Yeast volatiles promote larceny in bumble bee behavior

Area of Science:

• Ecology
• Behavioral Ecology
• Chemical Ecology

Background:

• Flower visitors sometimes exploit resources without providing pollination services.
• The mechanisms driving these exploitative behaviors, like nectar robbing, are not fully understood.

Purpose of the Study:

• To test if nectar-dwelling yeast mediates exploitative foraging in bumble bees.
• To investigate the role of yeast volatiles in bee behavior.

Main Methods:

• Field assays with bumble bees (Bombus bifarius, Bombus flavifrons) on inoculated and control flowers.
• Laboratory olfactometer assays to assess bee responses to yeast volatiles.
• Gas chromatography-mass spectrometry (GC-MS) to analyze nectar volatiles.

Main Results:

• Bumble bees found nectar robbing holes faster and foraged more on yeast-inoculated flowers.
• Olfactometer assays showed bees responded to volatile compounds from fermented nectar.
• Yeast fermentation significantly altered nectar scent profiles with 14 volatile compounds.

Conclusions:

• Yeast odors play a crucial role in mediating exploitative behaviors in bumble bees.
• Yeast volatiles act as reliable cues for resource presence, enhancing bee foraging efficiency.
• This interaction highlights a novel mechanism in plant-pollinator-microbe dynamics.