Pollination Services Research Articles

Future-proofing the pollination services to insect-pollinated crop production

Future-proofing the pollination services to insect-pollinated crop production

Effect of land-use intensity and adjacent semi-natural habitats on wild and honey bees of meadows

Most terrestrial ecosystems are shaped by the pollination service provided by insects, foremost bees. As bees are also important pollinators of crop plants, they are key for both the pollination of wild plants and for agricultural production. Meadows and semi-natural habitats (SNHs) are important habitats for bees. However, there is limited knowledge on how land-use intensity of meadows affects wild bees and managed Western honey bees. Further, it is unknown whether SNHs adjacent to meadows affect bees in meadows. Here, we examined in a landscape dominated by grasslands, the effects of land-use intensity (nitrogen input, grazing intensity, mowing frequency), flower availability and adjacent SNHs on bee communities in meadows. We recorded more than 5000 individuals of 87 species of bees and found no effect of land-use intensity on wild and honey bees. Flowering plant species richness had a positive effect on bee species richness in one study year. Though we recorded more bee species in SNHs than meadows, overall and specifically in ecologically specialized bee species (e.g. parasitic bees, oligoleges), the availability of adjacent SNHs did not affect bee abundance and richness in meadows. We discuss why land-use intensity and SNHs adjacent to meadows did not affect bees in meadows and conclude that SNHs are important in sustaining functionally diverse bee communities in landscapes dominated by grasslands.

Efecto de la contaminación atmosférica en los polinizadores del corredor industrial Guanajuato

In recent years, due to industrial activity, there has been an increase in pollutants, particularly ozone O3. The industrial corridor of the state of Guanajuato is not the exception, especially due to the various industries established in this corridor that covers the municipalities of Celaya, Salamanca, Irapuato, Silao and Leon. In the same way, this area is characterized by its agricultural activity with important crops, among which are those that need insects and animals for their pollination. The pollutants have shown negative effects on the emission of volatile organic compounds emitted by the flowers and, which fulfil pollinator attraction functions. In this review, we analyse the main pollutants and their negative effects on the pollination service performed by pollinators. This information points to the urgent need to consider air pollution as a negative factor in pollinator-mediated pollination service.

Parthenocarpic fruit quality and production under pollinator-exclusion in southern highbush blueberry

Parthenocarpy is the phenomenon of seedless fruit formation without fertilization. This trait has drawn the attention of many fruit and vegetable breeders due to its ability to overcome insufficient pollination and secure yield. Blueberry (Vaccinium spp.) maintains one of the highest pollination requirements of all crops, demanding growers invest in seasonal pollination services. Nevertheless, blueberry continues to suffer from suboptimal fruit set due to ineffective honeybee pollination, and adverse weather conditions during the brief bloom period. Therefore, developing parthenocarpic blueberry cultivars could provide an economical and effective way to ensure fruit set with decreased dependency on seasonal pollination services. However, the effects of parthenocarpy on berry quality and production-related traits in blueberry is unknown. Therefore, this study aims to evaluate these characteristics in 13 southern highbush blueberry genotypes under two pollination conditions (open-pollination and pollinator-exclusion cages). Open-pollinated and non-pollinated fruits from the 13 blueberry genotypes were assessed for seededness, firmness, size, sugar-to-acid ratio, fruit set, yield, week of peak harvest, and the duration of the fruit development period. Non-pollinated parthenocarpic fruits took longer to develop and tended to be smaller, sweeter, and less firm than open-pollinated fruits. Despite these differences, most parthenocarpic fruits still met market standards. Genotypic differences were also observed, suggesting the opportunity to select for enhanced parthenocarpy in future populations. The results of this study demonstrate that facultative parthenocarpy can be exploited and incorporated into blueberry breeding programs to ensure proper yield in inadequate pollination conditions.

