蜜蜂病毒学研究进展

蜜蜂是自然界最重要的授粉昆虫,对维护自然生态系统的生物多样性和保持农业生态系统的增产效应发挥着巨大的作用。作为世界第一养蜂大国,中国养蜂业健康发展的意义不仅在于获取大量高品质的蜂产品,更重要的是发挥蜜蜂授粉的农业增产效应,保证我国的粮食安全。和其他动物一样,蜜蜂健康也受到多种病害的威胁,近年来蜜蜂病毒病在世界范围内的广泛流行与传播,是导致世界蜂群持续下降的一个重要原因。蜜蜂病毒长期广泛的以无明显发病症状的低浓度隐性感染方式存在于蜜蜂蜂群中,但多数蜜蜂病毒在特定环境条件下可被激活,在寄主体细胞内快速复制,表现出强烈的致病性,引发致死性蜜蜂病毒病的流行与爆发。蜜蜂病毒病知识的缺乏,以及复杂的蜜蜂病毒鉴定技术使得蜜蜂病毒病难以及时确诊和防治,因此每年在养蜂生产上造成的巨大损失已严重阻碍了我国养蜂业的健康发展。本文将综述这一领域的研究成果和学科发展趋势,为在我国开展蜜蜂病毒学研究提供参考,并介绍国外的一些蜜蜂病毒病诊断方法与防治经验服务于我国养蜂生产实践。     

常见疾病、抗生素及农药对意大利蜜蜂(Apis mellifera ligustica)肠道微生物多样性的影响研究进展

蜜蜂是对农业生产十分重要的授粉昆虫。蜜蜂肠道微生物与蜜蜂健康有密切关系,但肠道微生物也会受多种外界因素的影响。本文就蜜蜂疾病、抗生素等蜂病治疗药物、农药,以及益生菌的应用等对意大利蜜蜂工蜂肠道微生物影响的研究进行了归纳总结,并对蜜蜂与其肠道菌关系研究进行了展望。     

蜜蜂级型分化机理

蜜蜂Apis spp.能有效地为多种植物及农作物授粉, 具有重要的经济和生态价值; 蜜蜂作为高度真社会性昆虫, 已成为社会生物学研究的模式生物。社会性昆虫的生殖劳动分工具有重要的进化意义, 而级型分化是形成生殖劳动分工的基础。近年来, 关于蜜蜂级型分化的研究已取得诸多重要成果, 其机理也得到了较为深入的阐释。营养差异引发蜜蜂幼虫的级型分化。蜂王浆中的主要蛋白组分之一--Royalactin是诱导蜂王发育的关键营养因子, 而脂肪体细胞的表皮生长因子受体介导了Royalactin的这种蜂王诱导作用。DNA甲基化是重要的表观遗传机制之一, 且与个体发育和疾病发生紧密相关, 近来的研究表明DNA甲基化在蜜蜂级型分化过程中发挥重要的调控作用。此外, 越来越多的研究进一步深化了人们对内分泌系统调节级型分化作用的认识。本文从关键营养因子调控、 表观遗传调控和内分泌调节3方面综述蜜蜂级型分化的机理, 并对未来的研究提出可能的方向。     

我国蜜蜂主要病原检测技术

蜜蜂是重要的经济昆虫。蜜蜂病害威胁蜜蜂产业的发展。蜜蜂病害检测及病原鉴定是病害防治的基础。文章详细介绍我国蜜蜂常见6种主要病害(美洲幼虫腐臭病,欧洲幼虫腐臭病,囊状幼虫病,慢性麻痹病,微孢子虫病,白垩病)的病原快速准确的检测方法。     

The habitat disruption induces immune-suppression and oxidative stress in honey bees

The honey bee is a major insect used for pollination of many commercial crops worldwide. Although the use of honey bees for pollination can disrupt the habitat, the effects on their physiology have never been determined. Recently, honey bee colonies have often collapsed when introduced in greenhouses for pollination in Japan. Thus, suppressing colony collapses and maintaining the number of worker bees in the colonies is essential for successful long-term pollination in greenhouses and recycling of honey bee colonies. To understand the physiological states of honey bees used for long-term pollination in greenhouses, we characterized their gene expression profiles by microarray. We found that the greenhouse environment changes the gene expression profiles and induces immune-suppression and oxidative stress in honey bees. In fact, the increase of the number of Nosema microsporidia and protein carbonyl content was observed in honey bees during pollination in greenhouses. Thus, honey bee colonies are likely to collapse during pollination in greenhouses when heavily infested with pathogens. Degradation of honey bee habitat by changing the outside environment of the colony, during pollination services for example, imposes negative impacts on honey bees. Thus, worldwide use of honey bees for crop pollination in general could be one of reasons for the decline of managed honey bee colonies.     

