Alien honeybees increase pollination risks for range‐restricted plants

Norfolk, Olivia; Gilbert, Francis; Eichhorn, Markus P.

doi:10.1111/ddi.12715

Cited by 18 publications

(13 citation statements)

References 40 publications

(46 reference statements)

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“…Moreover, land use change [6], the lack of flower diversity [7] (e.g. overgrazing or frequent mowing [8]), the reduction of natural ecosystems nearby fields [9], the spread of parasites and diseases [10], and the overwhelming competition from domesticated bees [11,12] also impact the dynamics of bumblebees and other pollinators’ populations. Several of these factors may lead to a significant reduction of workforce in a colony with important implications in the short term (feeding the developing larvae [13]) and in the long term (colony fitness [14]).…”

Section: Introductionmentioning

confidence: 99%

Foraging strategies are maintained despite workforce reduction: A multidisciplinary survey on the pollen collected by a social pollinator

et al. 2019

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The way pollinators gather resources may play a key role for buffering their population declines. Social pollinators like bumblebees could adjust their foraging after significant workforce reductions to keep provisions to the colony optimal, especially in terms of pollen diversity and quantity. To test what effects a workforce reduction causes on the foraging for pollen, commercially-acquired colonies of the bumblebee Bombus terrestris were allowed to forage in the field and they were experimentally manipulated by removing half the number of workers. For each bumblebee, the pollen pellets were taxonomically identified with DNA metabarcoding of the ITS2 region followed by a statistical filtering based on ROC curves to filter out underrepresented OTUs. Video cameras and network analyses were employed to investigate changes in foraging strategies and behaviour. After filtering out the false-positives, HTS metabarcoding yielded a high plant diversity in the pollen pellets; for plant identity and pollen quantity traits no differences emerged between samples from treated and from control colonies, suggesting that plant choice was influenced mainly by external factors such as the plant phenology. The colonies responded to the removal of 50% of their workers by increasing the foraging activity of the remaining workers, while only negligible changes were found in diet breadth and indices describing the structure of the pollen transport network. Therefore, a consistency in the bumblebees’ feeding strategies emerges in the short term despite the lowered workforce.

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Section: Introductionmentioning

confidence: 99%

Foraging strategies are maintained despite workforce reduction: A multidisciplinary survey on the pollen collected by a social pollinator

et al. 2019

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“…Replacement of narrowly distributed species by geographically widespread species has been observed in other systems and taxa impacted by habitat alteration (McKinney and Lockwood 1999, Scott and Helfman 2001, Godet et al 2015, including native bees (Harrison et al 2017), and may be an important force driving reductions in biological diversity across large spatial scales (Godet et al 2015). While the loss of narrowly distributed bee species serves as an indicator of ecological filtering, this process may in turn have strong ecological consequences, as narrowly distributed bee species can be especially important pollinators for rangerestricted plant taxa (Norfolk et al 2018).…”

Section: Discussionmentioning

confidence: 99%

“…While the loss of narrowly distributed bee species serves as an indicator of ecological filtering, this process may in turn have strong ecological consequences, as narrowly distributed bee species can be especially important pollinators for range‐restricted plant taxa (Norfolk et al. ).…”

Section: Discussionmentioning

confidence: 99%

Ecological filtering in scrub fragments restructures the taxonomic and functional composition of native bee assemblages

Hung

Ascher

Davids

et al. 2019

Ecology

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Predicting the long‐term consequences of habitat alteration for the preservation of biodiversity and ecosystem function requires an understanding of how ecological filters drive taxonomic and functional biodiversity loss. Here, we test a set of predictions concerning the role of ecological filters in restructuring native bee assemblages inhabiting fragmented coastal sage scrub ecosystems in southern California, USA. In 2011 and 2012, we collected native bees in scrub habitat belonging to two treatment categories: large natural reserves and small habitat fragments embedded in an urban landscape. We compared bee assemblages in reserve and fragment sites with respect to their taxonomic and functional alpha diversity, beta diversity, assemblage composition, and mean geographical range size estimated via distribution maps compiled for this study from digitized specimen records. We found multiple lines of evidence that ecological filtering drove bee diversity loss in fragments: a disproportionate loss of functional diversity relative to taxonomic diversity, shifts in assemblage composition driven largely by the preferential extirpation of reserve‐associated indicator species, and disproportionate loss of range‐restricted species. However, we found no evidence of taxonomic or functional homogenization across fragment bee assemblages, suggesting that filtering was not sufficiently strong to cause a subset of functional traits (and their associated species) to dominate assemblages in fragments. Our results suggest that ecological filtering altered bee assemblages in habitat fragments, even when such fragments contained well‐preserved native plant assemblages, underscoring the importance of preserving large areas of natural habitat for the conservation of bees (especially range‐restricted taxa) and their associated ecological functions.

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“…While A. mellifera plays a substantial role in pollination in natural ecosystems around the world and may fill important empty pollination niches (Hung et al, 2018), studies have also found that honeybee presence can reduce the abundances of native pollinators without effectively replacing their pollination services to native plants (e.g. Norfolk et al, 2018).…”

Section: Introductionmentioning

confidence: 99%

Consequences of invasion for pollen transfer and pollination revealed in a tropical island ecosystem

Johnson

Ashman

2018

New Phytologist

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Pollination is known to be sensitive to environmental change but we lack direct estimates of how quantity and quality of pollen transferred between plant species shifts along disturbance gradients. This limits our understanding of how species compositional change impacts pollen receipt per species and structure of pollen transfer networks. We constructed pollen transfer networks along a plant invasion gradient in the Hawaiian dry tropical forest ecosystem. Flowers and stigmas were collected from both native and introduced plants, pollen was identified and enumerated and floral traits were measured. We also characterized pollen loads carried by individuals of the dominant invasive pollinator, Apis mellifera. Species flowering in native-dominated sites were more tightly connected by pollen transfer than those in heavily invaded sites. Compositional turnover in the pollen loads of A. mellifera was correlated (70%) with turnover in the composition of pollen transfer networks. Floral traits predicted species roles within pollen transfer networks, but many of these differed qualitatively depending on whether plants were native or introduced. Our work indicates that pollen transfer networks change with invasion. Floral morphology and foraging behaviour of the introduced super-generalist pollinator are implicated as key in determining the roles introduced species play within native pollen transfer networks.

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Alien honeybees increase pollination risks for range‐restricted plants

Cited by 18 publications

References 40 publications

Foraging strategies are maintained despite workforce reduction: A multidisciplinary survey on the pollen collected by a social pollinator

Foraging strategies are maintained despite workforce reduction: A multidisciplinary survey on the pollen collected by a social pollinator

Ecological filtering in scrub fragments restructures the taxonomic and functional composition of native bee assemblages

Consequences of invasion for pollen transfer and pollination revealed in a tropical island ecosystem

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