熊蜂生物学及种群影响因素研究进展

熊蜂是膜翅目蜜蜂科熊蜂属内物种的统称,全球约有250种,中国已知125种,是全球熊蜂资源最丰富的国家。该类昆虫是众多野生植物和农作物的重要传粉者,对维持自然生态系统和农业粮食生产极为重要。一些群势强、易于人工饲养的熊蜂物种被开发利用,为多种目标作物授粉。本文介绍了熊蜂的生物学特性和授粉应用现状,综述了栖息地丧失、气候变化、病原体传播、外来物种入侵及化学农药等多重因素对熊蜂种群的影响,并从熊蜂的应用基础研究、资源保护及授粉经济价值评估等多方面作了展望,旨在为中国本土熊蜂的保护、应用和生态功能研究提供参考。     

A comparison of supervised learning techniques in the classification of bat echolocation calls

Today's acoustic monitoring devices are capable of recording and storing tremendous amounts of data. Until recently, the classification of animal vocalizations from field recordings has been relegated to qualitative approaches. For large-scale acoustic monitoring studies, qualitative approaches are very time-consuming and suffer from the bias of subjectivity. Recent developments in supervised learning techniques can provide rapid, accurate, species-level classification of bioacoustics data. We compared the classification performances of four supervised learning techniques (random forests, support vector machines, artificial neural networks, and discriminant function analysis) for five different classification tasks using bat echolocation calls recorded by a popular frequency-division bat detector. We found that all classifiers performed similarly in terms of overall accuracy with the exception of discriminant function analysis, which had the lowest average performance metrics. Random forests had the advantage of high sensitivities, specificities, and predictive powers across the majority of classification tasks, and also provided metrics for determining the relative importance of call features in distinguishing between groups. Overall classification accuracy for each task was slightly lower than reported accuracies using calls recorded by time-expansion detectors. Myotis spp. were particularly difficult to separate; classifiers performed best when members of this genus were combined in genus-level classification and analyzed separately at the level of species. Additionally, we identified and ranked the relative contributions of all predictor features to classifier accuracy and found measurements of frequency, total call duration, and characteristic slope to be the most important contributors to classification success. We provide recommendations to maximize accuracy and efficiency when analyzing acoustic data, and suggest an application of automated bioacoustics monitoring to contribute to wildlife monitoring efforts.     

Population structure,dispersal and colonization history of the garden bumblebee <Emphasis Type="Italic">Bombus hortorum</Emphasis> in the Western Isles of Scotland

New methods of analysing genetic data provide powerful tools for quantifying dispersal patterns and reconstructing population histories. Here we examine the population structure of the bumblebee Bombus hortorum in a model island system, the Western Isles of Scotland, using microsatellite markers. Following declines in other species, B. hortorum is the only remaining long-tongued bumblebee species found in much of Europe, and thus it is of particular ecological importance. Our data suggest that populations of B. hortorum in western Scotland exist as distinct genetic clusters occupying groups of nearby islands. Population structuring was higher than for other bumblebee species which have previously been studied in this same island group (F_st = 0.16). Populations showed significant isolation by distance. This relationship was greatly improved by using circuit theory to allow dispersal rates to differ over different landscape features; as we would predict, sea appears to provide far higher resistance to dispersal than land. Incorporating bathymetry data improved the fit of the model further; populations separated by shallow seas are more genetically similar than those separated by deeper seas. We argue that this probably reflects events following the last ice age when the islands were first colonized by this bee species (8,500–5,000 ybp), when the sea levels were lower and islands separated by shallow channels would have been joined. In the absence of significant gene flow these genetic clusters appear to have since diverged over the following 5,000 years and arguably may now represent locally adapted races, some occurring on single islands.     

Construction and characterization of a BAC-library for a key pollinator, the bumblebee Bombus terrestris L.

