Honey Bees Reduce Pollen Viability While Foraging

Area of Science:

• Ecology
• Botany
• Entomology

Background:

• Pollen serves dual roles: plant gametophyte and essential bee nutrition.
• Honey bees (Apis mellifera) process pollen into 'bee bread' for larval consumption, diverting it from plant reproduction.
• The viability of pollen collected by bees (corbicular pollen) during foraging is poorly understood.

Purpose of the Study:

• To determine the viability of pollen during honey bee foraging bouts.
• To understand the implications of pollen viability on the bee-pollinator mutualism, specifically the food vs. fertilization tradeoff.
• To investigate the contribution of corbicular pollen versus 'body pollen' to plant fertilization.

Main Methods:

• Observed pollen germination rates for two plant species: Allium tuberosum and Solidago rigida.
• Compared bee-collected pollen viability against fresh anther pollen, de-ionized water-soaked pollen, and sucrose solution-washed pollen (nectar substitute).
• Quantified pollen germination success across different treatment groups.

Main Results:

• Bee-collected pollen showed significantly reduced germination for both A. tuberosum and S. rigida compared to controls.
• Pollen viability was substantially lower in bee-collected samples than in pollen treated with sucrose solution.
• Pollen viability was significantly reduced during honey bee foraging activities.

Conclusions:

• Honey bees significantly reduce pollen viability during the foraging process.
• This reduction in viability explains the limited contribution of corbicular pollen to plant fertilization.
• The findings underscore the ecological importance of non-corbicular 'body pollen' in bee-mediated plant reproduction.