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Resource partitioning is considered a key factor in alleviating competitive interactions, enabling coexistence among consumer species. However, most studies have focused on resource partitioning between species, ignoring the potentially critical role of intraspecific variation in resource use. We investigated floral resource partitioning across species, colonies, and individuals in a species‐rich bumblebee community in the diversification center of bumblebees. We used a total of 10,598 bumblebees belonging to 13 species across 5 years in the Hengduan Mountains of southwest China. First, we evaluated the influence of a comprehensive set of floral traits, including both those related to attractiveness (flower color and shape) and rewards (pollen, sugar ratio, nectar volume, sugar concentration, and amino acid content) on resource partitioning at the species level in bumblebee–plant networks. Then, we explored intraspecific resource partitioning on the colony and individual levels. Our results suggest that bumblebee species differ substantially in their use of the available floral resources, and that this mainly depends on flower attractiveness (floral color and shape). Interestingly, we also detected floral resource partitioning at the colony level within all commonest bumblebee species evaluated. In general, floral resource partitioning between bumblebee individuals decreased with species‐ and individual‐level variation in body size (intertegular span). These results suggest that bumblebee species may coexist via the flexibility in their preferences for specific floral traits, which filters up to support the co‐occurrence of high numbers of species and individuals in this global hotspot of species richness. [ABSTRACT FROM AUTHOR]

Simple Summary: Bumblebees are well-suited pollinators of economic crops. This study evaluated the foraging behavior and pollination effects of Bombus terrestris on cherry tomatoes and pears in northern China. B. terrestris pollination can improve cultivation efficiency, increase yield, and produce more economic benefits, which indicates that it has great potential in pollination applications for cherry tomatoes and pears in northern China. Bumblebees (Bombus terrestris) have strong environmental adaptability and high pollen transfer efficiency, making them well-suited pollinators of economic crops. However, bumblebee pollination is still not widely applied in northern China due to the lack of data on foraging behavior and pollination effects. We conducted a three-year experiment involving cherry tomatoes (Solanum lycopersicum L.) and pears (Pyrus spp.) treated with bumblebee pollination to evaluate the foraging behavior and pollination effects on these two crops. Results showed that B. terrestris had enhanced foraging activities as daytime temperatures rose from 18 °C to 26 °C, as indicated by the increased number of bees leaving the hive and returning bees carrying pollen in greenhouses in winter. There were two peaks in the foraging activity of bumblebees in pear orchards in early spring, which was closely related to the temperature change in the daytime. Undoubtedly, cherry tomatoes treated with B. terrestris had higher fruit setting rate, weight, seed number, and fruit yields compared to those with hormone 2,4-dichlorophenoxyacetic acid treatments, as well as a lower rate of deformed fruits. B. terrestris pollination can significantly increase the fruit setting rate and fruit yield of pears, compared with open pollination, and can fully achieve the effect of hand pollination. B. terrestris pollination can improve cultivation efficiency, increase yield, and produce more economic benefits. Moreover, it can also contribute to reducing hormone residues and ensure the safety of agricultural products. We recommend its application to cherry tomatoes in greenhouses in winter and potential application to pears in orchards in early spring in northern China. However, the risk to local bumblebee species of introducing commercially available bumblebees into orchards should be considered and evaluated in future research. This study provides both empirical support and a theoretical basis for the selection of bumblebees as pollinators in the production of economically important crops and the improvement of crop cultivation management in northern China. [ABSTRACT FROM AUTHOR]

Simple Summary: Our study investigated the dynamics of pathogen communities within Chinese bumblebee populations, a key issue for understanding emerging infectious diseases and their impacts on insect biodiversity loss. By employing computational modeling on extensive pathogen data from bumblebees, we uncover that the host species variation significantly influences pathogen assembly and occurrences, compared to environmental factors like climate and location. Moreover, our results reveal significant pathogen–pathogen interactions, with similar pathogens exhibiting facilitatory relationships and distinct pathogen types showing strong negative associations, possibly due to immune response interactions and competitive dynamics within hosts. Our findings highlight the role of host–pathogen coevolution and other ecological interactions in shaping pathogen communities. The implications of this work are substantial for bumblebee conservation, improving our understanding of pathogen dynamics that could inform strategies to stop declines in bumblebee populations. Bumblebees have been considered one of the most important pollinators on the planet. However, recent reports of bumblebee decline have raised concern about a significant threat to ecosystem stability. Infectious diseases caused by multiple pathogen infections have been increasingly recognized as an important mechanism behind this decline worldwide. Understanding the determining factors that influence the assembly and composition of pathogen communities among bumblebees can provide important implications for predicting infectious disease dynamics and making effective conservation policies. Here, we study the relative importance of biotic interactions versus interspecific host resistance in shaping the pathogen community composition of bumblebees in China. We first conducted a comprehensive survey of 13 pathogens from 22 bumblebee species across China. We then applied joint species distribution modeling to assess the determinants of pathogen community composition and examine the presence and strength of pathogen–pathogen associations. We found that host species explained most of the variations in pathogen occurrences and composition, suggesting that host specificity was the most important variable in predicting pathogen occurrences and community composition in bumblebees. Moreover, we detected both positive and negative associations among pathogens, indicating the role of competition and facilitation among pathogens in determining pathogen community assembly. Our research demonstrates the power of a pluralistic framework integrating field survey of bumblebee pathogens with community ecology frameworks to understand the underlying mechanisms of pathogen community assembly. [ABSTRACT FROM AUTHOR]

