USU Ecologists Probe Bee, Plant, Microbe Interactions

Researchers study how nectar-robbing bumble bees are attracted to yeast-fermented nectar

Published on Feb. 10, 2026

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Utah State University ecologists Valerie Martin and Robert Schaeffer are studying the relationship between bumble bees, plants, and microbes like yeast. They have found that nectar-robbing bees are attracted to the volatile organic compounds produced by yeast that ferment nectar, even though this nectar-robbing behavior doesn't directly benefit the plants. The researchers believe this larcenous behavior may ultimately benefit the ecosystem by helping the bees survive and continue pollinating other plant species.

Why it matters

Understanding the complex interactions between pollinators, plants, and microbes is crucial for maintaining healthy ecosystems. While nectar-robbing behavior may seem detrimental to plants, it could have broader benefits for the overall ecosystem by supporting pollinator populations. This research sheds light on the nuanced dynamics at play in ecological mutualisms.

The details

Valerie Martin, a doctoral candidate at USU, and her faculty mentor Robert Schaeffer are studying nectar-robbing behavior in bumble bees. Nectar robbers extract nectar from flowers without providing pollination services in return. They do this either by creating their own holes in the flowers (primary robbing) or by using holes already made by other robbers (secondary robbing). The researchers suspect that nectar-inhabiting microbes, specifically yeast, may be attracting pollinators to these accessible feeding opportunities through the production of volatile organic compounds. To test this, they conducted experiments at the Rocky Mountain Biological Laboratory, where they conditioned bumble bees to either sterile nectar or nectar fermented by yeast. Their findings suggest that the yeast microbes do indeed attract nectar robbers, although the researchers believe this behavior may ultimately benefit the ecosystem by helping the bees survive and continue pollinating other plant species.

  • The research was conducted at the Rocky Mountain Biological Laboratory near Crested Butte, Colorado.
  • The researchers assembled source colonies of bumble bees from the USDA-ARS Pollinating Insects Research Unit in Logan, Utah.

The players

Valerie Martin

A doctoral candidate in the Department of Biology and the USU Ecology Center at Utah State University, who is leading the research on nectar-robbing behavior in bumble bees.

Robert Schaeffer

Valerie Martin's faculty mentor and a professor at Utah State University, who is collaborating on the research.

Rocky Mountain Biological Laboratory

A nearly century-old high-altitude biological field station in Colorado that provides an ideal setting for the researchers to conduct their pollination biology studies.

USDA-ARS Pollinating Insects Research Unit

The unit in Logan, Utah that provided the researchers with the source colonies of bumble bees for their experiments.

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What they’re saying

“Mutualism is a common example of interspecies cooperation. Scientists have long studied mutualisms between plants and pollinators, but understanding their origin and maintenance remains a challenge. Curiously, exploitative behaviors — including cheating — are rampant among mutualists and we're trying to understand why.”

— Valerie Martin, Doctoral candidate (iScience)

“Though nectar robbers may cheat the flowers from which they're stealing nectar of pollination, their larceny may ultimately benefit the ecosystem. Bumble bees require a lot of nutrition to fuel their very fast metabolism — that is, to survive. By surviving, they live to pollinate other plant species and contribute to a thriving ecosystem.”

— Valerie Martin, Doctoral candidate (iScience)

The takeaway

This research highlights the complex and sometimes counterintuitive relationships within ecological systems. While nectar-robbing behavior may seem detrimental to plants, it could have broader benefits for the overall ecosystem by supporting pollinator populations and enabling continued pollination of other plant species. Understanding these nuanced dynamics is crucial for maintaining healthy, thriving ecosystems.