传粉昆虫物种多样性监测、评估和保护概述

欧洲和北美等国相继建立起传粉昆虫物种多样性监测和评估体系。基于传粉昆虫的监测资料,能够对欧美部分区域和某些传粉昆虫类群的现状、下降程度以及影响因素进行研究。欧洲和北美等地已开展部分传粉昆虫保护措施和项目,如欧洲部分国家实施的＂农田环境计划＂项目（Agri-Environmental Schemes）能够保护农田生态系统中传粉昆虫的栖境,恢复和提高传粉昆虫物种多样性。我国传粉昆虫物种多样性十分丰富,但目前还没有一个以监测和评估传粉昆虫物种多样性为主的平台,也未对某区域或某类群传粉昆虫多样性的变化进行评估,传粉昆虫多样性的保护也未引起足够重视。为了解我国传粉昆虫物种多样性现状及变化情况,作者建议在我国建立传粉昆虫物种多样性监测和评估体系,以提高我们在该领域的认识水平,并为开展相应的保护工作提供理论基础。     

Benefits and limitations of isolated floral patches in a pollinator restoration project in Arizona

This study examined invertebrate floral visitor responses to floral richness, floral abundance, and distance between floral patches within a newly planted pollinator restoration habitat in an arid ecosystem in central Arizona, United States. We created a pollinator habitat experiment consisting of a large central garden (11‐m diameter) surrounded by concentric rings of smaller habitat patches (1‐m diameter), separated from one another by 1, 8, 13, and 21 m, respectively, and including four flowering species. We observed plant and visitor interactions via structured 10‐minute flower visitation observations over a 3‐month period. Key findings included: (1) each plant species interacted with a variety of flower visitors, but flower visitor groups differed only marginally among the plant species; (2) floral patches outside the central garden exhibited reduced quantities of floral structures; and (3) number of floral structures per patch, but not isolation of floral patches within the habitat, affected the number of visitors and visitor taxa richness. For practitioners and land managers looking to restore pollination systems in arid ecosystems with low establishment via seeding, the results of this study suggest that installing species‐rich and florally abundant patches of flowering plant species within a habitat could efficiently support plant‐pollinator interactions.     

玉叶金花种内性状置换的初步研究

通过对茜草科玉叶金花属植物玉叶金花传粉生物学及种内形态分化和分布特点的初步研究,发现该种的两个变种玉叶金花和白花玉叶金花在形态和生境适应上都有一定的规律。研究表明,楠藤与开黄花的玉叶金花原变种的传粉者主要是鳞翅目昆虫,而玉叶金花的白花变种的有效传粉者是膜翅目昆虫。认为变种白花玉叶金花居群的出现与同属植物楠藤的同域分布及避免相互竞争传粉者有关。白花玉叶金花变种的出现属于性状置换现象。     

Variation in context‐dependent foraging behavior across pollinators

Pollinator foraging behavior has direct consequences for plant reproduction and has been implicated in driving floral trait evolution. Exploring the degree to which pollinators exhibit flexibility in foraging behavior will add to a mechanistic understanding of how pollinators can impose selection on plant traits. Although plants have evolved suites of floral traits to attract pollinators, flower color is a particularly important aspect of the floral display. Some pollinators show strong innate color preference, but many pollinators display flexibility in preference due to learning associations between rewards and color, or due to variable perception of color in different environments or plant communities. This study examines the flexibility in flower color preference of two groups of native butterfly pollinators under natural field conditions. We find that pipevine swallowtails (Battus philenor) and skippers (family Hesperiidae), the predominate pollinators of the two native Texas Phlox species, Phlox cuspidata and Phlox drummondii, display distinct patterns of color preferences across different contexts. Pipevine swallowtails exhibit highly flexible color preferences and likely utilize other floral traits to make foraging decisions. In contrast, skippers have consistent color preferences and likely use flower color as a primary cue for foraging. As a result of this variation in color preference flexibility, the two pollinator groups impose concordant selection on flower color in some contexts but discordant selection in other contexts. This variability could have profound implications for how flower traits respond to pollinator‐mediated selection. Our findings suggest that studying dynamics of behavior in natural field conditions is important for understanding plant–pollinator interactions.     