Bumble bees are globally important pollinators, contributing hundreds of millions of dollars annually in crop pollination services. Several species are in decline, making it paramount to understand how pathogens and nutrition shape bee health. Previous work has shown that consuming sunflower pollen (Helianthus annuus) dramatically reduces infection by the trypanosomatid gut pathogen, Crithidia bombi , in the common eastern bumble bee (Bombus impatiens). Sunflower pollen may therefore be useful as a dietary supplement for reducing this pathogen in managed bumble bee colonies. Here, we assessed the efficacy of freezer-stored sunflower pollen that was collected in different years and locations for reducing pathogen infection. We tested sunflower pollen that was 1, 3, 4, or 5 yr old and from sunflowers grown in the United States or China against a control of 1-yr-old buckwheat pollen from China, since buckwheat pollen results in high infection. We hypothesized that older pollen would have weaker medicinal effects due to degradation of pollen quality. We found that all sunflower pollen treatments significantly decreased Crithidia infection compared to controls. These results suggest that sunflower pollen can be freezer-stored for up to 5 yr and sourced from a wide range of geographic areas and still maintain its medicinal effects against Crithidia in the common eastern bumble bee. This is helpful information for stakeholders who might administer sunflower pollen as a dietary supplement to manage Crithidia in commercial bumble bee colonies. [ABSTRACT FROM AUTHOR]

Impatiens namchabarwensis was described as a new species in 2005 by Morgan et al. As already mentioned in the species description, I. namchabarwensis is morphologically similar to I. arguta and the small range of I. namchabarwensis in the eastern Himalaya is nested within the large, Himalayan range of I. arguta. Therefore, I. namchabarwensis has frequently been treated as synonym of I. arguta (e.g. in the Flora of China). We compared plant longevity, flower morphology and other functional floral traits and analyzed the differences between the two taxa. We found that I. namchabarwensis is a short‐lived perennial reaching maximally three years whereas I. arguta is a long‐lived perennial. Further, the floral traits of the two species differ significantly. These differences are also reflected in the main pollinator groups of the two species, which are hawk moths for I. namchabarwensis and bumblebees for I. arguta. Hence, we follow the argumentation of Morgan et al. and conclude that I. namchabarwensis and I. arguta are two distinct species. [ABSTRACT FROM AUTHOR]

Simple Summary: Bombus breviceps is an important native species of bumblebee in southern China. As a pollinator, it has the potential for domestication and commercial rearing. In this study, in order to identify the nutritional requirements for the egg-laying, hatching, and colony foundation stages, we selected three common local types of pollen, including camellia pollen, oilseed rape pollen, and apricot pollen, as well as mixtures of them, to feed B. breviceps queens to evaluate the reproductive performance, and feasibility of these pollens as a diet and the nutritional requirements. The results showed that the pollen with a higher essential amino acid content had advantages in laying time, the number of eggs laid, larval ejection, and the time of first worker emergence, while the pollen with a higher crude protein content had advantages in the time the colony took to reach ten workers. These results may guide the selection of feed in B. breviceps artificial feeding and help to explore the nutritional requirements in oviposition and the colony stage from the perspective of conventional pollen. Pollen is an important source of nutrition for bumblebees to survive, reproduce, and raise their offspring. To explore the nutritional requirements for the egg laying and hatching of queenright Bombus breviceps colonies, camellia pollen, oilseed rape pollen, apricot pollen, and mixtures of two or three types of pollen in equal proportions were used to feed the queens in this study. The results showed that the camellia pollen with a higher essential amino acid content was superior to the pollen with a lower essential amino acid content in the initial egg-laying time (p < 0.05), egg number (p < 0.05), larval ejection (p < 0.01), time of first worker emergence (p < 0.05), and the average weight of workers in the first batch (p < 0.01). It took less time for colonies under the camellia pollen and camellia–oilseed rape–apricot pollen mix treatments, both with a higher crude protein content, to reach ten workers in the colony (p < 0.01). On the contrary, the queens fed apricot pollen never laid an egg, and larvae fed oilseed rape pollen were all ejected—both pollens with a lower essential amino acid content. The results emphasize that the diet should be rationally allocated to meet the nutritional needs of local bumblebees at various stages when guiding them to lay eggs, hatch, and develop a colony. [ABSTRACT FROM AUTHOR]

