In new research published in the magazine Royal Society Open Science, buff-tailed bumblebee (Western bumblebee) individuals exposed to a brood-killing fungus changed their foraging habits in search of nectar containing natural antibacterial compounds, providing a glimpse of behavior consistent with self-medication in social insects.
Debeukelaere others. Bumblebee (Western bumblebee) focus on quercetin, a common nectar secondary compound with antimicrobial activity, altering nectar selection after exposure to pathogens. Image credit: Josef Pichler.
“The field of animal pharmacology studies how animals use natural compounds for medicinal purposes, such as relieving pain, fighting infections, and defending against parasites,” said Dr. Maria Pozo of the University of Valladolid and colleagues at the University of Leuven in Belgium.
“A central behavior in this field is self-medication, which refers to the ability of an organism to ingest organic compounds that stop or reduce current infections or prevent infections, despite the high cost of such compounds for healthy individuals.”
“This behavior represents a form of adaptive plasticity, in which individuals change their diet in response to pathogen pressure.”
“We expect that self-medication will primarily occur when an individual is infected, as pharmaceutical compounds are often toxic and nutritionally suboptimal, but healthy people should avoid such compounds.”
“In this study, social bees Western bumblebee self-medicated behavior when exposed to pathogens. ”
In the study, the authors used robotic flowers to track how bumblebee colonies choose between regular sugar nectar and nectar spiked with quercetin, a flavanol with demonstrated antibacterial activity against a wide range of Gram-positive and Gram-negative bacteria, fungi, and viruses.
Colonies can either remain healthy or be exposed to one of two pathogens: fungi. Acosphaera apis causing chalkbrood disease in bee progeny, or bacteria Serratia marcescens which infects the intestines of adult bees.
After a 5-day free-feeding period, colonies infected with the fungus increased both the time they spent visiting and feeding on quercetin-containing flowers as the experiment progressed.
Healthy colonies showed no such changes, and colonies exposed to bacteria did not change their preferences.
The researchers suggest that this pattern may reflect the different ways the two pathogens affect the colony.
Because chalkbrood primarily harms the larvae rather than the foraging adults themselves, the increased interest in quercetin among colonies exposed to the fungus may represent a social drug therapy in which workers collect compounds that benefit the larvae rather than themselves.
In contrast, Serratia marcescens primarily affects adult hunter-gatherers directly, and the medicinal effects of quercetin on it are likely less direct, potentially explaining why no changes were observed.
“These results show that pathogen identity shapes behavioral plasticity in nectar foraging and demonstrate the value of robotic flowers for studying adaptive foraging responses to pathogens,” the scientists concluded.
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Camiel Debeukeleale others. 2026. Tips for self-treatment? Bumblebee foraging decisions dependent on pathogen exposure. R. Soc. Open Science 13 (8): rsos260777;doi: 10.1098/rsos.260777
Source: www.sci.news
