Nectar yeasts enhance the interaction between Clematis akebioides and its bumblebee pollinator

Area of Science:

• Ecology
• Microbiology
• Plant Biology

Background:

• Plant-microbe-pollinator interactions are crucial for ecosystem function.
• The role of nectar-inhabiting yeasts (NIY) in mediating these interactions is not well understood.
• Hypotheses suggest NIY alter nectar chemistry, affecting pollinators and plant fitness.

Purpose of the Study:

• To investigate the impact of Metschnikowia reukaufii, a NIY, on the pollination ecology of Clematis akebioides.
• To determine if NIY presence influences pollinator behavior and plant reproductive success.
• To identify volatile compounds produced by NIY and their role in plant-pollinator communication.

Main Methods:

• Quantified incidence and density of M. reukaufii in C. akebioides nectar using cultivation and microscopy.
• Assessed bumblebee visitation rates and seed set in flowers with and without yeast-inoculated nectar.
• Analyzed volatile metabolites in nectar using gas chromatography-mass spectrometry (GC-MS).

Main Results:

• M. reukaufii was present in 79.3% of C. akebioides flowers at high densities.
• Flowers with NIY showed increased bumblebee visitation rates and seed set.
• GC-MS analysis identified volatile fatty acid derivatives produced by M. reukaufii.

Conclusions:

• The presence of M. reukaufii in nectar enhances bumblebee pollination of C. akebioides.
• Volatile compounds produced by NIY act as signals attracting pollinators.
• This study reveals a tripartite mutualism between the plant, yeast, and bumblebee pollinators.