The managed bumblebee Bombus terrestris L. (Hymenoptera: Apidae) has become established on multiple continents and various islands globally, potentially impacting fauna and flora alike. Its introduction could prove especially problematic in Asia, where bumblebee biodiversity is the highest worldwide. Here, we report the active, unregulated commercial management and sale of non-native Bombus terrestris in China, also including its use in open environments, which has resulted in at least two introductions into the wild that we newly report here (Beijing and Kunming, China), although whether they are established is unknown. National and international regulations on the trade and use of this species are needed, and some of the many native species should instead be targeted for domestication. [ABSTRACT FROM AUTHOR]

Bumble bees are vital to our agro-ecological system, with approximately 250 species reported around the world in the single genus Bombus. However, the health of bumble bees is threatened by multiple factors: habitat loss, climate change, pesticide use, and disease caused by pathogens and parasites. It is therefore vitally important to have a fully developed phylogeny for bumble bee species as part of our conservation efforts. The purpose of this study was to explore the phylogenetic relationships of the dominant bumble bees on the Tibetan plateau and in northern China as well as their placement and classification within the genus Bombus. The study used combined gene analysis consisting of sequence fragments from six genes, 16S rRNA, COI, EF-1α, Argk, Opsin and PEPCK, and the phylogenetic relationships of 209 Bombus species were explored. Twenty-six species, including 152 gene sequences, were collected from different regions throughout China, and 1037 gene sequences representing 183 species were obtained from GenBank or BOLD. The results suggest that the 209 analyzed species belong to fifteen subgenera and that most of the subgenera in Bombus are monophyletic, which is in accordance with conventional morphology-based classifications. The phylogenetic trees also show that nearly all subgenera easily fall into two distinct clades: short-faced and long-faced. The study is the first to investigate the phylogenetic placement of Bombus turneri (Richards), Bombus opulentus Smith, Bombus pyrosoma Morawitz, Bombus longipennis Friese, Bombus minshanensis Bischoff, and Bombus lantschouensis Vogt, all of which are widely distributed throughout different regions of China. The knowledge and understanding gained from the findings can provide a molecular basis to accurately classify Bombus in China and to define strategies to conserve biodiversity and promote pollinator populations. [ABSTRACT FROM AUTHOR]

Hiptage lushuiensis, a new species from the Hengduan Mountains, northwestern Yunnan Province, China, is described and illustrated here. This species was found growing at the margin of an open forest in the Nujiang Gorge of Lushui City. Hiptage lushuiensis is distinctive for its pink petals, 2 or more calyx glands, and large and pink samara with white hairs. This species is isolated in the deep gorge (25°51′N, 98°51′E, altitude 917 m), at the northern edge distribution range of the genus. These distinctive morphological differences and the geographic isolation suggest a history of long‐distance dispersal and allopatric speciation. Hiptage lushuiensis has a shorter filament but larger herkogamy than related species, suggesting that H. lushuiensis may have adapted to other pollinators with short but fat body such as Amegilla or Bombus spp. [ABSTRACT FROM AUTHOR]

