Historical changes in northeastern US bee pollinators related to shared ecological traits

Summary Declining populations of bee pollinators are a cause of concern, with major repercussions for biodiversity loss and food security. RNA viruses associated with honeybees represent a potential threat to other insect pollinators, but the extent of this threat is poorly understood.This study aims to attain a detailed understanding of the current and ongoing risk of emerging infectious disease (EID) transmission between managed and wild pollinator species across a wide range of RNA viruses.Within a structured large‐scale national survey across 26 independent sites, we quantify the prevalence and pathogen loads of multiple RNA viruses in co‐occurring managed honeybee (Apis mellifera) and wild bumblebee (Bombus spp.) populations. We then construct models that compare virus prevalence between wild and managed pollinators.Multiple RNA viruses associated with honeybees are widespread in sympatric wild bumblebee populations. Virus prevalence in honeybees is a significant predictor of virus prevalence in bumblebees, but we remain cautious in speculating over the principle direction of pathogen transmission. We demonstrate species‐specific differences in prevalence, indicating significant variation in disease susceptibility or tolerance. Pathogen loads within individual bumblebees may be high and in the case of at least one RNA virus, prevalence is higher in wild bumblebees than in managed honeybee populations.Our findings indicate widespread transmission of RNA viruses between managed and wild bee pollinators, pointing to an interconnected network of potential disease pressures within and among pollinator species. In the context of the biodiversity crisis, our study emphasizes the importance of targeting a wide range of pathogens and defining host associations when considering potential drivers of population decline.

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“…2007; Bartomeus et al . 2013) and the potential role of pathogens in these declines (Cameron et al . 2011; Meeus et al .…”

Section: Discussionmentioning

confidence: 99%

A sting in the spit: widespread cross‐infection of multiple RNA viruses across wild and managed bees

McMahon

Fürst

Caspar

et al. 2015

Journal of Animal Ecology

239

273

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“…In recent decades, pollinators with a long proboscis (longtongued pollinators) such as bumblebees and butterflies have declined drastically worldwide [25][26][27][28][29][30], likely resulting in a functional diversity loss in the pollinator guild. Owing to the usually intimate associations between long-tongued pollinators and flowers with specialized floral organs, such as long corolla tube and spur ( [31,32]; figure 1), declines in long-tongued pollinators can lead to such plants becoming pollinator-limited [16,19,20,33].…”

Section: Introductionmentioning

confidence: 99%

Low functional diversity promotes niche changes in natural island pollinator communities

Hiraiwa¹,

Ushimaru²

2017

Proc. R. Soc. B.

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Functional diversity loss among pollinators has rapidly progressed across the globe and is expected to influence plant-pollinator interactions in natural communities. Although recent findings suggest that the disappearance of a certain pollinator functional group may cause niche expansions and/or shifts in other groups, no study has examined this prediction in natural communities with high plant and pollinator diversities. By comparing coastal pollination networks on continental and oceanic islands, we examined how community-level flower visit patterns are influenced by the relative biomass of long-tongued pollinators (RBLP). We found that RBLP significantly correlated with pollinator functional diversity and was lower in oceanic than in continental islands. Pollinator niches shifted with decreasing RBLP, such that diverse species with various proboscis lengths, especially shorttongued species, increasingly visited long-tubed flowers. However, we found no conspicuous negative impacts of low RBLP and the consequent niche shifts on pollinator visit frequencies to flowers in oceanic island communities. Notably, fruit set significantly decreased as RBLP decreased in a study plant species. These results suggest that niche shifts by other functional groups can generally compensate for a decline in long-tongued pollinators in natural communities, but there may be negative impacts on plant reproduction.

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“…Some of the most important crop pollinators, such as bumble bees (Bombus spp. ), have declined over past decades in the United States (14)(15)(16). Among the numerous threats to wild bees, including pesticide use, climate change, and disease (17), habitat loss seems to contribute to most observed declines (18).…”

mentioning

confidence: 99%

Modeling the status, trends, and impacts of wild bee abundance in the United States

Koh

Lonsdorf

Williams

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

Self Cite

381

311

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Wild bees are highly valuable pollinators. Along with managed honey bees, they provide a critical ecosystem service by ensuring stable pollination to agriculture and wild plant communities. Increasing concern about the welfare of both wild and managed pollinators, however, has prompted recent calls for national evaluation and action. Here, for the first time to our knowledge, we assess the status and trends of wild bees and their potential impacts on pollination services across the coterminous United States. We use a spatial habitat model, national land-cover data, and carefully quantified expert knowledge to estimate wild bee abundance and associated uncertainty. Between 2008 and 2013, modeled bee abundance declined across 23% of US land area. This decline was generally associated with conversion of natural habitats to row crops. We identify 139 counties where low bee abundances correspond to large areas of pollinator-dependent crops. These areas of mismatch between supply (wild bee abundance) and demand (cultivated area) for pollination comprise 39% of the pollinator-dependent crop area in the United States. Further, we find that the crops most highly dependent on pollinators tend to experience more severe mismatches between declining supply and increasing demand. These trends, should they continue, may increase costs for US farmers and may even destabilize crop production over time. National assessments such as this can help focus both scientific and political efforts to understand and sustain wild bees. As new information becomes available, repeated assessments can update findings, revise priorities, and track progress toward sustainable management of our nation's pollinators.crop pollination | ecosystem services | habitat suitability | land-use change | uncertainty B ees and other flower-visiting animals provide essential pollination services to many US crops (1) and to wild plant species (2). Bees contributed an estimated 11% of the nation's agricultural gross domestic product in 2009 (3), equal to $14.6 billion per year (4). Of this, at least 20% ($3.07 billion) is provided by wild pollinators that depend on suitable land for nesting and foraging (5). As the consumption of specialty fruit and vegetable crops has grown (6), the demand for pollination services has increased. However, the supply of managed honey bees (Apis mellifera L.) has not kept pace (7), due to management challenges and colony losses over the last decade (8). There is growing evidence that wild, unmanaged bees can provide effective pollination services where sufficient habitat exists to support their populations (9, 10). They can also contribute to the long-term stability of crop pollination, thereby reducing the risk of pollination deficits from variable supply or activity of honey bees (11, 12). As a result, wild pollinators should be integrated into crop pollination management plans as a supplement or alternative to managed bees (13).Despite the agricultural importance of wild bees, there is increasing evidence that multiple species ...

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Historical changes in northeastern US bee pollinators related to shared ecological traits

Cited by 448 publications

References 39 publications

A sting in the spit: widespread cross‐infection of multiple RNA viruses across wild and managed bees

A sting in the spit: widespread cross‐infection of multiple RNA viruses across wild and managed bees

Low functional diversity promotes niche changes in natural island pollinator communities

Modeling the status, trends, and impacts of wild bee abundance in the United States

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