Stressed Out Bees Get the Blues13 June, 2011 at 20:16 | Posted in Animal welfare, Environmental issues, Nature, Science | 2 Comments
Tags: Animal welfare, environmental issues, Nature, Science
Bees are more likely to make pessimistic judgements when they are stressed, according to an article published online in Current Biology on June 2.
Humans are more likely to be pessimistic when experiencing stress, and prior research has shown that other vertebrates like dogs, rats, and birds are also more likely to make decisions reflecting negative emotions due to stress.
This new study shows that bees, which are invertebrates, are more similar to humans cognitively than previously believed.
“Bees stressed by a simulated predator attack exhibit pessimism mirroring that seen in depressed and anxious people,” said Geraldine Wright, leader of the research team at Newcastle University in the United Kingdom, in a press release.
“In other words, the stressed bee’s glass is half empty,” said first author Melissa Bateson in the release.
The researchers first trained honeybees to associate one scent with a sugary reward and a second scent with bitter quinine. The bees demonstrated they can differentiate the scents as they were more likely to extend their mouthparts toward the sweet odor.
Half of the bees were then shaken vigorously for one minute to simulate a beehive attack, while the other half of the bees were left alone. The bees were then exposed to the two scents again as well as to new scents made by combining the two.
The team found that the shaken bees were less likely than the unshaken bees to extend their mouthparts toward some of the new scents. “We show for the first time that agitated bees are more likely to classify ambiguous stimuli as predicting punishment,” the article summary states.
The researchers also found reduced levels of serotonin and other neurotransmitters in the shaken bees’ circulation systems. Imbalance in serotonin levels is believed by some scientists to cause depression in humans.
“What we have shown is that when a honeybee is subjected to a manipulation of its state that in humans would induce a feeling of anxiety, the bees show a similar suite of changes in physiology, cognition, and behavior to those we would measure in an anxious human,” said Wright.