The Root of the Rootworm Problem: What a Tiny Beetle Can Tell Us About Our Broken Agricultural System

The re-emergence of the corn rootworm due to pesticide resistance reflects a broken cycle of pests and pesticides, and a broken agricultural system.


A recent article in The Progressive Farmer sounded an alarm about the re-emergence of the corn rootworm, a beetle was once called the “billion dollar pest” due to the big impact it has had on valuable corn crops and the costs farmers have racked up trying to control it.

In recent months, the rootworm has caused damage in fields planted with Bt corn, which is engineered to kill the pest, and, as the Progressive Farmer article points out, has “long been a stronghold against rootworm damage for Corn Belt farmers.” These Bt seeds are just the latest in a long list of engineered seeds and insecticides that have failed to stand up against the rootworm, “which has now officially shown some level of resistance to every rootworm Bt protein on the market.”

While this is clearly an immediate problem for commodity farmers, it also points to a much larger, systemic failure of genetic engineering technology to change farming—and control pests—in ways that are fundamentally more sustainable. In fact, it can be argued that genetic engineering has actually exacerbated the huge failures of industrial monoculture farming.

Promising Beginnings Followed by Mounting Failures  

Given the challenges involved with controlling rootworm, conventional farmers have welcomed the advent of engineered Bt genes designed to control the insect, beginning with a Monsanto version in 2003. Since the Bt gene was built into the plant’s genetic material, it saved farmers the time they would have devoted to spraying insecticide. And that might have reduced their exposure to those chemicals as well.

Unfortunately, reports of rootworm damage in Bt corn started surfacing within a few years, suggesting rootworm resistance to Monsanto’s Bt, although the company denied it. Stonewalling by Monsanto delayed what might have been an effective action to slow the spread of resistance, but would have likely come at the cost of reduced sales of Monsanto’s expensive seed. Then resistance was formally confirmed in 2011.

Meanwhile, other companies had introduced several other types of Bt genes to control rootworm. This gave farmers a reprieve from the pest, but it was short-lived. Soon it was discovered that some of the rootworms that were resistant to Monsanto’s trait were also cross-resistant, and the billion dollar pest reared its head again. That left a single Bt, from Dow, that remained universally effective—until now. New research strongly suggests that rootworms are now developing resistance to this last bulwark of engineered protection.

Western_corn_rootwormFailing Technology or Failing Agriculture?

Why did Monsanto drag its feet in the identification of resistance, delaying action, when it might have helped the company preserve the efficacy of its products? Certainly it didn’t want to see the gratuitous loss of these traits, which were costly to develop.

On the other hand, the company likely understood that it would soon lose market share, as other companies would develop similar products. And acknowledging resistance would likely have involved reduced use (read: sales) in affected regions. So Monsanto prioritized its desire to increase short-term sales to maximize profit before competition or regulatory restrictions encroached—at the expense of sustainability.

In another example, in 2003, a majority of expert scientists convened by EPA, advised the agency to require that 50 percent of corn be set aside as a “refuge” without the GE rootworm Bt, to help prevent or delay resistance. A minority of scientists and the seeds industry argued that only a 20 percent refuge was needed (the larger refuge would have reduced short-term sales for Monsanto). Against the more protective majority recommendation, EPA sided with the industry. The result has very likely been a more rapid development of rootworm resistance against Monsanto’s product, and the other Bts that are now falling like dominoes.

To illustrate that this is not an isolated phenomenon, we can look at crops engineered to be resistant to the herbicide glyphosate (i.e., roundup). Monsanto argued vigorously that unlike with other herbicides, resistance to glyphosate was unlikely, and—contrary to good practice—encouraged farmers to spray it to their hearts’ content. The company even placed advertisements in the farm press to this effect. All this was severely criticized and opposed by academic weed scientists, who, needless to say, were spot on in their criticism.

As a result, we are now facing an epidemic of glyphosate resistant weeds that have led to increased herbicide use and a new generation of crops engineered to be immune to older herbicides like dicamba. Use of dicamba on these new GE crops is extensively damaging nearby crops that are not engineered to be resistant to it. It will also lead to increased industry sales of seed, drastically more herbicide use, and will foster more resistant weeds.

All of this is reminiscent of the long-recognized “pesticide treadmill” wherein farmers have to keep adopting new insecticides often, just to keep pace with the evolving pests. When scientist and author Robert Van den Bosch, the author of The Pesticide Conspiracy, wrote about this phenomenon in 1978, he was mercilessly hounded by the pesticide industry, much as was Rachel Carson before him.

