Climate change contributes to widespread declines among bumble bees across continents

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Science  07 Feb 2020:
Vol. 367, Issue 6478, pp. 685-688
DOI: 10.1126/science.aax8591

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  • Heterogeneity in large-scale databases and the role of climate change as a driver of bumble bee decline.
    • John Stoskopf Ascher, Assistant Professor, Department of Biological Sciences, National University of Singapore, 16 Science Drive 4, 117558, Singapore.
    • Other Contributors:
      • Leon Marshall, Post-doctoral researcher, Agroecology Lab, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 264/02, B-1050 Brussels, Belgium.
      • Joan Meiners, Ecologist & Environmental Data Journalist, School of Natural Resources and Environment, University of Florida, Gainesville, Florida 32603, USA.
      • Doug Yanega, Senior Museum Scientist at the Entomology Research Museum, Department of Entomology, University of California Riverside, California 92521-0314, USA.
      • Nicolas Jean Vereecken, Associate Professor, Agroecology Lab, Université Libre de Bruxelles (ULB), Boulevard du Triomphe CP 264/02, B-1050 Brussels, Belgium.

    In their article entitled “Climate change contributes to widespread declines among bumblebees across continents” recently published in Science and reported upon worldwide, Soroye, Newbold & Kerr (1) used extensive specimen records to explore patterns of geographic range loss and expansion of bumble bees in Europe and North America, and, in line with their previous findings, invoked climate change as the key contributor to their declines (see 2-3). Here, we question the reliability of these findings, considering the flawed interpretation of extensive data sources used in this and other recent studies, particularly related to notable spatio-temporal heterogeneity in methods of collecting, curation, and identification. We are concerned that the attendance to only some of these relevant biases led the authors to reach over-extrapolated and imprecisely characterized conclusions that will be amplified by the media to produce a misinformed public.

    Involving data providers may not be necessary in every instance, but in the case of Soroye et al. (1), not consulting the experts behind the datasets before using compiled records from various sources has resulted in both factual errors and a dismissal of nuances of historical museum records that significantly influence results about bee trends (4). For example, not consulting dataset experts resulted in the inclusion of erroneous records of B. pyrenaeus in the Netherlands in their models (this species is endemic to the Pyren...

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    Competing Interests: None declared.
  • RE: Climate change contributes to widespread declines among bumble bees across continents
    • Michael Aucott, adjunct professor, chemistry, The College of New Jersey

    As Soroye, Newbold, and Kerr (1) demonstrate, exceedances of the normal range of temperature tolerances due to climate change could be contributing to widespread declines in bumblebee populations. While this is an important finding, there is a potentially significant contributing factor in these declines that these authors fail to mention; this is the impact of the rising atmospheric concentration of carbon dioxide itself.

    CO2 plays a central role in plant metabolism, and its recent rise is dramatic and sudden. With the current atmospheric concentration approaching 415 ppm, the concentration of CO2 is now nearly 50% higher than it was in the pre-industrial world. As documented in an extensive review of published findings (2), elevated CO2 has a considerable impact on the accumulation of minerals and protein in plants, with many plant species showing declines in both quality and quantity of key nutrients. These changes have worrisome implications for human nutrition, and may already be responsible for increasing incidences of dietary deficiency in some areas. There seems no reason why declines in key plant nutrients due to enriched CO2 might not have similar negative impacts on insect populations.

    Pollen is the sole source of protein for bees, and also fulfills dietary requirements for lipids, sterols, vitamins, and minerals needed for larval development. A recent study (3) estimates that the protein concentration of Solidago canadensis (Canada goldenro...

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    Competing Interests: None declared.
  • RE: colony collapse disorder as reversion from eusocial to solitary behavior

    Ratnieks and Carreck asked, "So what is killing honey bee colonies worldwide, and what are the implications for agriculture?"

    IF colony collapse evidenced by abandoned broods resembling behavior characteristic of solitary, rather than eusocial, bees, THEN as such, agriculture practices linked to solitary species should prevail.

    Disruptions in hormone signaling might underlie Colony Collapase Disorder (CCD). From descriptions of the disorder -- abandoned broods, no workers, single queen -- it almost seems that honeybee hives have regressed from eusocial behavior to solitary behavior.

    Does the lack of diversity precludes reversion to solitary behavior? Could an epigenetic basis for eusociality challenge a claim of selective advantage precluding reversion to solitary behavior?

    According to Hughes, W. O., Oldroyd, B. P., Beekman, M., & Ratnieks, F. L. "The data do not allow us to determine whether monandry was already present in the solitary ancestors or whether monandry and eusociality evolved concurrently, but they are clearly linked" (2008).

    In his Science interview, Hughes (2008) remarks, "So that’s the point – is that a lot of the modern day species are irreversibly eusocial – they can’t go back. They’ve got these sterile workers living within a colony – it’s going to be very, very difficult for them to subsequently re-evolve a solitary lifestyle – because the honeybee worker is so highly adapte...

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    Competing Interests: None declared.

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