Bombus bicoloratus is an important pollinator of wild flowers in the oriental region. We confirmed a total of 451 specimens of B. bicoloratus from China based on DNA sequences from mitochondrial cytochrome oxidase subunit I (COI) barcodes. Bombus bicoloratus is distributed mainly in tropical and subtropical areas of southern China. This species exhibits a striking intraspecific colour-pattern polymorphism both in females and males. The distribution frequency of the different colour patterns is heavily skewed, with 50.9% of the workers sharing the same colour pattern that predominates in most locations. Workers from the islands of Hainan and Taiwan possess a very distinct colour pattern, and its spatial distribution is correlated with the climate factor irradiance. Bombus bicoloratus has been recorded to collect nectar and pollen from 14 plant families, indicating that this species is polylectic. This study will be helpful for recognising bumblebee species with variable colour patterns, especially B. bicoloratus, in Asia. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Pollinators are under threat from climate and climate-induced land cover changes. • Distributional responses were predicted for 29 bumblebee species in East Asia. • Of the studied species, 59–93 % experienced range loss in the future. • Species richness declined within central mainland China and northeastern Asia. • Conserving regions with high species richness and dominant land covers is needed. Abstract Pollinators play a key role in agricultural and natural ecosystems, but their biodiversity is highly vulnerable to the impact of environmental changes. Here, we evaluated the distributional responses of 29 bumblebee species endemic to East Asia to future (2050s and 2070s) climate and land cover changes, and 17–27 (59–93 %) of the species exhibited range contraction. A decrease in species richness from 25 to 19 species in the highest region of central China was also detected due to range shifts of 17 km to 574 km. Furthermore, one (3.44%), three to five (10–17 %), and two to eight (7–28 %) of the 29 bumblebee species were predicted to become critically endangered, endangered and vulnerable in the future, respectively. Our study highlights the strong impact of environmental changes on species distributions, and we suggest strategies for the conservation of vulnerable species that include protecting the regions of high species richness and the most dominant land covers within the current range to mitigate the threat of environmental changes. [ABSTRACT FROM AUTHOR]

Honey bees and wild bees provide critical pollination services to agricultural ecosystems; however, the relative contributions of different bee taxa are not well understood. The natural habitats surrounding farmland support food and nesting resources for wild bees and therefore play an important role in the maintenance of crop pollination. In this study, we selected Cucurbita pepo L. (squash) as a model crop to investigate the relative importance of honey bees and bumblebees in pollinating the crop. Thirteen fields, which were surrounded by a gradient of natural habitat, were investigated on the Yunnan-Guizhou Plateau in China. We measured the visit densities of honey bees and bumblebees, the number of pollen grains deposited in a single visit by the two bee taxa, as well as the overall pollen grains deposited on stigmas during a flowering day, and then used Bayesian inference to decouple the pollen grains deposited by either the honey bees or the bumblebees. Compared with honey bees, bumblebees deposited a higher number of pollen grains on stigmas in a single visit, but had a lower visit density than honey bees. Meanwhile, the bumblebee visit density increased along the proportion of natural habitat, while the honey bee visit density was not affected by the surrounding natural habitat. Data simulations using Bayesian inference showed that on a flowering day, the number of pollen grains deposited by bumblebees increased with the proportion of natural habitat in the surrounding landscape, but the number of pollen grains deposited by honey bees did not. Moreover, the total numbers of pollen grains deposited by honey bees or bumblebees alone were all below 2000 (the critical level to satisfy the pollination requirement of this crop). Pollen calculations demonstrated that the number of pollen grains deposited by the two bee taxa was greater than 2000 in fields surrounded by more than 13% natural habitat (grasslands and forests). The results revealed that bumblebees ensured C. pepo pollination in combination with honey bees in the highland agricultural ecosystems. [ABSTRACT FROM AUTHOR]

Abstract: Bumblebees (Bombus spp.) are important pollinators of many economically important crops and microsporidia are among the most important infections of these hosts. Using molecular markers, we screened a large sample (n =1,009 bees) of workers of 27 different Bombus spp. from China (Sichuan, Qinghai, Inner Mongolia, and Gansu provinces). The results showed that 62 individuals representing 12 Bombus spp. were infected by microsporidia with an overall prevalence of 6.1%. Based on the haplotypes (ssrRNA sequences), we confirmed the presence of Nosema bombi, Nosema ceranae and (likely) Nosema thomsoni. In addition, four new putatively novel taxa were identified by phylogenetic reconstruction: Nosema A, Nosema B-complex, Nosema C-complex and Nosema D-complex. In many cases, hosts were infected by more than one Nosema taxon. Possible caveats of sequence analyses are discussed. [Copyright &y& Elsevier]

Most Cypripedium species are specialized orchids pollinated by, in a broad sense, bees or flies. Here we present the first evidence that a slipper orchid, Cypripedium flavum, is pollinated by both bees and flies, i.e., bumblebees and blowflies. Artificial pollination experiments demonstrated that the flowers of C. flavum are self-compatible, but need pollen vectors for successful reproduction. Field observations detected 25 insects visiting the flowers, and 14 of these insects entered into the labellum of the flowers, but only female bumblebees, Bombus hypnorum, B. remotus, and the blowfly Calliphora vomitoria exited of the labellum with pollen smears of C. flavum. The floral functional morphology of C. flavum appears to be more suited to bumblebees than to blowflies . The bumblebees are more efficient pollinators of the orchid, but blowflies are more frequent visitors, so they pollinated more flowers despite being less efficient. [ABSTRACT FROM AUTHOR]

