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Current Opinion in Insect Science Apr 2021Microbes (fungi, bacteria and viruses) living within flowers are hypothesized to affect pollination. We evaluate current support for this idea at each stage of the... (Review)
Review
Microbes (fungi, bacteria and viruses) living within flowers are hypothesized to affect pollination. We evaluate current support for this idea at each stage of the pollination process. Evidence to date is convincing that microbes influence pollinator attraction, but data are heavily weighted toward bumblebees and the effects of nectar yeasts. Effects of microbes on the efficacy of pollinator visits is understudied and variable outcomes from field studies suggest quality of pollinator visits, not only quantity, are likely involved. The effect of microbes on pollen performance is underappreciated. Beyond the effect of pathogenic viruses, the impacts of pollen-transmitted endophytic microbes on pollen viability or tube growth are unknown but could affect the outcome of pollen receipt. Future research integrating microbes into pollination should broaden taxonomic diversity of microbes, pollinators and plants and the processes under study.
Topics: Animals; Behavior, Animal; Endophytes; Flowers; Host-Pathogen Interactions; Pollen; Pollination
PubMed: 33248285
DOI: 10.1016/j.cois.2020.11.002 -
Philosophical Transactions of the Royal... Jun 2022Nectar, the main floral reward for pollinators, varies greatly in composition and concentration. The assumption that nectar quality is equivalent to its sugar (energy)... (Review)
Review
Nectar, the main floral reward for pollinators, varies greatly in composition and concentration. The assumption that nectar quality is equivalent to its sugar (energy) concentration is too simple. Diverse non-sugar components, especially amino acids and secondary metabolites, play various roles in nutrition and health of pollinators. Many nectar compounds have indirect effects by altering the foraging behaviour of pollinators or protecting them from disease. This review also emphasizes the water component of nectar, often ignored because of evaporative losses and difficulties in sampling small nectar volumes. Nectar properties vary with environmental factors, pollinator visits and microbial contamination. Pollination mutualisms depend on the ability of insect and vertebrate pollinators to cope with and benefit from the variation and diversity in nectar chemistry. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
Topics: Amino Acids; Plant Nectar; Pollination
PubMed: 35491604
DOI: 10.1098/rstb.2021.0163 -
PloS One 2019Some floral visitors collect nectar by piercing flower external whorls, acting as nectar robbers. They leave robbery vestiges, which can cause changes in floral...
Some floral visitors collect nectar by piercing flower external whorls, acting as nectar robbers. They leave robbery vestiges, which can cause changes in floral characteristics, including physical and chemical signals that may influence flower recognition by pollinators. If pollinating bees associate these changes with absence or reduction in nectar volume, they can avoid these flowers, negatively affecting pollination. We aimed to investigate the effect of robbery on primary and secondary attractants. Additionally, we experimentally investigated if the visual signs present in robbed flowers affect the bee pollination of this plant species by discouraging pollinator visits. This study was performed in a very common pollinator-plant-cheaters system comprised by a bee-pollinated Bignoniaceae species and a nectar-robber bee that lands on the corolla tube and makes slits at its base during the nectar robbery. We experimentally isolated the effect of nectar consumption by this nectar-robber and investigated if the slits caused by the nectar-robbers affected the floral scent emission. In addition, we experimentally evaluated the effect of visual signs (slits) associated to the nectar robbery and the effect of nectar depletion on the pollination of Jacaranda caroba (Bignoniaceae). The robbers visited around 75% of the flowers throughout the day and removed significant amounts of nectar from them. However, the damages the robbers cause did not affect floral scent emission and we did not verify significant differences on pollen deposition neither when comparing flowers with slits and control nor when comparing flowers with and without nectar. We showed that even though nectar-robbers visually honestly signal the robbery and deplete high amounts of nectar, they did not affect pollinator visitation. These results showed that presumably antagonistic interactions might in fact not be so.
