Yeast volatiles promote larceny in bumble bee behavior

Daniel Souto-Vilarós; Valerie N Martin; Nicholas Dabagia; Drew M Freshour; Natalie Rodriguez; Jade Stryker; Oriana Gutierrez; Caitlin C Rering; Rebecca E Irwin; Robert N Schaeffer

doi:10.1016/j.isci.2026.114946

Yeast volatiles promote larceny in bumble bee behavior

iScience. 2026 Feb 7;29(3):114946. doi: 10.1016/j.isci.2026.114946. eCollection 2026 Mar 20.

Authors

Daniel Souto-Vilarós^{1

2}, Valerie N Martin^{1

2}, Nicholas Dabagia^{2

3}, Drew M Freshour^{1

2}, Natalie Rodriguez^{2

4}, Jade Stryker^{2

5}, Oriana Gutierrez^{2

6}, Caitlin C Rering⁶, Rebecca E Irwin^{2

7}, Robert N Schaeffer^{1

2}

Affiliations

¹ Department of Biology, Utah State University, Logan, UT 84322, USA.
² Rocky Mountain Biological Laboratory, Gothic, CO 81224, USA.
³ Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA.
⁴ School of Biological Sciences, University of California, Irvine, Irvine, CA 92697, USA.
⁵ Natural Sciences Division, New College of Florida, Sarasota, FL 34243, USA.
⁶ Chemistry Research Unit, Center for Medical, Agricultural and Veterinary Entomology, Agricultural Research Service, United States Department of Agriculture, Gainesville, FL 32608, USA.
⁷ Department of Applied Ecology, North Carolina State University, Raleigh, NC 27606, USA.

Abstract

The proximate mechanisms that encourage flower visitors to choose to seek benefits without conferring a service in return, such as robbing flowers of their nectar without providing any pollination, remain largely unknown. In this study, we combined field and laboratory assays with gas chromatography-mass spectrometry (GC-MS) to test the hypothesis that a nectar-inhabiting yeast can mediate exploitative behaviors displayed by bumble bees with flexible foraging tactics. In field assays, Bombus bifarius and Bombus flavifrons secondary nectar robbers discovered robbing holes 2.2 s faster on average and foraged 63% more on Metschnikowia reukaufii-inoculated flowers of both Corydalis caseana and Mertensia ciliata than on controls (or uninoculated flowers). Olfactometer assays confirmed a yeast volatile-mediated response, with nectar scent enhanced with 14 volatile compounds when fermented with yeast for 2 days relative to unfermented nectar. Collectively, our results suggest an important role for yeast odors in mediating exploitative behaviors displayed by mutualist species, acting as a potential reliable cue for resource presence and improving bee foraging efficiency.

Keywords: Ecology; Entomology.