The natural hybridization that occurs between two sympatric species of Rhododendron subgenus Hymenanthes in Yunnan, China, was investigated. In field observations, it was noted that the putative hybrids between R. delavayi Franch. and R. cyanocarpum (Franch.) Franch. ex W.W. Sm. had intermediate morphologies. On the basis of morphology, chloroplast DNA ( trnL-rpl32) and nuclear DNA ( waxy), hybrids and parental species were identified. Hybridization occurred in both directions, but was asymmetrical, with R. delavayi as the major maternal parent. Reciprocal hand pollination treatments showed that either species, as pollen donor or pollen receiver, could produce fruits. It was noted that fruit set varied among treatments. The same pollinators (bumblebees) were shared in both parental species. From these results, we conclude that individuals with intermediate morphologies are indeed of hybrid origin from natural hybridization between R. cyanocarpum and R. delavayi. Furthermore, we presume the hybridization at the study site could have been initiated by habitat disturbance in the 1950s, and we may hence witness the early stages of hybrid swarm formation. [ABSTRACT FROM AUTHOR]

Using scanning electron microscope, eight types of sensilla were found on the antennae of all castes in eight Bombus species (Hymenoptera: Apidae) collected in Jilin Province, China. The numbers of various types of antennal sensilla were analyzed by rough set data analysis method to determine which sensillum type might be useful in species and caste discrimination. The results showed that the number of sensilla basiconica A, B (s. t. a, s. t. b), sensilla trichodea A, B, C/ D (s. t. a, s. t. b, s. t. c/ d) and sensilla placodea (s. p) can be used in species discrimination, whereas only types s. t. a, s. t. b, and s. t. b are relevant in caste discrimination. Other types of sensilla had a lower taxonomic value for species and caste discrimination. This study provides a mathematic reference for the function research of antennal sensilla of Bombus determined by single-cell recording at both peripheral and antennal lobe (central nervous system) levels. [ABSTRACT FROM AUTHOR]

Delayed selfing could provide ovules with an opportunity to be fertilized as a means of “pollination assurance” before the flowers wilt. It could, thus, be regarded as an adaptation to unpredictable pollinator environments. Within the alpine biennial Gentianopsis paludosa, the showy flowers and herkogamy at the early stage of a flower's life cycle may favor outcrossing. As the flower ages, anthers contact the central stigma due to the elongation of all filaments, resulting in autonomous selfing. Flower visitors are extremely rare in a high altitude population; and examination of the mating system indicates that G. paludosa is self-pollinated under natural conditions in this population. While at the lower altitude, the bumblebee visitation rate is relatively high but possibly unreliable. Stigma receptivity is the highest on the third day of anthesis, and decreases thereafter. Pollen viability is the highest when flowers open, and gradually decreases later. Self-pollination of G. paludosa occurs at the late stage of a flower's lifecycle when stigma receptivity and pollen viability have both decreased, suggesting delayed selfing and assurance of seed production. This delayed selfing could assure seed production under the constraints of pollinator scarcity, but ensure outcrossing when pollinators were available. Such a flexible pollination mechanism is highly adaptive in the alpine environment of the Qinghai-Tibetan Plateau. [ABSTRACT FROM AUTHOR]

This study was conducted to evaluate the effects of four pesticides (Mosplian, Kingbo, Score and Lvrtong) applied commonly in greenhouses in China, on three bumblebee species ( Bombus hypocrita, Bombus ignitus and Bombus patagiatus). The study used a contact experiment and oral toxicity LD50 values. The results showed that the mortality for B. hypocrita after contacting the four pesticides was significantly lower than B. patagiatus and B. ignitus, but there was no significant difference between B. patagiatus and B. ignitus. The oral toxicity median lethal dose (LD50) value of Mosplian to B. hypocrita (0.0028 μg active ingredient/bee) was significantly higher than that to B. ignitus (0.0023 μg active ingredient/bee) and B. patagiatus (0.0021 μg active ingredient/bee). Of the bee species, it can be concluded that B. hypocrita was the least susceptible to the four pesticides. The mortality rates of each bumblebee species after contact with Mosplian were significantly higher than for the other three pesticides and the control group. For Kingbo, the rates were significantly higher than the control group, but Score and Lvrtong exposed groups showed no significant increase in mortality relative to the control group. It can therefore be concluded that the pesticides differ in their negative influences on bumblebees, and that Mosplian is the most harmful. [ABSTRACT FROM AUTHOR]