Herbivory-induced effects on pollination services to undamaged neighboring flowering species

Herbivory-induced effects on pollination services to undamaged neighboring flowering species

Urbanisation and agricultural intensification modulate plant–pollinator network structure and robustness

Abstract Land use change is a major pressure on pollinator abundance, diversity and plant–pollinator interactions. Far less is known about how land‐use alters the structure of plant–pollinator networks and their robustness to plant–pollinator coextinctions. We analysed the structure of plant–pollinator networks sampled in 12 landscapes along an urbanisation and agricultural intensity gradient, from early spring to late summer 2021, and used a stochastic coextinction model to correlate plant–pollinator coextinction risk with network structure (species and network‐level metrics) and landscape context. Networks in intensively managed (i.e., agricultural and urban) landscapes had a lower risk of initiating a coextinction cascade, while networks in less intensively managed landscapes may be less robust. Network structure modulated the frequency and severity of coextinctions and species loss, while the strength of species interactions increased robustness. Urban networks were more species rich and symmetrical due to the high diversity of ornamental plants, while intensively managed agricultural landscapes had smaller, more tightly connected and nested networks. Network structure modulated the frequency of extinctions, which was decreased by greater linkage density, interaction asymmetry and interaction dependence in the networks, while once an extinction occurred, nestedness and linkage density propagated the degree of the coextinction cascade and species loss. At the species level, species strength was inversely correlated with extinction risk, implying that generalist species with a high number of interactions with specialists had the lowest extinction risk. An interplay between land‐use and network structure affects community robustness to coextinctions with implications for pollination services and plant reproduction. Land‐use change or other global change pressures by reorganising species interactions can alter communities and their potential functioning. Read the free Plain Language Summary for this article on the Journal blog.

Geographies of the pollinator commons

The problem of insect pollinator declines and pollination scarcity is impacting food production and ecosystem integrity worldwide. The term “pollinator commons” has often been invoked in existing literature, but there is little actual evidence of collective action to manage pollinators, pollination services or foraging resources. This may be due to the availability of a technical fix to the problem of pollination scarcity in some places, or the purported lack of awareness and undervaluation of pollination services. Given the increasing extent of the problem, there may be some conditions under which collective governance of the pollinator commons could emerge. We predict that collective action to manage a pollinator commons is more likely to emerge among farmers: (a) whose farms are small, and livelihoods are dependent on high-value crops for which wild pollination services cannot be easily substituted; (b) whose neighbors are similarly dependent on pollinator-dependent crops; and (c) who are able to make reasonable cost-benefit determinations based on information about other farmers and pollinator status. Geographers are particularly well-positioned with the theoretical and methodological tools to engage with this important, yet under-explored system to understand the potential for collective action to manage pollinators as a common pool resource.

Extreme heat reduces host and parasite performance in a butterfly-parasite interaction.

Environmental temperature fundamentally shapes insect physiology, fitness and interactions with parasites. Differential climate warming effects on host versus parasite biology could exacerbate or inhibit parasite transmission, with far-reaching implications for pollination services, biocontrol and human health. Here, we experimentally test how controlled temperatures influence multiple components of host and parasite fitness in monarch butterflies (Danaus plexippus) and their protozoan parasites Ophryocystis elektroscirrha. Using five constant-temperature treatments spanning 18-34°C, we measured monarch development, survival, size, immune function and parasite infection status and intensity. Monarch size and survival declined sharply at the hottest temperature (34°C), as did infection probability, suggesting that extreme heat decreases both host and parasite performance. The lack of infection at 34°C was not due to greater host immunity or faster host development but could instead reflect the thermal limits of parasite invasion and within-host replication. In the context of ongoing climate change, temperature increases above current thermal maxima could reduce the fitness of both monarchs and their parasites, with lower infection rates potentially balancing negative impacts of extreme heat on future monarch abundance and distribution.

Systemic pesticides in a solitary bee pollen food store affect larval development and increase pupal mortality

