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SW FarmPress
California cotton
Researchers have found that crossing Bt cotton with non-Bt cotton can reverse issues of resistance by the pink bollworm to the transgenic efforts to control them.

Researchers able to reverse resistance of pink bollworm to Bt cotton

Collaborative effort by researchers in China and the University of Arizona find unique method to reverse resistance of pink bollworm to Bt cotton. Implications exist for transgenic corn and soybeans as well.

Farm Press Staff | May 09, 2017

Researchers with the University of Arizona and China discovered a surprising strategy to reverse pink bollworm resistance to genetically engineered cotton.

Cotton growers have been able to use genetically engineered cotton to fight the pink bollworm. This has happened as scientists have been able to produce pest-killing proteins from the widespread soil bacterium Bacillus thuringiensis, or Bt. Without adequate countermeasures, scientists have discovered that pests can quickly evolve resistance.

According Bruce Tabashnik, one of the authors of the study and a regents’ professor with the University of Arizona, these Bt proteins are considered environmentally friendly because they are not toxic to people and wildlife. They have been used in sprays by organic growers for more than 50 years, and in engineered Bt crops planted by millions of farmers worldwide on more than 1 billion acres since 1996.

Scientists from the U.S. and China discovered that by hybridizing genetically-engineered cotton with conventional cotton, it reduced the resistance of the pink bollworm. Details of the 11-year study that tested more than 66,000 pink bollworm caterpillars from China’s Yangtze River Valley are published in the Proceedings of the National Academy of Sciences.

Tabashnik says this is the first-ever case where scientists have seen substantial reversal to resistance developed by a pest.

The primary strategy for delaying resistance is providing refuges of the pests’ host plants that do not make Bt proteins, according to Tabashnik. This allows survival of insects that are susceptible to Bt proteins and reduces the chances that two resistant insects will mate and produce resistant offspring.

Before 2010, the U.S. Environmental Protection Agency required refuges in separate fields or large blocks within fields. Planting non-Bt cotton refuges is credited with preventing evolution of resistance to Bt cotton by pink bollworm in Arizona for more than a decade.

By contrast, despite a similar requirement for planting refuges in India, farmers there did not comply and the pink bollworm rapidly evolved resistance.

The ingenious strategy used in China entails interbreeding Bt cotton with non-Bt cotton, then crossing the resulting first-generation hybrid offspring and planting the second-generation hybrid seeds. This generates a random mixture within fields of 75 percent Bt cotton plants side-by-side with 25 percent non-Bt cotton plants, according to the University of Arizona.

“Because cotton can self-pollinate, the first-generation hybrids must be created by tedious and costly hand pollination of each flower,” said Tabashnik, “However, hybrids of the second generation and all subsequent generations can be obtained readily via self-pollination. So, the hybrid mix and its benefits can be maintained in perpetuity.”

Tabashnik calls this strategy revolutionary because it was not designed to fight resistance and arose without mandates by government agencies. Rather, it emerged from the farming community of the Yangtze River Valley. While most previous attention has focused on the drawbacks of interbreeding between genetically engineered and conventional plants, the authors point out that the new results demonstrate gains from such hybridization.

“For the growers in China, this practice provides short-term benefits,” Tabashnik added. “It’s not a short-term sacrifice imposed on them for potential long-term gains. The hybrid plants tend to have higher yield than the parent plants, and the second-generation hybrids cost less, so it’s a market-driven choice for immediate advantages, and it promotes sustainability. Our results show 96 percent pest suppression and 69 percent fewer insecticide sprays.”

There are implications in transgenic corn and soybeans as well.

“This study gives a new option for managing resistance that is very convenient for small-scale farmers and could be broadly helpful in developing countries like China and India,” explained coauthor Kongming Wu, who led the work conducted in China and is a professor in the Institute of Plant Protection in Beijing.

“A great thing about this hybrid seed mix strategy is that we don’t have to worry about growers’ compliance or regulatory issues,” Tabashnik said. “We know it works for millions of farmers in the Yangtze River Valley. Whether it works elsewhere remains to be determined.”

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Xin news

Chinese, U.S. scientists make first reversal of pest resistance to GM cotton – Xinhua | English.news.cn

Source: Xinhua| 2017-05-09 03:55:08|Editor: yan

WASHINGTON, May 8 (Xinhua) — The issue of pest resistance to genetically modified (GM) crops has received widespread attention, and researchers from China and the United States revealed on Monday the success of a surprising new strategy for countering this problem.