蜜蜂肠道菌群结构功能研究进展

在长期的共同进化中,肠道菌群与其宿主形成了紧密的联系,为宿主提供了许多有益的作用。作为一种社会性昆虫,蜜蜂的生活习性为其肠道菌群提供了良好而稳定的传播途径,因此,蜜蜂与其肠道菌群形成了一种紧密的互惠互利共生关系。近年来,随着对蜜蜂肠道菌群了解的不断加深,对蜜蜂肠道菌群功能的研究也不断深入,大量研究表明蜜蜂的肠道菌群在宿主食物的消化代谢、宿主免疫的激活和抵抗致病菌、调节宿主生理等方面都有着重要的作用,同时破坏肠道菌群的稳定对蜜蜂的健康有着明显的负面影响。本文对近年来西方蜜蜂肠道菌群功能研究进行了总结,旨在为进一步深入探索蜜蜂肠道菌群与其宿主的相互作用及在养蜂生产上应用肠道菌群防控疾病提供参考。     

Infestation of Japanese Native Honey Bees by Tracheal Mite and Virus from Non-native European Honey Bees in Japan

Invasion of alien species has been shown to cause detrimental effects on habitats of native species. Insect pollinators represent such examples; the introduction of commercial bumble bee species for crop pollination has resulted in competition for an ecological niche with native species, genetic disturbance caused by mating with native species, and pathogen spillover to native species. The European honey bee, Apis mellifera, was first introduced into Japan for apiculture in 1877, and queen bees have been imported from several countries for many years. However, its effects on Japanese native honey bee, Apis cerana japonica, have never been addressed. We thus conducted the survey of honey bee viruses and Acarapis mites using both A. mellifera and A. c. japonica colonies to examine their infestation in native and non-native honey bee species in Japan. Honey bee viruses, Deformed wing virus (DWV), Black queen cell virus (BQCV), Israeli acute paralysis virus (IAPV), and Sacbrood virus (SBV), were found in both A. mellifera and A. c. japonica colonies; however, the infection frequency of viruses in A. c. japonica was lower than that in A. mellifera colonies. Based on the phylogenies of DWV, BQCV, and SBV isolates from A. mellifera and A. c. japonica, DWV and BQCV may infect both honey bee species; meanwhile, SBV has a clear species barrier. For the first time in Japan, tracheal mite (Acarapis woodi) was specifically found in the dead honey bees from collapsing A. c. japonica colonies. This paper thus provides further evidence that tracheal-mite-infested honey bee colonies can die during cool winters with no other disease present. These results demonstrate the infestation of native honey bees by parasite and pathogens of non-native honey bees that are traded globally.     

Detection of deformed wing virus in the greenhouse for possible horizontal transmission of virus in honey bee colony

The honey bee Apis mellifera L. is a crucial insect in the agricultural industry and natural ecosystem by being a major pollinator. Nevertheless, honey bee population has been recently facing a decline. Among the several factors responsible for this decline, deformed wing virus (DWV) is considered a primary cause that negatively affects honey bee health. DWV is a cosmopolitan honey bee pathogen and causes morphological disadvantages in individual honey bees and colony collapse. Regarding the horizontal transmission of DWV, in addition to Varroa destructor, a well-known major vector of DWV, flowers have recently been implied as a transmission route. Therefore, in this study, we detected DWV from various substances, including flowers, honey bee feces, pupa, larva, nurse bee, surface of nurse bee, pollen collected by forager bee, and forager bee samples in four strawberry greenhouses, which could suggest the potential for the horizontal transmission of DWV in the semi-field condition. We also detected DWV in pollen collected by DWV-negative forager bees, implying that flowers can serve as a potential source of virus infection. These findings suggest that the surrounding environment such as shared floral sources affects the spread of DWV.     

