible functional changes implicated in responses to Varroa destructor mite infestation toward this. We performed in-depth functional annotation methods to identify -600 candidates that are relevant, genes involved in pathways such as microbial recognition and phagocytosis, peptidoglycan recognition protein family, Gram negative binding protein family, phagocytosis receptors, serpins, Toll signaling pathway, Imd pathway, Tnf, JAK-STAT and MAPK pathway, heamatopioesis and cellular response pathways, antiviral, RNAi pathway, stress factors, etc. were selected. Finally, we have cataloged function-specific polymorphisms between A. mellifera and A. m. syriaca that could give better understanding of varroa mite resistance mechanisms and assist in breeding. We have identified immune related embryonic development （Cactus, Relish, dorsal, Ank2, baz）, Varroa hygiene （NorpA2, Zasp, LanA, gasp, impl3） and Varroa resistance （Pug, pcmt, elk, elf3-s10, Dscam2, Dhc64C, gro, futsch） functional variations genes between A. mellifera and A. m. syriaca that could be used to develop an effective molecular tool for bee conservation and breeding programs to improve locally adapted strains such as syriaca and utilize their advantageous traits for the benefit of apiculture industry.

Association of Varroa destructor females in multiply infested cells of the honeybee Apis mellifera

The genetic diversity of Varroa destructor (Anderson &Trueman)is limited outside its natural range due to population bottlenecks and its propensity to inbreed.In light of the arms race between V.destructor and its honeybee (Apis mellifera L.)host, any mechanism enhancing population admixture of the mite may be favored.One way that admixture can occur is when two genetically dissimilar mites coinvade a brood cell, with the progeny of the foundresses admixing.We determined the relatedness of 393 pairs of V.destructor foundresses,each pair collected from a single bee brood cell (n =five colonies).We used six microsatellites to identify the genotypes of mites coinvading a cell and calculated the frequency of pairs with different or the same genotypes.We found no deviation from random coinvasion,but the frequency of cells infested by mites with different genotypes was high.This rate of recombination,coupled with a high transmission rate of mites,homogenized the allelic pool of mites within the apiary.

Varroa destructor mite infestations in capped brood cells of honeybee workers affect emergence development and adult foraging ability

Given recent higher declines in managed Apis mellifera honeybees,which are the most commonly managed bee species around the world(Garibaldi et al.2013),numerous health threats involved in the losses have been received great attention.To date,Varroa destructor mite infestation has become the biggest challenge in commercial beekeeping,which is considered as a thorn stuck in the throat of beekeepers.The Varroa mite threatens bee health by absorbing the fat body and hemolymph of immature and mature bees(Ramsey et al.2019).Varroa mite infestation during the development of worker bees was found to reduce birth weight,influence water content and protein level in hemolymph of newly emerged worker bees,decrease flight performance of drones,change gene expression patterns related to immune system of honeybees,and result in honeybee colony losses(Duay et al.2002;Bowen-Walker and Gunn 2010;Zhang et al.2010;Annoscia et al.2012;Dooremalen et al.2013;Locke 2016).The Varroa mite,as an ectoparasite of the honeybee,prefers living in the sealed brood cells(Bogdanov 2006).Thus,bees are more likely to become hosts of mites in the pupal stage.In this study,we systematically investigated the current impacts of V.destructor infestations on the development from capped larvae to emerged bees.

Changing climate patterns risk the spread of Varroa destructor infestation of African honey bees in Tanzania

