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Oecologia Oct 2023Pollinators mediate interspecific and intraspecific plant-plant indirect interactions (competition vs. facilitation) via density-dependent processes, potentially shaping...
Pollinators mediate interspecific and intraspecific plant-plant indirect interactions (competition vs. facilitation) via density-dependent processes, potentially shaping the dynamics of plant communities. However, it is still unclear which ecological drivers regulate density-dependent patterns, including scale, pollination niches (i.e., the main pollinator functional group) and floral attractiveness to pollinators. In this study, we conducted three-year field observations in Hengduan Mountains of southwest China. By gathering data for more than 100 animal-pollinated plant species, we quantified the effect (positive vs. negative) of conspecific and heterospecific flower density on pollination at two scales: plot-level (4 m) and site-level (100-5000 m). Then, we investigated how pollination niches and floral attractiveness to pollinators (estimated here as average per-flower visitation rates) modulated density-dependent pollination interactions. Pollinator visitation depended on conspecific and heterospecific flower density, with rare plants subjected to interspecific competition at the plot-level and interspecific facilitation at the site-level. Such interspecific competition at the plot-level was stronger for plants pollinated by diverse insects, while interspecific facilitation at the site-level was stronger for bee-pollinated plants. Moreover, we also found stronger positive conspecific density-dependence for plants with lower floral attractiveness at the site-level, meaning that they become more frequently visited when abundant. Our study indicates that the role of pollination in maintaining rare plants and plant diversity depends on the balance of density-dependent processes in species-rich communities. We show here that such balance is modulated by scale, pollination niches and floral attractiveness to pollinators, indicating the context-dependency of diversity maintenance mechanisms.
Topics: Bees; Animals; Pollination; Plants; Flowers; Insecta; China
PubMed: 37823959
DOI: 10.1007/s00442-023-05461-3 -
PloS One 2022Cross-pollination can increase fruit production in both self-incompatible and self-compatible fruit crops. However, it is often unclear what proportions of the fruit...
Cross-pollination can increase fruit production in both self-incompatible and self-compatible fruit crops. However, it is often unclear what proportions of the fruit crop result from cross-pollination. We quantified the proportion of cross-pollinated seeds and the proportion of fertilised seeds in two strawberry cultivars, Red Rhapsody and Sundrench, at increasing distances from a cross-pollen source. We assessed whether fully self-pollinated fruit and partly cross-pollinated fruit differed in fruit size, colour, firmness, Brix and acidity. We also assessed whether fruit size and quality were affected by the number or percentage of fertilised seeds. Almost all seeds of both cultivars resulted from self-pollination (~98%), even at only 1 m from a cross-pollen source. Distance from a cross-pollen source did not affect the proportion of partly cross-pollinated fruit or the proportion of cross-pollinated seeds per fruit. The mass and diameter of fully self-pollinated Sundrench fruit, and the redness and Brix of fully self-pollinated Red Rhapsody fruit, were higher than partly cross-pollinated fruit. Fruit mass, length and diameter increased, and acidity decreased, with increasing numbers of fertilised seeds in both cultivars. Fruit mass also increased with the percentage of fertilised seeds. Our results show that cross-pollination was not required for Red Rhapsody and Sundrench fruit production, and that cross-pollination was a rare occurrence even close to cross pollen source. Self-pollen deposition on stigmas is required to maximise the number of fertilised seeds, and consequently fruit size and quality. Our research indicates that bees improve strawberry fruit size by increasing the number of stigmas that receive pollen. Our results suggest that placing bee hives on strawberry farms during flowering and establishing nearby pollinator habitat to support wild pollinators could improve strawberry yield and fruit quality.
Topics: Animals; Bees; Fragaria; Fruit; Paternity; Pollination; Seeds
PubMed: 36099262
DOI: 10.1371/journal.pone.0273457 -
Ecological Applications : a Publication... Dec 2022Urbanization poses a major threat to biodiversity and food security, as expanding cities, especially in the Global South, increasingly compete with natural and...