And while the industry touts a reduction in insecticide use in the U.S. and elsewhere, the numbers don’t include some of the most widely used insecticides in the world—seeds coated with neonicotinoids. All this is despite the fact that there is strong and mounting evidence that neonicotinoids kill the pollinators needed to produce a third of our food. And while the volume of insecticides may be lower, the area treated with insecticides has gone up. Whereas about 30 percent of the corn grown was treated with insecticides before genetic engineering, that number now stands at about 90 percent.

Genetic engineering was supposed to solve these problems. So what has gone wrong?

The Inconvenient Truths of Industrial Agriculture

The larger context here is the role of industrial agriculture in exacerbating dependence on insecticides and fostering higher levels of resistant insects. Growing large acreage of the same or just a few crops—as is often the case with corn, soybeans, and wheat—is widely understood to encourage high rates of pest infestations. Pests that are well-adapted to a crop will often multiply if that crop is grown year after year without a break. This actually results in lower yields than would occur otherwise when crops are rotated (alternated each year).

The rarely-discussed truth of the corn rootworm problem is that, in most places, simply growing other crops in rotation with corn largely eliminates the need for either chemical insecticides or Bt, and provides higher yields (except in places where industrial corn-soy crop rotations have led to rootworms resistant to crop rotation itself).

Instead, the main GE crops have been associated with increasing industrial monoculture agriculture, where single crops are grown repeatedly. This system also supports larger farms that are more dependent on monocultures. And it results in higher dependency on pesticides, locking farmers into buying these and other harmful products.

At the core of this broken cycle of pests and pesticides is a broken agriculture system, supported by companies that lobby heavily for farm policies against the interest of the public and the environment. Until we confront these issues—and begin to see them as our collective problem and not just a problem for farmers—and work to change the policies and other structures that prop this system up, we may never get at the root of the rootworm problem or others like it.

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  1. Jack Berezny
    Thursday, August 25th, 2016
    The author is spot on correct. Farming is/must be a symbiotic undertaking where diversity is encouraged in order to remain sustainable. Genetic engineering is a false hope. Hybridized seeds, developed through natural selection and cross-pollination must be tailored to the unique environment of a farming region.

    Some weeds in a field are vital to soil and pollinator health. Animal manure is good for the soil as is judicious, occasional use of chemical fertilizers. Integrated farming may mean higher food prices, but it guarantees future food supply.
  2. Brenda Freeland
    Thursday, August 25th, 2016
    Monsanto is the problem. This is Natures way to correct a man made problem!!!!
  3. Dr Karl L. Smith
    Thursday, August 25th, 2016
    Seems like an echo of words that started 30 years ago even before Monsanto and few other evil chemists got their way. All the seed companies went looking for new seed because they ran out of seed they hadn't messed with.....they took seed from 2000 year old corn raised by the Native Americans. So hear we are.... rich chemical companies, rich farming companies, rich farmers, poor land, unhealthy people, poor environment. Seems to match the times we live in; poor politics, lies, cheating, harmful, abusive, short minded rulers. They must be eating the crops!
  4. Jan
    Thursday, August 25th, 2016
    Thank you for this article. I will educate others with this information. This adds to the teaching.
  5. Ron
    Thursday, August 25th, 2016
    This article is long on accusations, and has no proposed solutions. BT corn ha saved farmers billions of dollars, and reduced pesticide use. Would you prefer that farmers had stuck to using pesticides?
  6. Thursday, August 25th, 2016
    I buy only non GMO corn! What are these pesticides doing to us? How about the animals that the corn is fed to? Why are bees dying off? Years ago corn had worms, and not all rows of the kernnels were perfect. We ate it anyway! Today Corporate farms only care about high profits. High frutose corn syrup seems to be in so many items that we consume. We are eating to much of the pesticides. Support local non GMO farmers!
  7. Jen
    Thursday, August 25th, 2016
    It's interesting that resistant pests existed long before the industrial use of GE crops. It is also interesting to learn the purely exacerbating quantities of "natural" pesticides that organic farms use, that they are not required to track or report. The application of large quantities of these "natural" pesticides has been proven poisonous and toxic.
  8. Judith Volpe MD
    Thursday, August 25th, 2016
    Humans think they know better than nature. Mother Nature will always turn around and bite you in the ass.
  9. Thursday, August 25th, 2016
    Good article!
  10. Miguelito
    Thursday, August 25th, 2016
    There has to be a balance between profits and environmental/human costs in all endeavors. There has to be a balance between the short term and the long term. This is well known, so it is a question of doing the right thing. We do not need new technologies as much as we need a new moral imperative. ... Check back at this same spot next week for a new moral strategy that will allow long term human survival and development.
  11. Jason
    Thursday, August 25th, 2016
    The author seems to be blaming these problems on "monocultures" or "industria ag" when the reality is that these are problem of agriculture in general. All forms of agriculture seek to control pests and improve crop production. In doing so, they artificially select for pests that are resistant to that control measure. Even simple crop rotation as a control measure ended up developing insects resistant to crop rotation.