Solitary bees are often exposed to various pesticides applied for pest control on farmland while providing pollination services to food crops. Increasing evidence suggests that sublethal toxicity of agricultural pesticides affects solitary bees differently than the social bees used to determine regulatory thresholds, such as honey bees and bumblebees. Studies on solitary bees are challenging because of the difficulties in obtaining large numbers of eggs or young larvae for bioassays. Here we show the toxic and sublethal developmental effects of four widely used plant systemic pesticides on the Japanese orchard bee (Osmia cornifrons). Pollen food stores of this solitary bee were treated with different concentrations of three insecticides (acetamiprid, flonicamid, and sulfoxaflor) and a fungicide (dodine). Eggs were transplanted to the treated pollen and larvae were allowed to feed on the pollen stores after egg hatch. The effects of chronic ingestion of contaminated pollen were measured until adult eclosion. This year-long study revealed that chronic exposure to all tested pesticides delayed larval development and lowered larval and adult body weights. Additionally, exposure to the systemic fungicide resulted in abnormal larval defecation and increased mortality at the pupal stage, indicating potential risk to bees from fungicide exposure. These findings demonstrate potential threats to solitary bees from systemic insecticides and fungicides and will help in making policy decisions to mitigate these effects.

Effective population size mediates the impact of pollination services on pollen limitation.

Inadequate pollen receipt limits flowering plant reproduction worldwide. Ecological causes of pollen limitation (PL), like pollinator scarcity and low plant abundance, have been a primary research focus. The genetic diversity of plant populations could impact both quantity and quality components of PL in concert with ecological factors, yet empirical examples are lacking. We evaluated joint effects of ecological factors (flower abundance, pollinator visitation) and genetic effective population size (NE) on PL across 13 populations of the common herb Argentina anserina. We used a histological approach with 5504 styles from 1137 flowers to separate quantity and quality components of PL, and link these to reproductive output. NE and pollinator visitation interacted to shape PL, but NE had stronger direct effects. Effectively smaller populations experienced stronger quantity PL, and controlled crosses in a pollinator-free environment revealed that stigmatic pollen quantity was an intrinsic population-level attribute that increased with NE. Pollinator visitation enhanced pollen quality, but only in effectively larger populations. Quantity and quality PL negatively impacted fruit and seed set, respectively. Results highlight that PL is dictated by plant population genetic diversity in addition to commonly evaluated ecological factors. Efforts to support pollinators will more strongly enhance plant reproduction in genetically diverse populations.

Episyrphus balteatus symbiont variation across developmental stages, living states, two sexes, and potential horizontal transmission from prey or environment.

Episyrphus balteatus is one representative Syrphidae insect which can provide extensive pollination and pest control services. To date, the symbiont composition and potential acquisition approaches in Syrphidae remain unclear. Herein, we investigated microbiota dynamics across developmental stages, different living states, and two sexes in E. balteatus via full-length 16S rRNA genes sequencing, followed by an attempt to explore the possibility of symbiont transmission from prey Megoura crassicauda to the hoverfly. Overall, Proteobacteria and Firmicutes were the dominant bacteria phyla with fluctuating relative abundances across the life stage. Cosenzaea myxofaciens is dominant in adulthood, while Enterococcus silesiacus and Morganella morganii dominate in larvae and pupae of E. balteatus, respectively. Unexpectedly, Serratia symbiotica, one facultative endosymbiont commonly harbored in aphids, was one of the predominant bacteria in larvae of E. balteatus, just behind Enterococcus silesiacus. In addition, S. symbiotica was also surprisingly most dominated in M. crassicauda aphids (92.1% relative abundance), which are significantly higher than Buchnera aphidicola (4.7% relative abundance), the primary obligate symbiont of most aphid species. Approximately 25% mortality was observed among newly emerged adults, of which microbiota was also disordered, similar to normally dying individuals. Sexually biased symbionts and 41 bacteria species with pairwise co-occurrence in E. balteatus and 23 biomarker species for each group were identified eventually. Functional prediction showed symbionts of hoverflies and aphids, both mainly focusing on metabolic pathways. In brief, we comprehensively explored the microbiome in one Syrphidae hoverfly using E. balteatus reared indoors on M. morganii as the model, revealed its dominated symbiont species, identified sexually biased symbionts, and found an aphid facultative endosymbiont inhabited in the hoverfly. We also found that the dominated symbiotic bacteria in M. crassicauda are S. symbiotica other than Buchnera aphidicola. Taken together, this study provides new valuable resources about symbionts in hoverflies and prey aphids jointly, which will benefit further exploring the potential roles of microbiota in E. balteatus.

