UHPLC–QTOF MS Maps Honeybee Heat Stress Chemistry

Sudden exposure to high temperatures puts stress on worker honeybees, but scientists still don’t fully understand how their body chemistry responds or how their diet might affect that response. To find out, researchers fed worker bees one of two diets for a week: either bee bread (pollen that bees store and ferment in the hive, their main source of protein) along with sugar water (B + S), or sugar water alone (S). The bees were then either kept at a normal hive temperature of 37 °C or exposed to 45 °C for three hours. Afterward, the researchers analyzed the small molecules in the bees’ middle and rear body sections using ultrahigh-pressure liquid chromatography–quadrupole time-of-flight mass spectrometry (UHPLC–QTOF MS) to get a broad picture of the chemicals present. A paper based on their findings was published in the International Journal of Molecular Science.¹

How Does Diet Affect the Way Honeybees Cope with Heat?

How well-fed a honeybee is likely affects how its body responds to stress. Bees with access to good-quality flowers seem to cope better with heat, and the amount of protein and fat in the pollen they eat affects how well they handle other kinds of stress; at the same time, extreme heat can make pollen less nutritious in the first place ^2-4 On top of this, the quality of a honeybee’s diet changes how the genes involved in its metabolism and immune system respond when it is suddenly exposed to heat.⁵ “Thus,” write the authors of the paper,¹ “the metabolic consequences of heat should be considered in the context of the nutritional resources available before and during the thermal challenge.

What Gap in Knowledge Did This Study Set Out to Fill?

Previous studies looking at the chemistry of honeybees have shown how their bodies respond to eating pollen, and that sudden exposure to hot, humid conditions changes their levels of sugars, sugar alcohols, and free amino acids.^6,7 “However,” write the authors of the paper,¹“studies explicitly aimed at identifying acute heat-responsive metabolic markers across contrasting nutritional conditions remain limited, particularly at the whole-body untargeted-metabolome level.”

How Was the Study Carried Out, and What Did It Reveal About How Diet Shapes the Worker Bees’ Chemical Response to Heat?

For each combination of diet and temperature, the researchers set up three separate cages. They pooled 15 worker bees from each cage into a single sample, giving three samples per group.¹

To identify the molecules they detected, the team matched each one’s precise mass and isotope pattern against two large reference databases, then checked the matches by hand. Because they didn’t confirm these identities with additional fragmentation analysis or by comparing them with pure reference compounds, the identifications are considered tentative. After filtering the data statistically and removing results that didn’t make biological sense, they were left with 149 molecules that responded to heat in the B+S diet group and 123 in the S diet group.¹

The researchers then went back to the same raw data and looked specifically for the amino acids that make up proteins. They found 16 that appeared in every sample. When the temperature was raised to 45 °C, 15 of these went up in both diet groups, while one, proline, went down. For 14 of the 16, the change was bigger in the B+S group.¹

Of all the processes examined, those involving the amino acid phenylalanine stood out most clearly. They showed up consistently across three different lines of evidence: the targeted amino acid analysis, the broader search that detected a related compound called phenylpyruvate, and a database analysis of which biological pathways were most affected. The two diets also appeared to affect fats differently. In the B+S group, heat tended to lower levels of free fatty acids, while in the S group it tended to lower levels of the fats that make up cell membranes.¹

“These findings,” write the authors of the paper,¹ “define coordinated metabolic markers of acute heat exposure in worker bees and show that, within the targeted amino-acid dataset, response magnitudes were generally larger under B+S while retaining the same overall direction.”

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References

1. Jang, H.; Kim, H.; Frunze, O. et al. Metabolomic Profiling Reveals Heat-Responsive Metabolic Markers in Honey Bee Workers Under Contrasting Diets. Int J Mol Sci. 2026, 27 (20), 9237. DOI: 10.3390/ijms27209237
2. Vanderplanck, M.; Martinet, B.; Carvalheiro, L. G. et al. Ensuring Access to High-quality Resources Reduces the Impacts of Heat Stress on Bees. Sci Rep. 2019, 9 (1), 12596. DOI: 10.1038/s41598-019-49025-z
3. Crone, M. K.; Grozinger, C. M. Pollen Protein and Lipid Content Influence Resilience to Insecticides in Honey Bees (Apis mellifera). J Exp Biol. 2021, jeb.242040. DOI: 10.1242/jeb.242040
4. Walters, J.; Fisher, R.; Sharkey, T. D. et al. Extreme Heat Affects Blueberry Pollen Nutrition, Bee Health, and Plant Reproduction. Sci Rep. 2025, 15 (1), 6249. DOI: 10.1038/s41598-025-90676-y
5. Kim, H.; Frunze, O.; Han, S. M. et al. Diet Quality Shapes Metabolic and Immune Transcriptional Responses of Honey Bees Under Acute Heat Stress. Insects 2026, 17 (8), 780. DOI: 10.3390/insects17080780
6. Chang, H.; Ding, G.; Jia, G. et al. Hemolymph Metabolism Analysis of Honey Bee (Apis mellifera L.) Response to Different Bee Pollens. Insects 2022, 14 (1), 37. DOI: 10.3390/insects14010037
7. Li, X.; Ma, W.; Jiang, Y. Honeybees (Hymenoptera: apidae) Adapt to the Shock of High Temperature and High Humidity Through Changes in Sugars and Polyols and Free Amino Acids. J Insect Sci. 2023, 23 (1), 4. DOI: 10.1093/jisesa/iead002