    Humans can do things to slow the development of resistance, but so long as they seek to control crop pests, they can't stop it. Bt went a long way toward reducing the dependence on soil insecticides which is a big win for the environment. If they become ineffective, it wont erase two decades of excellent results!
  12. Tim
    Thursday, August 25th, 2016
    Buy Organic!
  13. Myron Anduri
    Thursday, August 25th, 2016
    Resistant weeds in our region have become extreme and virtually impossible to deal with without heavy spraying and use of newer GMO seed. We have moved our farm over to irrigated grasses and are raising natural beef, which help in the control of undesirable plants. My larger concern and one that is rarely discussed is the degradation of soil bacteria. Soil was long believed to be dirt with NPK, organic matter and other various minerals. The thousands of species of bacteria where disregarded. Now we know better but don't know just what these microbes actually do. We do know that anhydrous ammonia and various pesticides kill them. Perhaps to the benefit of pests like the rootworm.
  14. Dominic Mucci
    Thursday, August 25th, 2016
    Informative article the farmers of this stupid culture but if the future agriculture community knows the truth we can change.
  15. Phil Moshell
    Thursday, August 25th, 2016
    Okay, you pointed out a problem. ( I am a retired farmer. )What is the solution that you propose that will enable adequate production and still keep food costs at the historic low percentage of average income?
  16. James Weatherford
    Thursday, August 25th, 2016
    Everyone who lives on planet Earth and eats food can benefit from the understanding this article provides.
    For the naysayers:
    yes, proposed solutions ARE offered -- crop rotation, polyculture, resource conservation; and
    no, all farming IS NOT developing resistant pests.
  17. Allison
    Thursday, August 25th, 2016
    I'm glad people are writing and reading about agriculture and express ft he need for many solutions for farmers. It's crucial we continue to use science-based evidence to report facts-not reference other www opinion articles. We're going to need all farmer's hands on deck for the growing population. I think we're all rooting for sustainable farming & feeding the world. We're not all looking to cast a stone to "Organic", "Monsanto" or any other generalization . It's simply not productive & won't move technological progress forward.
  18. Thursday, August 25th, 2016
    It is a case of too little, and too late. With Monsanto controlling USDA for years with secretaries of agriculture that were their employees or soon to be employee. Monsanto has bullied everyone, that only the chemicals that they produced, were the answer to the problems.
  19. jay c gregory
    Friday, August 26th, 2016
    Dr. Doug,
    Thank you for myself and our countrymen/women. Corruption is the correct term in these circumstances. We as people have to elect new leaders to fight this insidious problem. Reliance on the same pliable elected officials is not an option. Monsanto is disgusting in the least. Go for it big boy, and thanks again.
    Jay Gregory
    Very concerned citizen
    Central Texas (farmlands)
  20. Jim
    Friday, August 26th, 2016
    The chemical assault has to stop. Farmers have to go back to the old ways with non GMO seeds and farm the way it was in the past. Monsanto and the others must be shut down. The bees and other pollinators must be saved or we will have no food.
  21. bil posey
    Friday, August 26th, 2016
    More miserable failing archaic GMO farming technology. As soon as we move back to the tried proven old methods of farming developed by Cornell, Michigan State, Perdue, Iowa State, University of Nebraska, before they were corrupted by Big Biotech Ag, we will get back to where it was mean to be. #ToxicGMO food system is not only killing US and our families but a complete failure. FOIA documents now show how the project was a total sham to rob farmers of profits and monopolize the food system!
  22. Jared Smith
    Friday, August 26th, 2016
    What a bunch of manure. I am a farmer, and have been engaged in this business since before I even started high school. GMO's work, plain and simple and are safe to consume and beneficial to the environment. Before transgenic Bt corn came along rootworms, corn borers, and earworms would frequently decimate fields unless they were sprayed with expensive toxic insecticides. Now there is so much transgenic corn planted that we farmers don't even have to spray any sort of insecticides in most locales. All this alarm is for what? If Bt corn stops working then it just means going back to business as usual using more pesticides with more toxic residues. Hello, logic!
  23. Fred Garvin
    Friday, August 26th, 2016