Topics: Animals; Bees; Behavior, Animal; Brazil; Flowers; Plant Nectar; Pollination; Quantitative Trait Loci
PubMed: 31751426
DOI: 10.1371/journal.pone.0225252 -
Current Biology : CB Jan 2021The majority of flowering plants relies on animal pollinators for sexual reproduction and many animal pollinators rely on floral resources. However, interests of plants... (Review)
Review
The majority of flowering plants relies on animal pollinators for sexual reproduction and many animal pollinators rely on floral resources. However, interests of plants and pollinators are often not the same, resulting in an asymmetric relationship that ranges from mutualistic to parasitic interactions. Our understanding of the processes that underlie this asymmetry remains fragmentary. In this Review, we bring together evidence from evolutionary biology, plant chemistry, biomechanics, sensory ecology and behaviour to illustrate that the degree of symmetry often depends on the perspective taken. We also highlight variation in (a)symmetry within and between plant and pollinator species as well as between geographic locations. Through taking different perspectives from the plant and pollinator sides we provide new ground for studies on the maintenance and evolution of animal pollination and on the (a)symmetry in plant-pollinator interactions.
Topics: Animals; Bees; Biological Evolution; Birds; Butterflies; Feeding Behavior; Geography; Magnoliopsida; Pollination; Symbiosis
PubMed: 33497641
DOI: 10.1016/j.cub.2020.11.020 -
The Plant Journal : For Cell and... Aug 2020The great diversity of flowers, their color, odor, taste, and shape, is mostly a result of the metabolic processes that occur in this reproductive organ when the flower... (Review)
Review
The great diversity of flowers, their color, odor, taste, and shape, is mostly a result of the metabolic processes that occur in this reproductive organ when the flower and its tissues develop, grow, and finally die. Some of these metabolites serve to advertise flowers to animal pollinators, other confer protection towards abiotic stresses, and a large proportion of the molecules of the central metabolic pathways have bioenergetic and signaling functions that support growth and the transition to fruits and seeds. Although recent studies have advanced our general understanding of flower metabolism, several questions still await an answer. Here, we have compiled a list of open questions on flower metabolism encompassing molecular aspects, as well as topics of relevance for agriculture and the ecosystem. These questions include the study of flower metabolism through development, the biochemistry of nectar and its relevance to promoting plant-pollinator interaction, recycling of metabolic resources after flowers whiter and die, as well as the manipulation of flower metabolism by pathogens. We hope with this review to stimulate discussion on the topic of flower metabolism and set a reference point to return to in the future when assessing progress in the field.
Topics: Flowers; Fusarium; Nitrogen; Plant Nectar; Pollination
PubMed: 32410253
DOI: 10.1111/tpj.14814 -
Emerging Topics in Life Sciences Jul 2020The mutualism between plants and their pollinators provides globally important ecosystem services, but it is likely to be disrupted by global warming that can cause... (Review)
Review
The mutualism between plants and their pollinators provides globally important ecosystem services, but it is likely to be disrupted by global warming that can cause mismatches between both halves of this interaction. In this review, we summarise the available evidence on (i) spatial or (ii) phenological shifts of one or both of the actors of this mutualism. While the occurrence of future spatial mismatches is predominantly theoretical and based on predictive models, there is growing empirical evidence of phenological mismatches occurring at the present day. Mismatches may also occur when pollinators and their host plants are still found together. These mismatches can arise due to (iii) morphological modifications and (iv) disruptions to host attraction and foraging behaviours, and it is expected that these mismatches will lead to novel community assemblages. Overall plant-pollinator interactions seem to be resilient biological networks, particularly because generalist species can buffer these changes due to their plastic behaviour. However, we currently lack information on where and why spatial mismatches do occur and how they impact the fitness of plants and pollinators, in order to fully assess if adaptive evolutionary changes can keep pace with global warming predictions.
