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Ambient Air Temperature Does Not Predict whether Small or Large Workers Forage in Bumble Bees (Bombus impatiens).

Couvillon MJ, Fitzpatrick G, Dornhaus A - Psyche (Camb Mass) (2010)

Bottom Line: We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder.Instead, bees of all sizes successfully flew and foraged between 16°C and 36°C.Size variation therefore could not be explained in terms of niche specialization for foragers at different temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA ; Laboratory of Apiculture and Social Insects, Department of Biological and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QG, UK.

ABSTRACT

Bumble bees are important pollinators of crops and other plants. However, many aspects of their basic biology remain relatively unexplored. For example, one important and unusual natural history feature in bumble bees is the massive size variation seen between workers of the same nest. This size polymorphism may be an adaptation for division of labor, colony economics, or be nonadaptive. It was also suggested that perhaps this variation allows for niche specialization in workers foraging at different temperatures: larger bees might be better suited to forage at cooler temperatures and smaller bees might be better suited to forage at warmer temperatures. This we tested here using a large, enclosed growth chamber, where we were able to regulate the ambient temperature. We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder. Instead, bees of all sizes successfully flew and foraged between 16°C and 36°C. Thus, large bees foraged even at very hot temperatures, which we thought might cause overheating. Size variation therefore could not be explained in terms of niche specialization for foragers at different temperatures.

No MeSH data available.


Related in: MedlinePlus

Foragers of different body sizes did not significantly differ in the average temperatures at which they foraged (although linear fits are shown, slopes are not significantly different from zero). However, colonies differed significantly from each other. Shown are (a) ambient temperature and (b) temperature measured in nest; each data point is the average temperature across all days on which that bee foraged (each bee foraged on average on 13.9 days), and in total, 81 bees are shown.
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Figure 5: Foragers of different body sizes did not significantly differ in the average temperatures at which they foraged (although linear fits are shown, slopes are not significantly different from zero). However, colonies differed significantly from each other. Shown are (a) ambient temperature and (b) temperature measured in nest; each data point is the average temperature across all days on which that bee foraged (each bee foraged on average on 13.9 days), and in total, 81 bees are shown.

Mentions: The maximum temperature, out of the temperatures tested by us, at which a worker would forage seemed at first predicted by body size, with larger bees foraging at higher maximal ambient temperatures (ANOVA, df = 80, R2 = 0.25, thorax width P = .0009, colony P = .016, interaction P = .0003; Figure 5(a)). However, there was the single outlier of one bee that was only seen foraging once, at 16°C (Figure 5(a)). Since this single trip entered the analysis as a maximum foraging temperature of 16°C, it strongly affected the results. If that bee is removed from the analysis of maximum foraging temperature, there is no remaining effect of body size (R2 = 0.25, thorax width P = .48, colony P = .11, interaction P = .26). The same was true for the relationship between body size and maximal in-nest temperature at which the bee foraged, although there was always an effect of colony on in-nest temperature (with the outlier: R2 = 0.42, thorax width P = .006, colony P < .0001, interaction P = .003; without the outlier: R2 = 0.37, thorax width P = .80, colony P < .0001, interaction P = .64; Figure 5(b)).


Ambient Air Temperature Does Not Predict whether Small or Large Workers Forage in Bumble Bees (Bombus impatiens).

Couvillon MJ, Fitzpatrick G, Dornhaus A - Psyche (Camb Mass) (2010)

Foragers of different body sizes did not significantly differ in the average temperatures at which they foraged (although linear fits are shown, slopes are not significantly different from zero). However, colonies differed significantly from each other. Shown are (a) ambient temperature and (b) temperature measured in nest; each data point is the average temperature across all days on which that bee foraged (each bee foraged on average on 13.9 days), and in total, 81 bees are shown.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4440703&req=5

Figure 5: Foragers of different body sizes did not significantly differ in the average temperatures at which they foraged (although linear fits are shown, slopes are not significantly different from zero). However, colonies differed significantly from each other. Shown are (a) ambient temperature and (b) temperature measured in nest; each data point is the average temperature across all days on which that bee foraged (each bee foraged on average on 13.9 days), and in total, 81 bees are shown.
Mentions: The maximum temperature, out of the temperatures tested by us, at which a worker would forage seemed at first predicted by body size, with larger bees foraging at higher maximal ambient temperatures (ANOVA, df = 80, R2 = 0.25, thorax width P = .0009, colony P = .016, interaction P = .0003; Figure 5(a)). However, there was the single outlier of one bee that was only seen foraging once, at 16°C (Figure 5(a)). Since this single trip entered the analysis as a maximum foraging temperature of 16°C, it strongly affected the results. If that bee is removed from the analysis of maximum foraging temperature, there is no remaining effect of body size (R2 = 0.25, thorax width P = .48, colony P = .11, interaction P = .26). The same was true for the relationship between body size and maximal in-nest temperature at which the bee foraged, although there was always an effect of colony on in-nest temperature (with the outlier: R2 = 0.42, thorax width P = .006, colony P < .0001, interaction P = .003; without the outlier: R2 = 0.37, thorax width P = .80, colony P < .0001, interaction P = .64; Figure 5(b)).

Bottom Line: We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder.Instead, bees of all sizes successfully flew and foraged between 16°C and 36°C.Size variation therefore could not be explained in terms of niche specialization for foragers at different temperatures.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, USA ; Laboratory of Apiculture and Social Insects, Department of Biological and Environmental Science, University of Sussex, Falmer, Brighton BN1 9QG, UK.

ABSTRACT

Bumble bees are important pollinators of crops and other plants. However, many aspects of their basic biology remain relatively unexplored. For example, one important and unusual natural history feature in bumble bees is the massive size variation seen between workers of the same nest. This size polymorphism may be an adaptation for division of labor, colony economics, or be nonadaptive. It was also suggested that perhaps this variation allows for niche specialization in workers foraging at different temperatures: larger bees might be better suited to forage at cooler temperatures and smaller bees might be better suited to forage at warmer temperatures. This we tested here using a large, enclosed growth chamber, where we were able to regulate the ambient temperature. We found no significant effect of ambient or nest temperature on the average size of bees flying to and foraging from a suspended feeder. Instead, bees of all sizes successfully flew and foraged between 16°C and 36°C. Thus, large bees foraged even at very hot temperatures, which we thought might cause overheating. Size variation therefore could not be explained in terms of niche specialization for foragers at different temperatures.

No MeSH data available.


Related in: MedlinePlus