探讨监测传粉者的方法

种子植物的有性生殖依赖于花粉传递, 传粉者是花粉传递的媒介。传粉者为野生植物和农作物提供的传粉服务, 是我们绿色星球最重要的生态过程之一, 在维持生物多样性和农作物生产方面具有重要作用。农业集约化、生境破碎、全球气候变暖等因素加剧了传粉者衰减和灭绝的风险, 对生态系统的功能和农业生产造成了不利影响。为了维系植物与传粉者生态互作关系的稳定性, 人们建立了一系列从局部地区到国际、由普通民众到科研人员参与的传粉者监测项目, 以期掌握传粉生态系统的状况和发展趋势, 为自然和农业生态系统的健康提供预警和反馈。本文强调了监测传粉者的首要前提条件, 即正确区分传粉者和访花者; 总结了监测传粉者的直接和间接方法, 包括群落水平的直接观察监测, 以及利用关联数据进行间接推断与调查; 介绍了具有潜力的由大众参与的公众监测项目。针对7种常见传粉者类群, 讨论了可行的适用于各类群的监测方法, 为监测拓展到更多的传粉者类群提供了可能。期望能为生物多样性的保护、传粉者动态的精准监测提供建议与参考。     

Constructing more informative plant–pollinator networks: visitation and pollen deposition networks in a heathland plant community

Interaction networks are widely used as tools to understand plant–pollinator communities, and to examine potential threats to plant diversity and food security if the ecosystem service provided by pollinating animals declines. However, most networks to date are based on recording visits to flowers, rather than recording clearly defined effective pollination events. Here we provide the first networks that explicitly incorporate measures of pollinator effectiveness (PE) from pollen deposition on stigmas per visit, and pollinator importance (PI) as the product of PE and visit frequency. These more informative networks, here produced for a low diversity heathland habitat, reveal that plant–pollinator interactions are more specialized than shown in most previous studies. At the studied site, the specialization index was lower for the visitation network than the PE network, which was in turn lower than for the PI network. Our study shows that collecting PE data is feasible for community-level studies in low diversity communities and that including information about PE can change the structure of interaction networks. This could have important consequences for our understanding of threats to pollination systems.     

Severe pollen limitation in populations of the New Zealand shrub Alseuosmia macrophylla (Alseuosmiaceae) can be attributed to the loss of pollinating bird species

The loss of bird species following human colonization of New Zealand has raised concerns about the consequences for crucial ecosystem functions such as pollination. The understorey shrub Alseuosmia macrophylla (Alseuosmiaceae) exhibits characteristics typical of a bird pollination syndrome, but populations still persist in northern North Island forest remnants despite the local extinction of most endemic bird pollinators, leading to the suggestion that moths – rather than birds – may be the primary pollinators. The aim of this study was to quantify the importance of endemic birds as pollinators of A. macrophylla over several years by comparing plants on Little Barrier Island (LBI), where all extant endemic bird pollinators still occur, to plants at sites on the adjacent North Island in the Waitakere Ranges (WTK), where only one of these species remains common. Flowers on LBI were visited by endemic bellbirds (Anthornis melanura) and stitchbirds (Notiomystis cincta), while at WTK sites the most common visitors were the recently arrived silvereye (Zosterops lateralis) and the introduced honeybee (Apis mellifera), both of which acted principally as nectar robbers. Caged flowers on LBI had significantly lower fruit set than open flowers, and plants at WTK were significantly more pollen‐limited than plants on LBI. This provides evidence that the loss of endemic pollinating birds is the most likely reason for the high pollen limitation found in some North Island A. macrophylla populations, and the very low seed set of these populations could have serious implications for the long‐term persistence of this species.     

Pollination ecology and inbreeding depression control individual flowering phenologies and mixed mating

We analyze evolution of individual flowering phenologies by combining an ecological model of pollinator behavior with a genetic model of inbreeding depression for plant viability. The flowering phenology of a plant genotype determines its expected daily floral display which, together with pollinator behavior, governs the population rate of geitonogamous selfing (fertilization among flowers on the same plant). Pollinators select plant phenologies in two ways: they are more likely to visit plants displaying more flowers per day, and they influence geitonogamous selfing and consequent inbreeding depression via their abundance, foraging behavior, and pollen carry‐over among flowers on a plant. Our model predicts two types of equilibria at stable intermediate selfing rates for a wide range of pollinator behaviors and pollen transfer parameters. Edge equilibria occur at maximal or minimal selfing rates and are constrained by pollinators. Internal equilibria occur between edge equilibria and are determined by a trade‐off between pollinator attraction to large floral displays and avoidance of inbreeding depression due to selfing. We conclude that unavoidable geitonogamous selfing generated by pollinator behavior can contribute to the common occurrence of stable mixed mating in plants.     