Large-scale field application of RNAi technology reducing Israeli acute paralysis virus disease in honey bees (Apis mellifera, Hymenoptera: Apidae)

The importance of honey bees to the world economy far surpasses their contribution in terms of honey production; they are responsible for up to 30% of the world's food production through pollination of crops. Since fall 2006, honey bees in the U.S. have faced a serious population decline, due in part to a phenomenon called Colony Collapse Disorder (CCD), which is a disease syndrome that is likely caused by several factors. Data from an initial study in which investigators compared pathogens in honey bees affected by CCD suggested a putative role for Israeli Acute Paralysis Virus, IAPV. This is a single stranded RNA virus with no DNA stage placed taxonomically within the family Dicistroviridae. Although subsequent studies have failed to find IAPV in all CCD diagnosed colonies, IAPV has been shown to cause honey bee mortality. RNA interference technology (RNAi) has been used successfully to silence endogenous insect (including honey bee) genes both by injection and feeding. Moreover, RNAi was shown to prevent bees from succumbing to infection from IAPV under laboratory conditions. In the current study IAPV specific homologous dsRNA was used in the field, under natural beekeeping conditions in order to prevent mortality and improve the overall health of bees infected with IAPV. This controlled study included a total of 160 honey bee hives in two discrete climates, seasons and geographical locations (Florida and Pennsylvania). To our knowledge, this is the first successful large-scale real world use of RNAi for disease control.     

Pollination of strawberry by the stingless bee,Trigona minangkabau,and the honey bee,Apis mellifera: An experimental study of fertilization efficiency

To know basic information about the stingless bee, Trigona minangkabau, and the European honey bee, Apis mellifera, as pollinator of strawberry, we set three greenhouse areas: the honey bee introduced area, the stingless bee introduced area and the control area. Foraging and pollination efficiencies of the two bee species were studied comparatively. During the experimental period (10 days), the stingless bee foraged well and the nest weight did not change, though the honey bee often foraged inefficiently and the nest weight decreased by 2 kg. The average nectar volume of a flower was lower in the honey bee area (0.02 μl) and nearly the same in the other two areas (0.1 μl). We make a numerical model to describe pollination and fertilization process. This model shows that one visit of the honey bee pollinated 11% of achenes and one visit of the stingless bee did 4.7% on average and that 11 visits of the honey bee or 30 visits of the stingless bee are required per flower to attain normal berry (fertilization rate, 87%). In this study, the rate of deformed berries in the stingless bee area (73%) was lower than that of the control area (90%), but higher than that of the honey bee area (51%). From our numerical model, we conclude the stingless bee could pollinate strawberry as well as the honey bee if we introduced 1.8 times of bees used in this experiment.     

Genomic changes underlying host specialization in the bee gut symbiont Lactobacillus Firm5

Bacteria that engage in long‐standing associations with particular hosts are expected to evolve host‐specific adaptations that limit their capacity to thrive in other environments. Consistent with this, many gut symbionts seem to have a limited host range, based on community profiling and phylogenomics. However, few studies have experimentally investigated host specialization of gut symbionts and the underlying mechanisms have largely remained elusive. Here, we studied host specialization of a dominant gut symbiont of social bees, Lactobacillus Firm5. We show that Firm5 strains isolated from honey bees and bumble bees separate into deep‐branching host‐specific phylogenetic lineages. Despite their divergent evolution, colonization experiments show that bumble bee strains are capable of colonizing the honey bee gut. However, they were less successful than honey bee strains, and competition with honey bee strains completely abolished their colonization. In contrast, honey bee strains of divergent phylogenetic lineages were able to coexist within individual bees. This suggests that both host selection and interbacterial competition play important roles in host specialization. Using comparative genomics of 27 Firm5 isolates, we found that the genomes of honey bee strains harbour more carbohydrate‐related functions than bumble bee strains, possibly providing a competitive advantage in the honey bee gut. Remarkably, most of the genes encoding carbohydrate‐related functions were not conserved among the honey bee strains, which suggests that honey bees can support a metabolically more diverse community of Firm5 strains than bumble bees. These findings advance our understanding of the genomic changes underlying host specialization.     

Population structure of honey bees in the Carpathian Basin (Hungary) confirms introgression from surrounding subspecies

