The Bt Battle

Can Cotton Make Room for Bt Soybeans in the U.S.?

Emily Unglesbee
By  Emily Unglesbee , DTN Staff Reporter
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The soybean podworm is among the pests targeted by Monsanto's Bt-soybean product. (Photo courtesy Wayne Bailey, University of Missouri)

ST. LOUIS (DTN) -- Bt soybeans designed to put a dent in defoliating pests such as looper, podworm and velvetbean caterpillar wait in the wings for U.S. growers. The question is, can the landscape handle another Bt crop?

Entomologists from seven southern U.S. universities are evaluating whether Monsanto's second-generation, two-protein Bt-soybean product is a good fit for U.S. farmers.

Beyond looking at pest control, the studies are examining the role soybeans have been assumed to play as a "natural refuge" for Bt-cotton fields, North Carolina State University entomologist Dominic Reisig told DTN.

If, as the first year of data from these trials suggest, soybeans do not actually serve as major hosts for cotton pests, the company could launch soybean varieties with Bt proteins here as early as the end of the decade, Monsanto representatives said.

A NATURAL REFUGE?

In 2006, Monsanto submitted data to the EPA which suggested that the C3 category of plants, which includes soybeans, tobacco, and peanuts, supplied a sufficient natural refuge for the new Bollgard II Bt-cotton trait in the southern U.S.

As a result, EPA agreed to eliminate the 20% required refuge acres in Bt-cotton fields. The decision hinged on the assumption that any Bt-resistant pests emerging from those fields would find plenty of non-resistant mates emerging from neighboring soybean acres.

"We made a hypothesis that based on number of soybean acres in the surrounding area, it was one of the key hosts [for cotton pests]," said Miriam Paris, a spokesperson for Monsanto. "And that's why we're going back now and testing that assumption."

University researchers collected adult moths of cotton pests like the tobacco budworm and cotton bollworm (also known as the corn earworm), and sent them to Monsanto laboratories in Chesterfield, Mo. There, company scientists used a new, proprietary test to determine if the C3 plants these moths fed on were specifically soybean plants.

Paris declined to comment on the results of these trials, but Reisig said so far, data suggest that soybeans are not actually a significant natural refuge for cotton pests. However, more data are needed to account for environmental differences such as weather, geography and changes in crop mixes from year to year, Reisig added.

U.S. LAUNCH

If the university trials definitively prove that cotton pests are not emerging in significant numbers from soybean fields, Monsanto is likely to move forward with a U.S. launch of Bt-soybeans.

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"The reason we initiated this assessment two years ago is because we heard from the marketplace that there was an interest," explained Paris. "We heard from our soybean growers and we heard from our academic community that they were interested in a solution" to soybean pests, she said.

However, "one of key imperatives is to ensure our corn and cotton growers primarily get to continue to enjoy natural refuge," she added.

Reisig doesn't see North Carolina growers clamoring for Bt-soybeans. "We can actually manage these pests cheaper and as effectively with insecticides as we can with Bt-soybeans," he said. However, geography and pest pressure differ by region, he added.

"In the mid-South, they really, really want these traits," Reisig said. "They have higher pest pressure than we do in the upper Southeast."

The decision to launch Bt-soybeans in the U.S. has not yet been made, Paris stressed. The company is hoping the second year of university trials confirms the results they saw in the previous year's data first.

If the company does decide to introduce Bt-soybeans to American growers, it would launch their second-generation product, which contains two Bt proteins, by the end of the decade at the earliest, Paris said.

Dow AgroSciences is also gearing up for the commercialization of its two-protein Bt-soybean product, Conkesta, in South America. The trait will be available as a stack with the company's Enlist trait in Brazil and Argentina sometime between 2016 to 2018, pending regulatory approvals.

Dow is not planning a U.S. launch at this time, said company spokesperson Kenda Resler-Friend. "Dow AgroSciences will continue to monitor the pest pressure, grower needs and product fit for the southern U.S.," she said. "At the current time this is not the focus for the product concept."

RESISTANCE CONCERNS

Farmers in South America are expected to grow between 10 million and 12 million acres of Monsanto's single-protein Bt-soybean product, called Intacta RR2 Pro, this season.

The Intacta RR2 Pro launch last year came at a critical time for Brazilian farmers, after an aggressive caterpillar pest called the Old World Bollworm was detected in the country in January 2013. In September 2014, the Old World Bollworm was found as far north as Puerto Rico, and American officials have said a U.S. mainland invasion of the pest is very possible.

Known officially as Helicoverpa armigera, the caterpillar is a serious global pest with a history of rapidly developing resistance to insecticides and some Bt proteins.

The prospect of insect resistance looms large for South American Intacta growers, Reisig said. In Brazil, growers are not required to plant a refuge in Bt acres, and millions of soybean acres planted with the Intacta trait will put enormous pressure on just one Bt protein, he pointed out.

"I think without a mandated refuge in soybeans, the single-protein product, and [Bt] resistance already seen in corn, it's probably just a matter of time before that particular product breaks down," he said.

Paris said Monsanto is working hard to ensure that does not happen before they can bring their two-protein Bt-soybean product to Argentina and Brazil in 2018 and 2019, respectively.

The company encourages South American growers to join a voluntary program that gives them special access to Monsanto products and assistance, but includes on-farm audits by Monsanto employees to ensure refuges have been planted.

Last year, this program produced 95% refuge compliance on 3 million acres of Intacta, Paris said. Whether that rate of success can continue as Intacta acres quadruple this year remains to be seen, but the company "is increasingly investing in education campaigns to instruct farmers" in South America, said Monsanto oilseeds communications manager Lindsey Dario.

Should Bt soybeans come to the U.S., resistance will be a concern here, too, Reisig pointed out. The two proteins in Monsanto's second-generation product are Cry1A.105, already present in Bt-corn varieties in the U.S., and Cry2Ab2, present in Bt-cotton varieties in the U.S.

"We have some third-generation corn and cotton products in the pipeline that are scheduled to be commercially introduced, pending regulatory approvals, toward the end of the decade," Paris said. "So there would be an added protein in the landscape mix," when the Bt-soybean product would potentially be launched, she added.

Emily Unglesbee can be reached at emily.unglesbee@dtn.com
Follow Emily Unglesbee on Twitter @Emily_Unglesbee.

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Emily Unglesbee