Plant Pollinator Research Articles

The role of floral traits in community assembly processes at high elevations in the Himalayas

Abstract There is a common agreement that, to maximise our understanding of trait‐based community assembly, traits related to different organs should be considered as they relate to different ecological niche axes. Floral traits, in particular, have been suggested to play an important role in the plant community assembly along with environmental gradients as they determine reproductive success, one of the key functions in plants. However, the role of floral traits in community assembly research remains largely unverified empirically. Using a large and novel dataset on plant traits and plant communities, we analysed the variability of six floral traits of 139 herbaceous species in 21 sites located along an elevation gradient (2000–4000 m) in the western Himalayas. The variability of floral traits along the gradient was analysed using community‐weighted mean (CWM) trait values and functional diversities (FDs) calculated for each study community. The CWMs showed that with increasing elevation, flowering began later, and flowers tended to be larger with decreasing specific flower area (SFA). Along with the convergence in the onset of flowering and SFA (i.e. lower FD at high‐elevation sites), these patterns suggest that abiotic filtering and plant–pollinator interactions could affect the floral trait composition of the communities. Most likely, increasing low‐temperature stress towards high‐elevation sites selected for late‐flowering species that produce flowers with larger display areas. The low abundance and activity of pollinators at high elevation could also explain why these traits were selected in the communities studied. Delayed flowering with increasing elevation might facilitate the phenological overlap of plants and their pollinators, as pollinator activity at higher elevation peaks in the second half of the vegetation period. The dominance of a species with low SFA and larger display area in high‐altitude communities could be attributable to increased flower longevity and attraction of pollinators, respectively, to maximise pollination success under pollinator scarcity. Synthesis. Our study provides empirical support for the recent argument that floral traits contribute considerably to the assembly of plant communities along environmental gradients. Thus, such traits should be included in community assembly research as they represent key ecological functions for reproduction.

Complexity of plant–pollinator interaction networks in East African high‐elevation wetlands

AbstractFor six selected Afromontane wetlands in Volcanoes National Park (VNP), Rwanda, located at varying elevations, we present preliminary insights into the pollination biology of six selected plant species. We found bees and flies to be particularly common flower visitors across plants and wetlands, followed by five species of birds, beetles, butterflies, and moths. We observed no obvious elevational trends in visitation rates, but pollinator specialisation did seem to vary across both plant species and wetlands. We provide insights into a partial pollinator network as a baseline reference for further studies or monitoring efforts of plant–pollinator interaction patterns and processes.

Proximity to oilseed rape fields affects plant pollination and pollinator-mediated selection on a co-flowering plant on the Tibetan Plateau.

The ecological effects of mass-flowering crops on pollinator abundance and species richness of neighbouring habitats are well established, yet the potential evolutionary consequences remain unclear. We studied effects of proximity to a mass-flowering crop on the pollination of local co-flowering plants and on patterns of natural selection on a pollination-generalised plant on the Tibetan Plateau. We recorded pollinator visitation rates and community composition at different distances (near vs. far) to oilseed rape (Brassica napus) fields in two habitat types and quantified pollinator-mediated selection on attractive traits of Trollius ranunculoides. The proximity to oilseed rape increased pollinator visitation in neighbouring alpine meadows and changed pollinator composition in neighbouring shrub meadows. Trollius ranunculoides in the alpine meadow near oilseed rape received three times more pollinator visits (mainly bees) and consequently had a 16.5% increase in seed set but also received slightly more heterospecific pollen per stigma. In contrast, pollinator visitation to T. ranunculoides in the shrub meadow near oilseed rape was three times lower (mainly flies), leading to a 10.7% lower seed despite no effect on pollen deposition. The proximity to the oilseed rape field intensified pollinator-mediated selection on flower size and weakened selection on flower height of T. ranunculoides in the alpine meadow but did not affect phenotypic selection on either trait in the shrub meadow. Our study highlights context-dependent variation in plant-pollinator interactions close to mass-flowering oilseed rape, suggesting potential effects on the evolution of flower traits of native plants through altered pollinator-mediated selection. However, context dependence may make these effects difficult to predict.

