When does temperature limit bee flight? Identifying the missing pieces of the puzzle
Data files
Dec 03, 2025 version files 390.03 KB
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Andrena_Bombus_FTS.R
6.21 KB
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bee_tree_cwc.csv
19.44 KB
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bee_tree.nwk
35.58 KB
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lit_review_mass.WBF.FMR.csv
104.21 KB
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PGLS_CWC_mass.R
15.94 KB
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PGLS_fmr_wbf_mass_k.R
41.49 KB
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raw.K.data.csv
68.83 KB
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README.md
10.10 KB
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Reflectance_C.caesalpinae_Fig.5A.csv
1.46 KB
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Reflectance_C.caesalpinae_Fig.5B.csv
19.68 KB
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Supplementary_table_to_support_Table_1.csv
23.18 KB
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Table1CorrelationData.csv
435 B
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Thermal_stability_meta_reduced.csv
43.48 KB
Abstract
Bees are the most important insect pollinators, and nearly all bee-mediated pollination depends on flight. In this review, we identify five key gaps that limit our ability to predict how abiotic factors shape bee flight performance and ecology. First, while clade strongly influences endothermy and flight temperature limits, we still know little about how phylogeny, body size, and ecological traits shape thermal biology across the full diversity of bee species - most data come from temperate, northern hemisphere Apinae. Second, because the mechanisms of thermal balance during flight have only been studied in a handful of species, and these vary, we clearly lack a predictive understanding of when bees will be physiologically stressed by temperature during flight. Third, although some studies suggest desiccation may limit flight more than overheating, the links between thermal balance and water regulation remain poorly understood. Fourth, we know very little about bees’ capacity to respond to thermal variation through acclimation, developmental plasticity, or evolutionary adaptation. Finally, we need advances in biophysical modeling to better simulate heat and water exchange in bees, including the role of cuticular structures and internal heat transfer among body regions. Filling these gaps is essential for building predictive, mechanistic models of how climate change will affect bee physiology and the pollination services bees provide.
Dataset DOI: 10.5061/dryad.4qrfj6qpt
Description of the data and file structure
This review is organized around specific ‘missing pieces’ of information needed to build predictive models of how environmental temperature affects bee flight. Ecological and morphological differences affect flight energetics and thermoregulation. Therefore, the following data consist of physiological (e.g., CO2 production and O2 consumption rates, CTmax, and other metrics of thermoregulation and performance), morphological (e.g., pubescence, reflectance, emissivity, body size, and body mass), and behavioral measurements (e.g., activity time, thermal thresholds for flight, etc.). These data are either original to this study or are from the primary literature. Here, we consider phylogenetic contexts and ecological niches when interpreting patterns of thermal performance across clades of bees. Wherever the values are not known, the cells were left empty.
Files and variables
File: PGLS_fmr_wbf_mass_k.R
Description: Code used to analyze the phylogenetic relationships between physiology (e.g., flight metabolic rate), morphology (e.g., body mass, thermal conductivity), and behavior (e.g., flight kinematics) across clades of bees.
File: Andrena_Bombus_FTS.R
Description: Code for calculating, analyzing, and visualizing the field thermal stability of Andrena versus Bombus bees.
File: PGLS_CWC_mass.R
Description: Code used to analyze the phylogenetic relationships between physiology (e.g., critical water content) and morphology (e.g., body mass) across clades of bees.
File: bee_tree.nwk
Description: Super-matrix phylogeny of the world's bees (generated from the Bee Tree of Life; beetreeoflife.org).
File: lit_review_mass.WBF.FMR.csv
Description: Data extracted from the primary literature used for phylogenetically corrected analyses.
Variables
- Genus: Name of genus.
- Species: The genus and species name.
- Body mass (g): Body mass in g.
- FMR (mL h-1): Flight metabolic rate in mL of gas per hour (either from VCO2 or VO2 values, standardized assuming carbohydrate catabolism and an oxyjoule equivalent of 21.164 J per mL of O2).
- spFMR (mL CO2 h-1 g-1): Mass-specific flight metabolic rate in mL of gas per hour per gram of bee.
- WBF (Hz): Wingbeat frequency in cycles per second (Hz).
- Study: The study that which the data were extracted from.
File: Thermal_stability_meta_reduced.csv
Description: Primary literature data used to calculate the field thermal stability of Andrena versus Bombus bees.