Carniolan honey bees (Apis mellifera carnica) are considered as an indigenous subspecies in Hungary adapted to most of the ecological and climatic conditions in this area. However, during the last decades Hungarian beekeepers have recognized morphological signs of the Italian honey bee (Apis mellifera ligustica). As the natural distribution of the honey bee subspecies can be affected by the importation of honey bee queens or by natural gene flow, we aimed at determining the genetic structure and characteristics of the local honey bee population using molecular markers. All together, 48 Hungarian and 84 foreign (Italian, Polish, Spanish, Liberian) pupae and/or workers were used for mitochondrial DNA analysis. Additionally, 53 sequences corresponding to 10 subspecies and the Buckfast hybrid were downloaded from GenBank. For the nuclear analysis, 236 Hungarian and 106 foreign honey bees were genotyped using nine microsatellites. Heterozygosity values, population‐specific alleles, FST values, principal coordinate analysis, assignment tests, structure analysis, and dendrograms were calculated. Haplotype and nucleotide diversity values showed moderate values. We found that one haplotype (H9) was dominant in Hungary. The presence of the black honey bee (Apis mellifera mellifera) was negligible, but a few individuals resembling other subspecies were identified. We proved that the Hungarian honey bee population is nearly homogeneous but also demonstrated introgression from the foreign subspecies. Both mitochondrial DNA and microsatellite analyses corroborated the observations of the beekeepers. Molecular analyses suggested that Carniolan honey bee in Hungary is slightly affected by Italian and black honey bee introgression. Genetic differences were detected between Polish and Hungarian Carniolan honey bee populations, suggesting the existence of at least two different gene pools within A. m. carnica.     

Twenty-five-year study of Nosema spp. in honey bees (Apis mellifera) in Serbia

A total of 7386 samples of adult honey bees from different areas of Serbia (fifteen regions and 79 municipalities) were selected for light microscopy analysis for Nosema species during 1992–2017. A selection of honey bee samples from colonies positive for microsporidian spores during 2009–2011, 2015 and 2017 were then subjected to molecular diagnosis by multiplex PCR using specific primers for a region of the 16S rRNA gene of Nosema species. The prevalence of microsporidian spore-positive bee colonies ranged between 14.4% in 2013 and 65.4% in 1992. PCR results show that Nosema ceranae is not the only Nosema species to infect honey bees in Serbia. Mixed N. apis/N. ceranae infections were detected in the two honey bee samples examined by mPCR during 2017. The beekeeping management of disease prevention, such as replacement of combs and queens and hygienic handling of colonies are useful in the prevention of Nosema infection.     

An emerging paradigm of colony health: microbial balance of the honey bee and hive (<Emphasis Type="Italic">Apis mellifera</Emphasis>)

Across the globe, honey bee populations have been declining at an unprecedented rate. Managed honey bees are highly social, frequent a multitude of environmental niches, and continually share food, conditions that promote the transmission of parasites and pathogens. Additionally, commercial honey bees used in agriculture are stressed by crowding and frequent transport, and exposed to a plethora of agricultural chemicals and their associated byproducts. When considering this problem, the hive of the honey bee may be best characterized as an extended organism that not only houses developing young and nutrient rich food stores, but also serves as a niche for symbiotic microbial communities that aid in nutrition and defend against pathogens. The niche requirements and maintenance of beneficial honey bee symbionts are largely unknown, as are the ways in which such communities contribute to honey bee nutrition, immunity, and overall health. In this review, we argue that the honey bee should be viewed as a model system to examine the effect of microbial communities on host nutrition and pathogen defense. A systems view focused on the interaction of the honey bee with its associated microbial community is needed to understand the growing agricultural challenges faced by this economically important organism. The road to sustainable honey bee pollination may eventually require the detoxification of agricultural systems, and in the short term, the integrated management of honey bee microbial systems.     

Honey bee (Hymenoptera: Apidae) distribution and potential for supplementary pollination in commercial tomato greenhouses during winter

This study examined the use of honey bees, Apis mellifera L., to supplement bumble bee, Bombus spp., pollination in commercial tomato, Lycopersicon esculentum Miller, greenhouses in Western Canada. Honey bee colonies were brought into greenhouses already containing bumble bees and left for 1 wk to acclimatize. The following week, counts of honey and bumble bees foraging and flying throughout the greenhouse were conducted three times per day, and tomato flowers open during honey bee pollination were marked for later fruit harvest. The same counts and flower-marking also were done before and after the presence of honey bees to determine the background level of bumble bee pollination. Overall, tomato size was not affected by the addition of honey bees, but in one greenhouse significantly larger tomatoes were produced with honey bees present compared with bumble bees alone. In that greenhouse, honey bee foraging was greater than in the other greenhouses. Honey bees generally foraged within 100 m of their colony in all greenhouses. Our study invites further research to examine the use of honey bees with reduced levels of bumble bees, or as sole pollinators of greenhouse tomatoes. We also make specific recommendations for how honey bees can best be managed in greenhouses.     