It is widely agreed that in many parts of the world some bumblebee (Bombus ) species have declined, and that this has often been driven by land-use changes that cause reductions in the abundance of food plants. There is much less agreement about how changes in food plants affect some bumblebee species more than others. We sought to identify which species' characteristics are generally associated with the relative winners and losers by comparing the 3 independent bumblebee faunas from parts of Britain, Canada, and China. Using available survey data, we assessed species characteristics, including competition with congeners, climatic specialization, proximity to climatic range edge, food specialization, phenology, body size, and range size. Results of our meta-analysis of correlations showed support for the hypotheses that decline susceptibility is generally greater for species that have greater climatic specialization, for species in areas where they occur closest to the edges of their climatic ranges, and for species that have queens that become active later in the year. The latter characteristic may render a species at a particular disadvantage when they have long colony cycles if there are losses of food plants in mid to late colony development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The pollination ecology of small, short, and two-flowered Pedicularis muscoides subsp. himalayca was studied during its full blooming period in alpine areas of western Sichuan Province, China, part of the putative origin and diversification center of the genus. Pedicularis muscoides subsp. himalayca was nototribically pollinated exclusively by queens of four bumblebee species (Bombus Latr.) that foraged for nectar on flowers in an upright position. Of the four Bombus species, B. friseanus Smith occurred in the highest frequency and was the major pollinator of P. muscoides subsp. himalayca. It comprised 81% of the bumblebees collected on P. muscoides subsp. himalayca. Queen bumblebees stood on the ground while foraging on flowers, which has not previously been reported in other Pedicularis species. During the study period almost all the foragers were confined to the studied subspecies and very occasionally visited other associated blooming species at the study site. The low plant height; outcurved terminal flowers; short-tubed, erostrate, and copiously nectariferous flowers; corolla morphology; and highly synchronized short-blooming period of P. muscoides subsp. himalayca made this plant well adapted to pollination by queen bumblebees within a short growing season. Thus this study provides evidence for coadaptation between Pedicularis and bumblebee pollinators. [ABSTRACT FROM AUTHOR]

The genus Pedicularis manifests great variation in corolla morphology, including corolla tube length. Previous observations conducted during daytime have documented bumblebees to be important pollinators for short- and long-tubed Pedicularis species. However, the potential role of night-flying long-proboscid insects (moths) as selective agents for the evolution of corolla length has not been determined. Three Pedicularis species, Pedicularis densispica, Pedicularis gruinea, and Pedicularis siphonantha, in montane meadows of Yunnan Province, southwestern China, have extremely divergent corolla tube lengths of 7.1, 22.0, and 50.6 mm, respectively. We find that all three species are pollinated by similar bumblebee species. Pollination treatments indicate that seed sets of inflorescences enclosed in fine-meshed nylon nets in the night are not different from open-pollinated inflorescences, but those bagged in the day have significantly decreased seed set, indicating that moth pollinators are not important for the study species. We present anatomical evidence that the loss of nectaries in long-tubed species, and hence the loss of nectar production, is a derived trait. The loss of nectaries may be a key innovation, releasing the corolla from the mechanical constraint imposed by pollinators reaching for nectar. [ABSTRACT FROM AUTHOR]

Pollination ecology and habitat preference of Pedicularis species were studied in a transitional zone between subalpine coniferous forests and alpine meadows in northwestern Sichuan of China. Pedicularis species exhibited apparent preferences for different microhabitats. Species with long rostrate and contorted galea were nectarless and their mean corolla tube length ranged from 7 to 50 mm while species without long rostrate and contorted galea produced nectar and their corolla tube length averaged from 8 to 18 mm. Bumblebees were the sole pollinators of the studied species and five bee species pollinated seven Pedicularis species with one species pollinating all the Pedicularis species. Pollinators that visited nectariferous species had longer tongues than those that visited nectarless species and they spent longer time on nectariferous than on nectarless species. All Pedicularis species except for P. rex subsp. lipskyana were pollinated by worker bees. Pedicularis rex subsp. lipskyana was pollinated nototribically by worker, male and queen bumblebees through stigmatic contact with residual pollen on the left side of the bee's head. Morphology of pollinators, rather than pollinator species, may play the key role in diversification of Pedicularis. Microhabitats rather than pollination may be the separation barrier in propagation. Factors contributing to high diversity of Pedicularis need further study. [ABSTRACT FROM AUTHOR]