The power of sister crops: intercropping courgette and common bean changes floral morphology and increases diversity of flower visitors

ABSTRACT Acknowledging species interactions is essential for managing diversity in complex agricultural systems. To understand the neighbouring plant effect on flower number and size, we performed a greenhouse experiment with paired pots in three treatments: focal plant (common bean/courgette) with conspecific neighbour, heterospecific neighbour or empty pot. Common beans without neighbours produced more flowers than when accompanied. Common bean with conspecific neighbours produced more flowers than with heterospecific neighbours, with larger standard petals. Courgettes with heterospecific neighbours had flowers with deeper corollas than with conspecific neighbours. To understand effects on visitation and production, we performed a field experiment comparing courgette monoculture, common bean monoculture and three intercroppings, varying the crop ratio. Species composition of floral visitors differed significantly between monoculture and intercropping. The six plots (6/21) with highest diversity were intercropping. Intercropping courgette and common bean can change floral morphology and alter plant–pollinator interactions in the agroecosystem, enhancing pollinator diversity.

Importance of honey bee in cherry species pollination (Kocaeli/Turkey)

This study was carried out in 3 gardens determined in Başiskele, Körfez and Karamürsel districts of Kocaeli province in 2017-2018. A cherry tree was caged and covered with a 4 mm x 4 mm perforated net before flowering to prevent the penetration of honey bees. Before the beginning of flowering, a honey bee colony was placed in 4 decares in each garden and the net was removed at the end of the flowering period. As a result of our study in two field of application gardens aged 10 and 20 (with Ziraat 900 cherry varieties), it was determined that the approximate yield of the caged tree was 1.5 kg in the garden where the bee colony was placed, whereas the other cherry trees which were not caged yielded approximately 50 kg per tree in the same garden. As a result of the study in our third field of application garden aged 7 (with Regina cherry variety), it was determined that the approximate yield of the caged tree was 2.5 kg in the garden where the bee colony was placed, whereas the other cherry trees which were not caged yielded approximately 30-35 kg per tree in the same garden. This situation concretely shows that dependency on honey bee in cherry pollination is even higher than 90%. Consequently, flowers need bees for pollination and bees need flowers for nutrition. The use of honey bees in the pollination of cherry plant should be made widespread.

Economic Benefits of Using Essential Oils in Food Stimulation Administrated to Bee Colonies

Bees are the most important pollinators of agricultural plants. The decline of bee colonies is caused by a multitude of factors of which diseases, pesticides, and climate change seem to be the most important. Losses can be huge when several factors act together. In recent years, there has been a growing interest in the use of alternative sources such as medicinal plants in the form of extracts or essential oils. The purpose of our research was to evaluate the economic efficiency of the use of essential oils of basil (Ocimum basilicum), cinnamon (Cinnamomum veruum), clove (Syzgium aromaticum), juniper (Juniperus communis L.), oregano (Oreganum vulgare), mint (Mentha piperita), rosemary (Rosmarius officinalis), and thyme (Thymus vulgaris L.) in the additional feeding of bee colonies in the spring. Ninety colonies of Apis mellifera bees were used, which were additionally fed with sugar syrup and one of the essential oils. Our results showed strong positive correlations between the total number of germs in the gut of worker bees and the number of brood cells when using the essential oil of oregano (Oreganum vulgare) (R2 = 0.786) and thyme (Thymus vulgaris L.) (R2 = 0.729), and between the total number of germs and the yield of honey obtained at the first harvest in the case of the essential oil of basil (Ocimum basilicum) (R2 = 1), mint (Mentha piperita) (R2 = 0.718), oregano (Oreganum vulgare) (R2 = 0.621), and Thyme (Thymus vulgaris L) (R2 = 0.859). The best profit from the sale of honey was obtained in the case of the use of essential oils of mint, oregano, thyme, and basil, in a range of EUR 139.16–144.73/bee colony.