Background:Climate change creates opportune conditions that favour the spread of pests and diseases outside their known active range.Modelling climate change scenarios is oftentimes useful tool to assess the climate analogues to unveil the potential risk of spreading suitability conditions for pests and diseases and hence allows development of appropriate responses to address the impending challenge.In the current study,we modelled the impact of climate change on the distribution of Varroa destructor,a parasitic mite that attacks all life forms of honey bees and remains a significant threat to their survival and productivity of bee products in Tanzania and elsewhere.Methods:The data about the presence of V.destructor were collected in eight regions of Tanzania selected in consideration of several factors including potentials for beekeeping activities,elevation(highlands vs.lowlands)and differences in climatic conditions.A total of 19 bioclimatic datasets covering the entire country were used for developing climate scenarios of mid-century 2055 and late-century 2085 for both rcp4.5 and rcp8.5.We thereafter modelled the current and future risk distribution of V.destructor using MaxEnt.Results:The results indicated a model performance of AUC=0.85,with mean diurnal range in temperature(Bio2,43.9%),mean temperature(Bio1,20.6%)and mean annual rainfall(Bio12,11.7%)as the important variables.Future risk projections indicated mixed responses of the potential risk of spreads of V.destructor,exhibiting both decrease and increases in the mid-century 2055 and late-century 2085 on different sites.Overall,there is a general decline of highly suitable areas of V.destructor in mid-and late-century across all scenarios(rcp4.5 and rcp8.5).The moderately suitable areas indicated a mixed response in mid-century with decline(under rcp4.5)and increase(under rcp8.5)and consistent increase in late century.The marginally suitable areas show a decline in mid-century and increase in late-century.Our results suggest that the climate change will continue to significantly affect the distribution and risks spread of V.destructor in Tanzania.The suitability range of V.destructor will shift where highly suitable areas will be diminishing to the advantage of the honey bees’populations,but increase of moderately suitable sites indicates an expansion to new areas.The late century projections show the increased risks due to surge in the moderate and marginal suitability which means expansion in the areas where V.destructor will operate Conclusion:The current and predicted areas of habitat suitability for V.destructor’s host provides information useful for beekeeping stakeholders in Tanzania to consider the impending risks and allow adequate interventions to address challenges facing honey bees and the beekeeping industry.We recommend further studies on understanding the severity of V.destructor in health and stability of the honey bees in Tanzania.This will provide a better picture on how the country will need to monitor and reduce the risks associated with the increase of V.destructor activities as triggered by climate change.The loss of honey bees’colonies and its subsequent impact in bees’products production and pollination effect have both ecological and economic implications that need to have prioritization by the stakeholders in the country to address the challenge of spreading V.destructor.

一种消杀蜜蜂狄斯瓦螨方法的研究

狄斯瓦螨(Varroa destructor)是危害西方蜜蜂的主要寄生螨之一。为了提高养蜂生产实践中消杀狄斯瓦螨的能力,试验组采用本团队研发的“一种规模化养蜂用高效杀螨装置”,放置在底箱或继箱上,每群自动喷洒药剂90~120 s;对照组采用传统杀螨剂喷洒法,比较两组的落螨数量、治螨时间以及对蜂群的影响。结果表明,在治螨20 min、40 min、1 h、2 h和24 h后,试验组落螨数量均显著高于对照组(P<0.05);试验组治螨时间明显少于对照组;试验组和对照组均对蜂群无不良的影响。使用“一种规模化养蜂用高效杀螨装置”比传统杀螨剂喷洒法消杀瓦螨见效快、效果好,且方便快捷,节约劳动成本。

植物成分对蜂螨繁殖影响研究

【目的】狄斯瓦螨(Varroa destructor)感染是导致西方蜜蜂(Apis mellifera)蜂群死亡的主要因素。研究旨在筛选出安全高效的植物成分杀螨剂,为研发绿色杀螨剂提供依据。【方法】以西方蜜蜂为试验材料,检测筛选原儿茶酸、青蒿素、芹菜汁饲喂,芹菜籽熏蒸对狄斯瓦螨及其感染的西方蜜蜂死亡率、免疫与残翅病毒(DWV)基因表达水平;运用代谢组学鉴定分析狄斯瓦螨死亡的代谢通路,进一步探究芹菜籽中3个主要挥发性成分对狄斯瓦螨的抑制作用。【结果】原儿茶酸、青蒿素和芹菜汁在饲喂出房蜂的情况下杀螨效果不显著(P>0.05)。但在熏蒸试验中,使用芹菜籽和芹菜籽主成分均有较好的杀螨效果。芹菜籽熏蒸的试验结果显示瓦螨死亡率高达80%,显著高于对照组(P<0.05),蜜蜂存活率与对照组无显著差异(P>0.05),使用芹菜籽处理蜜蜂24 h后,其体内的免疫基因abaecin、pqrpsc2505和残翅病毒(DWV)基因表达量相较于对照组显著降低。在芹菜籽3种主效挥发物质香芹酚、邻伞花烃和萜品烯中,气味浓郁的香芹酚表现出最强的杀螨效果,但对蜜蜂存活率表现出负面影响,试验组与对照组蜜蜂死亡率差异不显著(P>0.05)。【结论】芹菜籽熏蒸具有较好的杀螨作用,其3种主效挥发物质香芹酚、邻伞花烃和萜品烯都可作为杀螨剂的候选成分。