Urbanization poses a major threat to biodiversity and food security, as expanding cities, especially in the Global South, increasingly compete with natural and agricultural lands. However, the impact of urban expansion on agricultural biodiversity in tropical regions is overlooked. Here we assess how urbanization affects the functional response of farmland bees, the most important pollinators for crop production. We sampled bees across three seasons in 36 conventional vegetable-producing farms spread along an urbanization gradient in Bengaluru, an Indian megacity. We investigated how landscape and local environmental drivers affected different functional traits (sociality, nesting behavior, body size, and specialization) and functional diversity (functional dispersion) of bee communities. We found that the functional responses to urbanization were trait specific with more positive than negative effects of gray area (sealed surfaces and buildings) on species richness, functional diversity, and abundance of most functional groups. As expected, larger, solitary, cavity-nesting, and, surprisingly, specialist bees benefited from urbanization. In contrast to temperate cities, the abundance of ground nesters increased in urban areas, presumably because larger patches of bare soil were still available beside roads and buildings. However, overall bee abundance and the abundance of social bees (85% of all bees) decreased with urbanization, threatening crop pollination. Crop diversity promotes taxonomic and functional diversity of bee communities. Locally, flower resources promote the abundance of all functional groups, and natural vegetation can maintain diverse pollinator communities throughout the year, especially during the noncropping season. However, exotic plants decrease functional diversity and bee specialization. To safeguard bees and their pollination services in urban farms, we recommend (1) preserving seminatural vegetation (hedges) around cropping fields to provide nesting opportunities for aboveground nesters, (2) promoting farm-level crop diversification of beneficial crops (e.g., pulses, vegetables, and spices), (3) maintaining native natural vegetation along field margins, and (4) controlling and removing invasive exotic plants that disrupt native plant-pollinator interactions. Overall, our results suggest that urban agriculture can maintain functionally diverse bee communities and, if managed in a sustainable manner, be used to develop win-win solutions for biodiversity conservation of pollinators and food security in and around cities.
Topics: Bees; Animals; Farms; Pollination; Biodiversity; Urbanization; Crops, Agricultural; Ecosystem
PubMed: 35751512
DOI: 10.1002/eap.2699 -
Journal of Economic Entomology Oct 2021Agricultural dependency on insect-mediated pollination is increasing at the same time that pollinator populations are experiencing declines in diversity and abundance....
Agricultural dependency on insect-mediated pollination is increasing at the same time that pollinator populations are experiencing declines in diversity and abundance. Current pollinator research in agriculture focuses largely on diurnal pollinators, yet the evidence for pollination by moths and other nocturnal pollinators is growing. Apples are one of the most valuable and important fruits produced globally, and apple production is dependent on insect-mediated cross-pollination to generate a profitable crop. We examined contributions to apple production provided by nocturnal insects via an exclusion experiment. We compared the relative contributions to apple production provided by nocturnal and diurnal pollinators using fruit set, the likelihood of cluster pollination, and seed set. We found nocturnal pollinators capable of facilitating the production of as many apples at similar levels of pollination as diurnal pollinators. We further found evidence that nocturnal and diurnal pollinators pollinate synergistically, with pollination contributions being additive in one year of our study. Our research identifies significant contributions to apple production provided by nocturnal pollinators, which may interact with diurnal pollinators in ways that are currently unrecognized. Expansions of this research into additional pollinator-dependent crops and focused investigations on specific nocturnal insects will provide more accurate assessments of nocturnal-pollinator roles in agriculture and improve our overall understanding of pollination in agriculture.
Topics: Animals; Crops, Agricultural; Flowers; Insecta; Malus; Pollination
PubMed: 34293132
DOI: 10.1093/jee/toab145 -
Environmental Health Perspectives Dec 2022Animal pollination supports agricultural production for many healthy foods, such as fruits, vegetables, nuts, and legumes, that provide key nutrients and protect against...
BACKGROUND
Animal pollination supports agricultural production for many healthy foods, such as fruits, vegetables, nuts, and legumes, that provide key nutrients and protect against noncommunicable disease. Today, most crops receive suboptimal pollination because of limited abundance and diversity of pollinating insects. Animal pollinators are currently suffering owing to a host of direct and indirect anthropogenic pressures: land-use change, intensive farming techniques, harmful pesticides, nutritional stress, and climate change, among others.
OBJECTIVES
We aimed to model the impacts on current global human health from insufficient pollination via diet.
METHODS
We used a climate zonation approach to estimate current yield gaps for animal-pollinated foods and estimated the proportion of the gap attributable to insufficient pollinators based on existing research. We then simulated closing the "pollinator yield gaps" by eliminating the portion of total yield gaps attributable to insufficient pollination. Next, we used an agriculture-economic model to estimate the impacts of closing the pollinator yield gap on food production, interregional trade, and consumption. Finally, we used a comparative risk assessment to estimate the related changes in dietary risks and mortality by country and globally. In addition, we estimated the lost economic value of crop production for three diverse case-study countries: Honduras, Nepal, and Nigeria.
