A small laboratory just off North Campbell Avenue could be a key site in the fight to solve a terrifying phenomenon: the mass disappearance of honeybees needed to pollinate America’s crops.

But whether the Carl Hayden Bee Research Center is uncovering the most likely causes of so-called colony collapse disorder — that turns out to be a complicated question.

I found this out as I blindly felt my way into the national discussion of the disappearance of honeybees from their hives, a problem that emerged in about 2006 and remains unsolved today.

The reason to care is simple: Commercial beekeepers play an essential role in our food system. They drive thousands of hives around the country, farm to farm and state to state, letting bees loose to feed on crops’ pollen or nectar. Those bees fertilize the crops, allowing the edible part of the plants to grow.

Without commercial beehives, much of our agriculture would be impossible.

On Friday, the White House issued a “federal strategy to promote the health of honey bees and other pollinators.”

Having been clued in to the existence of the bee research center by a local bee hobbyist, I visited research leader Gloria Degrandi-Hoffman at the laboratory on Tuesday to ask about the center’s research. The Carl Hayden center, at 2000 E. Allen Road, is one of three U.S. Department of Agriculture bee research centers in the country, and employs seven researchers.

The center focuses, she told me, on varroa mites and the nutrition of bee colonies as possible factors in the collapse of bee colonies. That disorder, she explained, “is a syndrome.”

“It’s a culmination of various stress factors that come together,” she said. “In my opinion, the varroa mites and poor nutrition are really key.”

Varroa mites arrived in the United States in the 1990s, and can devastate hives.

What Degrandi-Hoffman does not emphasize in her discussion and the center’s research is a factor that many others have accepted as the key cause of colony collapse disorder: insecticides, especially substances called neonicotinoids.

“There is evidence that neonicotinoids can affect (bee) behavior,” she told me. But research has shown, she said, “the effects on honeybees are inconsistent. The jury’s still out.”

Among beekeepers, that’s not the case. Their jury is back, and they’ve found insecticides guilty of causing their hives to empty out.

I found this out by asking Degrandi-Hoffmann for the names of a couple of Arizona beekeepers I could contact. She suggested I call Rick Smith of Yuma, a commercial beekeeper who travels the West with his hives, and Fred Terry of Oracle, a producer of honey and other bee products.

In January 2008, Smith lost 83 percent of his hives to colony collapse disorder, but he’s kept on, trying to avoid the most damaging pesticides.

He told me via email, “The USDA states that bee decline is caused by a number of factors which include, Varroa mites, diseases (both bacterial and viruses), pathogens, nutrition (which includes forage and supplemental feeds) and, lastly pesticides. From the beekeeping industry’s perspective, USDA down plays the role of pesticides.”

This is evident in the USDA Agricultural Research Service’s Web page on colony collapse disorder, which describes the service’s “research directions.” They are listed as (1) pathogens such as certain viruses; (2) parasites such as mites; (3) management problems such as overcrowding of apiaries; and (4) environmental stressors such as scarcity and lack of diversity in nectar and pollen.

As a subpoint to No. 4, the website says, “Stressors also include accidental or intentional exposure to pesticides at lethal or sub-lethal levels.”

Terry, who sells his honey at the St. Philips Plaza farmers market on Sundays, has not had any problems with colony collapse disorder, he told me. The apparent reason: He doesn’t move his bees anywhere or use them to pollinate crops. He looses them on the wild national forest land adjacent to his home where they feed off the pollen of saguaro cactus, mesquite trees, catclaw acacia and other desert plants.

Terry also blames colony collapse disorder on agrochemicals and says, in the United States, the commercial interests of the the pesticide makers influence science more than in Europe. In December 2013, the European Union began a two-year ban on three pesticides containing neonicotinoids out of concern they are destroying honeybee colonies.

Smith recommended I speak with David Hackenberg, a Pennsylvania beekeeper who was one of the first to experience collapsed colonies and one of the industry’s leaders. He has known Degrandi-Hoffman and other USDA researchers for decades.

“Big ag controls USDA,” Hackenberg told me from the office of a vast blueberry operation in Maine. “Big ag is controlled by the chemical and seed companies.”

One of the complications with assessing blame for the disorder is the way modern systemic insecticides work, he explained. In the old days, if a bee colony were killed by chemicals, you would find lots of dead bees. Newer, systemic insecticides work their way into the plants and can sicken or otherwise harm bees without killing them, he said.

When Hackenberg first experienced colony collapse in fall of 2006, he was at a Florida field with his hives, and discovered something was wrong.

“All of a sudden I realized, there was nobody home. I started jerking covers, and there wasn’t anybody there. They (the hives) were empty,” he said. “If there were dead bees they would be on the ground. But they weren’t there.

“I had 400 hives and you couldn’t find enough bees to fill a good size coffee can.”

Beekeepers point to the research of a Harvard professor named Chensheng Lu, published in May, as showing what USDA seems reticent to pursue. Lu took a set of 18 hives, gave 12 of them food that contained neonicotinoids, and left the others untreated with chemicals.

Of the 12 treated hives, six emptied out in the winter months, suffering from colony collapse disorder. The six surviving colonies were heavily depleted. Only one of the untreated hives experienced problems, and it was full of bees killed by a common parasite.

I spoke with Lu Wednesday, and he told me he thinks varroa mites and bee nutrition are beside the point, because mites don’t cause bees to leave their hives and beekeepers can treat their hives for mites, as well as employ better nutrition. In his study, the 18 hives had the same levels of mite infestation, so that was not the likely cause of the 12 collapsed and depleted colonies.

“If you’re a doctor taking care of a patient, you rule out one thing at a time,” he said. “We tried to rule out all other possible causes.”

His conclusion: Neonicotinoids are the cause.

Bayer Corp., the primary maker of neonicotinoid-based insecticides, called his study “seriously flawed” and went on to say it “represents a disservice to genuine scientific investigation related to honey bee health.” Their chief critique was that the levels of insecticide he put in the bee food were higher than what bees would likely find in real-world situations.

The USDA and the Tucson lab are not averse to considering the impact of pesticides. The lab’s current five-year plan, which started in February, focuses on the impacts of pesticide and nutrition problems on honeybee colonies.

But so far Degrandi-Hoffman remains skeptical, pointing to a recent study reviewing all the research, other than Lu’s study, on neonicotinoids and colony collapse disorder.

“To say that the neonicotinoids are doing the damage — there’s no consistent evidence of that.”

After talking with the beekeepers, I’m concerned that the demands for ever more evidence just serve to delay the inevitable federal action — banning neonicotinoids, and perhaps other insecticides, to save bees.

Certainly we’d have a better chance at coming to a solid conclusion if the USDA and its labs would stop circling around the issue and take it on directly.

Contact columnist Tim Steller at tsteller@azstarnet.com or 807-7789. On Twitter: @senyorreporter