The primitively social bumblebee Bombus terrestris is an ecological model species as well as an important agricultural pollinator. As part of the ongoing development of genomic resources for this model organism, we have constructed a publicly available bacterial artificial chromosome (BAC) library from males of a field-derived colony. We have shown that this library has a high coverage, which allows any particular sequence to be retrieved from at least one clone with a probability of 99.7%. We have further demonstrated the library’s usefulness by successfully screening it with probes derived both from previously described B. terrestris genes and candidate genes from another bumblebee species and the honeybee. This library will facilitate genomic studies in B. terrestris and will allow for novel comparative studies in the social Hymenoptera. Received 12 March 2008; revised 13 September 2008; accepted 17 September 2008. R. Schmid-Hempel: contact for data repository of this BAC library     

Object-based classification of land cover and tree species by integrating airborne LiDAR and high spatial resolution imagery data

We evaluated the effectiveness of integrating discrete return light detection and ranging (LiDAR) data with high spatial resolution near-infrared digital imagery for object-based classification of land cover types and dominant tree species. In particular we adopted LiDAR ratio features based on pulse attributes that have not been used in past studies. Object-based classifications were performed first on land cover types, and subsequently on dominant tree species within the area classified as trees. In each classification stage, two different data combinations were examined: LiDAR data integrated with digital imagery or digital imagery only. We created basic image objects and calculated a number of spectral, textural, and LiDAR-based features for each image object. Decision tree analysis was performed and important features were investigated in each classification. In the land cover classification, the overall accuracy was improved to 0.975 when using the object-based method and integrating LiDAR data. The mean height value derived from the LiDAR data was effective in separating “trees” and “lawn” objects having different height. As for the tree species classification, the overall accuracy was also improved by object-based classification with LiDAR data although it remained up to 0.484 because spectral and textural signatures were similar among tree species. We revealed that the LiDAR ratio features associated with laser penetration proportion were important in the object-based classification as they can distinguish tree species having different canopy density. We concluded that integrating LiDAR data was effective in the object-based classifications of land cover and dominant tree species.     

Abundance,body size,and morphology of bumblebees in an area where an exotic species, <Emphasis Type="Italic">Bombus terrestris</Emphasis>, has colonized in Japan

An exotic bumblebee species, Bombus terrestris, has colonized in Japan and becomes dominant in some local communities. We examined the effects of land use and bumblebee abundance on the number and body size of bumblebees collected using window traps in a lowland area in the southern Ishikari district, Hokkaido. In 2004, we collected 922 bumblebees of six species using 70 traps at 17 sites. A statistical model fitted to the data demonstrated that dispersion from commercial B. terrestris colonies used in greenhouses positively affected the number of B. terrestris caught by each trap. This exotic species was abundant in sites where paddy fields were prevalent, but three native species, B. hypocrita, B. ardens, and B. diversus, were abundant in sites where farms and woodlands were widespread. The local abundance of B. terrestris was not associated negatively with the number and body size of native bumblebees. Thus, we did not find any competitive interactions between exotic and native bumblebees although habitat conditions seem to be common determinants of the bumblebee populations. A morphological analysis showed that B. terrestris had intermediate tongue length between B. hypocrita and B. ardens.     

Models of large-scale breeding-bird distribution as a function of macro-climate in Ontario, Canada

Aim We modelled the relationship of breeding evidence for five species of forest songbirds (ruby-crowned kinglet (Regulus calendula) Blackburnian warbler (Dendroica fusca), black-throated blue warbler (Dendroica caerulescens), bay-breasted warbler (Dendrioca castanea) and Connecticut warbler (Oporornis agilis)) and a variety of macro-climate variables to examine the importance of climate as a factor determining distribution of breeding in these species and to assess the usefulness of spatial predictions generated from these models. Location Modelling was conducted over the entire province of Ontario, Canada, an area of ≈900,000 km². Methods Data on the distribution of breeding in the province was derived from the Breeding Bird Atlas of Ontario. We used logistic regression to model the relationship between the probability of breeding (assessed in 10 km×10 km blocks) and estimates of a variety of climate variables at the same scale. Models were selected that had the least number of explanatory variables while at the same time having close to the best possible classification accuracy. Results The final models for these five species had from one to six explanatory variables and an overall concordance of 70.4% to 86.3% indicating a good classification accuracy. Results from subsampling 50% of the original data ten times indicate that (1) the classification accuracy of the model for data used to generate the model is not very sensitive to the specific observations used to generate the model (2) the classification accuracy of test data is close to the classification accuracy of the model data and (3) the classification accuracy of the test data is not dependent on the specific observations used to generate the model. We generated a spatial prediction of the probability of occurrence of each species for Ontario using the relationships defined by the logistic regression models and using 1 km gridded estimates of the necessary climate variables. These probability maps closely matched the maps of observed evidence of breeding from the Atlas. Main conclusions Although mechanisms controlling breeding distribution cannot be determined using this method, we can conclude that (1) macro-climate is an important factor directly and/or indirectly determining distribution of breeding in these species and (2) spatial predictions of probability of breeding are accurate enough to be useful in predicting probability of breeding in unsampled areas.     

