蜜蜂残翅病研究进展

蜜蜂残翅病毒(Deformed Wing Virus,DWV)是引发蜜蜂残翅病的病原体,常以隐性感染方式普遍存在于饲养蜂群中,在特定条件下发病,危害幼虫或羽化失败,感染蜜蜂表现翅膀残疾的典型发病症状。DWV是造成蜜蜂蜂群崩溃综合征(CCD)和越冬蜂群损失(OCL)的主要病因,在世界范围的流行已严重危害蜂群健康。综合近年蜜蜂残翅病的研究数据,试从病原学、流行病学、临床症状及防控等方面阐述DWV研究取得的进展。     

蜜蜂残翅病及其防制技术研究进展

蜜蜂残翅病病毒（DWV）是感染蜜蜂最常见、传播最广泛的病毒之一,通常以隐性感染的形式存在。在蜜蜂的各个发育阶段都能检测到DWV,严重时会导致感染蜜蜂表现出典型的发病症状并且使蜜蜂寿命缩短。DWV在其传播媒介狄斯瓦螨Varroa destructor的作用下传播范围更为广泛,在32个国家的蜂群中DWV的平均感染率至少为55%。DWV的大肆流行是导致蜂群损失的重要原因,给养蜂业造成了巨大损失,严重影响了我国养蜂业的健康发展。本文将从DWV的流行与分布、发病特征及危害、传播途径、遗传多样性以及其防制措施等方面对蜜蜂残翅病病毒近年来的研究进展进行综述。为我国进一步开展蜜蜂病毒学研究提供参考,为开发防治技术方法提供新思路。     

蜜蜂残翼病毒RT-PCR检测及衣壳蛋白VP1基因的序列分析

为了研究蜜蜂残翼病毒(DWV)的遗传变异特点,试验从吉林某地蜂场疑似蜜蜂残翼病的病蜂中初步分离得到1株DWV毒株,采用RT-PCR技术扩增VP1基因并对其进行检验分析。结果表明:基因测序结果与Gen Bank中的DWV毒株衣壳蛋白VP1基因序列同源性为99%左右;将此分离毒株DWV的VP1基因核苷酸序列与Gen Bank中的10个序列进行系统遗传进化树分析,证实其与AB070959.1、NC_005876.1的同源性最近,而与HM067437.1、KJ437447.1的同源性最低。     

蜜蜂残翼病RT-PCR快速检测方法的建立

为了建立蜜蜂残翼病病毒(Deformed wing virus,DWV)RT-PCR快速检测方法,试验采用GenBank公布的蜜蜂残翼病病毒全基因序列设计1对特异性引物,对所提取的RNA进行反转录合成cDNA后,进行聚合酶链式反应,并对这种快速检测方法的特异性和敏感性进行研究。结果表明:在约702 bp处出现目的条带,其他病原无目的条带出现,灵敏性可达1×104的模板稀释度。     

蜜蜂残翼病病毒PCR检测及5′-UTR基因序列分析

从吉林省某蜂场疑似蜜蜂残翼病病料中分离到一株蜜蜂残翼病病毒(DWV),命名为DWVJL1,提取该分离株的总RNA,采用RT-PCR技术扩增其基因组的5′-UTR并测序。测序结果与GenBank公布道的DWV 5′-UTR序列同源性在95%~99%之间。将测序结果与GenBank上公布的9个相关序列进行系统遗传进化树分析,证实其与JX878304同源性最近,而与GU109335、KJ437447同源性最远。     