Honeys from Patagonia revealed notable pesticide residues in small-scale agricultural landscapes in the past decade

Bees are major pollinators of wild and cultivated plants. Pesticides have been pointed out as a major driver of wild bee declines and of notorious honey bee colony losses, with high pesticide inputs frequently linked to large-scale agriculture. We explored the presence of pesticide residues in Apis mellifera honeys from a region characterised by small-scale agriculture in North-western Patagonia, Argentina in 2014. We compared Argentine and European Union (EU) regulations for pesticide residues found, and investigated the correlation with the botanical diversity of honey palynological spectrum. We identified residues of four pesticides in seven out of ten samples (the organophosphates Chlorpyrifos-ethyl, Pirimiphos-methyl and Dichlorvos, and the pyrethroid Cypermethrin); with concentrations higher than the maximum residue levels allowed in honey by UE. We found moderate evidence that the number of pesticides in honey correlated negatively with the diversity of pollen spectrum. Our results suggest risks due to pesticides to pollinators and human health also in small-scale agricultural areas. We highlight the need of strengthen regulations and controls in Argentina and Latin America regarding pesticide use in agriculture and pesticide residues in honey.

Does Reproductive Success in Natural and Anthropogenic Populations of Generalist Epipactis helleborine Depend on Flower Morphology and Nectar Composition?

The purpose of our study was to determine the role of flower structure and nectar composition in shaping the reproductive success (RS) of the generalist orchid Epipactis helleborine in natural and anthropogenic populations. We supposed that the distinct character of two groups of habitats creates different conditions for plant-pollinator relationships, thus influencing reproductive success in E. helleborine populations. Both pollinaria removal (PR) and fruiting (FRS) were differentiated between the populations. On average, FRS was almost two times higher in the anthropogenic than in the natural populations. The difference between the two population groups in PR was smaller but still statistically significant. RS parameters were correlated with some floral display and flower traits. Floral display influenced RS only in three anthropogenic populations. Flower traits had a weak influence on RS (10 of the 192 cases analyzed). The more important trait in shaping RS was nectar chemistry. The nectar of E. helleborine is relatively diluted with a lower sugar concentration in the anthropogenic than in the natural populations. In the natural populations, domination of sucrose over hexoses was found, while in the anthropogenic populations, hexoses were more abundant and the participation of sugars was balanced. In some populations, sugars influenced RS. In E. helleborine nectar, 20 proteogenic and 7 non-proteogenic amino acids (AAs) were found with a clear domination of glutamic acid. We noted relationships between some AAs and RS, but distinct AAs shaped RS in different populations, and their impact was independent of their participation. Our results indicate that the flower structure and nectar composition of E. helleborine reflect its generalistic character and meet the requirements of a wide range of pollinators. Simultaneously, the differentiation of flower traits suggests a variation in pollinator assemblages in particular populations. Knowledge about the factors influencing RS in distinct habitats helps to understand the evolutionary potential of species and to understand mechanisms and processes crucial for shaping interactions between plants and pollinators.

Transient dynamics in plant–pollinator networks: fewer but higher quality of pollinator visits determines plant invasion success

Invasive plants often use mutualisms to establish in their new habitats and tend to be visited by resident pollinators similarly or more frequently than native plants. The quality and resulting reproductive success of those visits, however, have rarely been studied in a network context. Here, we use a dynamic model to evaluate the invasion success and impacts on natives of various types of non‐native plant species introduced into thousands of plant–pollinator networks of varying structure. We found that network structure properties did not predict invasion success, but non‐native traits and interactions did. Specifically, non‐native plants producing high amounts of floral rewards but visited by few pollinators at the moment of their introduction were the only plant species able to invade the networks. This result is determined by the transient dynamics occurring right after the plant introduction. Successful invasions increased the abundance of pollinators that visited the invader, but the reallocation of the pollinators' foraging effort from native plants to the invader reduced the quantity and quality of visits received by native plants and made the networks slightly more modular and nested. The positive and negative effects of the invader on pollinator and plant abundance, respectively, were buffered by plant richness. Our results call for evaluating the impact of invasive plants not only on visitation rates and network structure, but also on processes beyond pollination including seed production and recruitment of native plants.

