This Happy Hour, How About Pesticide Cocktails?

October 26, 2012 | 9:50 am
Doug Gurian-Sherman
Former contributor

A recent blog post by Tom Philpott pointed to growing evidence that neonicotinoid insecticide seed treatments of corn are harming bees. There is new evidence that combining several common insecticides, a “pesticide cocktail” in the jargon, may increase harm. Pesticide cocktails are the main item on agriculture’s menu, with seeds treated with fungicides, as well as insecticide, and crops sprayed with various pesticides. EPA regulations do not take the effects of mixtures into account.

Honey bee on an apple blossom. USDA photo

Bees are our most important pollinators, ensuring the productivity of 30 percent of our crops—especially fruits and veggies. Bees and other helpers are needed to transfer pollen between flowers of many crops including squashes, apples, and almonds.

And it is not just bees that are threatened. Studies have found that neonic seed treatments may harm other helpful  insects. There is an army of different beneficial organisms that help protect our crops. Many insects, spiders, birds and bats consume tons of insects that would otherwise harm crops and reduce food production, and neonics may be harming some of them.

But this raises the question of why so much corn seed is treated with these insecticides. And not just corn. Neocotinoid seed treatments are also being used more commonly in other major crops, such as soybeans.

The nearly ubiquitous use of insecticde seed treatments is a relatively new phenomenon. Their widespread use on seeds started in the past decade. Why is agriculture still using so much pesticide?

Genetically engineered crops, which were promoted as pesticide-reducing, have probably driven up pesticide use in the U.S. Somewhat reduced insecticide use is more than offset by increased herbicide use, driven by millions of acres of resistant weeds. Industry’s answer, more herbicide resistant crops, will likely exacerbate this trend. Some weeds have already developed resistance to multiple herbicides, including weed killers that will be used on the new engineered crops, making this a questionable (but profitable) strategy.

“It’s a joy to be simple”? Well, not always

At the root of the problem is the biological simplification of agriculture, as I discussed in earlier posts on the rise of neonicotinoids and the importance of diversity in the farm landscape. Most pests attack only a limited number of crops. When other crops are grown, those pests cannot increase their numbers as easily.

Crop diversity provides beneficial organisms with habitat that supplies them with food and shelter throughout the year.

By contrast, simple farming systems, which grow large amounts of one or two crops year after year, promote pest outbreaks.

On the simple farms in the Midwest, engineered Bt corn kills some insect pests, but leaves others uncontrolled, which is probably one reason that neonicotinoid seed treatments have replaced sprayed or soil-applied insecticides. The soil insecticides killed more types of insect pests than Bt, so switching to Bt left corn vulnerable to insects that are immune to Bt but susceptible to insecticide. The limited number of insect types killed by Bt is an environmental benefit, because it means Bt is less likely to harm beneficial insects. But it is also a limitation because of the pest insects that are not controlled.

This dilemma is largely a byproduct of the simplified farming systems where Bt is popular. In more complex systems, the pests not controlled by Bt would be less of a problem. Resistance to Bt, which is now developing  in corn rootworm and may drive up insecticide use, would also be less likely to occur.

On the other hand, there would be much less need for Bt on diverse farms. For example, rootworm is not usually a problem when crops are rotated (alternated) from year to year, because it does not survive well on most other crops. Less need for Bt would mean less demand, and therefore Bt corn seed would command a lower price. This raises the question of whether the companies could afford to produce these crops for a more sustainable farming system, given the high price tag of genetic engineering—mostly R&D and infrastructure—about $140 million per trait according to an industry study.

Meanwhile, we are learning more about practical ways to increase the biological complexity of the landscape, both on and near the farm. Longer crop rotations dramatically reduced the use of pesticides while maintaining productivity and profits, according to new research from Iowa State University (as discussed by my colleague Karen Stillerman, and also here) .

We also know that biological complexity in the non-farmed landscape is important for supplying farms with pollinators and organisms that control pests. Work at Michigan State University found that the amount of extra insecticide needed in several Midwestern states due to the reduction of hedgerows, woodlots and so on, would be enough to blanket the State of Connecticut.

Revenge of the Red Queen

In Louis Carroll’s Through the Looking Glass, the Red Queen finds herself running faster and faster just to stay in place. Biologists have used this analogy in a number of contexts, such as the co-evolution between pathogens and hosts. In agriculture, our simplified systems have created their own version of the Red Queen effect. It is often called the “pesticide treadmill,” and is the legacy of the kind of agriculture favored by big ag companies, facilitated by the accommodating research and policy agenda of the USDA.

This “Alice in Wonderland” world is not the way things have to be, as recent research has shown.

Fortunately, we have seen some movement in the right direction. For example, recent Farm Bills have increased funding for sustainable agriculture research through programs like OREI and SARE, support for farmers transitioning to organic farming, and so on. But they still receive a pittance of the funding that goes toward continuing our current misguided agriculture system. And much of this progress is threatened by the dysfunctional farm bill negotiations in Congress that you can help turn around.

Farmers will do the right thing if we help or encourage them instead of pushing in the wrong direction. They have an interest in exposing themselves, their workers, and their families to fewer pesticides.

Why the current system is so entrenched is part of a much longer discussion that I hope to take up in coming posts.