CORVALLIS, Ore. — The solution to a huge problem may be hiding in the minutia of labs like this one at Oregon State University, where researchers examine the period-size brains of honey bees, test their blood and grind their guts for inspection under a microscope.
They’re looking for signs of parasites, viruses or nutritional lapses that may help explain colony collapse disorder.
Ramesh Sagili, who leads the OSU research effort, believes there is no single “smoking gun” cause of CCD. Instead, he and most other researchers say a combination of factors is most likely to blame.
Parasitic Varroa destructor mites top the list, because they weaken bees and make them susceptible to viruses and other problems. Other factors include pesticide use, mono-crop diets, loss of natural forage due to agricultural plantings or development, climate change, drought, the stress of travel and poor hive management.
“I still believe it’s a perfect storm” of combined factors, Sagili said.
But the lack of a definitive answer, eight years after CCD was discovered and despite millions spent on multiple research projects, has left the door open for claim and conjecture by activists and conspiracy theorists. Cell phones, solar flares and government antenna arrays have all been blamed. Environmentalists point to the sins of “Big Ag,” especially pesticide use and mono-cropping.
The stakes are extremely high. An estimated one-third of the world’s food supply depends on the work of pollinators, and commercial beekeeping services are especially critical to U.S. producers.
California’s almond crop alone requires about 1.6 million colonies, more than 60 percent of the nation’s commercial hives. Many beekeepers from Oregon, Washington and Idaho truck their hives south in February and work their way north, moving crop to crop as berries, nuts and fruit come into season.
Colony losses nationwide ranged from 28 percent to 33 percent from 2007 to 2011, double or even triple the historical rate for over-winter hive loss. Experts say such losses are economically unsustainable.
Sagili believes proper nutrition is crucial to bee health, just as a good diet helps us stave off sickness. Bees transported from crop to crop are subjected to an unrealistic diet, he said.
Bees working California’s almond orchards, for example, are limited to “nothing but almonds” within the three-mile radius of their forage range. Almond blossoms are a good source of protein, but bees need more diverse fare, he said.
There is no doubt pesticides harm bees, Sagili said, but studies about their impact have been flawed. In some cases, a link to CCD was proclaimed after bees were subjected to unrealistic pesticide doses, he said.
Some activists have called for a ban on the use of neonicotinoids, a class of pesticides commonly used to coat the seeds of food crops before planting. The U.S. Fish and Wildlife Service recently announced it would quit using neonicotinoids on its refuges in the Pacific Northwest and Hawaii.
Sagili agrees pesticides deserve continued study, especially on the “sub-lethal” effect of exposure.
“They are a contributing factor for sure,” he said, but finding a realistic concentration to test is a difficult challenge, because foraging conditions in the field vary greatly from controlled lab settings.
A 2012 USDA report made note of that, saying it “remains a challenge to measure the effects of low-level, field-relevant exposure where it matters most: in real honey bee colonies. The social complexity of honey bees and the uncontrollable aspects of field research present substantial challenges to determining pesticide effects in whole-colonies.”
An OSU experiment attempts to account for that: Forty hives have been set up at an OSU-owned research field, and the bees are allowed free flight and to forage in a natural manner. But the hive boxes contain a tight opening called a pollen trap, which knocks off most of the pollen bees are bringing back to the colony. Researchers have replaced the pollen with food containing varying levels of pesticide or fungicide. After a month’s exposure, the bees will be checked for health problems.
Bees have a high degree of communal intelligence, however, which complicates the work. Sagili said foraging bees learn to bring back smaller loads of pollen so they can evade the pollen traps. In that case, researchers have to open the hives and remove the natural food by hand.
Sagili and other researchers put Varroa mites at the top of their list of bees’ problems. The USDA has labeled Varroa mites the “single most detrimental pest of honey bees” and says it is “closely associated” with colony declines. Sagili calls them a “huge, huge concern.”
“If you can control Varroa, you can improve honey bee health 70 to 80 percent without doing anything else,” said Jerry Hayes, a researcher who directs Beeologics LLC, a biotechnology firm purchased by Monsanto Co. in 2011.
He and others describe Varroa destructor mites in graphic terms. Make a fist, Hayes said, and hold it to your chest. That’s the relative size of the mite to its host.
“It’s a big, big parasite,” Hayes said. “It’s like you having a parasitic rat on your chest.”
“It’s like you and I walking around with an orange on our back,” offered Dan Cummings, a beekeeper and almond grower in Northern California. “It’s such a burden to the bees. It feeds on the bee and is a vector for other viruses.”
Treating for it is no easy matter — “Imagine trying to kill an insect on an insect,” Cummings said — but a new biotechnology approach spearheaded by Monsanto has caught the attention of researchers.
It’s called RNAi, or ribonucleic acid interference. In the body, RNA is the messenger system, delivering DNA instructions to cells. But a double-stranded form of RNA can “silence” or turn off specific genes. It can shut down parasites, and in the lab has achieved 50 percent Varroa reduction
Hayes, a former apiary inspection chief with the Florida Department of Agriculture, was hired by Monsanto two years ago to direct the work.
“The research is zooming forward, but you never know when you’ll hit a hurdle or hit the wall,” Hayes said. “It has a lot of potential.”