A stark reminder of the effects of climate change and the danger this represents to life on Earth, was published recently in the form of a study into the effects of global warming on the population of bumblebees in North America. The study was conducted by scientists from Simon Fraser University, Burnaby, B.C., Canada, led by Hanna Jackson, in collaboration with scientists from the U.S.-based Pollinator Partnership, the Xerces Society for Invertebrate Conservation, and the Department of Biological Sciences at the University of Southern California.
Their findings were published, open access, in the Royal Society's Biology Letter
bumblebees are essential pollinators on which many plants depend for their reproduction and without which many plants would not produce the next generation. They are also essential for pollinating a number of human food crops from oilseed rape to fruit, so a significant loss of bumblebees would be economically catastrophic.
The Simon Fraser University press release explains the team's methodology and main findings:
Jackson and her colleagues analyzed an existing dataset containing records on 46 bumble bee species across North America between 1900 – 2020. They created two occupancy models – one focused on time and the other on environmental factors – to estimate effects of climate and land-use variables on species’ occupancy, a measure of where species are found. They found that six bumble bee species decreased through time, 22 increased and the remaining 18 were stable.
They note that temperature and precipitation both increased, on average, between 1900 and 2020 in the post-industrial revolution period. Temperature changes had primarily negative impacts on bumble bees, with 37 of the 46 species exhibiting greater declines or less positive increases in occupancy under observed temperature changes compared to if the temperature had remained constant.bumble bees are important pollinators for wild plants and for the crops humans rely on for food. That’s why we need to develop conservation strategies that account for the future impacts of climate change on bee populations.
Because bumble bee species likely vary in their future responses to land-use and climate change, conservation action should prioritize individual species, taking into account their unique climate and habitat preferences.
Hanna Jackson, lead author,
Masters student in the M’Gonigle Lab
Simon Fraser University, Burnaby, B.C., Canada.
Importantly, nine species of bumble bee exhibited declines that link to changing temperatures within their ranges. The team did not find patterns in the other factors that were studied, such as precipitation and only one species declined based on floral resources.
In fact, both floral resources and precipitation had mixed results. Approximately half of the bumble bee species were negatively impacted by changes in precipitation or floral resources while the other half were positively impacted.
Therefore, researchers conclude that changing temperatures are a major environmental factor driving changes in bumblebee community composition.
AbstractBees have been described as the single most important group of living organisms on the planet. Their loss or even their significant reduction in numbers will ultimately impact not only on us and our food supply but on the whole range of plant, and animal biodiversity.
Mounting evidence suggests that climate change, agricultural intensification and disease are impacting bumblebee health and contributing to species’ declines. Identifying how these factors impact insect communities at large spatial and temporal scales is difficult, partly because species may respond in different ways. Further, the necessary data must span large spatial and temporal scales, which usually means they comprise aggregated, presence-only records collected using numerous methods (e.g. diversity surveys, educational collections, citizen-science projects, standardized ecological surveys). Here, we use occupancy models, which explicitly correct for biases in the species observation process, to quantify the effect of changes in temperature, precipitation and floral resources on bumblebee site occupancy over the past 12 decades in North America. We find no evidence of genus-wide declines in site occupancy, but do find that occupancy is strongly related to temperature, and is only weakly related to precipitation or floral resources. We also find that more species are likely to be climate change ‘losers’ than ‘winners’ and that this effect is primarily associated with changing temperature. Importantly, all trends were highly species-specific, highlighting that genus or community-wide measures may not reflect diverse species-specific patterns that are critical in guiding allocation of conservation resources.
Jackson Hanna M., Johnson Sarah A., Morandin Lora A., Richardson Leif L., Guzman Laura Melissa and M’Gonigle Leithen K. 2022
Climate change winners and losers among North American bumblebees
Biol. Lett. 18 20210551 20210551; DOI: 10.1098/rsbl.2021.0551
Copyright: © 2022 The authors.
Published by The Royal Society. Open access
Reprinted under a Creative Commons Attribution 4.0 International license (CC BY 4.0)
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