我国东、西方蜜蜂中七种病毒感染状况的调查

旨在了解我国东方蜜蜂及西方蜜蜂中病毒病的流行现状及其发生差异,并分析不同地区、不同饲养环境对蜜蜂感染病毒的影响。2012—2013年从8省市采集东方蜜蜂50群和西方蜜蜂108群,利用RT-PCR技术检测残翅病毒(DWV)、黑色王台病毒(BQCV)、囊状幼虫病毒(SBV)、克什米尔蜜蜂病毒(KBV)、慢性麻痹病病毒(CBPV)、急性麻痹病病毒(ABPV)以及以色列急性麻痹病病毒(IAPV)等7种病毒在蜂群中的感染情况。结果表明,东、西方蜜蜂均被KBV之外的6种病毒感染,其中BQCV最为流行,其次为DWV。SBV对西方蜜蜂的感染率显著高于东方蜜蜂(P0.01),CBPV、ABPV以及IAPV对两蜂种的感染率均较低,无明显差异。在东方蜜蜂的4个取样省份中,IAPV只在辽宁和海南发现,CBPV只在福建和辽宁发现,而ABPV只在广东检测到。在西方蜜蜂的7个取样省市中,DWV、BQCV及SBV均有分布,但SBV在福建的感染率明显低于其他地点(P0.01),在新疆、北京和辽宁检测到5种病毒,在山西、山东、海南和福建则检出4种病毒。3种类型的蜜蜂饲养区中,在西方蜜蜂饲养区检测到6种病毒,东、西方蜜蜂混养区检测到5种病毒,而在东方蜜蜂饲养区只检出3种病毒。两种蜜蜂同时感染多种病毒较为普遍,多数样品被DWV、BQCV两种病毒或DWV、BQCV及SBV三种病毒共同感染。以上结果表明,中国东、西方蜜蜂中流行的病毒以BQCV与DWV为主,感染的6种病毒在不同采样地及不同类型饲养区的分布及感染水平不同,但普遍存在多种病毒的混合感染现象。     

贵州省中华蜜蜂病毒病感染状况调查

为了检测贵州中华蜜蜂病毒病的潜伏情况,为蜂群防治提供依据。根据已建立的高效灵敏的病毒特异性RT-PCR检测方法,对贵州省中华蜜蜂进行了6种病毒病——蜜蜂畸翅病毒(Deformed wing virus,DWV)、蜜蜂黑王台病毒(Black queen cell virus,BQCV)、蜜蜂囊状幼虫病毒(Sacbrood virus,SBV)、蜜蜂克什米尔病毒(Kashmir bee virus,KBV)、蜜蜂急性麻痹病毒(Acute bee paralysis virus,ABPV)和蜜蜂慢性麻痹病毒(Chronic bee paralysis virus,CBPV)感染状况调查。调查结果,贵州省的中华蜜蜂中潜伏着BQCV、SBV和DWV,其中以正安县感染的病毒病最少、盘县次之、锦屏最高,蜂病有不同程度的混合感染;各种蜂病以BQCV(20%)感染率最高、DWV(8.9%)次之、SBV(6.7%)最低。     

七种蜜蜂病毒病的流行病学调查

对东、西方蜜蜂实验蜂群以及蜂场周围的部分有花植物进行七种蜜蜂病毒病的流行病学调查。该研究采用特异性引物对，对七种蜜蜂病毒病的流行病学情况进行RT-PCR检测，发现该研究中东、西方蜜蜂样品中均发现BQCV、DWV和SBV三种病毒，除此以外，西方蜜蜂样品中还发现了IAPV。几种病毒中的DWV检出率都最高，其次是BQCV。另一方面，蜂场附近的部分有花植物中仅存在DWV和BQCV两种病毒；其中，DWV的检出率最高；相比较而言，植物的花组织最容易检出DWV，茎组织最难检出DWV。从结果来看，实验蜂场内的DWV感染率相对较高，因此，提高对DWV的认识，加强监测和防控迫在眉睫。该研究在有花植物的花、茎和叶组织检出DWV，也为蜜蜂病毒病的蜜源植物至蜜蜂寄主传播途径研究提供了基础数据。     

蜂螨危害可导致“爬蜂病”

