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Male Bombus occidentalis Greene (background) and B. terricola Kirby (foreground) in Regina, Saskatchewan, possibly the most eastern location in Canada where both species at risk co-occur naturally. Photo by Cory S. Sheffield.
Source publication
In Canada, the Common Eastern Bumble Bee ( Bombusimpatiens Cresson) is native to southern Ontario and Quebec, but since being developed as a managed commercial pollinator, it has been exported to several other provinces for use in greenhouse and field crop settings. This has enabled this species to become established outside its natural range and i...
Citations
... In Canada, the honey bee is by far the most used managed pollinator but managed bumble bees are a growing industry with inadequate oversight in which B. impatiens (native to Canada east of Manitoba) are used in many regions where they are not native to pollinate greenhouse crops and, to a lesser extent, field crops. Escaped or improperly disposed B. impatiens have now established nonnative populations in the wild in these regions, which poses a great risk to surrounding native bee communities (Palmier and Sheffield 2019). Solitary bees are also reared to pollinate various crops and include the nonnative alfalfa leafcutting bee and the blue orchard mason bee. ...
Invertebrate pollinators are in trouble: particularly documented are declines among bees and butterflies. Interacting stressors include pesticides, pathogens, habitat loss, nonnative species, and climate change. Many governments have strategies to reduce negative pressures on pollinators, but Canada does not despite widespread public interest in pollinator health. This study serves as a needs assessment for science-based policy solutions for wild pollinator conservation in Canada. We designed a Policy Delphi survey technique to identify solutions that experts deem both desirable and feasible. Our secondary aim was to identify research priorities that would inform the implementation of these solutions. Sixty % of the 83 unique solutions were supported and feasible at a high consensus level (10% were “strongly” supported and “definitely” feasible). General themes included improving the Canadian government's approach in assessing pesticide risk to pollinators, curbing pathogen spillover/spillback between managed and wild pollinators, and reducing the reliance of Canadian agricultural systems on pesticides, among others. We discuss solutions in reference to pollinator conservation policies recommended by the broader scientific community and identify policy levers within the context of Canada's highly decentralized approach to biodiversity conservation/management and a political economy that uses high numbers of managed, mostly nonnative bees for pollination services.
... In fact, nearly 20% of the bumble bee species that occur in Ontario are now considered species at risk (Colla 2016). Causes of decline are from multiple stressors including habitat loss and fragmentation, climate change, exposure to agrochemicals, disease, and pressure from invasive and managed species (Colla et al. 2006;Kerr et al. 2015;Baron et al. 2017;Palmier and Sheffield 2019;Cameron and Sadd 2020). Although bumble bees are generally diet and habitat generalists, capable of collecting pollen from a variety of plants and with adaptable nesting practices, some species are declining while others remain stable or are increasing in abundance Cameron and Sadd 2020). ...
... It is unknown how scaling of nest density and size of original sampling area may impact nest density numbers.It is important to note that using one bumble bee species, as in this case B.impatiens, may not be a suitable proxy for other bumble bee species. B. impatiens is somewhat unusual, at least in eastern North America, because it is a species that is not experiencing any observable declines, perhaps aided by its use in agricultural systems where it has been introduced and has expanded beyond its native range into areas like western United States and CanadaPalmier and Sheffield 2019).Likewise, B. hypnorum is a commonly occurring bumble bee species and has also experienced range expansion from throughout Europe and some parts of Asia expanding further into the United Kingdom, and Iceland(Crowther et al. 2014;Crowther et al. 2019). Both B. impatiens and B. hypnorum are species in the subgenus Pyrobombus so perhaps the two species share similarities in that regard. ...
Understanding how restoration and land management practices may impact the structure of native bee communities is important especially considering reported global bee declines. I assessed bee community and vegetation composition in tallgrass prairie and oak savanna, some of the most endangered and biodiverse habitats in Canada. I found distinct differences in bee abundance and diversity among land management types, with remnant sites in most cases having comparably low bee diversity. This was driven by differences in floral abundance, canopy cover, and presence of woody debris. Bee community composition was unique at each locality, and I documented several bee species for the first time in Canada. I also found more bumble bee colonies and greater floral resources at restored compared to remnant sites using non-lethal DNA sampling and microsatellite markers to estimate colony densities. Linking landscape structure with use will improve habitat management and bee conservation in this rare habitat.
... Despite population decline and range contraction in many bumble bee species, several have established outside historical ranges (Palmier & Sheffield, 2019) and increased in occurrence regionally (Hemberger et al., 2021). One species, Bombus impatiens Cresson, has thrived, particularly in the agriculturally intensive Midwestern US despite unfavourable floral conditions and the decline of other bumble bee species (e.g., B. affinis, B. terricola). ...
Centuries of landscape changes associated with agriculture have dramatically reduced the amount and increased the temporal variability of the floral resources that support key pollinating insects such as bumble bees. Adapting to these novel resource conditions is important to ensure the persistence of bumble bee species. While several species appear to be in decline in modern agricultural landscapes, others have thrived, suggesting adaptation to exploit highly variable floral resources. Bombus impatiens , the common eastern bumble bee, is a prime example of such a species.