Comparative reproduction of <Emphasis Type="Italic">Varroa destructor</Emphasis> in different types of Russian and Italian honey bee combs

Earlier studies showed that Russian honey bees support slow growth of varroa mite population. We studied whether or not comb type influenced varroa reproduction in both Russian and Italian honey bees, and whether Russian bees produced comb which inhibited varroa reproduction. The major differences found in this study concerned honey bee type. Overall, the Russian honey bees had lower (2.44 ± 0.18%) levels of varroa infestation than Italian honey bees (7.20 ± 0.60%). This decreased infestation resulted in part from a reduced number of viable female offspring per foundress in the Russian (0.85 ± 0.04 female) compared to the Italian (1.23 ± 0.04 females) honey bee colonies. In addition, there was an effect by the comb built by the Russian honey bee colonies that reduced varroa reproduction. When comparing combs having Russian or Italian colony origins, Russian honey bee colonies had more non-reproducing foundress mites and fewer viable female offspring in Russian honey bee comb. This difference did not occur in Italian colonies. The age of comb in this study had mixed effects. Older comb produced similar responses for six of the seven varroa infestation parameters measured. In colonies of Italian honey bees, the older comb (2001 dark) had fewer (1.13 ± 0.07 females) viable female offspring per foundress than were found in the 2002 new (1.21 ± 0.06 females) and 1980s new (1.36 ± 0.08 females) combs. This difference did not occur with Russian honey bee colonies where the number of viable female offspring was low in all three types of combs. This study suggests that honey bee type largely influences growth of varroa mite population in a colony.     

Horizontal and vertical transmission of viruses in the honey bee, Apis mellifera

The most crucial stage in the dynamics of virus infections is the mode of virus transmission. In general, transmission of viruses can occur through two pathways: horizontal and vertical transmission. In horizontal transmission, viruses are transmitted among individuals of the same generation, while vertical transmission occurs from mothers to their offspring. Because of its highly organized social structure and crowded population density, the honey bee colony represents a risky environment for the spread of disease infection. Like other plant and animal viruses, bee viruses use different survival strategies, including utilization of both horizontal and vertical routes, to transmit and maintain levels in a host population. In this review, we explore the current knowledge about the honey bee viruses and transmission routes of bee viruses. In addition, different transmission strategies on the persistence and dynamics of host-pathogen interactions are also discussed.     

Bumble bee abundance and richness improves honey bee pollination behaviour in sweet cherry

Pollination service in agricultural crops increases significantly with pollinator diversity and wild pollinator abundance. Differences in the foraging behaviour of pollinating insects are one of the reasons why pollinator diversity and abundance enhances crop pollination. Here, we focused on the foraging behaviour of honey bees and bumble bees in sweet cherry orchards. In addition, we studied the influence of bee diversity and abundance on the foraging behaviour of honey bees and bumble bees. Honey bees were found to visit fewer flowers than bumble bees. Bumble bees also showed a higher probability of changing trees between rows than honey bees. Both visitation rate and probability of row changes of honey bees increased with bumble bee diversity and with bumble bee abundance. We also found that the probability of row changes of honey bees increased with increasing bumble bee abundance. These effects of bumble bee richness and abundance on the pollination behaviour of honey bees can improve the pollination performance of honey bees in crops that depend on cross pollination. Our results highlight the higher pollination performance of bumble bees and the facilitative effect of wild pollinators to crop pollination.     

Management increases genetic diversity of honey bees via admixture

The process of domestication often brings about profound changes in levels of genetic variation in animals and plants. The honey bee, Apis mellifera, has been managed by humans for centuries for both honey and wax production and crop pollination. Human management and selective breeding are believed to have caused reductions in genetic diversity in honey bee populations, thereby contributing to the global declines threatening this ecologically and economically important insect. However, previous studies supporting this claim mostly relied on population genetic comparisons of European and African (or Africanized) honey bee races; such conclusions require reassessment given recent evidence demonstrating that the honey bee originated in Africa and colonized Europe via two independent expansions. We sampled honey bee workers from two managed populations in North America and Europe as well as several old-world progenitor populations in Africa, East and West Europe. Managed bees had highly introgressed genomes representing admixture between East and West European progenitor populations. We found that managed honey bees actually have higher levels of genetic diversity compared with their progenitors in East and West Europe, providing an unusual example whereby human management increases genetic diversity by promoting admixture. The relationship between genetic diversity and honey bee declines is tenuous given that managed bees have more genetic diversity than their progenitors and many viable domesticated animals.