Honeybee colonies have been in a sharp decline because of a change in their hunting behavior. A study found that this decline has been mainly observed in younger bees brought on by environmental stress from pesticides or parasitic attacks. When honeybees experience stress they respond by summoning younger, inexperienced worker bees to search for food. Scientists stated these bees are more likely to die at a younger age than older worker bees who forage for food later in life. Scientists are calling this colony collapse disorder.
Although the source of the disorder remains unknown, many scientists believe it is the effect of a consolidation of many factors, including attacks from parasites leading to disease, global warming, and agricultural pesticides. Nevertheless, researchers have concluded the suddenness of a colony collapse seems to be caused by the change in foraging behavior, whereby younger worker bees disembark from the hive to scavenge for food rather than remaining in the hive to gain more experience.
Lead author of a study regarding colony collapse, Clint Perry of Queen Mary University of London, explained that younger bees leaving the hive earlier than before is probably an adaptive behavior to a decline in the number of the elder worker bees of the hive. Perry also said if the death rate among young bees continues to rise, the hive will be threatened with catastrophic consequences. The natural response to have the young bees take the place of the older bees will throw off the societal balance of the colony.
The study Perry authored was published in the Proceedings of the National Academy of Sciences. In the study, researchers attached tiny radio receivers to the honeybees of varying ages so that scientists would be able to receive data to analyze about their foraging movements outside the hive. One of the researchers explained that some younger bees completed fewer hunting trips throughout their lives and had a much higher risk of death during their first flight out of the hive.
A computerized algorithm found that as younger bees completed more foraging missions, the effect resulted in positive feedback with the variations in behavior, causing a greater number of young worker honeybees to leave the hive. Researchers explained this effect resulted in a societal breakdown within the hive, leading to a collapse of the division of labor and loss of the adult population.
Within the last decade, colony collapse disorder has contributed to a 30 percent loss per year of honeybees in North America. One of the main features of the disorder is the decimation of worker bees, leaving the hive populated only by older bees.
Perry stated his research suggests that tracking the honeybees at the time they begin to leave the hives to forage may be a good indicator of the health of the hive. Perry’s work with honeybees in North America has shown that bees react to external stressors. His research has unearthed one of the most important factors regarding colony collapse disorder and the disappearance of honeybees.
By: Alex Lemieux
Picture: Maja & Marko – Flickr License