In a study published in the U.S. journal Proceedings of the National Academy of Sciences, they reported that hybridizing genetically engineered cotton with conventional cotton reduced resistance in the pink bollworm, a voracious global pest.

The findings were based on an 11-year study, in which researchers at the Chinese Academy Of Agricultural Sciences (CAAS) and the University of Arizona (UA) tested more than 66,000 pink bollworm caterpillars from China’s Yangtze River Valley, a vast region of southeastern China that is home to millions of smallholder farmers.

According to the study’s authors, this is the first reversal of substantial pest resistance to a crop genetically engineered to produce pest-killing proteins from the widespread soil bacterium Bacillus thuringiensis, or Bt.

“This study gives a new option for managing resistance that is very convenient for small-scale farmers and could be broadly helpful in developing countries like China and India,” study coauthor Kongming Wu, who led the work conducted in China and is a professor in the CAAS’s Institute of Plant Protection in Beijing, said in a statement.

Crops genetically engineered to produce insecticidal proteins from Bt kill some major pests and reduce use of insecticide sprays.

However, evolution of pest resistance to Bt proteins decreases these benefits.

The primary strategy for delaying resistance is providing refuges of the pests’ host plants that do not make Bt proteins. This allows survival of insects that are susceptible to Bt proteins and reduces the chances that two resistant insects will mate and produce resistant offspring.

Before 2010, the U.S. Environmental Protection Agency required refuges in separate fields or large blocks within fields.

Planting such non-Bt cotton refuges is credited with preventing evolution of resistance to Bt cotton by pink bollworm in Arizona for more than a decade.

By contrast, despite a similar requirement for planting refuges in India, farmers there did not comply and pink bollworm rapidly evolved resistance.

The new strategy used in China entails interbreeding Bt cotton with non-Bt cotton, then crossing the resulting first-generation hybrid offspring and planting the second-generation hybrid seeds.

This generates a random mixture within fields of 75 percent Bt cotton plants side-by-side with 25 percent non-Bt cotton plants.

“We have seen blips of resistance going up and down in a small area,” said senior author Bruce Tabashnik, a professor in the UA’s College of Agriculture and Life Sciences. “But this isn’t a blip. Resistance had increased significantly across an entire region, then it decreased below detection level after this novel strategy was implemented.”

Tabashnik called this strategy revolutionary because it was not designed to fight resistance and arose without mandates by government agencies. Rather, it emerged from the farming community of the Yangtze River Valley.

“For the growers in China, this practice provides short-term benefits,” Tabashnik added. “It’s not a short-term sacrifice imposed on them for potential long-term gains. The hybrid plants tend to have higher yield than the parent plants, and the second-generation hybrids cost less, so it’s a market-driven choice for immediate advantages, and it promotes sustainability.”

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From PestNet

Courthouse news update

https://www.courthousenews.com/cornell-researchers-set-use-gmo-moths-control-pests/

DAVID REESE

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 April 26, 2017

The diamondback moth costs farmers over $4 billion annually. (Photo: The Shelton lab at Cornell University)

(CN) – Researchers at Cornell University hope to tackle a small pest and a big problem that has plagued agriculture since the 1800s: controlling the destructive diamondback moth through genetic engineering.

The diamondback moth is a small creature, about the length of two grains of rice, but they are capable of inflicting billions of dollars of damage on cabbage and broccoli crops every year. In fact, the moth is Enemy No. 1 when it comes to the cabbage and broccoli family. Cornell University’s agriculture research division in Geneva, New York, is studying how to invade the invaders with genetically engineered male diamondback moths that mate with females, which then die before reaching adulthood.

The federal Animal and Plant Health Inspection Service said last week it is seeking public comment on Cornell’s plan to release sterile male diamondback moths from the United Kingdom on Cornell’s research grounds.

The diamondback moth (Plutella xylostella) is the world’s worst insect pest of brassica crops (cabbages, canola, broccoli, cauliflower and kale). The pest costs farmers $4 to $5 billion annually worldwide, according to the U.S. Department of Agriculture. The pest arrived on ships in the 1800s, according to Tony Shelton, head of the Shelton Lab at Cornell University’s agriculture research station.

