Bumblebees, which can carry impressive loads of either pollen or nectar, have been found to alter their flight characteristics depending on which they're carrying, researchers report.
When carrying nectar in a small pouch on their abdomen, their flight pattern is highly maneuverable, like a fighter jet, but when they have a heavy load of pollen, which they carry with their legs, they fly in a highly stable fashion like a cargo-carrying jumbo jet, they say.
Researchers at Harvard University and the Royal Melbourne Institute of Technology in Australia say they wanted to confirm it was the different positions of the two types of load that were affecting how the bumblebees flew.
Bumblebees can carry more than half their body mass in pollen and their full weight in nectar.
The researchers suspected their flight would be more stable when carrying pollen because it would act as stabilizing weight further from their body mass, something like a human tightrope walker carrying his long balancing pole.
Nectar, being carried closer to the bee's center of gravity, would allow it to be more maneuverable, they suggest.
They experimented with bees in a wind tunnel, using high-speed video to measure their flight characteristics with different food payloads.
The results show "there's a trade off between stability and maneuverability," says researcher Sridhar Ravi of RMIT University.
"So if something is stable it's not going to be maneuverable and if something is maneuverable it's probably not going to be stable."
Unlike honeybees, which have dedicated foraging bees for nectar or pollen, bumblebees are generalists that will collect either pollen or nectar based on what the colony most needs.
The necessary tradeoff of stability or maneuverability depending on the load carried may be why bumblebees prefer to forage for pollen on windy days, to take advantage of the flight stability it offers during windy conditions, the researchers suggest in their study published in the journal Proceedings of the National Academy of Sciences.
No matter what type of load they carry, bumblebees are known to be excellent fliers, able to keep aloft and forage in different types of weather.
Now, it seems that weather conditions may play a part in what type of food — nectar or pollen — a bumblebee chooses to go after on its aerial shopping trips, the researchers say.
