Threats to an ecosystem service: pressures on pollinators

Pollinating insects are the most important pollinators in nature; they pollinate vegetables, fruits, oil crops, and wild plants, so that crop yields can be increased, wild plants can live and reproduce, and human food security and ecosystem stability are maintained. To identify the pollination network of plants-insects and the pollination service value in Hanzhong City, the methods of random net capture and transect counting in field work were used. The agricultural statistical data from Hanzhong City in 2023 was combined in the analysis. The results showed that Hanzhong City is rich in pollinator resources, with a total of 80 species of pollinators and 59 species of pollinating crops and wild nectar plants. The abundant pollinator resources provide sufficient pollination services for the production of local vegetables, fruits, and oil crops. The characteristics of the pollination networks are obvious, showing the structural characteristics of low connectivity, medium nesting, and low network specialization. In 2023, the pollination service value of pollinators in Hanzhong City was CNY 3524-4878 billion, accounting for 10.02-13.87% of the city's agricultural output value of the year. Suggestions for the protection of pollinators in Hanzhong City: Reduce the use of pesticide, support beekeeping, intercrop nectar plants, and rationally plant crops.

Insect pollination constitutes an ecosystem service of global importance, providing significant economic and aesthetic benefits as well as cultural value to human society, alongside vital ecological processes in terrestrial ecosystems. It is therefore important to understand how insect pollinator populations and communities respond to rapidly changing environments if we are to maintain healthy and effective pollinator services. This chapter considers the importance of conserving pollinator diversity to maintain a suite of functional traits and provide a diverse set of pollinator services. We explore how we can better understand and mitigate the factors that threaten insect pollinator richness, placing our discussion within the context of populations in predominantly agricultural landscapes in addition to urban environments. We highlight a selection of important evidence gaps, with a number of complementary research steps that can be taken to better understand: (i) the stability of pollinator communities in different landscapes in order to provide diverse pollinator services; (ii) how we can study the drivers of population change to mitigate the effects and support stable sources of pollinator services and (iii) how we can manage habitats in complex landscapes to support insect pollinators and provide sustainable pollinator services for the future. We advocate a collaborative effort to gain higher quality abundance data to understand the stability of pollinator populations and predict future trends. In addition, for effective mitigation strategies to be adopted, researchers need to conduct rigorous field testing of outcomes under different landscape settings, acknowledge the needs of end-users when developing research proposals and consider effective methods of knowledge transfer to ensure effective uptake of actions.

Apple is one of the most widely cultivated fruit crops world‐wide, and apple yield benefits from pollination by insects. The global decline in wild pollinator populations raises concern about the adequacy of pollination services in apple production. Here, we present a global meta‐analysis of pollination in apple. We assembled from the literature a dataset comprising results of 48 studies across five continents on fruit set and seed set in apple with insect pollination, artificial pollination and pollinator exclusion, and analysed the effects of explanatory factors such as variety and continent. Fruit set was on average 41% lower with open pollination than with artificial pollination, while seed set was 20% lower. These pollination deficits varied across continents and cultivars. Pollination deficits for fruit set were greatest in Asia (63%) followed by Europe (30%), whereas pollination deficits for seed set were greatest in Asia (47%) and South America (40%). Important differences in pollination deficit were also identified between cultivars but these differences were confounded with continent effects. Fruit set and seed set were 71% and 62% higher, respectively, when insects had open access to flowers than when they were artificially excluded, while results varied among cultivars. Synthesis and applications. Globally, there are substantial contributions of pollinators to fruit set and seed set in apple, as well as considerable limitations in apple pollination services, particularly in Asia, Europe and South America. Several management strategies could be applied to reduce the pollination deficits in apple production: (1) conserving wild bees and enhancing their abundance and diversity, (2) using managed bees for pollination, (3) using varieties with low pollinator dependency and/or (4) artificial pollination. These strategies should be tailored to the regional situation, considering the potential of landscapes for restoring wild pollinators, the acceptability of cultivated varieties for available pollinators, the acceptance in the market of self‐compatible varieties and the costs of management, such as artificial pollination, pollinator conservation, beekeeping and planting self‐compatible varieties. Conservation of wild pollinators is preferred in regions with sufficient potential for wild pollinators as it contributes to biodiversity conservation and improves pollination in both crops and wild plants.