RESULTS
Globally, we calculated that 3%-5% of fruit, vegetable, and nut production is lost due to inadequate pollination, leading to an estimated 427,000 (95% uncertainty interval: 86,000, 691,000) excess deaths annually from lost healthy food consumption and associated diseases. Modeled impacts were unevenly distributed: Lost food production was concentrated in lower-income countries, whereas impacts on food consumption and mortality attributable to insufficient pollination were greater in middle- and high-income countries with higher rates of noncommunicable disease. Furthermore, in our three case-study countries, we calculated the economic value of crop production to be 12%-31% lower than if pollinators were abundant (due to crop production losses of 3%-19%), mainly due to lost fruit and vegetable production.
DISCUSSION
According to our analysis, insufficient populations of pollinators were responsible for large present-day burdens of disease through lost healthy food consumption. In addition, we calculated that low-income countries lost significant income and crop yields from pollinator deficits. These results underscore the urgent need to promote pollinator-friendly practices for both human health and agricultural livelihoods. https://doi.org/10.1289/EHP10947.
Topics: Animals; Humans; Agriculture; Climate Change; Crops, Agricultural; Noncommunicable Diseases; Pollination; Diet
PubMed: 36515549
DOI: 10.1289/EHP10947 -
Neotropical Entomology Jun 2021A pollinator's efficacy is the result obtained from a single visit by a species and is often used to measure the importance of different species of floral visitors as...
A pollinator's efficacy is the result obtained from a single visit by a species and is often used to measure the importance of different species of floral visitors as pollinators. Therefore, this study aimed to measure the efficacy of fruit and seed set in Passiflora edulis f. flavicarpa Deg. (Passifloraceae) by manual cross-pollination, natural pollination and by Xylocopa (Neoxylocopa) frontalis (Olivier 1789), performed through a single and two visits, to evaluate if there is occurrence of pollen limitation and pollinators' limitation in the studied crop fields. Four different treatments were performed: (1) manual cross-pollination (n = 37 flowers); (2) natural pollination (n = 52 flowers); (3) pollination by a single visit of X. frontalis (n = 41 flowers); and (4) pollination by two visits of X. frontalis (n = 31 flowers). We verified that fruit set occurred in all the treatments performed. Fruit set rate by manual cross-pollination was significantly higher than that obtained under natural conditions indicating the occurrence of pollen limitation and pollinators' limitation under natural pollination. Regarding the number of seeds, analysis of variance (ANOVA) did not indicate a significant difference between the mean seed set for the different types of pollination evaluated. The management of occupied nests, the introduction of trap-nests, and the conservation of native vegetation in areas close to the yellow passion fruit crops can increase pollinators' population. The greater richness and abundance of pollinators are essential to promote a greater number of fruit and seed set in the yellow passion fruit crops.
Topics: Animals; Bees; Flowers; Fruit; Passiflora; Pollination
PubMed: 33721235
DOI: 10.1007/s13744-020-00846-y -
Ecology Jun 2023Selection leading to adaptation to interactions may generate rapid evolutionary feedbacks and drive diversification of species interactions. The challenge is to...
Selection leading to adaptation to interactions may generate rapid evolutionary feedbacks and drive diversification of species interactions. The challenge is to understand how the many traits of interacting species combine to shape local adaptation in ways directly or indirectly resulting in diversification. We used the well-studied interactions between Lithophragma plants (Saxifragaceae) and Greya moths (Prodoxidae) to evaluate how plants and moths together contributed to local divergence in pollination efficacy. Specifically, we studied L. bolanderi and its two specialized Greya moth pollinators in two contrasting environments in the Sierra Nevada in California. Both moths pollinate L. bolanderi during nectaring, one of them-G. politella-also while ovipositing through the floral corolla into the ovary. First, field surveys of floral visitors and the presence of G. politella eggs and larvae in developing capsules showed that one population was visited only by G. politella and few other pollinators, whereas the other was visited by both Greya species and other pollinators. Second, L. bolanderi in these two natural populations differed in several floral traits putatively important for pollination efficacy. Third, laboratory experiments with greenhouse-grown plants and field-collected moths showed that L. bolanderi was more efficiently pollinated by local compared to nonlocal nectaring moths of both species. Pollination efficacy of ovipositing G. politella was also higher for local moths for the L. bolanderi population, which relies more heavily on this species in nature. Finally, time-lapse photography in the laboratory showed that G. politella from different populations differed in oviposition behavior, suggesting the potential for local adaptation also among Greya populations. Collectively, our results are a rare example of components of local adaptation contributing to divergence in pollination efficacy in a coevolving interaction and, thus, provide insights into how geographic mosaics of coevolution may lead to coevolutionary diversification in species interactions.
