Friday, September 16, 2016

Is There Still Value in GM Crops?

The day after the Bayer/Monsanto agreement was announced this week, The Wall Street Journal had an article entitled "Behind the Monsanto Deal, Doubts About the GMO Revolution" (subscription required or article can be purchased). The paragraph that best summarizes the article was, "Today, farmers are finding it harder to justify the high and often rising prices for modified, or GMO, seed, given the measly returns of the current farm economy. Spending on crop seeds has nearly quadrupled since 1996, when Monsanto Co. became the first of the companies to launch biotech varieties. Yet major crop prices have skidded lower for three years, and this year, many farmers stand to lose money."

The article contained a graphic that showed that since 1996, the year GM soybeans were introduced on a commercial scale, soybean seed prices have risen 305% to $60.75 per acre, but commodity prices have risen only 31% to $9.79.  It is a bit puzzling why the Wall Street Journal did not choose to plot the yield increases per acre since 1996; we all know that higher yields are good but reduce prices, all other things being equal.

This is an entomological newsletter and I won't discuss the benefits to growers that have come from having herbicide tolerant GM crops that allowed greater yields through less weed competition while using a simpler and less expensive herbicide regimen. I will also not discuss the yield losses later incurred when weeds became resistant to those herbicides, or the additional expense of having to go back to a more complicated and expensive herbicide regimen. And I will not discuss the latest generation of herbicide tolerant GM crops that are tolerant to one of two types of older herbicides that have been reformulated to reduce off-target drift. These new crops are being sold in part as the answer to the resistance problem that was caused by the first generation of herbicide tolerant crops. The seed companies will charge on the order of $6 per acre for this trait ($25 - 30 per bag of seed) over and above the cost of current technology, and will additionally profit by selling growers the specific herbicides that must be used on these crops.

GM crops with toxins for insects (Bt crops) have reduced insecticide use and provided environmental benefits. In the Midwest, Bt corn with toxins for European corn borer has reduced the populations of that pest to the point that non-Bt corn can be grown without the need for an insecticide application. Similarly, in my part of the country we no longer fear southwestern corn borer; the planting of Bt corn has greatly reduced the size of the population. Obviously the widespread planting of Bt crops toxic to some insects has resulted in significant benefits.

However, 2016 has been a year of frustration for some farmers who plant GM corn, soybean and cotton. As the Wall Street Journal article said, this is in part because the price of seed seems to be high compared to the value of the commodity at the grain elevator or gin. It is also because some of our insect toxin traits in corn and cotton no longer work as well (or at all) on some of the insects that damage crops and reduce crop quality. This is not the first year for such frustration; resistance to corn rootworm Bt crops was first scientifically documented in 2011 and has spread geographically and to all four Bt toxins used in corn. At least two caterpillar toxins (probably three) have failed due to resistance, as corn growers in the Midwest and Canada are finding out this season due to extensive western bean cutworm damage in their Cry1F corn. This year cotton farmers found themselves having to spray GM crops with insecticides to prevent yield loss.

Our insect-protected Bt crops never were "bulletproof". In fact they never worked very well at all on some pests and were not intended as the sole control for other pests. In the latter case, the word "suppression" or some similar word was usually mentioned in company literature, or no mention was made at all and the grower was left to come to his or her own conclusion.  The job of selling seed being what it is, the nuances between the ability to control one pest and suppress others was often lost and these technologies competed with each other in the sales arena based on being oversold in their abilities. Sales material showed perfect ears of corn and growers were led to believe in the invincibility of the product.

The current frustration then is a result of resistance development in the pests the technologies were meant to control, and resistance in pests for which the technologies formerly provided suppression. In both cases it has become necessary to use traditional insecticides on top of the Bt technologies or suffer significant yield loss. And even when traditional insecticides are used there is often yield loss after the increased expense.

Why are seed prices so high? The Wall Street Journal article said that when GM crops were introduced Monsanto came up with a formula that was quickly adopted by the rest of the industry. "For every dollar that biotech seeds saved farmers in pesticides and labor, Monsanto would keep about 33 cents, in the form of a “technology fee” charged on top of each bag of seed." Seed prices keep going up, but GM crops are no longer saving growers as much in pesticides and labor as they once did. This is to say that in many places GM crops have less value now in terms of insect and weed control. It is not hard to understand the frustration at paying higher prices for something of lesser value.

However, our GM crops are not just herbicide tolerance and insect resistance traits, they are also improved genetics for yield and drought and disease tolerance. These qualities are expensive to produce, and the regulatory system in the US adds significant cost to some of them.

On the surface it would seem that growers could choose to buy non-GM seed and go back to the way we handled insect and weed control prior to 1996. This might work for insects, especially in places Bt crops have driven down populations of major pests. Unfortunately, non-GM crop breeding slowed considerably in the age of GM breeding, and the yield potential of many non-GM crops, even in the absence of pests, is not competitive with GM crops. (This is more true in corn than in cotton.) Another difficulty is that the introduction of GM crops coincided with the Food Quality Protection Act. This was convenient for the EPA because one could rationalize that Bt crops could replace many of the insecticides that would be cancelled. Today there are fewer insecticide options for use in non-Bt crops (or Bt crops with resistant insects), and many of the newer insecticides carry high price tags.

For sure there is still value in GM crops, but right now that value does not seem to be what it once was. It is unclear whether 2016 is the year we will look back on and point to as the start of a movement away from GM crops, or whether improved technologies and higher commodity prices in the future will make them look like a more valuable proposition.