Insect pollination establishes an ecosystem service around the globe, providing compelling budgetary and creative profits along with developmental values to humans and vital eco-friendly measures for the environment. It is, therefore, essential to understand how insect pollinator populations and communities respond to rapidly changing environments if we are to maintain healthy and effective pollinator services. Although insect pollinators are known to provide ecosystem services to more than 80% of the world’s flowering plants (including cultivated crops), a steep decline (∼20–40%) in their population has created an alarming situation for global biodiversity. Threats to bee populations in recent years have increased awareness about the critical role of pollinators for life on earth, as pollinators are predicted to persist only when all animal-pollinated plant species persist. Additionally, increased usage of chemical pesticides may result in the collapse of pollinators which leads to a decrease in food resource density and also facilitates the increasing isolation of natural habitats. So, to overcome pollinators’ decline, joint efforts of all stakeholders are needed to increase their numbers on the planet. We have to cut down the use of synthetic pesticides, ban highly toxic pesticides, tackle problems related to colony collapse disorder (CCD), climate change, habitat loss and provide much-needed help to the native pollinator species to revive their natural habitats. So, this paper aims to focus on appreciating the services of insect pollinators and rescuing them from the threats leading to their extinctions which in turn will help in enhancing global food production.

Insect pollination is an important ecosystem process for increased agricultural crop yield as well as for enhancing ecosystem production. We analyzed insect pollinators visiting fruits and flowers in different orchards and wild fields across Korea during the last three decades, published in scientific journals in Korea. A total of 368 species in 115 families of 7 orders were recorded to serve as pollinators in 43 different agricultural crops and wild flowers. The most diverse insect pollinators were the species of Hymenoptera followed by Diptera and Coleoptera. The dominant insect pollinator was the honey bee (Apis melliferas) followed by Eristalis cerealis, Tetralonia nipponensis, Xylocopa appendiculata, Eristalis tenax, Helophilus virgatus and Artogeia rapae. Study methods employed for diversity of pollinators were mostly sweep netting, but trapping was mostly employed for bee diversity and direct observation for lepidopteran diversity. Bee diversity was higher in orchards while insect order level diversity was higher in wild plant pollinators, suggesting the important roles of wild flowers for conservation of insect pollinators.

Stingless bees are vital pollinators for both wild and crop plants, yet their communities have been affected and altered by anthropogenic land-use change. Additionally, few studies have directly addressed the consequences of land-use change for meliponines, and knowledge on how their communities change across gradients in surrounding landscape cover remains scarce. Here, we examine both how local and landscape-level compositions as well as forest proximity affect both meliponine species richness and abundance together with pollination networks across 30 mixed fruit orchards in Southern Thailand. The results reveal that most landscape-level factors significantly influenced both stingless bee richness and abundance. Surrounding forest cover has a strong positive direct effect on both factors, while agricultural and urbanized cover generally reduced both bee abundance and diversity. In the local habitat, there is a significant interaction between orchard size and floral richness with stingless bee richness. We also found that pollinator specialization in pollination networks decreased when the distance to the forest patch increased. Both local and landscape factors thus influenced meliponine assemblages, particularly the forest patches surrounding an orchard, which potentially act as a key reservoir for stingless bees and other pollinator taxa. Preservation of forest patches can protect the permanent nesting and foraging habitat of various pollinator taxa, resulting in high visitation for crop and wild plants.

Societal Impact StatementThe global decline in pollinating insect populations has rightly received widespread news coverage as it imperils ecosystem function and human food security. Reversing and addressing this decline is an urgent global priority. However, in many locations we do not know what species are present, how large or small species populations are, or what types of specific resources the populations require. By adopting novel network analyses approaches and by working with monitoring programs, such as Oxford Plan Bee, we may be able to dramatically improve our ability to predict species extinctions and facilitate targeted conservation action to maintain abundant, diverse and stable pollinator communities. Summary Pollination is fundamentally important to ecosystem function and human food security. Recent reports of dramatic insect declines, and pollinator decline in particular, have increased public awareness and political motivation to act to protect pollinators. This article maps commonly proposed management interventions onto known drivers of bee decline, and identifies forage and nest site provision as a tractable management intervention that can simultaneously address multiple drivers of decline. However, it is recognized that there are gaps in the knowledge of exactly how much and which types of forage resources are necessary to support wild pollinator populations. A novel network analysis approach based on quantified floral resources and pollination services is proposed, which would illuminate the types and quantities of floral resources and pollinators necessary to maintain a diverse and abundant plant–pollinator community. The approach would also facilitate the prediction of species extinctions in plant–pollinator communities and help target conservation interventions. Finally, Oxford Plan Bee is introduced as a new, citizen‐science‐based project to monitor solitary bee populations, and provide empirical data to validate predictions from the proposed network approach. The over‐arching aim of the described network analysis approach and the Oxford Plan Bee project is to facilitate effective, evidence‐based conservation action to protect pollinators and the plants they pollinate into the future.