Topics: Animals; Female; Pollination; Flowers; Moths; Adaptation, Physiological; Plants; Saxifragaceae
PubMed: 36976166
DOI: 10.1002/ecy.4043 -
Journal of Comparative Physiology. A,... Jun 2019Pollination syndromes evolved under the reciprocal selection of pollinators and plants (coevolution). Here, the two main methods are reviewed which are applied to prove... (Review)
Review
Pollination syndromes evolved under the reciprocal selection of pollinators and plants (coevolution). Here, the two main methods are reviewed which are applied to prove such selection. (i) The indirect method is a cross-lineage approach using phylogenetical trees to understand the phylogeny. Thus, features of single origin can be distinguished from those with multiple origins. Nearly all pollination modes originate in multiple evolutionary ways. (ii) The most frequent pollinators cause the strongest selection because they are responsible for the plant's most successful reproduction. The European sexually deceptive orchid genus Ophrys provides an example of a more direct way to prove selection because the attraction of a pollinator is species specific. Most members of the genus have remarkably variable flowers. The variability of the signals given off by the flowers enables the deceived pollinator males to learn individual flower patterns. They thus avoid already visited Ophrys flowers, interpreting them as females rejecting them. As the males will not return to these individually recognizable flowers, the pollinators´ learning behavior causes cross-pollination and prevents the orchid's self-pollination.
Topics: Animals; Biological Evolution; Flowers; Orchidaceae; Pollination; Reproduction; Species Specificity
PubMed: 31134328
DOI: 10.1007/s00359-019-01350-4 -
Emerging Topics in Life Sciences Jul 2020Ecosystems are at increasing risk from the global pollination crisis. Gaining better knowledge about pollinators and their interactions with plants is an urgent need.... (Review)
Review
Ecosystems are at increasing risk from the global pollination crisis. Gaining better knowledge about pollinators and their interactions with plants is an urgent need. However, conventional methods of manually recording pollinator activity in the field can be time- and cost-consuming in terms of labour. Field-deployable video recording systems have become more common in ecological studies as they enable the capture of plant-insect interactions in fine detail. Standard video recording can be effective, although there are issues with hardware reliability under field-conditions (e.g. weatherproofing), and reviewing raw video manually is a time-consuming task. Automated video monitoring systems based on motion detection partly overcome these issues by only recording when activity occurs hence reducing the time needed to review footage during post-processing. Another advantage of these systems is that the hardware has relatively low power requirements. A few systems have been tested in the field which permit the collection of large datasets. Compared with other systems, automated monitoring allows vast increases in sampling at broad spatiotemporal scales. Some tools such as post-recording computer vision software and data-import scripts exist, further reducing users' time spent processing and analysing the data. Integrated computer vision and automated species recognition using machine learning models have great potential to further the study of pollinators in the field. Together, it is predicted that future advances in technology-based field monitoring methods will contribute significantly to understanding the causes underpinning pollinator declines and, hence, developing effective solutions for dealing with this global challenge.
Topics: Animals; Ecosystem; Electronic Data Processing; Environmental Monitoring; Host-Parasite Interactions; Insecta; Plants; Pollination; Video Recording
PubMed: 32558902
DOI: 10.1042/ETLS20190074 -
PeerJ 2022Many crop plants rely on insect pollination, particularly insect-pollinated crops which are functionally dioecious. These crops require insects to move pollen between...
Many crop plants rely on insect pollination, particularly insect-pollinated crops which are functionally dioecious. These crops require insects to move pollen between separate plants which are functionally male or female. While honey bees are typically considered the most important crop pollinator species, many other insects are known to visit crops but the pollination contribution of the full diversity of these flower visitors is poorly understood. In this study, we examine the role of diverse insect pollinators for two kiwifruit cultivars as model systems for dioecious crops: var. 'Hayward' (a green-fleshed variety) and A. var. 'Zesy002' (a gold-fleshed variety). In our round-the-clock insect surveys, we identified that psychodid flies and mosquitoes were the second and third most frequent floral visitors after honey bees ( L), but further work is required to investigate their pollination efficiency. Measures of single-visit pollen deposition identified that several insects, including the bees spp. and spp. and the flies and , deposited a similar amount of pollen on flowers as honey bees (). Due to their long foraging period and high pollen deposition, we recommend the development of strategies to boost populations of spp., and other hover flies, and unmanaged bees for use as synergistic pollinators alongside honey bees.
Topics: Bees; Animals; Pollination; Actinidia; Insecta; Flowers; Crops, Agricultural; Culicidae
PubMed: 35702253
DOI: 10.7717/peerj.12963