Decline in US bees linked to biofuel production, study says

The decline of bee populations remains one of those niggling fears at the back of everyone's mind in many ways. Now the first national effort to map the numbers of wild bee populations in the United States has shown that the decline is particularly severe in farming areas, bringing back those fears for conservationists and farmers alike.

Wild bees declined by up 200% in areas where land was being converted for biofuel

Wild bees declined by up 200% in areas where land was being converted for biofuel Image by Crabchick / CC BY 2.0

The new study suggests that bee numbers dwindled across almost a quarter of the US between 2008 and 2013. One of the key reasons for the decline is the conversion of land to grow corn for biofuels. Researchers estimate that wild bees contribute significantly to US crop production, which brings in an annual combined $3 billion. If the conversion of land to biofuel sites continues, it would threaten the wild bees and thereby US crops.

The study shows that between 2008 and 2013, bee populations declined by 23%  in vital agricultural regions such as California, the Midwest, the Great Plains states and across the Mississippi River valley. The study goes on to correlate the rise in biofuel areas with the decline of bees, proving that in selected areas where land had been turned over to grow grains and corn for biofuel, the bee populations suffered a shocking 200% decline.

The demand for biofuel increased when the US passed a law demanding that all gasoline sold should contain at least 10% ethanol, which is mostly made from corn.

Professor Taylor Ricketts from the University of Vermont who worked on the study, told The Guardian, "The pattern we show is consistent with the expansion of corn for ethanol, the reduction of areas around fields that weren't cultivated before." He went on to add,"If you look at the maps, the places that show the lowest abundance is essentially a map of intensified agriculture in the US."

So, ironically, while demand for crops is increasing (crops such as blueberries, pumpkins, watermelons) the pollination numbers are declining.

A honey bee pollinating a Wild Pennyroyal

A honey bee pollinating a Wild Pennyroyal Image by Bob Peterson / CC BY 2.0

The study goes on to argue that the fall in wild bees numbers will lead to farmers' increasing dependency on  commercial honey bee operators. These are bee-keepers with beehives for hire that travel around the country hiring out colonies for pollination.

But even commercial bee-keepers fail sometimes, and they are not seen as a  long-term solution to the problem.

Barack Obama made a memorandum about honey production and the state of health of the American wild bee in 2014, when news of  declining bee numbers first started to make headline news. The scientists behind this research are hoping it may help to find  the seven million acres that the White House is seeking to protect as pollinator habitat over the next five years.

Related content