Restoration and management of machair grassland for the conservation of bumblebees

Machair is a grassland habitat that supports nationally rare species including the bumblebee species Bombus distinguendus and Bombus muscorum. Changes in land management practices have resulted in a loss of floral diversity in some areas, reducing the availability of bumblebee foraging resources. In order to determine the most effective way of increasing forage plant availability on degraded machair, a restoration trial was established in western Scotland and comprised four seed mixes and a fallow treatment. Treatments were monitored over 3 years in order to compare the relative abundance of bumblebees and their forage plants. Two mixes contained wildflower species; one mix is currently used to create bird and bee foraging habitat on nature reserves and the fourth is a commercially available grass mix. There was little variation in inflorescence and bumblebee abundance between treatments early on but marked differences emerged later in the season in all 3 years. By the end of the monitoring period, the wildflower treatments contained between four and eighteen times more inflorescences than other treatment types. Similar trends were observed in bumblebee abundances. Some of the rarest bumblebee species exist primarily in areas that have largely escaped agricultural intensification. In these areas it is important that habitat management is specifically targeted and translated into appropriate agri-environment schemes. We suggest that the most effective method for restoring bumblebee forage plants on machair is to sow wildflower-rich seed mixes and this should be combined with late cutting and winter grazing practices to maintain sward diversity over time.     

Endangered by laws: potential consequences of regulations against thistles on bumblebee conservation

Many bumblebee (Bombus) species are undergoing a strong decline in Europe due to, amongst other things, a decrease of food resources. While leguminous plants (Fabaceae) are considered to be one of the main pollen sources of bumblebees, thistles (Asteraceae tribe Cardueae) have been suggested to be important for male diet. Yet, several European countries apply strict regulations against thistles since they are considered to be one of the principal weeds in agricultural landscapes. Such regulations could impact bumblebee conservation through disruption of male diet and ecology. Here, we assess the male-depending importance of thistles for bumblebee species based on field observations across countries where a legal regulation against thistles is in effect. We ultimately aim to evaluate the potential consequences of these regulations on bumblebee conservation. Our results confirm that most floral visit observations of males occur on thistles (mainly Cirsium spp. and Carduus spp.) and some species are almost exclusively observed on them. Thistle removal is thus most likely a threat for bumblebees. Therefore, we advocate repealing the thistle removal acts to make way for alternative thistle regulations which reconcile biodiversity conservation and agricultural requirements.     

Bumblebees experience landscapes at different spatial scales: possible implications for coexistence

Coexistence in bumblebee communities has largely been investigated at local spatial scales. However, local resource partitioning does not fully explain the species diversity of bumblebee communities. Theoretical studies provide new evidence that partitioning of space can promote species coexistence, when species interact with their environment at different spatial scales. If bumblebee species possess specific foraging ranges, different spatial resource utilisation patterns might operate as an additional mechanism of coexistence in bumblebee communities. We investigated the effects of the landscape-wide availability of different resources (mass flowering crops and semi-natural habitats) on the local densities of four bumblebee species at 12 spatial scales (landscape sectors with 250–3,000 m radius) to indirectly identify the spatial scales at which the bumblebees perceive their environment. The densities of all bumblebee species were enhanced in landscapes with high proportions of mass flowering crops (mainly oilseed rape). We found the strongest effects for Bombus terrestris agg. and Bombus lapidarius at large spatial scales, implying foraging distances of 3,000 and 2,750 m, respectively. The densities of Bombus pascuorum were most strongly influenced at a medium spatial scale (1,000 m), and of Bombus pratorum (with marginal significance) at a small spatial scale (250 m). The estimated foraging ranges tended to be related to body and colony sizes, indicating that larger species travel over larger distances than smaller species, presumably enabling them to build up larger colonies through a better exploitation of food resources. We conclude that coexistence in bumblebee communities could potentially be mediated by species-specific differences in the spatial resource utilisation patterns, which should be considered in conservation schemes.     

