Are pesticides the problem?

Honey bees populations are hurting. This isn’t new news. Last winter saw a 42% increase over the previous year’s losses due to colony collapse disorder. Yet the bees don’t seem to be recovering despite significant efforts to understand the causes. The BBC published a wonderful graphic detailing the myriad factors that can influence colony heath, which range from climate, to farming practices, to disease, to pesticide use. So what’s the deal with pesticides, specifically, a class called neonicotinoids, which are getting a lot of press lately because of the recent moratorium in the EU? (I wrote about them in a past blog about Dave Goulson’s research in May)

There is a lot of skepticism as to whether neonics are the root cause of the honey bee problem. For example, the UK stated that they were unconvinced by the science to date. A recent piece focusing on a new paper by vanEngelsdorp makes it seem like all banning neonics would do is bring back the 25,000 bumble bees that were massacred in Oregon after an application to a flowering tree in a parking lot this past summer (bumble bees are threatened by a variety of diseases and are the key pollinators in most natural ecosystems, plus critical crop pollinators, so this loss is not minuscule nor unimportant).

In fact, neonics, a neurotoxin, and are more deadly to invertebrates than DDT. They can be lethal, but also have sub-lethal side effects that can alter a bee’s ability to forage or navigate normally. Studies have found them in food and honey residues and in the pollen bees take back to their young. The orchard mason bee matures less quickly when exposed to neonics, and bumble bees produce less offspring. The effects on ground-nesting bees are not well known, but the pesticides accumulate in soil, and can remain there for up to 6 years, so there is the potential that they could harm bees even in the absence of direct spraying. Neonics are often used as seed coats, and are absorbed into all parts of the plant tissue (known as a systemic pesticide), including the pollen and nectar.

To help answer some of the questions surrounding neonicotinoids, the Xerces Society for Invertebrate Conservation just released a report entitled, Are Neonics Killing Bees? They found that both native bees and honey bees are exposed to neonicotinoids in a varieties of ways, yet there are still gaps in the research that need to be addressed before we can form a clear picture of all the effects on bee health. They recommend suspending currently approved uses of neonics until their effects are better understood (in ecology this is known as the Precautionary Principle- acting with caution about a potentially detrimental product until we can be sure it is safe).  Similarly, they also suggest the EPA adopt a more cautious approach to approval of new pesticides- with more rigorous assessments of the risks to wild and managed bees. They also suggest better labeling that warns both agricultural users and homeowners about the extreme risks to pollinators, with reference to the contamination of nectar. And finally, they suggest legislators consider banning use of neonics for ornamental plants, where rates of application are much higher than on crops.

The Center for Food Safety has already sued the EPA to enhance labeling on products containing neonics that homeowners readily spray in their gardens without knowing the deleterious effects they can have on beneficial insects. There are numerous campaigns to increase awareness about the potential negative effects of pesticides. Avaaz has gathered over 1 million signatures. And while it may be true that colony collapse disorder may not disappear if we eliminate neonicotinoids, it might help other native bees, and reduce one of the threats to honey bees.

For more information about neonics, check out summaries provided by the Pesticide Action Network (more honey bee related) and the Xerces Society.


What are your questions concerning native pollinators?

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