We designed an experiment to compare how free‐foraging colonies of B. impatiens performed adjacent to areas with either temporally continuous or variable (pulsed) patches of purple tansy ( Phacelia tanacetifolia ) plantings.
We found that colonies in Phacelia landscapes grew faster, had gained more mass, and produced more gynes than did colonies in reference landscapes with no Phacelia .
Comparing colony responses between pulsed and continuous flowering resources showed that total mass gain at the end of the experiment was greater with continuous flowering resources. In contrast, colony growth rate and total gyne production were comparable for colonies adjacent to Phacelia plantings that were continuous versus pulsed.
While low in statistical replication, given the scale of the experimental manipulation, our experiment shows that although B. impatiens colonies can exploit periods of resource discontinuity and gain mass, these continuously available floral resources appear important for colony growth and benefit gyne production.
The two-spotted bumble bee, Bombus bimaculatus Cresson, 1863 (Hymenoptera, Apidae), is a common species in central North America, with few published records of this species in Canada west of Ontario or east of Quebec.
Based on recently collected specimens from Saskatchewan and confirmed records posted to iNaturalist (https://www.inaturalist.org/) in the past 10 years (i.e. since 2013), we provide evidence that this species has only recently expanded its range in Canada, westwards into the Prairies Ecozone (Manitoba, Saskatchewan) and east into the Maritime Provinces (New Brunswick, Nova Scotia, Prince Edward Island).
A key question in pollination biology is that of how pollinators identify and choose foraging patches. Several approaches have been employed for this, including field studies and large greenhouse flight chambers. Most methods used to date are limited, though, by reliance on a combination of artificial flowers, large spatial scales, or lack of spatially distinct floral patches. To address this issue, we designed and tested a y-maze flight arena and tested it using the bumblebee Bombus impatiens and canola plants. Our results indicate that the system is not biased by environmental conditions, or by an innate “handedness” of Bombus impatiens. We found that bees made all the expected patch choices when presented with soil, plants without flowers, or plants with flowers. This new method is important and useful as it allows researchers to ask questions of both plant health and insect behavior and the chamber system is modular allowing for simple changes to the setup to focus on different questions.
Highlights
• Y-maze flight arena was designed to evaluate foraging behavior on intact plants.
• No evidence of side preference in individual bees.
• Behaviors observed in the y-maze appear to correspond to behaviors observed in other settings.
A key question in pollination biology is that of how pollinators identify and choose foraging patches. Several approaches have been employed for this, including field studies and large greenhouse flight chambers. Most methods used to date are limited, though, by reliance on a combination of artificial flowers, large spatial scales, or lack of spatially distinct floral patches. To address this issue, we designed and tested a y-maze flight arena and tested it using the bumblebee Bombus impatiens and canola plants. Our results indicate that the system is not biased by environmental conditions, or by an innate “handedness” of Bombus impatiens . We did find that bees made all the expected patch choices when presented with soil, plants without flowers, or plants with flowers. This new method is important and useful as it allows researchers to ask questions of both plant health and insect behavior and the chamber system is modular allowing for simple changes to the setup to focus on different questions.
Bumble bees are globally important pollinators, especially in temperate regions, and evidence suggests that many species are declining. One recent high profile study by Soroye et al. (2020) applied occupancy models to dated historical collection data to quantify declines across North America and Europe. The authors modelled 66 species across a set of sites spanning both North America and Europe, rather than confining species to sites where they might be expected to occur. In addition, they inferred non-detections for time intervals where there is no evidence that the site was visited (by forcing every site to have exactly 3 visits in each era). We use simulated data to (i) investigate the validity of methods used in that study and (ii) test whether a multi-species framework that incorporates species' ranges and site visitation histories produces better estimates. We show that the method used by Soroye et al. (2020) yields biased estimates of declines, whereas our framework does not. We use such a model to provide revised and appreciably lower estimates for bumble bee community declines, with species-specific trends more closely matching classifications from IUCN. The species level trends we provide can help inform future species-at-risk assessments. Well-parameterized occupancy models may be a powerful tool for assessing species-wide trends using curated historical collection data.
Bumble bees ( Bombus) are unusually important pollinators, with approximately 260 wild species native to all biogeographic regions except Africa, Australia, and New Zealand. As they are vitally important in natural ecosystems and to agricultural food production globally, the increase in reports of declining distribution and abundance over the past decade has led to an explosion of interest in bumble bee population decline. We summarize data on the threat status of wild bumble bee species across biogeographic regions, underscoring regions lacking assessment data. Focusing on data-rich studies, we also synthesize recent research on potential causes of population declines. There is evidence that habitat loss, changing climate, pathogen transmission, invasion of nonnative species, and pesticides, operating individually and in combination, negatively impact bumble bee health, and that effects may depend on species and locality. We distinguish between correlational and causal results, underscoring the importance of expanding experimental research beyond the study of two commercially available species to identify causal factors affecting the diversity of wild species.
Expected final online publication date for the Annual Review of Entomology, Volume 65 is January 7, 2020. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