The interplay between spatiotemporal overlap and morphology as determinants of microstructure suggests no ‘perfect fit’ in a bat-flower network

Plant–pollinator interactions in diverse tropical communities are often predicted by a combination of ecological variables, yet the interaction drivers between flower-visiting bats and plants at the community level are poorly understood. We assembled a network between Neotropical bats and flowering plants to describe its macrostructure and to test the role of neutral and niche variables in predicting microstructure. We found a moderately generalized network with internally nested modules comprising functionally similar plant and bat species. Modules grouped bats and plants with matching degrees of specialization but had considerable overlap in species morphologies and several inter-module interactions. The spatiotemporal overlap between species, closely followed by morphology, and not abundance, were the best predictors of microstructure, with functional groups of bats also interacting more frequently with plants in certain vegetation types (e.g., frugivores within forests) and seasons (e.g., long-snouted nectarivores in the dry season). Therefore, flower-visiting bats appear to have species-specific niche spaces delimited not only by their ability to exploit certain flower types but also by preferred foraging habitats and the timing of resource availability. The prominent role of resource dissimilarity across vegetation types and seasons likely reflects the heterogeneity of Neotropical savannas, and further research in biomes beyond the Cerrado is needed to better understand the complexity of this system.

The degree of urbanisation reduces wild bee and butterfly diversity and alters the patterns of flower-visitation in urban dry grasslands

Insect-provided pollination services are increasingly threatened due to alarming declines in insect pollinator populations. One of the main threats to insect pollinators and consequently pollination is urbanisation. Here, we investigate the effects of local habitat quality (patch size, flowering plant richness, bare soil cover, vegetation structure), degree of urbanisation (impervious surfaces) and 3D connectivity on bee, hoverfly and butterfly flower visitors and plant-flower visitor networks in flower-rich urban dry grasslands. Overall, the degree of urbanisation and the quality of the local habitat influenced the flowering plant and pollinator communities. Although flowering plant abundance increased with urbanisation, bee species richness and butterfly species richness decreased with increasing impervious surfaces. Flowering plant richness and ground nesting resource availability were positively related to bee richness and local vegetation structure boosted hoverfly and butterfly visitation rates. In terms of plant–pollinator interactions, insect pollinators visited a lower proportion of the available flowering plants in more urbanised areas and network modularity and specialisation increased with patch size. Our findings show that urban dry grasslands are valuable habitats for species-rich pollinator communities and further highlight the importance of minimizing the intensity of urbanisation and the potential of local management practices to support insect biodiversity in cities.

Climate mediates roles of pollinator species in plant–pollinator networks

AbstractAimUnderstanding how climate conditions influence plant–pollinator interactions at the global scale is crucial to understand how pollinator communities and ecosystem function respond to environmental change. Here, we investigate whether climate drives differences in network roles of the main insect pollinator orders: Diptera, Coleoptera, Lepidoptera and Hymenoptera.LocationGlobal.Time period1968–2020.Major taxa studiedDiptera, Coleoptera, Lepidoptera and Hymenoptera.MethodsWe collated plant–pollinator networks from 26 countries and territories across the five main Köppen–Geiger climate zones. In total, we compiled data from 101 networks that included >1500 plant species from 167 families and >2800 pollinator species from 163 families. We assessed differences in the composition of plant–pollinator interactions among climate zones using a permutational ANOVA. We calculated standard network metrics for pollinator taxonomic groups and used Bayesian generalized mixed models to test whether climate zone influenced the proportion of pollinator network links and the level of pollinator generalism.ResultsWe found that climate is a strong driver of compositional dissimilarities between plant–pollinator interactions. Relative to other taxa, bees and flies made up the greatest proportion of network links across climate zones. When network size was accounted for, bees were the most generalist pollinator group in the tropics, whereas non‐bee Hymenoptera were the most generalist in arid zones, and syrphid flies were the most generalist in polar networks.Main conclusionsWe provide empirical evidence at the global scale that climate strongly influences the roles of different pollinator taxa within networks. Importantly, non‐bee taxa, particularly flies, play central network roles across most climate zones, despite often being overlooked in pollination research and conservation. Our results identify the need for greater understanding of how global environmental change affects plant–pollinator interactions.