Orchards closer to forest patches produced fewer malformed fruits and more commercial fruits: The importance of legitimate floral visitors

Mexico is the main mango exporter worldwide, making ‘Ataulfo’ one of the most preferred cultivars. However, fruit production has been drastically diminished due to the high incidence of malformed fruits, known as nubbins. One of the possible causes of this is the lack of pollinators, which are necessary to set developed fruits. Since many pollinators depend on forest patches, the proximity of mango orchards to these is expected to decrease the incidence of nubbins. However, no study has evaluated the effect of distance from forest patches on the production of malformed fruits in any mango cultivar. The present study evaluates the incidence of nubbins and the production of commercial fruits, as well as the richness, composition, and frequency of visits of legitimate floral visitors (i.e., those that contact both reproductive parts of the flowers) over two consecutive years on ‘Ataulfo’ mango orchards located at different distances from tropical dry forest patches. Our results indicate that mango orchards located closer to forest patches were visited more frequently and by more species of legitimate floral visitors, showed less incidence of nubbins, and had greater production of commercial fruits than those located further away from the forest patches. Moreover, we found that older mango trees and the absence of exotic honeybees are also key factors to increasing fruit production. Our results highlight the importance of the conservation of tropical dry forest patches to ensure the provision of pollination services and to maintain or increase the production of mango orchards.

Impact of integrating pest and pollinator management training on knowledge, perceptions, and livelihoods of avocado farmers in Kenya

Abstract Synthetic pesticides reduce pest populations but also beneficial organisms like pollinators, thereby threatening the productivity of pollination-dependent crops such as avocados. Through the novel concept of integrated pest and pollinator management (IPPM), the negative effects of pest control on pollinators are mitigated, leading to synergistic benefits for crop yield and quality. In this study, we investigated the impact of IPPM training on farmers’ knowledge, attitude, and management of avocado pests, changes in the size of avocado orchards, avocado losses due to insect pests, expenditure on pesticides, and income. We compared farmers using IPPM against those using each component in isolation (integrated pest management (IPM) or pollination services (PS) through beehive supplementation (PS)) and a control group that used conventional practices without PS. We utilized 2 rounds of panel data obtained from avocado growers from Murang’a County, Kenya, and employed difference-in-difference (DiD) and multinomial logistic regression models. The results indicate that individuals utilizing IPM demonstrated notable enhancements in their perceptions of avocado pests, pollinators, and IPPM packages in comparison to the control group. Conversely, those utilizing IPPM employed more effective pest management strategies than users of IPM only. In contrast to using IPM and PS in isolation, farmers who utilized IPPM registered a significantly higher (9.6%) increase in the proportion of household annual income from avocado farming compared to the control group. Our findings further show that farmers who received training were more likely to adopt IPM, PS, and IPPM practices. We recommend wide promotion of IPPM to enhance avocado production and livelihoods of smallholders in sub-Saharan Africa.

Pollination services to crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in the coastal region of Jalisco, Mexico.

Bees play a pivotal role as pollinators in crops essential for human consumption. However, the global decline in bee populations poses a significant threat to pollination services and food security worldwide. The loss and degradation of habitats due to land use change are primary factors contributing to bee declines, particularly in tropical forests facing high deforestation rates. Here, we evaluate the pollination services provided to crops of watermelon (Citrullus lanatus) and green tomato (Physalis ixocarpa) in three municipalities in the state of Jalisco, Mexico, a place with Tropical Dry Forest, during years 2008, and 2014 to 2017. Both crops are cultivated in the dry season, approximately during the months of November to March. We describe the composition of the pollinator community and their visitation frequency (measured through the number of visits per flower per hour), and we assess the impact of pollinators on plant reproductive success and the level of pollinator dependence for each crop species (measured through the number of flowers that developed into fruits). We also evaluate how the landscape configuration (through the percentage of forest cover and distance to the forest) influences richness and abundance of pollinators (measured as number of species and individuals of pollinators per line of 50 m), and we use the model Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST) to map and value the pollination service in both crops. InVEST Crop pollination model is a simulation focuses on wild pollinators providing the pollinator ecosystem service. Our findings indicate that Apis mellifera was the primary pollinator of both crops, one of the few abundant pollinators in the study region during the dry season. In experiments where pollinators were excluded from flowers, watermelon yielded no fruits, while green tomato experienced a 65% reduction in production. In the case of green tomato, fruit set showed a positive correlation with pollinator abundance. A positive association between forest cover and total pollinator abundance was observed in green tomato in 2008, but not in watermelon. Additionally, a positive relationship was observed between the abundance of bees predicted by the InVEST model and the abundance of bees observed in green tomato flowers in 2008. In the study region, green tomato and watermelon rely on pollinators for fruit production, with honeybees (from feral and managed colonies) acting as the primary provider of pollination services for these crops. Consequently, the conservation of natural areas is crucial to provide food and nesting resources for pollinators. By doing so, we can ensure the diversity and abundance of pollinators, which in turn will help secure food security. The findings of this study underscore the critical need for the conservation of natural areas to support pollinator populations. Policymakers should prioritize the protection and restoration of habitats, particularly tropical forests, which are essential for maintaining the diversity and abundance of pollinators.

