We’ve all seen busy bees hard at work. They fly from one flower to the next collecting pollen to feed their offspring. As they toil to feed their young, bees are also playing a vital role in flower reproduction. While both roles are critically important, they can be in conflict with each other.
The conflict occurs when bees collect pollen to transport to their offspring. Once the pollen is collected in their transport organs, or groomed into their bodies, it is lost for flower reproduction. So how are bees able to bypass this conflict?
Previous studies suggest, based off of field observations, that flower-visiting bees have residual patches of pollen after grooming. It’s also been hypothesized that these ungroomed body parts serve as “safe sites” that transfer pollen from one flower to another.
Petra Wester a researcher at the Institute of Sensory Ecology at Heinrich-Heine-University in Germany decided to test this hypothesis with her colleagues. Her team developed two experiments: one assessed bee grooming patterns, and the other assessed whether plants contact these safe sites on bees.
This video shows a Bombus terrestris grooming after being dusted with pine pollen. You can see as the bee grooms the resulting safe sites on the rear dorsal thorax.
The researchers found that B. terrestris and A. mellifera had similar safe sites after grooming, and that these areas were less groomed by the bees’ legs. In both bee species, the waist had the most pollen, followed by the dorsal parts of the thorax and abdomen. In addition, the fluorescent dye experiment the researchers conducted showed that the flowers contacted these same safe sites, allowing for pollen deposition by the anther and for pollen uptake by the stigma.
These findings could help focus future studies on, for example, the morphological match between pollinators and flowers, as well as on strategies that both pollinators and flowers use to bypass the conflict over pollen.
The research was published in PLOS ONE.
Citation: Koch L, Lunau K, Wester P (2017) To be on the safe site – Ungroomed spots on the bee’s body and their importance for pollination. PLoS ONE 12(9): e0182522.
Image Credit: “Apis mellifera” by Petra Wester