Mite species inhabiting commercial bumblebee (<Emphasis Type="Italic">Bombus terrestris</Emphasis>) nests in Polish greenhouses

Nests of social insects are usually inhabited by various mite species that feed on pollen, other micro-arthropods or are parasitic. Well-known negative effects of worldwide economic importance are caused by mites parasitizing honeybee colonies. Lately, attention has focused on the endoparasitic mite Locustacarus buchneri that has been found in commercial bumblebees. However, little is known of other mites associated with commercial bumblebee nests. Transportation of commercial bumblebee colonies with unwanted residents may introduce foreign mite species to new localities. In this study, we assessed the prevalence and species composition of mites associated with commercial bumblebee nests and determined if the mites are foreign species for Poland and for Europe. The study was conducted on 37 commercial bumblebee nests from two companies (Dutch and Israeli), originating from two greenhouses in southern Poland, and on 20 commercial bumblebee colonies obtained directly from suppliers. The species composition and abundance of mites inhabiting commercial bumblebee nests were determined. Seven mite species from three families were found in nests after greenhouse exploitation. The predominant mite species was Tyrophagus putrescentiae (Acaridae) that was a 100-fold more numerous than representatives of the family Laelapidae (Hypoaspis marginepilosa, H. hyatti, H. bombicolens). Representatives of Parasitidae (Parasitellus fucorum, P. crinitus, P. ignotus) were least numerous. All identified mite species are common throughout Europe, foreign species were not found. Mites were not detected in nests obtained directly from suppliers. We conclude that probably bumblebee nests are invaded by local mite species during greenhouse exploitation.     

Bioacoustics of the Neotropical Eneopterinae (Orthoptera,Grylloidea, Gryllidae)

In members of the cricket subfamily Eneopterinae (Orthoptera, Grylloidea), songs with powerful high-frequency (HF) harmonics have evolved, which likely represents a distinctive acoustic adaptation. In this study, we analysed or reanalysed the songs of the three eneopterine genera present in the Neotropics to evaluate whether they also possess high-amplitude HF components. We present new data and combine several lines of evidence to interpret or reinterpret the calling signals of a representative species for each genus. We used new recordings in order to detect and analyse potential HF components of the songs. Stridulatory files were measured, and stridulation was studied using high-speed video recordings. The results suggest that all eneopterine genera from the Neotropics use HFs to communicate, based on the rich harmonic content of their songs. Strikingly, the Neotropical eneopterines possess high dominant frequencies, recalling the patterns observed in the tribe Lebinthini, the most speciose tribe of the subfamily distributed in the Western Pacific region and in Southeast Asia: Ligypterus and Ponca show dominant harmonic peaks, whereas Eneoptera possesses unique features. The three species under study, however, deal differently with HFs.     

中国熊蜂多样性、人工利用与保护策略

熊蜂是众多野生植物和农作物的重要传粉者, 在维持自然和农业生态系统平衡中发挥着十分重要的作用。中国地形多样、植被丰富, 是全球熊蜂多样性的热点地区, 但过去缺乏系统调查研究, 中国熊蜂多样性现状及其利用特性不详。本文介绍了近20年在中国熊蜂资源系统调查及其人工利用方面取得的主要研究结果: (1) 2002-2017年采集熊蜂标本5万余号, 先后揭示了一系列疑难类群的分类地位, 确认中国已知熊蜂125种, 占全球熊蜂已知物种总数的50%, 表明中国是全球熊蜂物种资源最丰富的国家; (2)首次报道了中国熊蜂物种名录, 其中22种为中国特有种。我国青藏高原东部向黄土高原、秦岭山地和四川盆地过渡的地带, 是全球熊蜂多样性分布中心; (3) 1998-2017年, 明亮熊蜂(Bombus lucorum)、密林熊蜂(B. patagiatus)、红光熊蜂(B. ignitus)、火红熊蜂(B. pyrosoma)、重黄熊蜂(B. picipes)和兰州熊蜂(B. lantschouensis) 6种本土熊蜂先后被驯养成功, 其中密林熊蜂和兰州熊蜂的繁殖性状优良, 已应用于我国设施作物传粉服务。同时, 我们从栖息地、食物资源、外来物种、农药使用等方面提出了保护中国熊蜂资源的策略, 以期为野生传粉昆虫特别是熊蜂资源的保护与可持续利用提供参考资料。     