Bumblebees are important pollinators for both crops and wild plants that require the special buzz pollination. Vast majority of the world's bumble bee species are concentrated in China, specifically in the west mountain regions. Like social honey bees, bumble bees possess a simple gut microbiota dominated by few host‐restricted bacterial species, and they are crucial for the metabolism, immune function, and many other aspects of the pollinator's health. By analyzing the gut community of bumble bees from different regions across China, it finds that they show two distinct gut enterotypes. Strains of the core gut member, Gilliamella, from different countries vary in gene repertoires related to sugar metabolism and antibiotic resistance (see pages 302‐314). Photo by Dr. Xin Zhou. [ABSTRACT FROM AUTHOR]

• A new type of mirror-image flowers is caused by lateral bending of the floral tube. • The lateral bending of floral tube selects for long-tongued bumblebees as legitimate pollinators. • Mirror-image flowers are normally associated with low pollen-ovule ratio. We studied a previously unreported form of mirror-image flowers in Rhabdothamnopsis sinensis (Gesneriaceae) endemic to China. The style in R. sinensis remains straight throughout the blooming period, while the basal part of the floral tube bends either to the left or right side, causing the style to lean towards the right or left side of the floral tube. R. sinensis has two epipetalous fertile stamens with twisted filaments, moving the fused anthers located at the opposite side of the style. This floral syndrome results in reciprocal mirror-image flowers in a relative simpler way as compared to typical types of mirror-image flowers. Pollinator observations revealed that the bending of the floral tube and twisted filament block the entrance to the floral tube, rendering long-tongued bumblebees as pollinators by transferring pollen with the side of the thorax. R. sinensis is self-compatible and the pollen-ovule ratio is strikingly low (37.41 ± 11.90). Thorax pollination probably is the main reason for such low pollen wastage because the thorax suffers less grooming than the abdomen, which is the main pollen-carrying part in other typical mirror-image flowers. The unusual type of mirror-image flowers described here suggests a specialized pollination adaptation with limited but high-fidelity pollinators. [ABSTRACT FROM AUTHOR]

Simple Summary: Bumblebees are very important pollinators for many wild and agricultural flowers and play significant roles in natural and agricultural ecosystems. The distribution of bumblebees varies between the species; some species occupy narrow areas, while others have a varied distribution from low to high elevation. Bombus pyrosoma is one of the bumblebee species with a highly varied geomorphological distribution range in China. To answer why some bumblebee species have a varied distribution, we compared the transcriptomic and metabolomic data of B. pyrosoma from the low-altitude North China Plain and the high-altitude Tibet Plateau. The results showed that energy metabolism and innate immunity of the high-altitude B. pyrosoma had been enhanced in order to adapt to the extreme environment of hypoxia and low temperature, compared to the low-altitude bumblebees. This study highlights the ecological adaptation of bumblebees distributed from low- to high-altitude conditions. Bombus pyrosoma is one of the most abundant bumblebee species in China, with a distribution range of very varied geomorphology and vegetation, which makes it an ideal pollinator species for research into high-altitude adaptation. Here, we sequenced and assembled transcriptomes of B. pyrosoma from the low-altitude North China Plain and the high-altitude Tibet Plateau. Subsequent comparative analysis of de novo transcriptomes from the high- and low-altitude groups identified 675 common upregulated genes (DEGs) in the high-altitude B. pyrosoma. These genes were enriched in metabolic pathways and corresponded to enzyme activities involved in energy metabolism. Furthermore, according to joint analysis with comparative metabolomics, we suggest that the metabolism of coenzyme A (CoA) and the metabolism and transport of energy resources contribute to the adaptation of high-altitude B. pyrosoma. Meanwhile, we found many common upregulated genes enriched in the Toll and immune deficiency (Imd)signaling pathways that act as important immune defenses in insects, and hypoxia and cold temperatures could induce the upregulation of immune genes in insects. Therefore, we suppose that the Toll and Imd signaling pathways also participated in the high-altitude adaptation of B. pyrosoma. Like other organisms, we suggest that the high-altitude adaptation of B. pyrosoma is controlled by diverse mechanisms. [ABSTRACT FROM AUTHOR]