Effectiveness of short‐tongued bees as pollinators of apparently ornithophilous New Zealand mistletoes

Abstract The flowers of two species of threatened New Zealand mistletoes (Peraxilla tetrapetala and Peraxilla colensoi, Loranthaceae) have explosive buds that do not open unless force is applied by birds or two species of native short‐tongued bees. Opened flowers are visited by a variety of birds and insects. Although both species of Peraxilla conform to a pollination syndrome of ornithophily, bees may be effective alternative pollinators. We investigated the effectiveness of bees and birds as pollinators of P. colensoi at one site and P. tetrapetala at two sites in the South Island. Bees and other insects outnumbered birds as flower visitors at all three sites. By excluding birds with wire cages, we showed that two bee species regularly open flowers of P. tetrapetala, but only rarely open flowers of P. colensoi. Few pollen grains were deposited when either birds or bees opened buds, so opening buds was not by itself sufficient for adequate pollination. Instead, pollen continued to accumulate over the next 6 or 7 days, even inside cages that excluded birds. Both populations of P. tetrapetala were regularly pollen‐limited, but in different ways. At Ohau, opened flowers gained enough pollen to produce seeds, but many buds were not opened and hence failed to set seed. In contrast, at Craigieburn, nearly all buds were opened, but many of these did not receive enough pollen. These results demonstrate that native bees can partially replace birds as pollinators of mistletoes, despite their apparent ornithophilous syndrome. Ongoing reductions in New Zealand forest bird numbers means that the service bees provide may be important for the long‐term future of these plants.     

Intraspecific divergence and convergence of floral tube length in specialized pollination interactions

Floral tubes are often thought to be a consequence of adaptive specialization towards pollinator morphology. We explore floral tube length evolution within Tritoniopsis revoluta (Iridaceae), a species with considerable geographical tube length variation. We ask whether tube lengths of T. revoluta populations are associated with pollinator proboscis lengths, whether floral divergence occurs in the presence of different pollinators and whether floral convergence occurs between distantly related populations pollinated by the same pollinator. Finally, we ask whether tube length evolution is directional. Shifts between morphologically different pollinators were always associated with shifts in floral morphology, even when populations were very closely related. Distantly related populations had similar tube lengths when they were pollinated by the same pollinator. Shifts in tube length tended to be from short to long, although reversals were not infrequent. After correcting for the population-level phylogeny, there was a strong positive, linear relationship between floral tube length and pollinator proboscis length, suggesting that plants are functionally specialized on different pollinators at different sites. However, because tube length evolution in this system can be a bidirectional process, specialization to the local pollinator fauna is unlikely to result in evolutionary or ecological dead-ends such as canalization or range limitation.     

PARENTAL FREQUENCIES AND SPATIAL CONFIGURATION SHAPE BUMBLEBEE BEHAVIOR AND FLORAL ISOLATION IN HYBRIDIZING RHINANTHUS

To shed light on the role played by pollinators in the diversification of angiosperms, focus is needed on how floral isolation varies locally in the early stages of plant divergence. The few studies performed so far have often used species pairs with distinct pollination syndromes and contrasting floral displays. Here, we focus on a hybridizing pair (Rhinanthus minor and Rhinanthus angustifolius) with strong similarities in flower morphology and pollinators (bumblebees). We examined how ethological isolation changes locally in relation to relative Rhinanthus frequencies, spatial configurations, and pollinator assemblages. Interestingly, floral divergence based on adaptation to different pollinators is unlikely in Rhinanthus: no relationship was found between floral isolation and the local pollinator assemblage. In contrast, species frequency and spatial arrangement strongly influenced bumblebee behavior, ethological isolation, and thus potentially hybrid formation. When both Rhinanthus were present in equal proportions, bees generally preferred the more rewarding and conspicuous species. However, when the Rhinanthus frequencies were unbalanced, the more abundant species was preferred, although this was less pronounced when the less rewarding R. minor predominated. Ethological isolation is highly sensitive to site characteristics, and can be as high as in species with contrasting floral displays and pollinator suites, even though flowers are similar.     