Viruses constitute the largest group of emerging pathogens, and geminiviruses (plant viruses with circular, single-stranded DNA genomes) are the major group of emerging plant viruses. With their high potential for genetic variation due to mutation and recombination, their efficient spread by vectors, and their wide host range as a group, including both wild and cultivated hosts, geminiviruses are attractive models for the study of the evolutionary and ecological factors driving virus emergence. Studies on the epidemiological features of geminivirus diseases have traditionally focused primarily on crop plants. Nevertheless, knowledge of geminivirus infection in wild plants, and especially at the interface between wild and cultivated plants, is necessary to provide a complete view of their ecology, evolution, and emergence. In this review, we address the most relevant aspects of geminivirus variability and evolution in wild and crop plants and geminiviruses' potential to emerge in crops.

Despite the importance of insect pollination to produce marketable fruits, insect pollination management is limited by insufficient knowledge about key crop pollinator species. This lack of knowledge is due in part to (1) the extensive labour involved in collecting direct observations of pollen transport, (2) the variability of insect assemblages over space and time and (3) the possibility that pollinators may need access to wild plants as well as crop floral resources. We address these problems using strawberry in the United Kingdom as a case study. First, we compare two proxies for estimating pollinator importance: flower visits and pollen transport. Pollen‐transport data might provide a closer approximation of pollination service, but visitation data are less time‐consuming to collect. Second, we identify insect parameters that are associated with high importance as pollinators, estimated using each of the proxies above. Third, we estimated insects' use of wild plants as well as the strawberry crop. Overall, pollinator importances estimated based on easier‐to‐collect visitation data were strongly correlated with importances estimated based on pollen loads. Both frameworks suggest that bees (Apis and Bombus) and hoverflies (Eristalis) are likely to be key pollinators of strawberries, although visitation data underestimate the importance of bees. Moving beyond species identities, abundant, relatively specialised insects with long active periods are likely to provide more pollination services. Most insects visiting strawberry plants also carried pollen from wild plants, suggesting that pollinators need diverse floral resources. Identifying essential pollinators or pollinator parameters based on visitation data will reach the same general conclusions as those using pollen transport data, at least in monoculture crop systems. Managers may be able to enhance pollination service by preserving habitats surrounding crop fields to complement pollinators' diets and provide habitats for diverse life stages of wild pollinators.

Current research, management and outreach programmes relevant to insect pollinator conservation are strongly focused on relationships between pollinators and insect‐pollinated crops and wild plants. Pollinators also visit wind‐pollinated plants to collect pollen, or for nest sites and materials, but these interactions are largely overlooked. I review documented records of bee and syrphid fly species collecting pollen from wind‐pollinated plant taxa, including economically important crops, and provide the most comprehensive collation of peer‐reviewed records of pollinators visiting wind‐pollinated plants to date. I argue for more basic research into functional relationships between insect pollinators and wind‐pollinated plants. I found over 200 visitation records for 101 wind‐pollinated plant genera in 25 families, including 4 of the 12 gymnosperm families. Almost half the records (49%) were for grasses and sedges (Poales). I also identified records of bees and/or syrphid flies visiting 10 economically important wind‐pollinated crop plant species, including three major grain crops (rice, corn, and sorghum). Most records (70%) were from indirect pollen analysis from hives, nest cells or insect bodies, highlighting the need for more direct observational studies of plant–pollinator interactions. Insect pollinator communities require resource diversity to persist in a landscape. Hence, researchers and land managers aiming to identify links between pollinators and ecosystem function should also consider broader interactions beyond the standard traits of the entomophily syndrome.

