Reason for bee deaths a mystery after years of studies

Reason for bee deaths a mystery after years of studies

University of California Extension Apiculturist Elino Lastro Niño says no single culprit has been found that could be held solely responsible for CCD. A variety of factors appear to contribute to honeybee decline, including habitat loss, stress, parasites, invasive species, nutritional deficits, pathogens, and others.

For more than a decade scientists have been busy attempting to figure out what is killing off honeybees.
I have written about this topic more than once in this space so I couldn’t pass up an opportunity to attend a workshop in early September at UC Davis dealing in pollinator health and colony collapse disorder (CCD), the label given to the mysterious deaths of honeybees.

The workshop had a list of expert speakers including: Brian Leahy, director of the California Department of Pesticide Regulation: Nick Condos, director of the Plant Health Division of the California Department of Food and Agriculture; Michael Parrella, professor and chair of the Department of Entomology and Nematology at UC Davis; and many other impressive names and titles.

The main focus of the meeting was on neonicotinoids, a specific class of insecticides called ‘neonics’ for short.

In the past decade, researchers worldwide have studied the effects of neonics on pollinators after beekeepers reported suspicions that the products were harming honeybees and hives.

Parrella says there’s no doubt that neonics and pollinator health is controversial because there’s people lined up on the side of science, and others concerned about politics “and people are passionate on both sides.”

He said the university is working to produce science-based information so that California lawmakers can “make the best policy decisions.”

DPR’s Leahy emphasized that his agency currently works with county agricultural commissioners, producers, beekeepers, and others to develop and implement regulatory ways along with voluntary methods to help protect bees.

He noted the obvious importance of maintaining good pollinator health since California is the largest agricultural state in the nation with roughly 400 crops which are specialty crops that create great protection challenges.

Leahy mentioned that DPR is focused on more “benign chemistry that is target specific,” and the process involves searching for new and unique approaches in dealing with the bee problem.

Neonics key to pest control

Neonics are important to California agriculture. Condos noted that neonics are currently used to combat the Asian citrus psyllid, the Japanese beetle, and the glassy-winged sharpshooter - the latter preferring to feast on table and wine grape plants.

He says CDFA uses a variety of mitigation practices involving neonics including: establishing project boundaries, avoiding over spraying, analyzing alternatives to neonics, calculating the best times and conditions for foliar applications, covering non-target plants, and the notification of applications to farmers and ranchers.

Condos said, “Our treatments are confined to small areas. We are trying to strike a balance.”

No single culprit

I was particularly impressed with Elino Lastro Niño, Extension apiculturist, who pointed out that during the last five years bee studies have doubled across the world.

As of yet, Niño says no single culprit has been identified that could be held solely responsible for CCD. Instead, she says that a variety of factors appear to contribute to honeybee decline, including habitat loss, stress, parasites, invasive species, nutritional deficits, pathogens, and others.

She added that a 2015 study in the Netherlands found that varroa mites play a key role in winter colony loss.

'Vampire with AIDS'

On the issue of varroa mites, Nasser Dean, a panelist with Bayer CropScience, said the mite attaches itself to the back of bees, sucks their blood, and returns to hives with the bee, and then attacks other bees.

“It’s like a vampire with AIDS,” Dean said.

According to Gene Brandi with the American Beekeeping Federation, local growers could not survive without neonics. He says today’s pesticides are a big improvement over chemicals used 40 years ago, and that “the sky is falling” headlines in the media often blow the situation out of proportion.

He said, “These stories go way beyond what they should be.”

Bee populations on increase

To expand on Brandi’s point, it’s worth noting that, according to the latest report from the Food and Agricultural Organization of the United Nations, worldwide bee populations have steadily increased over the past decade and hit a record high dating back to 1961.

Europe and the U.S. are at record highs since neonics first came on the market in the mid-1990s.

To take this bit of good news farther, the U.S. Department of Agriculture reported bee deaths have dropped nearly 25 percent over the past two winters and the overall population has increased 17 percent since 2008.

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Plus, the Department announced in March that honey production, which had been disrupted after CCD devastated the bee population nine years ago, continues to improve - up 14 percent. The total number of hives also increased again, by 100,000 or 4 percent, compared to the two previous years.

Lastly, beehives regenerate quickly in the summer so normal winter losses don’t necessarily translate into declining bee populations. This is why initial news reports should not be taken at face value, as many news reporters have a bad habit of doing.

In fact, overwinter losses in the U.S. are now just a few points above the 18.9 percent average losses considered acceptable by beekeepers, according to USDA’s Bee Informed Partnership, which runs the annual survey.

CCD complex puzzle

Returning to the UC Davis workshop, there was an overall consensus that the honeybee mystery is a “complex” and “challenging” puzzle which requires more examination to sort out the exact cause.

Not to put too fine a point on it, but it bears repeating that at this time bee experts can’t put their finger on one particular culprit and suspect a myriad of contributing factors. So don’t be swayed by alarmist headlines demanding a ban on neonicotinoid pesticides altogether because, quite frankly, there is no evidence to support these claims.

Apparently, those reporters would have had a different perspective had they taken the time to attend the UC Davis pollinator health workshop.

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