Topics: Animals; Biological Evolution; Diet; Ecosystem; Global Warming; Greenhouse Effect; Host-Parasite Interactions; Insecta; Plant Development; Plants; Pollination; Symbiosis; Temperature
PubMed: 32558904
DOI: 10.1042/ETLS20190139 -
Annual Review of Entomology Jan 2023There is growing awareness of pollinator declines worldwide. Conservation efforts have mainly focused on finding the direct causes, while paying less attention to... (Review)
Review
There is growing awareness of pollinator declines worldwide. Conservation efforts have mainly focused on finding the direct causes, while paying less attention to building a systemic understanding of the fragility of these communities of pollinators. To fill this gap, we need operational measures of network resilience that integrate two different approaches in theoretical ecology. First, we should consider the range of conditions compatible with the stable coexistence of all of the species in a community. Second, we should address the rate and shape of network collapse once this safe operational space is exited. In this review, we describe this integrative approach and consider several mechanisms that may enhance the resilience of pollinator communities, chiefly rewiring the network of interactions, increasing heterogeneity, allowing variance, and enhancing coevolution. The most pressing need is to develop ways to reduce the gap between these theoretical recommendations and practical applications. This perspective shifts the emphasis from traditional approaches focusing on the equilibrium states to strategies that allow pollination networks to cope with global environmental change.
Topics: Animals; Ecosystem; Ecology; Pollination; Plants
PubMed: 36206771
DOI: 10.1146/annurev-ento-120120-102424 -
Biological Reviews of the Cambridge... Dec 2021Global changes are severely affecting pollinator insect communities worldwide, resulting in repeated patterns of species extirpations and extinctions. Whilst negative... (Review)
Review
Global changes are severely affecting pollinator insect communities worldwide, resulting in repeated patterns of species extirpations and extinctions. Whilst negative population trends within this functional group have understandably received much attention in recent decades, another facet of global changes has been overshadowed: species undergoing expansion. Here, we review the factors and traits that have allowed a fraction of the pollinating entomofauna to take advantage of global environmental change. Sufficient mobility, high resistance to acute heat stress, and inherent adaptation to warmer climates appear to be key traits that allow pollinators to persist and even expand in the face of climate change. An overall flexibility in dietary and nesting requirements is common in expanding species, although niche specialization can also drive expansion under specific contexts. The numerous consequences of wild and domesticated pollinator expansions, including competition for resources, pathogen spread, and hybridization with native wildlife, are also discussed. Overall, we show that the traits and factors involved in the success stories of expanding pollinators are mostly species specific and context dependent, rendering generalizations of 'winning traits' complicated. This work illustrates the increasing need to consider expansion and its numerous consequences as significant facets of global changes and encourages efforts to monitor the impacts of expanding insect pollinators, particularly exotic species, on natural ecosystems.
Topics: Animals; Bees; Climate Change; Ecosystem; Insecta; Pollination; Species Specificity
PubMed: 34288353
DOI: 10.1111/brv.12777 -
Current Biology : CB Oct 2022Johnson gives an overview of bird pollinators and the plant species they pollinate.
Johnson gives an overview of bird pollinators and the plant species they pollinate.
Topics: Animals; Pollination; Flowers; Birds; Plants
PubMed: 36283359
DOI: 10.1016/j.cub.2022.06.081 -
Philosophical Transactions of the Royal... Jun 2022Evidence from the last few decades indicates that pollinator abundance and diversity are at risk, with many species in decline. Anthropogenic impacts have been the focus...
Evidence from the last few decades indicates that pollinator abundance and diversity are at risk, with many species in decline. Anthropogenic impacts have been the focus of much recent work on the causes of these declines. However, natural processes, from plant chemistry, nutrition and microbial associations to landscape and habitat change, can also profoundly influence pollinator health. Here, we argue that these natural processes require greater attention and may even provide solutions to the deteriorating outlook for pollinators. Existing studies also focus on the decline of individuals and colonies and only occasionally at population levels. In the light of this we redefine pollinator health and argue that a top-down approach is required focusing at the ecological level of communities. We use examples from the primary research, opinion and review articles published in this special issue to illustrate how natural processes influence pollinator health, from community to individuals, and highlight where some of these processes could mitigate the challenges of anthropogenic and natural drivers of change. This article is part of the theme issue 'Natural processes influencing pollinator health: from chemistry to landscapes'.
Topics: Ecosystem; Humans; Pollination
PubMed: 35491596
DOI: 10.1098/rstb.2021.0154