Variables
- study: The study from which the data were extracted from.Genus: The genus the bees belong tos.Speciess: The genus and species name of the bee.Castee: Defined by the role they play. Females, which reproduce, provision their brood, and do not have a worker caste to help. Queens are from social colonies and are primarily involved with reproduction, while workers provide and care fothe r closely related brood.
- Tair: Shaded air temperature in degrees Celsius.
- Tth: Thoracic temperature in degrees Celsius.
File: raw.K.data.csv
Description: Mean warming constants (k) and mass (g) values for 30 genera of bees taken from Herrera, C. M. (2024). Thermal biology diversity of bee pollinators: Taxonomic, phylogenetic, and plant community‐level correlates. Ecological Monographs, 94(4), e1625.
Variables
- species: Species name of bees measured.Genus: The genus to which the bee belongs.Family: The family to which the bee belongs.
- Number: The bee-specific identifier.Mass (g): Body mass in g.
- mass (mg): Body mass in mg.Datee: The date on which the data were collected.
- Location: The location where the bee was collected.
- Newton_K: The warming constant (k) per second.
- K_se: Standard error of the reported warming constant (k).
File: bee_tree_cwc.csv
Description: Primary literature data used to compare the critical water content (CWC) of different bee clades.
Variables
- genus: The genus to which the bee belongs.Family: The family to which the bee belongs.
- cwc: The critical water content, which is the lowest amount of body water a bee can have before physiological functions are impaired, expressed as mass of water divided by hydrated animal wet mass.Mass.mg: Body mass in mg.Mass.g: Body mass in g.Reference: The study from which the data were extracted from.
File: Reflectance_C.caesalpinae_Fig.5B.csv
Description: These are original, unpublished data. Reflectance as a function of wavelength for an unshaved abdomen and thorax of the same bee (n = 1).
Variables
- wavelength_nm: The wavelength at which measurements were taken.
- bee1unshavedabdomen: The reflectance (%) of the bee's unshaved abdomen.
- bee1unshavedthorax: The reflectance (%) of the bee's unshaved thorax.
File: Reflectance_C.caesalpinae_Fig.5A.csv
Description: These are original, unpublished data. The thoraxes of ten, freshly culled male Centris digger bees (C. caesalpiniae) were scanned in a Perkin-Lambda NIR-UC-VIS spectrophotometer. The thoraxes were carefully shaved with a surgical scalpel and re-scanned. Scans occurred from 250 to 2500 nm at 2 nm intervals. We calculated mean reflectance in near-infrared, visible, and ultraviolet bands.
Variables
- bee_id: Identifier. Status: Either shaved or unshaved, meaning the setae were shaved off or left intact.Spectrum: The range of light at which the bees were measured. For this study, measurements were made within the following ranges: nir = near-infrared (700 - 2,500 nm), vis = visible (450 - 700 nm), and UVv = ultraviolet (250 - 450 nm). Reflectance: The reflectance (%) of the bee's shaved or unshaved thorax.
File: Table1CorrelationData.csv
Description: Correlation data for different metrics of thermal performance and response.
Variables
- endothermic index: The maximum thoracic temperature (Tth) minus operative temperature (Top) of flying bees.Thermal stability: One minus the slope of thoracic temperature (Tth) vs shaded air temperature (Tair) of flying bees.Minimum air temperature for flight: The lowest air temperature at which a bee has been observed flying.Minimum thorax temperature for flight: The lowest thoracic temperature at which a bee has been observed able to fly.Maximall air temperature for flight: The highest air temperature at which a bee has been observed flying.Maximally thorax temperature for flight: The highest thoracic temperature at which a bee has been observed able to fly.
- CTmax: The highest body temperature the bee can tolerate before losing normal function, such as coordination or the ability to escape.
File: Supplementary_table_to_support_Table_1.csv
Description: Data extracted from the primary literature, used to calculate thermal metrics.
Variables
- Family: subfamily: tribe: The family, subfamily, and tribe to which the bee belongs.Total species in the clade: The total number of species in the clade.
