The sudden collapse of U.S. bee colonies—-reportedly one quarter of all colonies—-has stirred fears among beekeepers across the country as well as the many growers they serve. Regionally, it appears colony collapse disorder (CCD) has struck a significant number of beekeepers, while somehow sparing others.

MaryEllen Kirkpatrick, a Northern Virginia chef and hobbyist beekeeper who spoke to me last year for a column on Zola’s honey menu, lost two of her dozen-plus colonies over the winter. But she blames the losses on cold weather, not CCD, particularly the loss of her larger colony.

“The extended cold hit and while I thought they could easily reach their stored honey or at the least the fondant (cooked sugar candy that bees can eat) that I had placed on the top bars of the hive, they could not,” Kirkpatrick wrote via e-mail. “There were no signs of disease and a lot of dead bees in the hive. [With CCD, bees never return to their hives.] I believe that they starved because they would/could not leave the young brood to reach the food in their pantry.”

“I don’t think CCD had an impact on my bees this year, judging by the classic symptoms that have been in the news and described by the CCD Working Group,” she adds.

On the other hand, Dewey Caron, an apiculture professor at the University of Delaware, says 11 of the school’s 12 colonies have been lost since last August, when Caron harvested honey and monitored for parasites. “The losses were NOT typical of winter losses but were what we describe as CCD—no dead bees (they were gone!),” e-mails Caron, a leading expert on honeybees.

“I have had winter seasons where I might have lost 25% of the University (MD or UD) colonies I care for but never this heavy a loss in the past,” writes Caron, who was an apiculture professor at the University of Maryland from 1969 to 1980. “So it was something different and it was heavier than usual.”

What’s more, Caron’s been surveying Delmarva beekeepers for years, and their bee losses have reached about 25 percent this year, he writes, which is “heavier than normal and than it should be.” Caron adds: “One of our largest beekeepers has indicted he had 350 colonies and now only 60 are healthy enough to pollinate and he, like us at UD, have noticed that the bees are not expanding this spring as they should.”

Caron notes the university, as the result of its losses, has no bees available for pollination duty. Area beekeepers, the professor says, are in a similar position: Far fewer bees to rent out for pollination, which growers rely on for hundreds of agricultural crops.

“So this is a real issue, but we have not identified exactly what is involved,” he writes. “We do not have ‘the smoking gun’ to say what exactly CCD is—the pathogen loads are very heavy in colonies showing the collapse (that is, bees have several pathogens not just single ones for example) but are they cause or effect?…We still do not know. In the past we thought such mysterious losses were nutritional but loss patterns were much more limited than this current winter.”

Researchers are looking into a number of potential culprits, including varroa mites, mite-vectored viruses, some mutated virus or bacteria, fungal infections, a new strain of protozoa that causes dysentery, environmental toxins, pesticides, bee management practices, and even malnutrition.

“Maybe there is not one cause at all, but a whole symphony—all sorts of small contributors finally overwhelming the bees. ‘Death by a thousand little cuts’ is a phrase I have heard repeated at beekeepers meetings and have read in beekeeping journals and articles,” Kirkpatrick writes.

“Certainly I am worried about the continuing welfare these creatures that I steward,” she adds. “Simply put, mankind cannot support itself without the honey bee.”