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Can winter-active bumblebees survive the cold? Assessing the cold tolerance of Bombus terrestris audax and the effects of pollen feeding.

Owen EL, Bale JS, Hayward SA - PLoS ONE (2013)

Bottom Line: The first evidence of RCH in any Hymenoptera is shown.In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature.These results are discussed in the light of winter active bumblebees and climate change.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.

ABSTRACT
There is now considerable evidence that climate change is disrupting the phenology of key pollinator species. The recently reported UK winter activity of the bumblebee Bombus terrestris brings a novel set of thermal challenges to bumblebee workers that would typically only be exposed to summer conditions. Here we assess the ability of workers to survive acute and chronic cold stress (via lower lethal temperatures and lower lethal times at 0°C), the capacity for rapid cold hardening (RCH) and the influence of diet (pollen versus nectar consumption) on supercooling points (SCP). Comparisons are made with chronic cold stress indices and SCPs in queen bumblebees. Results showed worker bees were able to survive acute temperatures likely to be experienced in a mild winter, with queens significantly more tolerant to chronic cold temperature stress. The first evidence of RCH in any Hymenoptera is shown. In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature. These results are discussed in the light of winter active bumblebees and climate change.

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Related in: MedlinePlus

The affect of dietary pollen on supercooling point.Total number of pollen grains found in the guts of Bombus terrestris audax workers, plotted against their corresponding supercooling points (n = 14, 8 and 5 for 3, 7 and 14 day nectar-fed workers respectively), a significant relationship (R2 = 32.7%, p<0.01).
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pone-0080061-g006: The affect of dietary pollen on supercooling point.Total number of pollen grains found in the guts of Bombus terrestris audax workers, plotted against their corresponding supercooling points (n = 14, 8 and 5 for 3, 7 and 14 day nectar-fed workers respectively), a significant relationship (R2 = 32.7%, p<0.01).

Mentions: A significant relationship was found between the number of pollen grains in the gut and supercooling point across all groups (Figure 6; R2 = 32.7%, p<0.01). Two highly erroneous outliers were removed, having a total of 104 and 18 pollen grains and corresponding supercooling points of −7.01 and −7.99°C respectively. The frequency of ‘high’ SCPs was clearly greater in controls and 3 day nectar-only fed samples, compared to 14 day nectar-only fed bees (Figure 7), with all 14 day nectar-fed bees having SCPs below −12.42°C. Neither controls nor 3 day bees were in this lowest SCP group. Additionally, 100% of 14 day nectar fed bees had no pollen in their guts (Table 2), compared to 57 and 25% for 3 and 7 days of nectar feeding respectively.


Can winter-active bumblebees survive the cold? Assessing the cold tolerance of Bombus terrestris audax and the effects of pollen feeding.

Owen EL, Bale JS, Hayward SA - PLoS ONE (2013)

The affect of dietary pollen on supercooling point.Total number of pollen grains found in the guts of Bombus terrestris audax workers, plotted against their corresponding supercooling points (n = 14, 8 and 5 for 3, 7 and 14 day nectar-fed workers respectively), a significant relationship (R2 = 32.7%, p<0.01).
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3818302&req=5

pone-0080061-g006: The affect of dietary pollen on supercooling point.Total number of pollen grains found in the guts of Bombus terrestris audax workers, plotted against their corresponding supercooling points (n = 14, 8 and 5 for 3, 7 and 14 day nectar-fed workers respectively), a significant relationship (R2 = 32.7%, p<0.01).
Mentions: A significant relationship was found between the number of pollen grains in the gut and supercooling point across all groups (Figure 6; R2 = 32.7%, p<0.01). Two highly erroneous outliers were removed, having a total of 104 and 18 pollen grains and corresponding supercooling points of −7.01 and −7.99°C respectively. The frequency of ‘high’ SCPs was clearly greater in controls and 3 day nectar-only fed samples, compared to 14 day nectar-only fed bees (Figure 7), with all 14 day nectar-fed bees having SCPs below −12.42°C. Neither controls nor 3 day bees were in this lowest SCP group. Additionally, 100% of 14 day nectar fed bees had no pollen in their guts (Table 2), compared to 57 and 25% for 3 and 7 days of nectar feeding respectively.

Bottom Line: The first evidence of RCH in any Hymenoptera is shown.In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature.These results are discussed in the light of winter active bumblebees and climate change.

View Article: PubMed Central - PubMed

Affiliation: School of Biosciences, University of Birmingham, Birmingham, United Kingdom.

ABSTRACT
There is now considerable evidence that climate change is disrupting the phenology of key pollinator species. The recently reported UK winter activity of the bumblebee Bombus terrestris brings a novel set of thermal challenges to bumblebee workers that would typically only be exposed to summer conditions. Here we assess the ability of workers to survive acute and chronic cold stress (via lower lethal temperatures and lower lethal times at 0°C), the capacity for rapid cold hardening (RCH) and the influence of diet (pollen versus nectar consumption) on supercooling points (SCP). Comparisons are made with chronic cold stress indices and SCPs in queen bumblebees. Results showed worker bees were able to survive acute temperatures likely to be experienced in a mild winter, with queens significantly more tolerant to chronic cold temperature stress. The first evidence of RCH in any Hymenoptera is shown. In addition, dietary manipulation indicated the consumption of pollen significantly increased SCP temperature. These results are discussed in the light of winter active bumblebees and climate change.

Show MeSH
Related in: MedlinePlus