Land degradation in agricultural farms is mainly manifested through loss of ecosystem services such as pollination. In Kenya, farmers knowledge of pollination is limited, many farmers lump pollinators together with insect pests and do not explicitly manage to conserve them, although pollinators may contribute substantially to yields at no cost to the farmer. Insect pollinators of crops and wild plants are threatened worldwide by pesticide use and the spread of disease and parasites. This research is multidisciplinary in approach, in this research niche theory and ecosystem functions concepts to determine the status of insect pollinators in agro-ecosystems of Mua Hills location were used. The aim of this research was to determine the diversity and abundance of pollinator insects for their role in ecosystem function (pollination) and increase of passion fruit yield. The diversity and abundance of insect pollinators was found to be least in horticultural land use type and this was attributed to the use of agro-chemicals. This research is an issue of environmental management because it focuses on natural patch land use type for sustainable use of agro-ecosystems to avoid decline of pollinators. It advocates for conservation of the environment and management of carpenter bee (Xylocopa spp) because it is an efficient pollinator of passion fruit thus makes farming more profitable through higher yield of the crop. The findings from this research are aimed to help the subsistence farmers achieve good produce in passion fruit farming. The study promotes the conservation of insect biodiversity within the existing land use types to improve pollination of horticultural crops.

Pollinator declines have prompted efforts to assess how land‐use change affects insect pollinators and pollination services in agricultural landscapes. Yet many tools to measure insect pollination services require substantial landscape‐scale data and technical expertise. In expert workshops, 3 straightforward methods (desk‐based method, field survey, and empirical manipulation with exclusion experiments) for rapid insect pollination assessment at site scale were developed to provide an adaptable framework that is accessible to nonspecialist with limited resources. These methods were designed for TESSA (Toolkit for Ecosystem Service Site‐Based Assessment) and allow comparative assessment of pollination services at a site of conservation interest and in its most plausible alternative state (e.g., converted to agricultural land). We applied the methods at a nature reserve in the United Kingdom to estimate the value of insect pollination services provided by the reserve. The economic value of pollination services provided by the reserve ranged from US$6163 to US$11,546/year. The conversion of the reserve to arable land would provide no insect pollination services and a net annual benefit from insect‐pollinated crop production of approximately $1542/year (US$24∙ha–1∙year–1). The methods had wide applicability and were readily adapted to different insect‐pollinated crops: rape (Brassica napus) and beans (Vicia faba) crops. All methods were rapidly employed under a low budget. The relatively less robust methods that required fewer resources yielded higher estimates of annual insect pollination benefit.

Assessment of the economic value of crop pollination by bees necessitates the need for conserving the insect pollinator diversity. A decline in the population of insect pollinators in ecosystems can result in a decrease in crop production, vegetation cover, an extinction of a number of plant species, and as a result the degradation of ecosystem services and health. The economic value of bee pollinators was determined based on the portion of the value of crops attributed to pollination by bees. This value was calculated based on the yield and the value of each crop, the dependency of each crop on bee pollinators and the proportion of wild native bee and honey bee pollinators. The economic value of crop pollination by bees was 6.59 billion dollars, of which, 5.72 billion dollars is attributable to the pollinators that are honey bees and 0.87 billion dollars is attributable to native bees. The value of the crops pollinated by bees was estimated to be 25% of the total value of crops. The value of crops pollinated by honey bees was 54 times the value of honey production by bees. Based on the economic value of bee pollinators, the use of organic farming techniques, the use of less toxic and highly selective pesticides and herbicides, construction of nest boxes for pollinators and introduction of a variety of native plant species can help to conserve high level of diversity of bee pollinator species and the pollination services.

Pollinating insects are not only important in wild plant pollination, but also in the production of a large number of crops. Oilseed rape production is increasing globally due to demands for biofuels which may have impacts on pollinating insects which visit the crop and on the pollination services delivered to co-flowering wild plants. In this study, we tested (1) the degree of pollinator sharing between oilseed rape and native wild plants in field margins and hedgerows and (2) the effects of oilseed rape on the quality of pollination service delivered to these wild plants. We found large overlap between flower visitors of wild plants and oilseed rape, but the composition of species overlap differed with respect to each wild plant species. Nearly all individual visitors caught on both the crop and foraging on wild species carried crop pollen, but more than half the insects also carried pollen from wild plants. However, very little oilseed rape pollen was deposited on wild plant stigmas. This shows that (1) oilseed rape overlaps in pollinator niche with most co-flowering wild plants, and (2) crop pollen deposition on wild plant stigmas is low which may indicate that it is unlikely to cause reductions in seed set of wild plants, although this was not measured here. Furthermore, wild plants in field margins and hedgerows are important sources of alternative forage for pollinating insects even when a crop is mass flowering, and we suggest maintenance and augmentation of field margins and hedgerows to provide alternative forage for pollinator conservation to continue provision of pollination services to both crops and wild plants.

Temperate agroforestry systems provide greater pollination service than monoculture