Stress could be one of the causes linked to bee-colony collapse epidemic, a new study has shown. The decline in the number of bees could be due to changes in their behavior which, in turn, are provoked by stress.
Scientist from Queen Mary University of London have led a research study to analyze the effects of stress in bees and how such effects alter the colony. The study was carried out as an attempt to explain how changes in the social structure of the colony, due to the bees responses to stress, can lead to the failure of the colony.
This research study tries to cast some light on why the bee colonies react to different stressors in their environment by drastically dropping the number of adult bees so quickly, leading to a colony collapse. In the study, the researchers try to get an explanation by examining the social tendencies behind the collapsing of the colonies.
The scientists, accepting as a fact that bees respond to different stressors in their environment (i.e. pests, pathogens and agrochemicals) by starting foraging earlier in their life cycle, started their experiment by manipulating the demography of some colonies in order to provoke early foraging. They glued radio tags to some bees to monitor the consequences of becoming early foragers, and observed that bees that started precociously would complete less foraging trips before they died; and that the risk of them dying in their first flight increased considerably.
In a demographic model created by the experts, they explored how a high number of deaths amongst the forager bees caused workers to start foraging earlier than they should, which in turn caused positive feedback among the young bees, leading to a change in behavior that eventually causes a fatal decline in the population of the colony. The disappearance of most of the adult bees means that only food, the young and a few adults are left in the hive.
According to Clint Perry, the lead author of the study, the fact that young bees leave the hive early is possibly an adaptive behavior, consequence of a decreased number in older foragers. Young bees leaving earlier than they should means the colony is put under stress which could lead to bee colony collapse.
The findings can now explain the reasons for the quick drop in the number of bees in a colony from a social point of view. This study opens the door to exploring different approaches on how to avoid colonies from collapsing and to learn how to help them to improve their resistance.
In the last decade an average of 30 percent of bees has disappeared every year only in North America due to Colony Collapse Disorder. One of the main characteristics of such disorder is the fact that worker bees disappear, which leaves the hive with only a few adult bees. Being able to know how early bees start foraging for food can act as an indicator to the health of the colony, hence making it possible to help colonies thrive rather than disappear.
Causes of CCD are not very clear yet, it is believed a number of factors play a role in such phenomenon. Having discovered that stress may be linked to the quick collapse of bee colonies has now shed some light on the issue of CCD and may make it easier to prevent it in the future.
By Vanessa Pouso
Photo by Psycho Delia – Flickr License
Photo by Norm Hanson – Flickr License