Ресурсный потенциал медоносных растений степного Придонья

Melliferous lands comprise the categories of forest fund lands, where melliferous plants and plants that provide high pollen yield grow. Bees pollinating entomophilous plants are 6–10 times more beneficial to forest lands compared to the favours from productive honey flows. The research objectives included identifying the features of the ecological and biological characteristics of melliferous plants of the Fabacea family, specifying the onset, duration and intensity of flowering, determining the sugar content in the nectar of one flower and honey productivity in the steppe Don region. Registration plots were laid out by the route method for the assessment of melliferous resources and determination of the resource potential of forest lands. Necessary observations, registration work, mathematical and statistical data processing were carried out according to the generally accepted methods. The territory of the steppe Don region, where the forest fund lands of the Rostov region are located, has favorable weather conditions and a rich forage base for bees. Тhe honey potential of the studied resources is a dynamic indicator and is of interest both for forest beekeeping and for scientific research. We used the sums of effective temperatures to determine the flowering sequence and characteristics of melliferous plants. The dwarf Russian almond blossoms first among arboreal melliferous plants of the legume family, while the Japanese pagoda tree blossoms last in the middle of the summer honey flow period. Black locust forest stands (497 kg/ha), lands dominated by Japanese pagoda tree (484 kg/ha) and honey locust (245 kg/ha) have the highest honey productivity. The research results showed that the black locust plantations with a bioresource potential of 7111.29 ton in the eastern and central areas of the region are significant for honey flow on the forest fund lands. Forest lands with predominance of spring melliferous plants of boxthorn and dwarf Russian almond on non-forest lands of the forest fund provide a supporting honey flow with a bioresource potential of 2749.168 ton. The studies that were carried out are of practical importance and will allow determining the resource potential of forest lands for honey flow more accurately in the future. In case of a high level of forestry and beekeeping practices, even under adverse weather conditions during nectar harvesting, it will be possible to obtain a productive honey flow, while ensuring timely and effective pollination of forest plants.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Secondary pollinators contribute to reproductive success of a pink-flowered sand verbena population.

Nationwide Screening for Bee Viruses in Apis mellifera Colonies in Egypt

Honey bees are essential for crop and wild plant pollination. However, many countries have reported high annual colony losses caused by multiple possible stressors. Diseases, particularly those caused by viruses, are a major cause of colony losses. However, little is known about the prevalence of honey bee pathogens, particularly virus prevalence, in Egyptian honey bees. To address this shortfall, we determined the prevalence of widespread bee viruses in honey bee colonies in Egypt-whether it is affected by geography, the season, or infestation with Varroa destructor (varroa) mites. Honey bee worker samples were collected from 18 geographical regions across Egypt during two seasons: winter and summer of 2021. Three apiaries were chosen in each region, and a pooled sample of 150 worker bees was collected from five colonies in each apiary then screened by qPCR for 10 viral targets: acute bee paralysis virus (ABPV), black queen cell virus (BQCV), chronic bee paralysis virus (CBPV), deformed wing virus (DWV) genotypes A (DWV-A), B (DWV-B) and D (Egyptian bee virus), Israeli acute paralysis virus (IAPV), Kashmir bee virus (KBV), sacbrood virus (SBV), and slow bee paralysis virus (SBPV). Our results revealed that DWV-A was the most prevalent virus, followed by BQCV and ABPV; the DWV genotype now spreading across the world, DWV-B, was not detected. There was no difference in varroa infestation rates as well as virus prevalence between winter and summer. However, colonies infected with BQCV had a significantly higher varroa count (adjusted p < 0.05) in the winter season, indicating that there is a seasonal association between the intensity of infestation by varroa and the presence of this virus. We provide data on the current virus prevalence in Egypt, which could assist in the protection of Egypt's beekeeping industry. Moreover, our study aids in the systematic assessment of the global honey bee virome by filling a knowledge gap about the prevalence of honey bee viruses in Egypt.