近几年来,蜜蜂“爬蜂病”一直是蜂群管理中最让养蜂人头痛的一大病害“。爬蜂病”的发生与否不仅关系到蜂群的发展,而且影响着养蜂经济效益“。爬蜂病”的发生,除了与细菌、病毒、气候及管理不善有关外,蜂螨的危害,也是造成“爬蜂病”的重要原因。2003年7月,我场蜂群普遍患“爬蜂病”,其中有3群蜂爬得比较严重,在3次用药治疗后,其它蜂群很快痊愈,惟独这3群蜂治愈后很快复发,其主要症状是:部分幼虫及蜂蛹死亡,伴有白头蛹症状,出房的幼蜂翅膀残缺不全,在地面上蹦跳着爬行,腹部膨大。爬行蜂中有中、青年蜜蜂,但都是以幼蜂为主,这种症状在雨后的…     

浙江金华地区越冬意蜂群大量死亡原因调查与分析

2014年冬,浙江多地意蜂群出现大量死亡。为了探究这一突发事件的原因,我们实地察看了现场、发放了调查问卷,并取样进行了病毒和微孢子虫的检测分析。结果表明,本次突发事件的主要原因可以排除急性农药中毒和急性污染物中毒的可能性。在病毒感染率上,患病蜂群DWV的感染率显著高于健康蜂群,但健康蜂群BQCV的感染率却显著高于患病蜂群。在病毒多重感染水平和病毒滴度上,患病蜂群显著高于健康蜂群;同时,患病蜂群N.ceranae的感染率和感染水平都要显著高于健康蜂群。本研究提示多重病毒感染、DWV和IAPV的高病毒滴度及N.ceranae的感染和这次蜜蜂死亡事件密切相关。鉴于狄斯瓦螨在促进病毒病方面的作用,蜂螨也有可能是蜂群死亡的间接原因之一。此外,本研究同时表明,几乎所有的表面健康蜂群同时感染多种病原,健康情况堪忧。为避免类似死亡事件的发生,一方面需力求降低病原体的感染水平,另一方面可以调整饲养管理方式促进蜜蜂的健康水平,同时减少外界不良因素的刺激。     

Phase I evaluation of CCNU (lomustine) in tumor-bearing cats

1-(2-Chloroethyl)3-cyclohexyl-1-nitrosourea (CCNU) is an alkylating agent in the nitrosourea subclass. A prospective evaluation of CCNU was done to determine the maximally tolerated dosage of CCNU in tumor-bearing cats. Response data were obtained when available. Twenty-five cats were treated with CCNU at a dosage of 50-60 mg/m3 body surface area. Complete hematologic data were available for 13 cats. Neutropenia was the acute dose-limiting toxicity. The median neutrophil count at the nadir was 1,000 cells/microL (mean, 2,433 cells/microL; range, 0-9,694 cells/microL). The time of neutrophil nadir was variable, occurring 7-28 days after treatment, and counts sometimes did not return to normal for up to 14 days after the nadir. Based on these findings, a 6-week dosing interval and weekly hematologic monitoring after the 1st treatment with CCNU are recommended. The nadir of the platelet count may occur 14-21 days after treatment. The median platelet count at the nadir was 43,500 cells/microL. No gastrointestinal, renal, or hepatic toxicities were observed after a single CCNU treatment, and additional studies to evaluate the potential for cumulative toxicity should be performed. Five cats with lymphoma and 1 cat with mast cell tumor had measurable responses to CCNU. Phase II studies to evaluate antitumor activity should be completed with a dosing regimen of 50-60 mg/m3 every 6 weeks.     

Furosemide continuous rate infusion in the horse: evaluation of enhanced efficacy and reduced side effects