- # species studied: The number of species that have been studied to date. Speciess if one: The name of the genus and species if only one species has been studied thus far.Labb endothermic index (max Tth - Top, oC): The calculated endothermic index [i.e., the maximum thoracic temperature (Tth) minus operative temperature (Top)] of bees flying in laboratory settings.Field endothermic index: The calculated endothermic index [i.e., the maximum thoracic temperature (Tth) minus operative temperature (Top)] of bees flying in the field.Field thermal stability: One minus the slope of thoracic temperature (Tth) vs shaded air temperature (Tair) of flying bees measured in the field.Lab thermal stability: One minus the slope of thoracic temperature (Tth) vs shaded air temperature (Tair) of flying bees measured in the laboratory.Field's lowest flight air temp, oC: The lowest air temperature at which a bee has been observed flying in the field.Labb lowest flight air temp, oC: The lowest air temperature at which a bee has been observed flying in laboratory settings.Field's lowest flight Tth, oC: The lowest thoracic temperature at which a bee has been observed being able to fly within the field.Labb lowest flight Tth, oC: The lowest thoracic temperature at which a bee has been observed being able to fly within laboratory settings.
- Field highest flight air temp, oC: The highest air temperature at which a bee has been observed flying in the field.Labb's highest flight air temp, oC: The highest air temperature at which a bee has been observed flying in laboratory settings.Field's highest flight Tth, oC: The highest thoracic temperature at which a bee has been observed being able to fly within the field.Labb highest flight Tth, oC: The highest thoracic temperature at which a bee has been observed being able to fly within laboratory settings.
- Ctmax mean: The average reported CTmax value in degrees Celsius.
- Ctmax range: The range of reported CTmax values in degrees Celsius.
- Notes: Specific notes regarding the study or studies.
- Reference number: Arbitrarily assigned number to each reference.
- Reference: The reference the data were extracted from.
Code/software
Scripts are described above.
Most of our data were analyzed and visualized using R (v. 4.5.0), with two being analyzed and visualized using GraphPad Prism (v. 10.4.1).
R-packages are listed in the supplemental references (supplementary materials of the original published article).
Access information
Other publicly accessible locations of the data:
- The primary literature data can be found in its original publications.
- New data presented here cannot be found anywhere else.
Data was derived from the following sources:
- See the supplementary materials for the references where the data were sourced.
The table-1 presents clade-level variation in the thermal biology of bees, which was created by searching scholar.google.com and Web of Science using relevant keywords such as: bees, temperature, thermal, flight, activity, foraging, CTmax, and thermal limit. Many of the references were not found through web searches, but rather by investigating the bibliographies of in-hand papers. We are sure that additional relevant papers exist, but feel that it is very likely that the papers found and used will provide representative numbers for each parameter. Clades were based on Henriquez-Piskulich et al. 2024. To indicate the approximate number of species per clade, we relied on Danforth et al. 2019. To indicate the number of species in the clade whose flight thermal biology has been studied, we summed the number of species whose data contributed to Table 1. The endothermic index (thorax temperature – operative temperature) was taken from papers that directly measured minimal air and thorax temperatures for flight or from the largest thorax and air temperature differential for lab studies. We did not include field data for the thorax and air differential, as bees in cool conditions routinely raise their body temperatures by solar basking, so such data do not provide a good index of endothermy (Herrera et al. 2023). Thermal stability was calculated as (1 minus the slope of thorax temperature on air temperature), including for bees measured in either the field or laboratory, as surprisingly, thermal stability appeared similar for bees measured in both conditions, and there were some clades for which we lacked field data (Supplementary Table 1). Many studies reported these values directly. Herrera et al. 2023 and Herrera 2024 did not usually report clade-level slopes of thorax on air temperature, so we calculated these using linear regressions in Excel and the provided online data for these studies. The lowest and highest air temperatures and thorax temperatures at which bees could fly were calculated by pooling studies, which explicitly attempted to measure these in lab conditions and field studies that reported that they attempted to assess the full breadth of temperatures at which their target bees. If the study did not report these values explicitly, they were estimated from the presented figures. There were many more studies assessing minimal air temperatures for flight than maximal. For Herrera et al. 2023 and Herrera 2024, which provided raw data online, we assessed minimal and maximal air and thorax temperatures for each clade studied. CTmax data were mostly taken from Johnson et al. 2023, who recently compiled such data for pollinators, with the inclusion of a few new relevant studies. For each parameter and clade, we reported the median and range in Table 1.
We used the data in Table 1 to test for correlations across bee clades between degree of endothermy and thermal stability during flight, the lowest air and thorax temperature for flight, the highest air and thorax temperature for flight, and CTmax. We used Prism 10.5 for macOS for statistical analyses. All variables passed the Kolmogorov-Smirnov normality test, so we used Pearson's r to test for significant correlations.
