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Unraveling the mystery of Colony Collapse Disorder

March 5, 2014
Bee Eye
  • Bees still under siege — new facts emerge

By Susan Johnson
Copy Editor

The scientific evidence continues to come in, and, like pieces in a puzzle fitting together, a picture of what’s behind the dreaded bee nemesis Colony Collapse Disorder (CCD) becomes clearer. It’s not pretty, and as reported in a Quartz Internet article by Todd Woody, the problem is worse than we thought.
American honey bees (apis mellifera) are a vital part of agriculture, as farmers depend on them to pollinate $30 billion worth of crops. But things have gotten so bad that one severe winter could leave fields fallow. A recent study has revealed the probable causes of bee deaths; the frightening results show that hive mortality comes from attacks on several fronts, so a single-issue solution is not the answer.
What is Colony Collapse Disorder?

Beekeepers have reported higher than normal colony losses since 2006, which have been attributed to CCD. Bee colonies may appear healthy, but then the adult bees disappear from the colonies. The Mid-Atlantic Apiculture Research and Extension Consortium (MAAREC) is the current clearing house for CCD-based information produced by the CCD Working Group, which has defined the symptoms of CCD colonies as follows:
Collapsed colonies contain no adult bees with few to no dead bees around the colony; contain capped brood; contain food stores that are not robbed by neighboring bees or colony pests. Collapsing colonies do not have enough bees to maintain colony brood; have a workforce that consists of younger adult bees; contain a queen; and are reluctant to eat food provided by the beekeeper.

Looking for clues

Over the last six years, CCD has wiped out an estimated 10 million beehives valued at $2 billion. Pesticides, disease-carrying parasites and poor nutrition have all been suspected of causing harm. But in a new study published in the journal PLoS One, scientists at the University of Maryland and the U.S. Department of Agriculture have identified a combination of pesticides and fungicides that contaminate the pollen bees collect. This helps to explain why large numbers of bees are dying, though it doesn’t identify the specific cause of CCD, when an entire beehive dies at once.
Like physicians trying to track down the source of an epidemic, researchers were able to zero in on one cause of contagion. When researchers collected pollen from East Coast hives that pollinated cranberry, watermelon and other crops and fed it to healthy bees, those bees lost significant resistance to infection by a parasite called Nosema ceranae. This parasite has been implicated in CCD, although no direct connection has been found. Eight agricultural chemicals have been associated with increased risk of infection by the parasite.
Pesticide labels warn against spraying when pollinating bees are in the area, but so far, no such precautions apply to fungicides. Meanwhile, bee populations have fallen to such a dangerously low level that it now requires 60 percent of the nation’s surviving colonies just to pollinate one California crop, almonds. This problem is not restricted to the West Coast, either. California supplies 80 percent of the world’s almonds, worth $4 million.

Recently, a class of chemicals called neonicotinoids has been linked to bee deaths. Last April, the pesticide was banned for two years in Europe, where bee populations have also suffered. But Dennis vanEngelsdorp, an assistant research scientist at the University of Maryland, says the new study shows that bee health is affected by the interaction of multiple pesticides, proving the issue is more complex than it first appeared.

The study also revealed another aspect of the problem: U.S. honey bees, which are descendants of European bees, do not collect pollen from native North American crops, but regularly visit nearby weeds and wildflowers. However, that pollen was also contaminated with pesticides, although these plants were not targeted for spraying. This suggests that possibly some of the chemicals may have drifted over on the wind, which raises the issue of how to confine them to the intended area.
What is the real cause of Colony Collapse Disorder?

In October 2010, Mike Adams wrote in NaturalNews.com about a group of biologists who claimed the mysterious phenomenon was caused by the combination of a virus and a fungus (Iridovirus and Microsporidian). However, said Adams, this explanation “completely misses the far more important question of why honey bees are suddenly more susceptible to such viral and fungal infections.” He raises the question that the Iridovirus has been around for a long time, so why didn’t honey bees get infected before this? He points to recent environmental changes as the catalyst that promoted a vulnerability to infection that is causing the major die-off. He writes, somewhat facetiously, that some scientists might even try to come up with a vaccine for honey bees while ignoring the root cause of the problem. Instead, he suggests several environmental factors that could play a part in decimating the honeybee population.

Some of these include: an increase in the number of genetically engineered crops (GMOs) that are pollinated by honey bees; more cell phone towers emitting radiation that might affect the bees; an increase in the use of chemical pesticides on crops pollinated by honey bees; increased pollution of streams and rivers (water sources for honey bees) with trace levels of pharmaceutical chemicals; increased air pollution and coal-fired power plant emissions; changes in the atmosphere that may impact the amount of solar radiation reaching honey bees; lack of genetic diversity among honey bees, creating an “in-breeding” genetic vulnerability to disease.

The MAAREC lists a number of factors that may play a part but do not positively point to any one cause. These include: Traditional bee pests and diseases (most likely not responsible for CCD but may intensify the problem); bee management (varies among beekeepers, but poor management can make any colony problem worse); queen source (queens affect genetic diversity and bee lineage; in the U.S., only a few breeder queens are used to produce queen bees, which leads to poor genetic diversity); chemical use in bee colonies; chemical toxins in the environment; genetically modified crops (many GMO seeds are dipped in systemic insecticides); varroa mites and associated pathogens; malnutrition; undiscovered or new pests and diseases.

Thinking outside the box

As farmers try to find ways to get their crops pollinated and honey bee services are increasingly spread thinner, here are some other ideas. One proposed remedy for farmers is simply to switch from using beekeepers to the use of native bees, such as bumble bees and mason bees. Native bees can be helped to establish themselves by providing suitable nesting locations and some additional crops the bees could feed from (e.g., when the pollination season of the commercial crops on the farm has ended).
A British beekeeper successfully developed a strain of bees that are resistant to varroa mites. Russian honey bees also resist infestations of varroa mites but are still susceptible to other factors associated with CCD, and they have detrimental traits limiting their use in commercial apiculture.

From the March 5-11, 2014 print edition

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