Continuous rate infusion (CRI) of furosemide in humans is considered superior to intermittent administration (IA). This study examined whether furosemide CRI, compared with IA, would increase diuretic efficacy with decreased fluid and electrolyte fluctuations and activation of the renin-angiotensin-aldosterone system (RAAS) in the horse. Five mares were used in a crossover-design study. During a 24-hour period, each horse received a total of 3 mg/kg furosemide by either CRI (0.12 mg/kg/h preceded by a loading dose of 0.12 mg/kg IV) or IA (1 mg/kg IV q8h). There was not a statistically significant difference in urine volume over 24 hours between methods; however, urine volume was significantly greater after CRI compared with IA during the first 8 hours ([median 25th percentile, 75th percentile]: 9.6 L [8.9, 14.4] for CRI versus 5.9 L [5.3, 6.0] for IA). CRI produced a more uniform urine flow, decreased fluctuations in plasma volume, and suppressed renal concentrating ability throughout the infusion period. Potassium, Ca, and Cl excretion was greater during CRI than IA (1,133 mmol [1.110, 1,229] versus 764 mmol [709, 904], 102.7 mmol [96.0, 117.2] versus 73.3 mmol [65.0, 73.5], and 1,776 mmol [1,657, 2.378] versus 1,596 mmol [1,457, 1,767], respectively). Elimination half-lives of furosemide were 1.35 and 0.47 hours for CRI and IA, respectively. The area under the excretion rate curve was 1,285.7 and 184.2 mL x mg/mL for CRI and IA, respectively. Furosemide CRI (0.12 mg/kg/h) for 8 hours, preceded by a loading dose (0.12 mg/kg), is recommended when profound diuresis is needed acutely in horses.     

Prevalence of gastric lesions in racing Alaskan sled dogs

Human and equine athletes are reported to have a high prevalence of gastric disease, and anecdotal evidence suggests a similar phenomenon applies to racing sled dogs. To investigate the prevalence of gastric disease in racing sled dogs, we conducted 2 gastroscopy studies on dogs competing in the annual Iditarod Sled Dog Race. A pilot study of dogs that were either dropped from the 2000 Iditarod Sled Dog Race because of illness or that finished the race indicated that, approximately 5 days after competing, 10 of 28 dogs (35%) had endoscopic evidence of gastric ulceration, erosion, or hemorrhage. The next year, an endoscopic study of 73 dogs participating in the 2001 Iditarod race was performed in order to evaluate a larger population of dogs. Data from 70 of these dogs could be used; 34 (48.5%) had ulceration, erosion, gastric hemorrhage, or some combination of these findings. When this group of 70 dogs was compared retrospectively to a control group of 87 dogs presented to the Texas A&M University (TAMU) Veterinary Medical Teaching Hospital, the Iditarod sled dogs had a significantly higher prevalence (P = .049) of gastric lesions. These findings suggest that, similar to athletes of other species, elite canine athletes have an increased prevalence of gastric disease compared to the canine population at large.     

The Epidemiology of Gastrointestinal Nematodes of Dairy Cattle in Central Kenya

The epidemiology of H. placei and of other gastrointestinal nematodes in yearling dairy cattle was examined on two farms in Kiambu District, central Kenya during each of 13 one-month periods from April 1993 to April 1994. On each farm, 32 newly weaned dairy calves were given a single dose of albendazole and then placed on experimental pastures. Twelve of the animals were designated for bi-monthly slaughter (n = 2) and analysis of worm population characteristics and 20 were designated for blood and faecal collection and for weighing. Two parasite-free tracer calves were grazed alongside the weaner calves each month throughout the study period and were also slaughtered for analysis of worm populations. Faecal egg counts, haematological and serum pepsinogen determinations, herbage larval counts, and animal live weight changes were recorded monthly. The study revealed that Haemonchus placei, Trichostrongylus axei, Cooperia spp. and Oesophagostomum radiatum were responsible for parasitic gastroenteritis and that H. placei was the predominant nematode present in the young cattle on both farms. Faecal egg counts from resident cattle and necropsy worm counts revealed that pasture larval levels were directly related to the amount of rainfall. The total worm burdens in the animals were highest during the rainy season (March–June and October–December) and lowest during the dry seasons (July–September and January–February). The very low recovery of immature larvae of H. placei from the tracer calves indicated that arrested development is not a feature of the life cycle of this parasite in central Kenya. The maintenance of the parasite population depended on continuous cycling of infection between the host and the pasture. The agroclimatic conditions of the study area were such that, in general, favourable weather conditions for the development and survival of the free-living stages of gastrointestinal nematodes existed all year round.     