Pollen movement of the endemic Agave cupreata by bats and birds in western Mexico

Abstract We quantified the amount of pollen carried by bats and birds visiting the flowers of cultivated and wild individuals of the endemic Agave cupreata in western Mexico and estimated the distance to which pollen was moved using diurnal/nocturnal inflorescence exclusions and fluorescent powders. There were no differences in the amount of pollen transported by bats and birds near cultivated and wild agaves, but overall, bats transported greater loads than birds. Nocturnal pollen movement was more frequent, and the maximum distance recorded was 630 m (diurnal and nocturnal), with no transfer between cultivated and wild plants. Bats seem to provide a greater pollination service than birds in our focal anthropized landscape. It is necessary to incorporate management practices into mezcal production that ensure enough food for the wide array of animal species using this resource, which in turn will help to maintain the pollination service.

Roost characteristics of Indian flying fox along urban noise gradient: A case study in Sallaghari Forest, Kathmandu Valley, Nepal

The Indian flying fox, Pteropus medius is a fruit bat that contributes significantly to seed dispersal and pollination services. These bats face serious threats from the loss of roosting trees due to urbanization and deforestation. This study aimed to assess the roost characteristics of Indian flying foxes and the effects of anthropogenic noise on roost tier selection in an urban forest patch. We carried out population surveys of Indian flying foxes in the Sallaghari Forest in Kathmandu Valley, Nepal by direct roost count method from July to November 2023. Further, we quantified the intensities of anthropogenic noise at every five-meter interval along the transects from the forest edge towards the main forest and recorded the minimum roosting heights at each point. Indian flying foxes were found to be roosting on trees belonging to six species. Eucalyptus sp. was the most abundant roost tree (50%) in the forest whereas the highest relative abundance of roosting Indian flying foxes was on Populus ciliata (40.1%). The regression analysis revealed that tree DBH and height and the combined interaction of height and canopy cover significantly increase the abundance of Indian flying foxes. The noise intensity at ground level and roosting height of Indian flying foxes showed a significant strong positive relationship indicating their roosting at higher tier under intense noise. We recommend measures for reducing anthropogenic noises and conserving large and tall trees to ensure the roosting habitat of Indian flying foxes in urban setups.

The neglected floral polymorphism: mirror-image flowers emerge from the shadow of heterostyly

Abstract Morphological asymmetries in plants and animals raise intriguing questions concerning their function and how they have evolved. One of the most conspicuous asymmetries in plants involves mirror-image flowers (enantiostyly) in which styles are deflected to either the left or right sides (L or R, respectively) of the flower. Species with this floral polymorphism often possess two types of stamens (heteranthery): centrally located feeding anthers and a pollinating anther orientated in the opposite direction to the style (reciprocal enantiostyly). However, some species lack heteranthery and sex-organ reciprocity can be partial or absent (non-reciprocal enantiostyly). Many enantiostylous species have nectarless flowers and are ‘buzz-pollinated’ by pollen-collecting bees. In contrast to other stylar polymorphisms such as heterostyly, enantiostyly exists as either monomorphic or dimorphic conditions, with L and R flowers on the same plant in the former, and genetically determined floral morphs with either L or R flowers in the latter. Enantiostyly has been reliably reported from 11 angiosperm families, but in only two is there convincing evidence that dimorphic enantiostyly occurs. Various hypotheses concerning developmental or selective constraints attempt to explain the rarity of this genetic polymorphism. Experimental studies on the function of enantiostyly indicate that the reciprocity of stigmas and pollinating anthers promotes pollinator-mediated cross-pollination and limits geitonogamous selfing. Insufficient or inferior pollinator service can result in the evolutionary breakdown of enantiostyly, including reduced stigma–anther separation, increased selfing, and dissolution of heteranthery. In this article we review recent advances and knowledge gaps in understanding these curious asymmetries and discuss why they have received less attention than heterostyly.