Diversity and evolutionary patterns of bacterial gut associates of corbiculate bees

The animal gut is a habitat for diverse communities of microorganisms (microbiota). Honeybees and bumblebees have recently been shown to harbour a distinct and species poor microbiota, which may confer protection against parasites. Here, we investigate diversity, host specificity and transmission mode of two of the most common, yet poorly known, gut bacteria of honeybees and bumblebees: Snodgrassella alvi (Betaproteobacteria) and Gilliamella apicola (Gammaproteobacteria). We analysed 16S rRNA gene sequences of these bacteria from diverse bee host species across most of the honeybee and bumblebee phylogenetic diversity from North America, Europe and Asia. These focal bacteria were present in 92% of bumblebee species and all honeybee species but were found to be absent in the two related corbiculate bee tribes, the stingless bees (Meliponini) and orchid bees (Euglossini). Both Snodgrassella alvi and Gilliamella apicola phylogenies show significant topological congruence with the phylogeny of their bee hosts, albeit with a considerable degree of putative host switches. Furthermore, we found that phylogenetic distances between Gilliamella apicola samples correlated with the geographical distance between sampling locations. This tentatively suggests that the environmental transmission rate, as set by geographical distance, affects the distribution of G. apicola infections. We show experimentally that both bacterial taxa can be vertically transmitted from the mother colony to daughter queens, and social contact with nest mates after emergence from the pupa greatly facilitates this transmission. Therefore, sociality may play an important role in vertical transmission and opens up the potential for co‐evolution or at least a close association of gut bacteria with their hosts.     

Reconstructing the pollinator community and predicting seed set from hydrocarbon footprints on flowers

The measurement of insect visits to flowers is essential for basic and applied pollination ecology, but is often fraught with difficulty. Floral visitation is highly variable and observational studies are limited in scope due to the considerable time needed to acquire reliable data. Our study investigates whether the analysis of hydrocarbon residues (footprints) deposited by insects during flower visits allows the reconstruction of the visitor community and the prediction of seed set for large numbers of plants. In three consecutive years we recorded bumblebee visitation to wild plants of comfrey, Symphytum officinale, and later used gas chromatography/mass spectrometry (GC/MS) to quantify bumblebee-derived unsaturated hydrocarbons (UHCs) extracted from flowers. The UHCs washed from corollae were most similar to the tarsal UHC profile of the most abundant bumblebee species, Bombus pascuorum, in all 3 years. The species compositions of the bumblebee communities estimated from UHCs on flowers were also similar to those actually observed. There was a significant positive correlation between the observed number of visits by each of three bumblebee species (contributing 3–68% of the flower visits) and the estimated number of visits based on UHC profiles. Furthermore, significant correlations were obtained separately for workers and drones of two species. Seed set of comfrey plants was positively correlated with overall bumblebee visitation and the total amount of UHCs on flowers, suggesting the potential for pollen limitation. We suggest that quantifying cumulative footprint hydrocarbons provides a novel way to assess floral visitation by insects, and that this method can be used to predict seed set in pollen-limited plants.     

Targeted agri‐environment schemes significantly improve the population size of common farmland bumblebee species

Changes in agricultural practice across Europe and North America have been associated with range contractions and local extinction of bumblebees (Bombus spp.). A number of agri‐environment schemes have been implemented to halt and reverse these declines, predominantly revolving around the provision of additional forage plants. Although it has been demonstrated that these schemes can attract substantial numbers of foraging bumblebees, it remains unclear to what extent they actually increase bumblebee populations. We used standardized transect walks and molecular techniques to compare the size of bumblebee populations between Higher Level Stewardship (HLS) farms implementing pollinator‐friendly schemes and Entry Level Stewardship (ELS) control farms. Bumblebee abundance on the transect walks was significantly higher on HLS farms than ELS farms. Molecular analysis suggested maximum foraging ranges of 566 m for Bombus hortorum, 714 m for B. lapidarius, 363 m for B. pascuorum and 799 m for B. terrestris. Substantial differences in maximum foraging range were found within bumblebee species between farm types. Accounting for foraging range differences, B. hortorum (47 vs 13 nests/km²) and B. lapidarius (45 vs 22 nests/km²) were found to nest at significantly greater densities on HLS farms than ELS farms. There were no significant differences between farm type for B. terrestris (88 vs 38 nests/km²) and B. pascuorum (32 vs 39 nests/km²). Across all bumblebee species, HLS management had a significantly positive effect on bumblebee nest density. These results show that targeted agri‐environment schemes that increase the availability of suitable forage can significantly increase the size of wild bumblebee populations.     

