Bees have been in decline for some time now and it is no secret to scientists and wildlife experts around the world.

A recent 40 percent decline in bee populations has been blamed on harmful pesticides and mite infestations, but researchers have now found another troubling threat that could be impacting the bumblebees' cognitive functions -- aluminum.

In a new study from Keele University and the University of Sussex, bees are now suffering from high amounts of aluminum contamination that could be the cause of debilitating cognitive dysfunction.

"Aluminum is a known neurotoxin affecting behavior in animal models of aluminum intoxication. Bees, of course, rely heavily on cognitive function in their everyday behavior and these data raise the intriguing specter that aluminum-induced cognitive dysfunction may play a role in their population decline: are we looking at bees with Alzheimer's disease?" lead researcher Chris Exley says.

For their findings, Exely and his colleague Dave Goulson tested the aluminum levels of pupae from a variety of bumblebee colonies. They found that the pupae had aluminum levels as high as 200ppm. To put that figure into perspective, aluminum levels of just 3ppm would be harmful to the human brain.

The excess aluminum has a variety of origins, according to Exely and Goulson. "Human activities such as the burning of fossil fuels resulting in 'acid rain,' intensive agriculture producing acid sulphate soils and the mining of aluminum ores to make aluminum metal and salts have all contributed to the burgeoning biological availability of this non-essential metal."

Previous research has already linked high levels of aluminum exposure to the deaths of fish in acid lakes and even low crop productivity in highly acidified soil. Now, it seems, bee populations are now also suffering the same effects.

Commercial beekeepers currently have trouble with their bee populations as well. It was estimated that 40 percent of the commercial bee population was lost over the last year.

"Importantly, commercial beekeepers appear to consistently lose greater numbers of colonies over the summer months than over the winter months, whereas the opposite seems true for smaller-scale beekeepers," says the spokesperson for the Bee Informed Partnership.

Bumblebees are social insects that live in colonies with one queen. These colonies are smaller than their smaller relatives, the honeybees, and can consist of as few as 50 individual bees. These bees feed on nectar and are an important agriculture tool for pollination, making the cause for their decline a concern for many in both the scientific and agricultural communities. Pesticides, pollutants and habitat loss along with the mechanization of agriculture have largely been to blame for the decline of bee populations across both North America and Europe.