Pollen-Microbe Interactions in Nectar Weakly Influence Bee Foraging Behavior

Area of Science:

• Ecology
• Microbiology
• Behavioral Ecology

Background:

• Floral microbes, including bacteria and yeast, commonly inhabit nectar.
• Nectar microbes can interact with pollen, potentially altering nutrient availability for pollinators.

Purpose of the Study:

• To investigate the impact of nectar microbes (yeast Metschnikowia reukaufii, bacteria Acinetobacter nectaris) on pollen germination and bursting.
• To determine how these pollen-microbe interactions affect bumble bee (Bombus impatiens) foraging behavior.

Main Methods:

• Artificial nectar experiments were used to assess pollen germination and bursting in the presence of microbes.
• Bumble bee foraging behavior was observed in response to nectar treatments with varying levels of pollen and microbial contamination.

Main Results:

• Both yeast and bacteria reduced intact pollen, with bacteria causing the most germination and bursting.
• Bees did not show altered flower preference or constancy towards microbe-contaminated nectar.
• Bees significantly rejected flowers with nectar contaminated by pollen and yeast, or pollen, yeast, and bacteria.

Conclusions:

• Pollen-microbe interactions in nectar may have limited direct effects on pollinator preference and constancy.
• Floral nectar contamination by microbes and pollen can lead to nectar rejection by pollinators.
• These findings contribute to understanding plant-pollinator ecology and the role of microbial communities.