Neonicotinoid Exposure to Honeybees is Low

CLAIM: Neonicotinoids present the most significant pesticide exposure to honeybees.

FACT: Bees are exposed to much higher levels of other pesticides, including those that beekeepers use inside the hive to control mites and other disease-carrying vectors.

Worker honeybees are born in the early spring and pollinate crops for several weeks before they die. During their lifetime, they bring nectar and pollen to the hive to feed subsequent generations including the smaller number of bees that hibernate over the winter. Those wintering bees may be exposed to pesticides in the hive from pollen and nectar, which raises concerns about how those chemicals impact the hive’s health. While activists like to blame neonicotinoids for the disappearance of some the hibernating bees, little of these chemicals is actually found in the hives. Rather, trace-levels of many different chemicals appear in hives that may have some impact on hive health—to what extent is not fully clear.

For example, a 2010 study measured pesticide residues in 887 wax and pollen samples as well as bees themselves. It found traces of 121 different pesticides and metabolites of pesticides in the samples, of which neonicotinoids were among the lowest present. No neonicotinoid residues were found in bees, while 49 detections were obtained from pollen and wax. Only one sample contained a notable amount of one neonicotinoid, Thaicloprid, but it only appeared in 3 percent of samples with the low average amount of 2.1 parts per billion. Compared to the other chemicals, the traces of neonicotinoids were largely insignificant. For example, the chemical Fluvalinate appeared in 98 percent of the bees wax samples with an average concentration of 7,472 parts per billion. It also appeared in 88 percent of pollen samples at levels of 40 parts per billion and in 83 percent of bees at 1 ppb. The chemical Coumaphos appeared at levels nearly as high.

The high levels for Fluvalinate and Coumaphos are to be expected, given that beekeepers apply these products directly to the hive to control mites, which pose even greater risks to the bees than do the traces of chemicals. Still, there is some evidence that these two chemicals have adverse effects on queen bees, with obvious implications for overall hive health.

While beekeepers may often blame agricultural pesticides for annual hive losses, biologist and beekeeping blogger Randy Oliver calls on his colleagues to acknowledge “the elephant in the room” because they themselves use pesticides. “The plain truth is,” notes Oliver, “a colony of bees does not differentiate between agricultural pesticides, and beekeeper-applied miticides. What actually affects the colony is the cumulative load of all toxins that the colony is exposed to, whether from smokestack pollution, dust drifted over from China, pesticides sprayed by farmers, or miticides applied by beekeepers with the best intentions.”

“I think we have known for a long time that miticides can adversely affect queens and kill drone sperm,” says Bee Researcher Dennis vanEngelsdorp, who was one of the first to identify colony collapse disorder. However, he does not blame beekeepers for using them. “It’s like chemotherapy. They know it’s bad, but it’s a lot better than the alternative.”

Neonicotinoid exposure is far lower than that of those products used in the hive. There are periodically incidents where bees die in large numbers because mistakes made during application of chemicals, such as bee kills when chemicals are applied to the soil and sprayed. These isolated incidents are unlikely to be part of a trend related to substantial hive losses or CCD, and they can be reduced with careful management, such as proper timing of applications. Indeed, just as we do not ban airplanes or cars because of accidents, we need not ban chemicals that have valuable uses because a limited number of accidents. Fortunately, as highlighted in a study on such issues in Canada, these incidents are relatively few.

Accordingly, chemicals need to be used strategically and carefully for both farming and pest control in hives. In both cases, the products yield important benefits in disease reduction and food production, which is why risk management rather than product elimination offers the best course of action.


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