РОЛЬ БДЖІЛЬНИЦТВА В ДОСЯГНЕННІ СТАЛОГО РОЗВИТКУ АГРАРНИХ ПІДПРИЄМСТВ ТА СІЛЬСЬКИХ ТЕРИТОРІЙ

The improvement of the economic performance of agricultural enterprises should not be accompanied by the deterioration of the quality of the environment and cause social tension among the employees of the enterprise and the population living in the surrounding area. Therefore, the problem arose of finding such directions of development of agricultural enterprises that would simultaneously contribute to the improvement of financial and economic indicators of their activity, as well as ensure the sustainable development of both the enterprises themselves and the sustainable development of the surrounding rural areas. The article examines the positive value of the agricultural sector, in particular: production of products, creation of jobs, provision of foreign exchange revenues to the state budget, the possibility of providing services of unity with nature. However, it was noted that the agricultural industry has negative consequences of its activity, in particular: the deterioration of the quality of the soil, the increase in the level of plowing, the excessive use of chemical plant protection agents leads to an increase in the level of soil pollution, the death of representatives of the fauna, as well as an increase in the level of human illness. It is proposed to restore and develop the beekeeping industry in order to reorient the activities of the agrarian industry on the principles of sustainable development. Both existing agricultural enterprises and small peasant farms can be engaged in bee breeding. For agricultural enterprises, beekeeping is a direction of diversification that can bring additional income. For rural residents, beekeeping is a way to provide themselves with a workplace and to earn from the sale of beekeeping products and the provision of pollination services to agricultural enterprises, which will be able to sell their products as organic at higher prices. However, starting a beekeeping business requires significant investments, which are not at the disposal of small peasant farms. Therefore, they are suggested to join cooperatives. This will make it possible to carry out laboratory analysis, form large batches of honey and sell it at a higher price. The cooperative can also pack and process honey with possible independent export. In general, the development of the beekeeping industry will contribute to increasing the level of employment in rural areas and improving the ecological situation, which corresponds to the principles of sustainable development.

Bio-Spectrum of Flower Visiting Insects and Their Role in Pollination Service of An Indigenous Himalayan Shrub (Deutzia Staminea R.Br. Ex Wall.)

Bio-Spectrum of Flower Visiting Insects and Their Role in Pollination Service of An Indigenous Himalayan Shrub (Deutzia Staminea R.Br. Ex Wall.)

Can trait matching inform the design of pollinator‐friendly urban green spaces? A review and synthesis of the literature

AbstractLand use change is a major driver of pollinator decline and loss of pollination services. For plant and pollinator interactions to persist in rapidly changing urban systems, co‐occurring species must share matching traits, including phenological, morphological, and physiological traits. Thus, the knowledge of trait matching among interacting plants and pollinators can aid in the design of pollinator habitats and enhance the conservation value of urban green spaces, but this remains relatively understudied. Here, we review how trait matching facilitates the persistence of interactions and creation of new interactions in urban plant–pollinator networks. We highlight four major urban drivers facilitating the restructuring of plant–pollinator networks through species loss and gain in urban areas. We also show different pathways by which the matching of morphological, phenological, and physiological traits of interacting plants and pollinators is affected by urbanization. Furthermore, we show how the knowledge of functional traits can help to predict novel plant–pollinator interactions in urban environments, including those among exotic species. Finally, we show how the application of trait matching can aid management practices, facilitating the design and creation of sustainable green spaces that will accommodate functionally diverse pollinators and plants within the urban matrix.