    There is so much reported wrong in this story it boggles the mind. Bt traits for CRW are few, only 4 currently exist across the industry. Monsanto only owns one. It and the two that Syngenta owns are very similar in structure and were identified early on as being potentially cross resistant to each other. The other owned by Dow is not. CRW are very robust genetically. The refuge idea touted in the article has been proven to not provide any added benefit in delaying resistance since the resistant alleles are not mutations, but genes that already exist. Monsanto did not delay or deny. Rather they opened their records to the EPA and hired specialists to deal with the problem locally and nationwide. I could write more, but out of space
  24. Fred Garvin
    Friday, August 26th, 2016
    Additionally, CRW is a perennial problem even in many rotated fields. There are two variants of CRW. Extend diapause northern CRW that don't hatch for 2 years after they are laid as eggs. and there is the Soybean tolerant variant of the Western CRW, that can feed on soybean leaves and often lay its eggs in a soybean field. The next time that field is planted in corn, the rootworm is there and causes severe damage if there are enough of them. Finally, the neonicitinoid discussion is moot here because neonicitinoids are not used to control CRW... they were tried, but did not work well
  25. Doug Gurian-Sherman
    Monday, August 29th, 2016
    Fred, The limited number of Bt products, and your description of them, seems to confirm the limited potential of this approach so far. And the new RNAi product in the pipeline will also have one of the main flaws of the Bts—not providing a high enough dose to allow effect resistance management. It is irrelevant whether resistance is from existing alleles or new mutations, it is the frequency, dose, dominance that is important. And we can’t know how well a 50 percent refuge might have been because the industry got its 20 percent instead! Again, that these were so vulnerable to resistance makes my bigger point about the limited ultimate value of these Bts in an industrial ag system, as well as how the industry exacerbates these problems.
  26. Doug Gurian-Sherman
    Monday, August 29th, 2016
    See the link ” Stonewalling by Monsanto “ in the article for Monsanto’s perverse influence on resistance management and response. It links analysis from EPA and entomologists. You are right that it is not just about Monsanto, it is about the broader issues of the unsustainability and harm of current industrial agriculture. But Monsanto has been especially aggressive about advancing its agenda.
  27. Doug Gurian-Sherman
    Monday, August 29th, 2016
    Rootworms arose in the 90s resistant to the industrial corn-soy rotation, but most corn acreage is not affected so far (rotation still works). But also, had good (productive and profitable) agroecology with long rotations (at least 3 or 4 crops) been used, the fitness costs to those rootworms of egg loss and so forth likely would have prevented or greatly delayed this happening, although now we can’t find out for certain! In addition, using good ecological farming practices (rather than industrial monoculture) has been shown to supply predators of rootworm that reduce its populations significantly (research by Jon Lundgren and others). Again, all this really just illustrates the failures of industrial agriculture.
  28. Doug Gurian-Sherman
    Monday, August 29th, 2016
    You miss the point about neonicotinoids. It is not about rootworm control, but rather that the supposed reductions in insecticide use due to Bts, at least in terms of the area of farmland (and water) affected, and environmental impact, have been largely illusory. We are treating about three times as much corn with insecticide now as before Bt traits. Again, it is the failure of the industrial monoculture model that is the problem.
  29. Doug Gurian-Sherman
    Monday, August 29th, 2016
    Jared, the insects you mention, especially rootworms, were a problem mainly in corn-on-corn and short corn-soy rotations, which is exactly my main point. You have fellow farmers that get high yields with low insecticide use that use sustainable farming methods now. This has also been shown at Iowa State University and elsewhere. Second, maybe you don't notice because it is added to the seed, but there is actually much more corn acreage treated with insecticide (neonicotinoids) now, that are extremely harmful, than before Bts (see links above). Finally, yes "business as usual" was exactly the problem--we need an ecological farming system instead. This is not farmers vs. environmentalists, but how we can all solve these problems together.
  30. Tuesday, September 6th, 2016
    Coming from the corn-soy fields, the larger picture is this: why are we growing so much of these two non-food worthy crops? They are not fit for human consumption and must be manipulated in extreme ways to be added to the food supply. They are destroying the meat industry by feeding them to animals who shouldn't eat them. Ethanol is an inefficient fuel. Around 1/4 of these commodities rot. Our dumping them as "aid" instead of helping poorer countries' ag is perpetuating hunger and poverty. They require subsidies to keep farmers paid. The system is absurd. They aren't needed to feed the world. It is a false premise.