For the conservation of wild pollinators, instead of surveying the whole community, one or more indicator species can be used as monitoring targets for long-term conservation. China, the richest country in terms of bumblebee species with 125 species, was selected here to investigate the indicator species of the different biogeographic regions of bumblebees. Four principal biogeographic regions of bumblebee species, i.e., South China, North-Northeast China (North China), the Mongolian Plateau and surrounding mountains (Mongolian Plateau) and the Tibetan Plateau and surrounding mountains (Tibetan Plateau), were revealed by Ward's agglomerative cluster analysis. The role of climatic factors in defining the biogeographic regions was found to be greater than those of topographical factors and their joint effects. We found that 14, 13, 12 and 12 species were associated with the regions of South China, North China, the Mongolian Plateau and the Tibetan Plateau, respectively. In addition, among these species, seven (Bombus atripes, B. bicoloratus, B. breviceps, B. eximius, B. flavescens, B. montivagus and B. trifasciatus), five (B. deuteronymus, B. patagiatus, B. pseudobaicalensis, B. tricornis and B. ussurensis), ten (B. armeniacus, B. confusus, B. cryptarum, B. cullumanus, B. hortorum, B. muscorum, B. ruderarius, B. soroeensis, B. subterraneus and B. terrestris) and four species (B. kashmirensis, B. personatus, B. rufofasciatus and B. waltoni) were identified as important indicator species for South China, North China, the Mongolian Plateau and the Tibetan Plateau, respectively. Furthermore, we identified specific areas for targeted bumblebee diversity monitoring in each region. This study highlights the bioregionalization and the identification of indicator species of bumblebee pollinators for long-term monitoring in conservation., (Copyright © 2019 The Author(s). Published by Elsevier B.V. All rights reserved.)

Pollen is important not only for pollination and fertilization of plants, but also for colony development of bee pollinators. Anther dehiscence determines the available pollen that can be collected by foragers. In China, honeybees and bumblebees are widely used as pollinators in solar greenhouse agriculture. To better understand the effect of solar greenhouse microclimates on pollen release and pollen-foraging behaviour, we observed the anther dehiscence dynamics and daily pollen-collecting activity of Apis mellifera and Bombus lantschouensis during peach anthesis in a solar greenhouse in Beijing. Microclimate factors had a significant effect on anther dehiscence and bee foraging behaviour. The proportion of dehisced anthers increased with increasing temperature and decreasing relative humidity and peaked from 11:00 h to 14:00 h, coinciding with the peak pollen-collecting activity of bees. On sunny days, most pollen grains were collected by the two pollinators within two hours after anther dehiscence, at which time the viability of pollen had not yet significantly decreased. Our study helps us to better understand the relationship between food resources and pollinator foraging behaviour and to make better use of bees for pollination in Chinese solar greenhouses. [ABSTRACT FROM AUTHOR]

Mutillid wasps are ectoparasitic insects that parasitize the enclosed developmental stages of their hosts. Adults are sexually dimorphic, with brilliantly colored and hardened cuticles. The biology of parasitic mutillid wasps has rarely been addressed. Here, we investigated the parasitization by Mutilla europaea on an important pollinator, Bombus breviceps. The parasitic biology and dispersal ability of M. europaea were observed and tested under experimental conditions. We provide the first record of M. europaea parasitizing B. breviceps in southwestern China. As is the case with other bumblebee species, M. europaea mainly parasitized the puparia of males. The dispersal and invasion ability of this parasite under experimental conditions indicates that it spreads rapidly, as far as 20 m in one week, and invades different hosts (B. breviceps and Bombus haemorrhoidalis). This report not only clarifies the parasitic relationship between M. europaea and B. breviceps, but also has important ecological implications for the conservation of bumblebees in China. [ABSTRACT FROM AUTHOR]

Background and Aims Most research on the widespread phenomenon of nectar robbing has focused on the effect of the nectar robbers behaviour on host-plant fitness. However, attention also needs be paid to the characteristics of host plants, which can potentially influence the consequences of nectar robbing as well. A system of three sympatric Corydalis species sharing the same nectar-robbing bumble-bee was therefore studied over 3 years in order to investigate the effect of nectar robbing on host reproductive fitness. Methods Three perennial species of Corydalis were studied in the Shennongjia Mountain area, central China. Observations were conducted on visitor behaviour and visitation frequencies of nectar-robbers and legitimate pollinators. Key Results The results indicated that the effect of nectar robbing by Bombus pyrosoma varied among species, and the three species had different mating systems. Seed set was thus influenced differentially: there was no effect on seed set of the predominantly selfing C. tomentella; for the facultative outcrossing C. incisa, nectar robbing by B. pyrosoma had a positive effect; and nectar robbing had a significant negative effect on the seed set of outcrossing C. ternatifolia. Conclusions A hypothesis is proposed that the type of host-plant mating system could influence the consequences of nectar robbing on host reproductive fitness. [ABSTRACT FROM AUTHOR]