Sleep deprivation affects how a person feels and behaves, and it also impacts how that person can communicate with others. Is the same true for animals? If an animal that lives in a social system (where each animal relies on those in its pack, tribe or hive) experiences sleep deprivation, does that affect its ability to socialize with those around it?
For honey bees, the answer turns out to be "yes" according to research to be published this week in the PNAS Early Edition. If you force a honey bee to pull an all-nighter, that honey bee has trouble telling her sisters where to find food.
Exactly how does one keep a honey bee up all night to test this theory? Dr. Barrett Klein and his research partners developed a magnetic machine they dubbed the "insominator". They stuck a small iron tag onto the backs of some bees, then ran the insominator up and down the hive's frames. The magnets on the insominator attracted the iron tags on the bees, jostling them awake, if they'd managed to fall asleep in the first place.
Sleepless or not, when the sun rose most of the iron-tagged bees left the hive in search of food. Klein's team had already trained these bees to fly to a bee feeder 1 kilometer (just about 2/3 of a mile) from the hive. When the sleep deprived bees returned to the hive, the researchers videotaped how they told their sisters about the location of the feeder. The foraging bees got the distance (1 kilometer) right, but they erred on the direction by an average of about three degrees, theoretically sending their hive mates to the wrong location. (Watch a video of the sleep deprived bees.)
Does this faulty map mean fewer bees will find the food? A three-degree error translates to a distance of just over 160 feet away from the intended flower patch. How this affects the hive overall is the next question Klein hopes to tackle.
Food for thought
- Due to the study's parameters, Klein and his colleagues did not measure the effect of a partial night's sleep on bees. "Are foragers susceptible to effects of partial sleep deprivation?" Klein muses. "Unknown."
- Farmers often rent bees to pollinate their crops (almonds and apples are two well-known examples). In a real-world example of jostling bees at night, commercial beekeepers often transport their hives from one field to another after dark. (This helps prevent the hives from overheating during the day, and insures that most bees are in the hives, not out foraging.)
Comments
My bee-keeping next door neighbor says that bee hives can be moved only a foot or two, or else miles, from their original location if the bees are to find the hive again. He moved a hive three feet to the side and the bees buzzed around the old hive location, unable to find the hive that was right next to them. Would this imply that a bee 160 feet off a nectar source she had been directed to by a sleep-deprived bee would not be able to find the nectar? Or is finding hives somehow different from finding nectar sources?
The hive location is a little bit different - all bees orient themselves to the hive and use that location as an anchor. They don't rely on other bees telling them where to find the hive. Foragers are relying on directional information told to them. When you move a hive, you remove the anchor point that all bees have learned on their own.
But you've asked the exact question Dr. Klein hopes to pursue. If the foragers go to the wrong spot, is that distance error large enough that they won't find the nectar? I suspect probably not - bees have a very wide foraging range (up to 3 miles from the hive). When they go to the bad location, they'll probably eventually find the right nectar patch. But that has cost the foragers time, and decreased their efficiency.
I would not be surprised that fully rested bees would then return to the hive and utilize the "stop" signal on their sleepy sisters (see http://www.examiner.com/northeast-beekeeping-in-national/honey-bees-warn...). While Nieh's research focused on predator warnings, I can see bees using the stop signal to prevent bad mapping from throwing all of the foragers astray.
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