Diversity and Distribution of Floral Resources Influence the Restoration of Plant–Pollinator Networks on a Reclaimed Strip Mine

Plant–pollinator mutualisms are one of the several functional relationships that must be reinstated to ensure the long‐term success of habitat restoration projects. These mutualisms are unlikely to reinstate themselves until all of the resource requirements of pollinators have been met. By meeting these requirements, projects can improve their long‐term success. We hypothesized that pollinator assemblage and structure and stability of plant–pollinator networks depend both on aspects of the surrounding landscape and of the restoration effort itself. We predicted that pollinator species diversity and network stability would be negatively associated with distance from remnant habitat, but that local floral diversity might rescue pollinator diversity and network stability in locations distant from the remnant. We created plots of native prairie on a reclaimed strip mine in central Ohio, U.S.A. that ranged in floral diversity and isolation from the remnant habitat. We found that the pollinator diversity declined with distance from the remnant habitat. Furthermore, reduced pollinator diversity in low floral diversity plots far from the remnant habitat was associated with loss of network stability. High floral diversity, however, compensated for losses in pollinator diversity in plots far from the remnant habitat through the attraction of generalist pollinators. Generalist pollinators increased network connectance and plant‐niche overlap. As a result, network robustness of high floral diversity plots was independent of isolation. We conclude that the aspects of the restoration effort itself, such as floral community composition, can be successfully tailored to incorporate the restoration of pollinators and improve success given a particular landscape context.     

Relative effectiveness of insects versus hummingbirds as pollinators of Rubiaceae plants across elevation in Dominica,Caribbean

• Most angiosperms rely on animal pollination for reproduction, but the dependence on specific pollinator groups varies greatly between species and localities. Notably, such dependence may be influenced by both floral traits and environmental conditions. Despite its importance, their joint contribution has rarely been studied at the assemblage level.
• At two elevations on the Caribbean island of Dominica, we measured the floral traits and the relative contributions of insects versus hummingbirds as pollinators of plants in the Rubiaceae family. Pollinator importance was measured as visitation rate (VR) and single visit pollen deposition (SVD), which were combined to assess overall pollinator effectiveness (PE).
• In the wet and cool Dominican highland, we found that hummingbirds were relatively more frequent and effective pollinators than insects, whereas insects and hummingbirds were equally frequent and effective pollinators at the warmer and less rainy midelevation. Furthermore, floral traits correlated independently of environment with the relative importance of pollinators, hummingbirds being more important in plant species having flowers with long and wide corollas producing higher volumes of dilute nectar.
• Our findings show that both environmental conditions and floral traits influence whether insects or hummingbirds are the most important pollinators of plants in the Rubiaceae family, highlighting the complexity of plant–pollinator systems.

     

The effects of landscape on bumblebees to ensure crop pollination in the highland agricultural ecosystems in China

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.     

野生蜜蜂及其传粉作用的研究现状

传粉是维持与提升生物多样性的重要生态过程。膜翅目蜜蜂总科昆虫是自然界中最重要的传粉者, 但对野生蜜蜂的研究一直以来非常薄弱, 如野生蜜蜂类群的资源调查、种类的准确鉴别、营巢生物学与传粉生物学研究等方面。目前, 生物多样性与保护生物学方面的工作越来越多地涉及野生蜜蜂与植物的相互关系, 地方植物区系与农林作物的传粉生物学基础研究与应用项目也引起重视。本文综述了国内外野生蜜蜂的研究现状, 期望从分类学、营巢生物学与传粉生物学等方面推动野生蜜蜂传粉在农林业生产实践中的应用。     

Food or sex; pollinator–prey conflict in carnivorous plants

Carnivorous plants potentially trap their own pollinators and it has been argued that considerable spatial separation of flowers and traps has evolved to protect pollinators. We investigated flower-trap separation of Drosera and Utricularia . Short Drosera had a greater element of floral–trap separation than tall Drosera . Such a relationship is unexpected for plants whose peduncles were evolved to protect their pollinators. Utricularia can not trap pollinators but this genus still produces exceptionally long peduncles. We propose that flower-trap separation evolved because carnivorous plants are often short and need to project their flowers well above ground level to make them more attractive to pollinators.     

Pollinator activity and pollination success of Medicago sativa L. in a natural and a managed population

Medicago sativa L. is an important cash crop in the arid region of northwest China. Pollinator activity is an essential aspect of pollination success, but the relationships between pollinator visitation rate and seed set still need further study of M. sativa. We investigated the following characteristics of M. sativa in natural and managed populations: floral traits, pollinator activity, and breeding system. Our results indicated the management could affect the number of flowers produced; however, there was no detectable effect on the seed set per flower. We found the percentage of seeds among pollinated flowers in the managed population was significantly higher than that in the natural population. Moreover, the increase in the proportion of pollinated flowers could significantly increase seed set per flower, and pollinator visitation rate was the important limiting factor for seed set in both populations. Andrena lebedevi Popov was found to be the most frequent pollinator in both populations. Outcrossing was dominant in the breeding system and insect pollination played an important role in outcrossing. Our study suggested that proper management (artificial selection) could promote pollination success of M. sativa.