Research Reviews
Is bee pollen contaminated with anything?
Answer: Some is, but some isn't, with pesticides
The widespread use of pesticides didn't really take off in US agriculture until after WWII. The first synthetic pesticides were broad spectrum, highly toxic compounds that would pretty much kill anything and everything. Such broad-spectrum pesticides were clearly problematic for the environment, and many have been phased out (thankfully). Efforts ever since have been to develop more targeted pesticides to affect a limited number of pests and not non-target species. Numerous technologies, ranging from GMO crops to the systemic pesticides, have been introduced in an effort to reduce overall use of pesticides and employ more targeted approaches.
The conflict of interest between synthetic insecticides and honey bees has been going on just as long. For many aspects of agriculture, the downside of pest insects outweighs the upside of pollinators. For example, even though cotton can actually benefit from increased yield by honey bee pollination, the boll weevil was such a historically problematic pest that growers would spray intensely. As a result, it used to be a death sentence for colonies if a beekeeper placed their hives near cotton fields. With successful weevil eradication efforts, insecticide sprays are much less frequent, and beekeepers can finally take advantage of that mid-summer nectar flow from cotton (even though it can crystalize fairly readily!).
The widespread declines of honey bee and other pollinator populations has again raised pesticides to the top of public debate. Honey bees pick up many different chemicals in their environment and bring them back to their nests. At issue are potential problems that certain pesticides might have on honey bee health. A recent study by researchers at Penn State and the USDA report their findings on a survey of pesticides found in beehives, and their findings are troublesome at best and downright scary at worst. They found a total of 121 different pesticides (or evidence of them, based on the chemicals that they break down into) in almost 1000 samples of beeswax, adult bees, and bee bread. The paper reads like a laundry list, a huge catalog of different synthetic chemicals, many of them at very high levels (even though one-in-a-million may seem like a long shot, given how potent many of these chemicals are, their concentrations are relatively high).
A new study, this time conducted by a team of scientists in Europe (Spain, to be precise), took a slightly different approach but with the same aim in mind. The researchers analyzed thousands of sample of bee bread (stored pollen) for the residues and by-products of many different pesticides. Interestingly, pesticide residues were detected in 42% of samples collected in spring, and only in 31% of samples collected in autumn. This means that the majority of samples did not have any pesticides in them; whether or not this is good news depends if you're a "glass half full" or "glass half empty" type of person. Moreover, fluvalinate (the active product in Apistan strips for varroa control) and chlorfenvinphos (banned in the US since 1991) were the most frequently detected pesticides in the analyzed samples. Thus like the US study, some of the top detected pesticides are those used by beekeepers themselves. Fipronil was detected in 3.7% of all the spring samples but never in autumn samples, and neonicotinoid residues were not detected. These are very important findings, as there has been much speculation and debate about these particular pesticides being linked to CCD or other colony die-offs. Finally, the authors did not find a direct correlation between pesticide residues found in stored pollen samples and colony losses.
Collectively, these results are both disturbing and encouraging. While it certainly seems problematic that almost half of our bees' food is contaminated with pesticides, the fact that colonies can maintain function in spite of it has to be encouraging. Of course, this doesn't address the toxic effects of direct pesticide poisoning, nor does it delve further into the issue of sub-lethal effects and their impacts on colony productivity, so more careful studies are clearly warranted. But given that honey bees and pesticides have been at odds in agriculture for over half a century, it is clear that we will continue to live in that reality.
Reference
Bernal, J., E. Garrido-Balon, M. J. Del Nozai, A. V. Gonsalez-Porto, R. Martin-Hernandez, J. C. Diego, J. J. Jimenez, J. L. Bernal, and M. Higes. (2010). Overview of pesticide residues in stored pollen and their potential effect on bee colony (Apis mellifera) losses in Spain. Journal of Economic Entomology, 103: 1964-1971.