(A  2013 USDA publication called Genetically Engineered Crops in the United States provides a concise summary of the number of GM traits introduced and the economic returns from them. Unfortunately, the publication is somewhat outdated because it does not address the weed and insect resistance to GM crops that has occurred in the last four years.)

Saturday, September 10, 2016

Shuffling the Deck Chairs in Bt Crops

2016 has been a challenging year for our Bt crops. Cotton bollworms did an unusually high amount of damage in many fields of Bt cotton, and corn earworms (which are bollworms by another name) caused a significant amount of damage to corn crops from Texas through Kansas. Western bean cutworm caused severe damage in fields of Cry1F corn in the Midwest and Canada where once the toxin provided a reasonable level of control. Fall armyworm is known to be resistant to Cry1F corn in parts of the country. Corn rootworm is resistant to toxins that once did a good job of control.

One question this fall is whether we have resistance to our Bt toxins targeted at caterpillars and, if so, how far it has spread. Field observations suggest that we do have resistance, but we will have to wait for the results of the laboratory tests on the progeny of the insects collected from the field. We don't have a magic genetic test to detect resistance, so we do things the old fashioned way by crossing field collected insects with laboratory insects and seeing how their offspring survive known doses of Bt toxins as compared to progeny from a colony we know to be susceptible to the toxins.

This article is not about whether we have resistance, it is about why we will have more resistance. When Bt crops were originally registered and deployed some 20 years ago, the seed companies each had their own unique toxins that worked more or less well on specific pests. Effectively the percentage of the pest insect population exposed to any particular toxin depended to a great extent on the market share held by each company.

Over time, however, seed companies began licensing their toxins to their competitors. In addition to financial gain there was a good reason for this; two or three different toxins were far better than one for delaying resistance. If an insect had an allele to survive on toxin 1, it probably did not have different alleles to survive on toxins 2 and 3. The insect would be killed and its allele to survive toxin 1 would die with it and not be passed to the next generation.

This strategy of multiple toxins targeted at the same pest (a pyramid of toxins) was successfully employed when corn rootworm in the Midwest became resistant to Cry3Bb1; the answer was to make plants that expressed both Cry3Bb1 (from company A) and Cry34/35 (from company B). Rootworms resistant to Cry3Bb1 were still exposed to Cry34/35 and many of them died. However, because they were already resistant to one toxin they were really only being challenged by the remaining effective toxin, so they were back to having to overcome one toxin and not two. Astute readers will note that we have four toxins for corn rootworm, so why not add one or both of the other two? The answer is cross resistance; rootworms that are resistant to Cry3Bb1 are also resistant to mCry3a, even if their ancestors never encountered mCry3a. Researchers in Iowa have recently confirmed resistance to the fourth toxin, eCry3.1Ab. A good article on this problem is here, and it says, "Cry3Bb1, mCry3A and eCry3.1Ab all appear fairly similar to the rootworm, and resistance to one is likely to confer resistance to the other two."

The example above illustrates that there is a finite limit to the addition of new Cry toxins and, because companies are licensing their technologies to their competitors, essentially our whole arsenal of Bt toxins is being planted on the vast majority of our corn and cotton acres. On a national level we are effectively selecting several generations of insects, even on different crops, on the same or similar toxins. (Corn rootworm is only on corn, but many of the caterpillar species infest both crops.)

If you want to see an example of cross licensing of toxins, look at Chris DiFonzo's Handy Bt Trait Table for corn. For each company, the products listed toward the bottom of their offerings are the newer types of Bt. Regardless of company they all look pretty much the same. (Cry1A.105 is just a synthetic stack of Cry1Ab, Cry1F and Cry1Ac. Cry1F and Cry1Ac are also used in cotton.)

The newest silver bullet is Vip3a for caterpillars. It is fairly high dose and does a good job of controlling many species. In their latest generation of Bt corn and cotton, all of the seed companies are now adding Vip3a as a pyramid with older toxins. Once again the insects will have adapted, or partially adapted, to the older toxins, so selection for resistance will be on Vip3a.

There does not seem to be a way out of the box with corn rootworm toxins, and increasingly we are relying on Vip3a to protect yield while the other caterpillar toxins are failing. Cry toxins had a good run and will hang on for a while longer, but the era of the Cry toxin seems to be ending.

Thursday, September 8, 2016

Green cloverworms in alfalfa and soybeans

If you are growing soybeans or alfalfa on the Texas High Plains it would be a good idea to scout for green cloverworms. I was in a soybean field near Ralls earlier in the week that had approximately 8 larvae per plant, and I just got a call about soybeans near Clarendon that were heavily infested.

In both cases the people making the reports thought the worms were soybean loopers. It is easy to tell the two caterpillars apart because loopers have two pairs of prolegs on the abdomen while the green cloverworm has three pairs. Loopers are fairly lethargic, but green cloverworms hop around quickly when disturbed.

Green cloverworm larvae near Ralls

Typical defoliation in soybean caused by green cloverworm

Fortunately the green cloverworm is only a leaf feeder in soybean and it does not damage pods. For alfalfa here is a quote the Oklahoma guide, "These defoliators are rarely a significant problem in established alfalfa, although seedling stands can be heavily damaged by their feeding." However, if there are enough of them present they can cause defoliation, which in turn will reduce the amount of nutrients the plants can store for overwintering.

For soybeans, University of Tennessee has good list of insecticides in their publication here. Oklahoma State University has control suggestions for alfalfa here.