Much of the life of a bumblebee is spent collecting nectar and pollen from flowers. Both nectar and pollen are important recourses for bees. When a bee arrives at a flower, it collects nectar in its abdomen and pollen on its legs. A new study has shown that there is a trade-off between stability and maneuverability depending on what bees are carrying.
The team hypothesized that when bees are carrying nectar in their abdomen, the weight would be located at their centre of mass while when carrying pollen on their legs, the weight would allow greater balance but slower turning ability.
Scientists at the University of Illinois tested bee flight by attaching equal masses of simulated pollen grains and nectar to the legs of some bees and the abdomens of others. They then tested their flight and ability to land on a robotic flower in a wind tunnel under three different conditions; in an unsteady flow, while tracking the flower while it was oscillating in smooth flow, and tracking the flower while it was stationary in unsteady flow.
The team found that when bees are carrying pollen on their legs they lose much of they’re maneuverability but in turn get added stability. When nectar is carried in the abdomen, bees retain they’re ability to move quickly away from predators.
The increased stability helps the bee in situations where airflow is unsteady but the flower was stationary. While, wind was steady and the flower wasn’t however, bees carrying nectar in their abdomen had an advantage. They could use their maneuverability to safely land on the unstable flower. When there was unstable flow and an unsteady flower, the team found there was no advantage to the bees in either carrying pollen on their legs or nectar in their abdomens.
Sridhar Ravi of the RMIT University used a jumbo jet/fighter aircraft analogy to describe the trade-off. The stable jumbo jet cannot perform fast maneuvers but is very stable while fighter jets can spin and change direction quickly but is unstable. Trade-offs like this are seen everywhere in nature.
This study sheds light on the fact that resource selection may be dependent on weather conditions. On a windy day, a bumblebee may elect to gather pollen rather than nectar. This could have very important implications for the colony depending on whether the colony needs pollen or nectar.