Conservation measures or hotspots of disease transmission? Agri-environment schemes can reduce disease prevalence in pollinator communities.

Insects are under pressure from agricultural intensification. To protect pollinators, conservation measures such as the EU agri-environment schemes (AES) promote planting wildflowers along fields. However, this can potentially alter disease ecology by serving as transmission hubs or by diluting infections. We tested this by measuring plant-pollinator interactions and virus infections (DWV-A, DWV-B and ABPV) across pollinator communities in agricultural landscapes over a year. AES had a direct effect on DWV-B, reducing prevalence and load in honeybees, with a tentative general dilution effect on load in early summer. DWV-A prevalence was reduced both under AES and with increasing niche overlap between competent hosts, likely via a dilution effect. By contrast, AES had no impact on ABPV, its prevalence driven by the proportion of bumblebees in the community. Epidemiological differences were also reflected in the virus phylogenies, with DWV-B showing recent rapid expansion, while DWV-A and ABPV showed slower growth rates and geographical population structure. Phylogenies indicate that all three viruses freely circulate across their host populations. Our study illustrates how complex interactions between environmental, ecological and evolutionary factors may influence wildlife disease dynamics. Supporting pollinator nutrition can mitigate the transmission of important bee diseases, providing an unexpected boost to pollinator conservation. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.

The non-random assembly of network motifs in plant-pollinator networks.

Ecological processes leave distinct structural imprints on the species interactions that shape the topology of animal-plant mutualistic networks. Detecting how direct and indirect interactions between animals and plants are organised is not trivial since they go beyond pairwise interactions, but may get blurred when considering global network descriptors. Recent work has shown that the meso-scale, the intermediate level of network complexity between the species and the global network, can capture this important information. The meso-scale describes network subgraphs representing patterns of direct and indirect interactions between a small number of species, and when these network subgraphs differ statistically from a benchmark, they are often referred to as 'network motifs'. Although motifs can capture relevant ecological information of species interactions, they remain overlooked in natural plant-pollinator networks. By exploring 60 empirical plant-pollinator networks from 18 different studies with wide geographical coverage, we show that some network subgraphs are consistently under- or over-represented, suggesting the presence of worldwide network motifs in plant-pollinator networks. In addition, we found a higher proportion of densely connected network subgraphs that, based on previous findings, could reflect that species relative abundances are the main driver shaping the structure of the meso-scale on plant-pollinator communities. Moreover, we found that distinct subgraph positions describing species ecological roles (e.g. generalisation and number of indirect interactions) are occupied by different groups of animal and plant species representing their main life-history strategies (i.e. functional groups). For instance, we found that the functional group of 'bees' was over-represented in subgraph positions with a lower number of indirect interactions in contrast to the rest of floral visitors groups. Finally, we show that the observed functional group combinations within a subgraph cannot be retrieved from their expected probabilities (i.e. joint probability distributions), indicating that plant and floral visitor associations within subgraphs are not random either. Our results highlight the presence of common network motifs in plant-pollinator communities that are formed by a non-random association of plants and floral visitors functional groups.

Prevalence of honey bee pathogens and parasites in South Korea: A five-year surveillance study from 2017 to 2021

Honey bees play an important role in the pollination of crops and wild plants and provide important products to humans. Pathogens and parasites are the main factors that threaten beekeeping in South Korea. Therefore, a nationwide detection of 14 honey bee pathogens, including parasites (phorid flies, Nosema ceranae, and Acarapis woodi mites), viruses, bacteria, and fungal pathogens, was conducted from 2017 to 2021 in the country. The infection rate and the trend of detection of each pathogenic agent were determined. A total of 830 honey bee samples from Apis cerana (n = 357) and A. mellifera (n = 473) were examined. N. ceranae (35.53%), deformed wing virus (52.63%), sacbrood virus (SBV) (52.63%), and black queen cell virus (55.26%) were the most prevalent honey bee pathogens, and their prevalence rapidly increased from 2017 to 2021. The prevalence of Paenibacillus larvae, Israeli acute paralysis virus, Ascosphaera apis, A. woodi, Melissococcus plutonius, and chronic bee paralysis virus remained stable during the surveillance period, with infection rates ranging from 5.26% to 16.45% in 2021. Other pathogens, including acute bee paralysis virus, phorid flies, Kashmir bee virus, and Aspergillus flavus, had low infection rates that gradually declined during the detection period. The occurrence of honeybee pathogens peaked in July. SBV was the most common pathogen in A. cerana, whereas N. ceranae was predominant in A. mellifera. This study provides information regarding the current status of honey bee pathogens and presents the trend of the occurrence of each pathogen in South Korea. These data are important for predicting outbreaks of honey bee diseases in the country.