The effect of grazing on bumblebees in the high rangelands of the eastern Tibetan Plateau of Sichuan

Many Tibetans who were formerly nomadic yak herders are settling near towns. However, yak remain a traditional symbol of wealth, which can lead to increased local stocking densities and severe over-grazing. We used belt-transect counts to study the area around Hongyuan in Sichuan. We find that intensive summer grazing significantly reduces the vegetation height and is associated with significant reductions in bumblebee-food-plant abundance and bumblebee diversity. For the significantly reduced bumblebee species, we identify the most frequently used and preferred bumblebee-food plants. For the food plants, we identify changes in absolute flower availability and changes in bumblebee visits. In particular, reductions in the bumblebees Bombus supremus, B. filchnerae, B. humilis and B. impetuosus are associated with reductions in flowers of the food plants Hedysarum and Saussurea.     

Expressed sequence tag analysis of the diapausing queen of the bumblebee Bombus ignitus

We constructed a full‐length cDNA library from diapausing queens of the bumblebee Bombus ignitus. A total of 480 randomly selected clones was sequenced by single‐run 5′‐end sequencing. Of these, there were 437 high quality clones, 23 poor quality clones and 20 read‐fail clones. Each high quality clone sequence was searched against a public protein database. The most frequently found matching genes were ribosomal proteins (12.5%), p10 (3.58%), cytochrome P450 monooxygenase (3.13%) and sensory appendage protein (2.9%). Sequence similarity analysis between bumblebees and other insect species showed that 72 out of 437 (16.5%) bumblebee expressed sequence tags (EST) matched sequences of Apis mellifera, with matches to Drosophila melanogaster (6.6%), Caenorhabditis briggsae (6.2%), Lysiphlebus testaceipes (4.8%), Periplaneta americana (3.7%) and Anopheles gambiae (3.4%) following, suggesting that sequence similarity of bumblebee EST is closest to that of A. mellifera. Functional classification of EST based on Gene Ontology showed that most genes found by sequencing are associated with physiological processes in the bumblebee. The results of sequencing and analysis of our 437 cDNA demonstrated that high‐throughput EST sequencing and data analysis are powerful means for identifying novel genes and for expression profiling. Our bumblebee EST collection could be a useful platform for further studies of gene expression in diapausing bumblebees.     

Methods for species delimitation in bumblebees (Hymenoptera,Apidae, Bombus): towards an integrative approach

Delimitation of closely related species is often hindered by the lack of discrete diagnostic morphological characters. This is exemplified in bumblebees (genus Bombus). There have been many attempts to clarify bumblebee taxonomy by using alternative features to discrete morphological characters such as wing shape, DNA, or eco‐chemical traits. Nevertheless each approach has its own limitations. Recent studies have used a multisource approach to gather different lines of speciation evidence in order to draw a strongly supported taxonomic hypothesis in bumblebees. Yet, the resulting taxonomic status is not independent of selected evidence and of consensus methodology (i.e. unanimous procedure, majority, different weighting of evidence). In this article, we compare taxonomic conclusions for a group of taxonomically doubtful species (the Bombus lapidarius‐group) obtained from the four commonly used lines of evidence for species delimitation in bumblebees (geometric morphometric of wing shape, genetic differentiation assessment, sequence‐based species delimitation methods and differentiation of cephalic labial gland secretions). We ultimately aim to assess the usefulness of these lines of evidence as components of an integrative decision framework to delimit bumblebee species. Our results show that analyses based on wing shape do not delineate any obvious cluster. In contrast, nuclear/mitochondrial, sequence‐based species delimitation methods, and analyses based on cephalic labial gland secretions are congruent with each other. This allows setting up an integrative decision framework to establish strongly supported species and subspecies status within bumblebees.