关于狄斯瓦螨侵染澳大利亚蜂群及生物(瓦螨)安全应急反应概述

本文主要简述自2022年6月22日来关于狄斯瓦螨侵染澳大利亚新南威尔士州蜂群和政府相关行业部门生物(瓦螨)安全应急反应相关报道,从蜂螨种类、蜂螨侵染范围、澳大利亚蜂业和相关行业应急反应、蜂群分区限制管控、蜂螨监测、蜂群销毁赔偿、野生西方蜜蜂诱杀以及扁桃(巴旦木)授粉行业应急反应方面进行介绍,并就此次澳大利亚蜂螨防控对中国养蜂业生物安全应急反应启示进行探讨。

狄斯瓦螨的生活习性与防治

狄斯瓦螨(Varroa destructor)是危害西方蜜蜂(Apis mellifera)最严重的病敌害,狄斯瓦螨的防治效果决定着蜜蜂养殖的成败。本文介绍了狄斯瓦螨的生活习性,以及它的防治措施,以期能在对狄斯瓦螨有一定了解的基础上为防治狄斯瓦螨提供思路。

蜜蜂瓦螨敏感卫生行为研究进展

蜜蜂具有很高的生态价值和经济价值,对农业生产帮助巨大。然而,狄斯瓦螨Varroa destructor寄生给西方蜜蜂Apis mellifera蜂群造成重大损失,对蜜蜂健康构成严重威胁,因此,狄斯瓦螨的防治变得尤为紧要。虽然化学防治是防治狄斯瓦螨常用且有效措施,但仍存在许多缺点,如造成蜂产品污染、导致蜂螨产生抗药性等。另一方面,培育抗螨蜂种被证明是可持续的狄斯瓦螨防治方法。瓦螨敏感卫生行为(Varroa sensitive hygiene,VSH)是蜜蜂重要的抗螨性状之一。本文从狄斯瓦螨的生活周期、对蜜蜂的危害、蜜蜂抗螨行为、瓦螨敏感卫生行为调控和遗传育种等方面进行综述,为狄斯瓦螨防治和抗螨蜂种选育提供参考。

狄斯瓦螨VdesNPC2b蛋白的基因克隆、原核表达及其与寄主幼虫信息素结合机制研究

【目的】研究狄斯瓦螨Varroa destructor尼曼匹克C2型蛋白(Niemann-Pick type C2 protein,NPC2)VdesNPC2b与狄斯瓦螨寄主蜜蜂幼虫信息素油酸甲酯和β-罗勒烯的结合特性和机制,阐明VdesNPC2b在狄斯瓦螨寄主识别中的功能,为狄斯瓦螨生物防治提供理论依据。【方法】扩增狄斯瓦螨VdesNPC2b开放读码框(ORF)并进行生物信息学分析;基于pET-30a质粒构建原核表达载体,通过原核表达和亲和层析获得VdesNPC2b重组蛋白。利用荧光竞争结合实验检测VdesNPC2b与蜜蜂幼虫信息素油酸甲酯和β-罗勒烯的结合力,并通过荧光光谱变温实验测定22和32℃下VdesNPC2b与油酸甲酯和β-罗勒烯结合力变化来分析结合机制。采用SWISS-MODLE软件对VdesNPC2b进行同源建模,采用MVD软件对VdesNPC2b和β-罗勒烯进行分子对接模拟,初步分析VdesNPC2b与β-罗勒烯结合的关键氨基酸位点。【结果】VdesNPC2b(GenBank登录号:OR463903)的ORF全长531 bp,编码176个氨基酸,VdesNPC2b N端有一个16个氨基酸残基的信号肽。荧光竞争结合试验结果显示,VdesNPC2b与油酸甲酯和β-罗勒烯解离常数KD值分别为2.89和3.49μmol/L,结合过程为动态猝灭,维持VdesNPC2b与油酸甲酯和β-罗勒烯的相互作用力为疏水作用力。同源建模显示VdesNPC2b的二级结构主要为β-折叠,内部存在1个潜在的配基结合腔,VdesNPC2b与β-罗勒烯结合的关键氨基酸位点是Leu68,Ile103和Phe107等。【结论】狄斯瓦螨通过VdesNPC2b结合寄主蜜蜂幼虫长链酯类信息素油酸甲酯和挥发性的β-罗勒烯协同进行宿主定位和识别。