Rising temperature drives tipping points in mutualistic networks.

The effect of climate warming on species' physiological parameters, including growth rate, mortality rate and handling time, is well established from empirical data. However, with an alarming rise in global temperature more than ever, predicting the interactive influence of these changes on mutualistic communities remains uncertain. Using 139 real plant-pollinator networks sampled across the globe and a modelling approach, we study the impact of species' individual thermal responses on mutualistic communities. We show that at low mutualistic strength plant-pollinator networks are at potential risk of rapid transitions at higher temperatures. Evidently, generalist species play a critical role in guiding tipping points in mutualistic networks. Further, we derive stability criteria for the networks in a range of temperatures using a two-dimensional reduced model. We identify network structures that can ascertain the delay of a community collapse. Until the end of this century, on account of increasing climate warming many real mutualistic networks are likely to be under the threat of sudden collapse, and we frame strategies to mitigate this. Together, our results indicate that knowing individual species' thermal responses and network structure can improve predictions for communities facing rapid transitions.

The effect of global warming on the Australian endemic orchid Cryptostylis leptochila and its pollinator.

Ecological stability together with the suitability of abiotic conditions are crucial for long-term survival of any organism and the maintenance of biodiversity and self-sustainable ecosystems relies on species interactions. By influencing resource availability plants affect the composition of plant communities and ultimately ecosystem functioning. Plant-animal interactions are very complex and include a variety of exploitative and mutualistic relationships. One of the most important mutualistic interactions is that between plants and their pollinators. Coevolution generates clustered links between plants and their pollen vectors, but the pollination and reproductive success of plants is reduced by increase in the specialization of plant-animal interactions. One of the most specialized types of pollination is sexual deception, which occurs almost exclusively in Orchidaceae. In this form of mimicry, male insects are attracted to orchid flowers by chemical compounds that resemble insect female sex pheromones and pollinate the flowers during attempted copulations. These interactions are often species-specific with each species of orchid attracting only males of one or very few closely related species of insects. For sexually deceptive orchids the presence of a particular pollen vector is crucial for reproductive success and any reduction in pollinator availability constitutes a threat to the orchid. Because global warming is rapidly becoming the greatest threat to all organisms by re-shaping the geographical ranges of plants, animals and fungi, this paper focuses on predicting the effect of global warming on Cryptostylis leptochila, a terrestrial endemic in eastern Australia that is pollinated exclusively via pseudo copulation with Lissopimpla excelsa. As a species with a single pollinator this orchid is a perfect model for studies on the effect of global warming on plants and their pollen vectors. According to our predictions, global warming will cause a significant loss of suitable niches for C. leptochila. The potential range of this orchid will be 36%-75% smaller than currently and as a result the Eastern Highlands will become unsuitable for C. leptochila. On the other hand, some new niches will become available for this species in Tasmania. Simultaneously, climate change will result in a substantial expansion of niches suitable for the pollinator (44-82%). Currently ca. 71% of the geographical range of the orchid is also suitable for L. excelsa, therefore, almost 30% of the areas occupied by C. leptochila already lack the pollen vector. The predicted availability of the pollen vector increased under three of the climate change scenarios analysed. The predicted habitat loss is a serious threat to this orchid even with the potential colonization of Tasmania by this plant. In the reduced range of C. leptochila the pollen vector will also be present assuring fruit set in populations of this orchid. The genetic pool of the populations in New South Wales and Queensland will probably be lost.