It's been a bad few years for bees.
Colony collapse disorder, in which a colony or a colony's worker bee population mysteriously dies off, continues to vex scientists and claim more and more hives. A third of managed bees are dying every year, and the number of managed hives has fallen from 6 million in the 1940s to 2.5 million today. It's troubling not just for the loss of bees, but for the loss of our most able pollinators: Bees are crucial to maintaining crops and producing food, and as bees die off the remaining commercial bees are asked to travel farther, pollinate more crops, and, in the process, risk exposure to more chemicals, pesticides, and other potentially dangerous irritants. It's a vicious cycle indeed.
In addition to pesticides, mites, and poor nutrition, there's a new problem: Diesel fumes can confuse bees' sense of smell, making it harder for them to find food. A team of British scientists think bees might be starving to death in part because of diesel, a fuel with a bit of an image problem at the moment.
Bees largely rely on their sense of smell to find food, following their noses to find flowers. Researchers at the University of Reading and the University of Southampton found that the nitrous oxide in diesel fumes, which is toxic to humans, can chemically alter five of the 11 most common compounds within flowers. With their scent changed, flowers are harder to find for the bees, who can then starve.
Researchers don't think that diesel alone is killing off bees, but it is rather part of a toxic cocktail along with pesticides, mites, habitat destruction, climate change, and other problems that together lead to colony collapse disorder.
"Our research highlights that a further stress could be the increasing amounts of vehicle emissions affecting air quality," said the aptly named Guy Poppy, co-author of the new study published in the Journal of Chemical Ecology. "Whilst it is unlikely that these emissions by themselves could be affecting bee populations, [when] combined with the other stresses, it could be the tipping point."
The authors make a case for working toward better air quality, not just for the sake of the bees but also for people's health and the economy. In China, for example, poor air quality is expected to take 2.5 billion life years from 500 million people in the coming years. While the cost of poor air quality in total would be staggering, if hard to calculate, in the United States we can put a number on what would be lost if bee pollination was no more. The situation is serious enough that the White House issued a report on the economic challenge posed by declining pollinator populations, saying honey bees contribute $15 billion to the economy. Wild pollinators such as bumblebees and alfalfa-cutter bees chip in another $9 billion. Globally, 87 of the leading 115 food crops the White House studied are dependent on animal pollinators, counting for 35 percent of the world's food.
With bee populations dwindling, researchers continue to try to get to the bottom of what's killing them en masse. An unexpected faint ray of hope: a naturally occurring pesticide in hops, the flowers that give us beer, has been effective in repelling varroa mites, which are bees' public enemy number-one.
Beer, as usual, may be our hero.