蜂螨的种类及蜜蜂主要害螨研究进展

蜂螨是一类危害严重的蜜蜂寄生虫。随着蜂螨抗药性的产生和危害的加重,现已引起各国养蜂业的高度重视。本文从4个方面综述了近年来与蜂螨相关的研究进展:①蜂螨的种类;②重要蜜蜂害螨武氏蜂盾螨(Acarapis woodi),狄氏瓦螨(Varroa destructo)和小蜂螨(Tropilaelaps spp.)的分布、生物学特性、危害和防治方法;③与蜂螨相关的蜜蜂信息素研究;④与蜂螨相关的蜜蜂病害研究;并对今后蜂螨的研究趋势和方向进行了讨论。

香精油的抗蜂螨作用及其在蜂群中的应用

香精油及其组分具有显著的抗螨效果。研究者通过筛选试验测定了多种香精油及其组分的抗螨能力,多数在实验室中表现出良好的抗螨效果,但除了百里酚及其混合物外,很少在野外试验中表现出强抗螨能力。百里酚及其混合物的抑螨率超过了90%,对蜜蜂危害较小,长期使用后残留量很低。很有必要对香精油的抗蜂螨作用作进一步的研究,同时结合其它防治手段,建立一套全面的害虫防治策略,以控制蜂螨的危害。

升华硫配合杀螨剂防治蜂螨效果的比较研究

[目的]比较升华硫配合杀螨剂防治蜂螨效果。[方法]2007~2009年3次于同一个蜂场采用同一种方法对升华硫配合杀螨剂防治蜂螨效果进行了试验。[结果]升华硫配合杀螨剂对于消灭存在蜂脾上及寄生于封盖蛹的蜂螨有明显效果,对于消灭成年工蜂身体上的蜂螨效果不明显。施药后杀灭大蜂螨的效果以第1天最佳,此后逐日减少;杀灭小蜂螨的效果以第2天最佳,此后逐日减少,表明在2~5 d再施治1~2次,可达到理想的防治效果。在小蜂螨大量滋生时,采用升华硫配合杀螨剂有较为理想的防治效果。[结论]该防治技术可为大、小蜂螨严重危害地区的养蜂生产提供服务。

应用蜜蜂营养杂交技术培育抗螨蜂种

【目的】大蜂螨是中国饲养的西方蜜蜂最重要病虫害之一,多年来药物防治蜂螨,一方面蜜蜂对药物产生了很强的抗药性,另一方面治螨药物在一定程度上会污染蜂产品。本研究通过蜜蜂营养杂交,探讨培育抗螨蜂种的可行性。【方法】采用中华蜜蜂的蜂王浆饲喂意大利蜜蜂工蜂小幼虫,然后测定营养杂交后代工蜂形态指标、苹果酸脱氢酶Ⅱ的基因型频率和基因频率、蜂群遗传相似系数以及抗螨力。【结果】营养杂交子后代工蜂的吻长、右前翅面积、腹部第3+4背板总长、第4背板突间距、第6腹节面积、蜡镜面积6个指标与亲本工蜂之间存在显著差异,但肘脉指数、跗节指数和翅钩数与亲本差异不显著;营养杂交子后代工蜂的苹果酸脱氢酶Ⅱ基因型频率和基因频率存在一定的变异;营养杂交子后代之间遗传相似系数明显高于亲本意大利蜜蜂;营养杂交子后代的工蜂抗螨力显著高于亲本意大利蜜蜂。【结论】通过蜜蜂营养杂交,可以改变营养杂交后代工蜂形态、生理生化、分子遗传相似性及抗螨力等特性。蜜蜂营养杂交可成为蜜蜂育种一条新途径。