Stress could be one of the man forces driving the decline of honeybees around the world, according to a new study.

These insects, essential for pollinating crops, have been the victims of colony collapse disorder (CCD) the last few years, although the causes behind the widespread deaths is still unknown. On average, one of every three colonies has died each year over the last five years.

Colony collapse disorder was first noted in 2006, when Dave Hackenberg, a beekeeper, noticed 400 of 2,400 beehives he inspected to be empty. Unlike most cases of bee deaths, there were no bodies, as the insects apparently completely abandoned their hives.

"I'm so stunned I can't even talk. I'm on my hands and knees crawling around looking for dead bees [in] among the stones, and there wasn't any. I mean, there was no dead bees. Three weeks ago, these bees are fine. You got a murder scene, and nobody knows what happened. There are no weapons, there are no corpses," Hackenberg said.

People in the United Kingdom began to refer to the finding as the Mary Celeste syndrome. This was the name of a merchant ship, found off the coast of the Azores in 1872, without a single passenger or crew member onboard. Other people began to call the disappearance of the insects the "bee rapture," after the prophecy in the Book of Revelation in the Bible predicting people being called to Heaven just before the Apocalypse.

Beehives involve the cooperation of the insects into an incredibly intricate social network. Study of bee colonies revealed that, as bees experience losses of their population, that network breaks down. This results in young bees leaving the hive before they have the skills to come back. In short, the youngsters are disappearing as they become stressed from the loss of other members of the colony.

Butterflies as well as bees are dying off, with a recent loss of 90 percent of Monarchs.

Many researchers believe the loss of the insects could be caused by climate change. Even the White House has expressed concern humans could be driving the creatures to extinction through the release of greenhouse gases and other chemicals that alter the environment.

"If honeybee colonies are collapsing for a reason we don't understand, what is that telling us about our overall impacts and understanding of the ecosystems on which we depend?" President Obama reportedly stated to John Holdren, assistant to the Chief Executive for science and technology.

Analysis of how stress could be affecting the disappearance of bees, and perhaps other insects, was published in the Proceedings of the National Academy of Sciences of the United States of America (PNAS).

Photo: Paul Rollings | Flickr