Bee ‘Stop’ Signal Could Explain Colony Collapse Disorder

A team of researchers led by James Nieh, associate professor of biology and head of the Nieh Bee Laboratory, has spent the past two years recording the communicative behavior of honeybees. They discovered that bees have a specific “stop” signal used to alert other bees to the presence of danger at a food source.

According to Nieh, this discovery complements the knowledge that worker female honeybees perform a “waggle dance” to alert the rest of the hive to the exact location of food.

“We found the anti-waggle dance,” Nieh said. “We discovered that bees actually have a stop signal for danger that tells other bees when not to go to a location to find food.”

When a bee is attacked while visiting flowers to find nectar, it performs a “stop” signal at the site of the attack by pushing up its head and vibrating its tail — at the rate of 380 times a second — for a tenth of a second.

“This is different from a general alarm,” Nieh said. “It happens at the location where the bee is attacked, and it doesn’t make anything new happen. It just alerts other bees to stop going there to look for food.”

These experiments were conducted in a laboratory at the UCSD Biological Field. The bee hive was kept within an observational box, in which one glass panel was removed and replaced by a camera that recorded the various reactions of bees to different stimuli.

The bees were attacked by natural invaders, pinched and sprayed by various natural pheromones that they found distracting.

“We compared the behavior before and after the stimuli and found that honeybees created this response at the specific food site during the presence of danger,” Nieh said.

Nieh said the discovery is important because of the implications it has on understanding other organisms.

“Animals like bees and ants are considered superorganisms because the way their colony works is similar to a multicellular organism,” Nieh said. “A colony is the body, and bees are seen as the cells.”

Nieh said that, though superorganisms commonly use positive feedback reactions, there are few examples of them exhibiting negative feedback reactions — which occurs when organisms perform an action to stop operations. For example, a negative feedback reaction occurs when the endocrine system signals the pancreas to stop the production of insulin after low blood-sugar levels reach normal levels.

“This discovery is the most advanced example of negative feedback in a superorganism,” Nieh said. “I hope that other scientists consider this example as a type of negative feedback that might exist in other organisms.”

According to Nieh, this discovery could also help explain colony collapse disorder, or the disappearance of honeybees that began in 2006.

“There’s been so much concern about there being less bees to pollinate flowers,” Nieh said. “This discovery of how they signal when to stop going to a food source could go a long way toward explaining that phenomena.”

The findings will be published in the Current Bio Journal on Feb. 23.

Readers can contact Angela Chen at [email protected].