Diversity of Ectoparasites in Sheep Flocks in Sa~o Paulo,Brazil

The occurrence of ectoparasites in sheep flocks is frequently reported but seldom quantified. Sheep production used to be a predominantly family activity in the state of Sa~o Paulo (Brazil), but it began to become a commercial activity in the past decade. Thus, information about the ectoparasites existing in sheep flocks has become necessary. The present data were obtained by means of questionnaires sent to all sheep breeders belonging to the `Associaça~o Paulista de Criadores de Ovinos' (ASPACO; Sa~o Paulo State Association of Sheep Breeders). Response reliability was tested by means of random visits paid to 10.6% of the respondents. Most of the properties (89.5%) reported the presence of one or more ectoparasites. Screw-worm (Cochliomyia hominivorax) was the most frequent ectoparasite (72.5%), followed by bot fly larvae (Dermatobia hominis, 45.0%), ticks (Amblyomma cajennense) and Boophilus microplus, 31.3%) and finally lice (Damalinia ovis, 13.8%). Combined infestations also occurred, the most common one being screw-worm with bot fly larvae (36.0%) followed by bot fly larvae with ticks (13.9%), screw-worm with ticks (9.3%), bot fly larvae with lice (6.9%), and ticks with lice (5.0%). The most common triple combination was screw-worm, bot fly larvae and ticks (12.8%). Breeds raised for meat or wool were attacked by bot fly larvae and ticks more often than other breeds. Lice were only absent from animals of indigenous breeds. The relationships among these ectoparasites are discussed in terms of sheep breeds, flock size, seasonality and the ectoparasitic combinations on the host.     

Evaluation of biohydrogenation rate of canola vs. soya bean seeds as unsaturated fatty acids sources for ruminants in situ

An experiment was conducted to study disappearance of C14 to C18 fatty acids, lag times and biohydrogenation (BH) rates of C18 fatty acids of ground soya bean and canola seeds in situ. Three ruminally fistulated Dallagh sheep were used to determine ruminal BH of unsaturated fatty acids (UFAs). Differences in the disappearance of fatty acids through the bags and lag times were observed between the oilseeds. We saw that the longer the incubation time of the oilseeds in the rumen, the lower the content of C18:2 and C18:3. Significantly higher lag times for both C18:2 and C18:3 were observed in ground canola compared to ground soya bean. BH rates of C18:2 and C18:3 fatty acids in soya bean were three times higher than those of canola. These results suggest that the fatty acid profile of fat source can affect the BH of UFAs by rumen micro‐organisms. So that UFAs of canola had higher ability to escape from ruminal BH. It seems that fatty acid profile of ruminant products is more affected by canola seed compared to soya bean seed.     

Serum biochemical values and mineral element contents of tissues in yaks

Serum biochemical values and the wet weight to dry weight ratios of tissues were determined in yaks in Shandan county of Gansu province. The liver, kidney, heart and muscle contents of seven elements in yaks were also analysed. Most serum biochemical values were similar to those of cattle, camels and sheep, but the calcium concentration was considerably above the normal range for other ruminants. The liver contained the highest concentrations of copper, manganese and cobalt and the kidney of selenium, iron and calcium.Abbreviations Alb albumin - ALT alanine aminotransferase - AST aspartate aminotransferase - BUN blood urea nitrogen - Chol cholesterol - Glob globulin - -GT -glutamyl transpeptidase - IP inorganic phosphorus - TP total protein     

Avian brood parasitism — a growing research area in behavioral ecology (part Ⅱ)

正We are pleased to publish the second special issue on avian brood parasitism and to be responsible guest editors for the two special issues of Chinese Birds (Vol. 3, No. 4, 2012 and Vol. 4, No. 1, 2013), entitled "Avian Brood Parasitism - A Growing Research Area in Behavioral Ecology". The first issue was published in December 2012. The goal of the two special issues is to publish accumulated knowledge and some of the recent developments in     

Internal Parasites and Haematological Values in Cattle Slaughtered in Buea Subdivision of Cameroon

Tropical Animal Health and Production -