Female diamondback moths can lay over 150 eggs during their short lifetime, and a generation can be produced in as little as two weeks. This invasive pest probably originated in Europe, but is now found throughout the world, including New York and other states that farm brassica vegetables.

Shelton is the leader of the diamondback moth project at Cornell University. The Shelton Lab is part of Cornell University’s Department of Entomology and is about 50 miles from the main campus at the New York State Agricultural Experiment Station in Geneva, New York, in the heart of the Finger Lakes.

Cauliflower

Damage to a cauliflower plant caused by diamondback moths. (Photo: The Shelton lab at Cornell University)

Shelton works with crucifer farmers globally, and this week he was off on a plane to Bangladesh. “Wherever crucifers are grown, diamondback moths are there,” he said in an interview.

Biological controls are part of the solution to controlling the tiny invaders, Shelton said. Best methods of controlling the pests are a combination of biological controls, plowing fields after harvest, and “judicious use of insecticides,” Shelton said. “Genetic control using a self-limiting method could make a valuable contribution of integrated pest management.”

Diamondback moths infest crucifer crops in all U.S. states, but most severe damage occurs in warmer areas where more generations of the moth are produced, Shelton said.

The proposed release of diamondback moths would be at the Cornell research station and would not exceed two years, according to the application. The release would be limited to an experimental field, up to 10 acres. The release site is surrounded by other agricultural fields within the research station’s 870 acres where diamondback moths occur naturally. Shelton’s team would release up to 10,000 male genetically engineered moths per release, up to 30,000 males per week.

The moths that Cornell University is looking to release onto its research grounds are genetically engineered to be sterile, and they also have a fluorescent red marker that shows up under special light. The field studies at Cornell are funded by the U.S. Department of Agriculture and Oxitec, the company that designs and breeds the diamondback moths to be released.

This biological approach to controlling pests has been used for about 50 years and is known as the sterile insect technique. In this technique, male insects are sterilized with radiation and then released to mate with female pest insects of the same species. Because the males have been sterilized, there are no offspring from the mating and this reduces the pest population over time with multiple releases, according to the USDA.

There is one problem with this technique in diamondback moths, though. The radiation used to sterilize the males can affect many other genes and the sterilization reduces the fitness of the male insects to the point they are actually less able to mate with the females.

Affiliated with Oxford University, Oxitec scientists developed a way to produce the same sterility effect using genetic control instead of radiation. By adding two self-limiting genes into the species, the moth offspring are unable to survive into adulthood. Scientists also added a color marker into the genetically engineered moths to be able to track and trace the insects in the environment and to distinguish Oxitec insects from the local pests.

Until now, farmers have sprayed crops to reduce infestation from diamondback larvae, but the moths have developed resistance to the poison, according to the USDA.


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Study identifies ways to encourage ‘refuge’ planting, slowing resistance to Bt crops

April 3, 2017 by Matt Shipman

Study identifies ways to encourage ‘refuge’ planting, slowing resistance to Bt crops
Credit: Alexander Steinhof

A new study from North Carolina State University finds a significant shortfall in the amount of “refuge” cropland being planted in North Carolina – likely increasing the rate at which crop pests will evolve the ability to safely devour genetically engineered Bt crops. However, the study also identified actions that may make farmers more likely to plant refuge crops in the future.

For about 20 years, have made use of Bt to limit crop damage from pests. Bt crops, including corn, are genetically engineered to produce proteins from the Bacillus thuringiensis (Bt) bacterium. These proteins are harmless to vertebrates, but toxic to a specific class of invertebrate crop pests.

To date, these Bt crops have been remarkably successful. However, insect pests have shown the ability to evolve resistance to Bt proteins. In order to slow down the development of Bt resistance, farmers who plant Bt crops are urged to plant a certain percentage of their fields with non-Bt crops – called refuge crops. In fact, in the case of Bt corn, farmers are required to plant a section of their fields with refuge crops.

That’s because refuge crops provide fodder for insect pests that are not resistant to Bt proteins. These pests are then able to breed with their Bt-resistant counterparts, diluting Bt resistance in the overall population.

But compliance with planting refuge crops is variable. Some growers plant too little of their fields with Bt crops, and some don’t plant refuge crops at all.

This raised some interesting questions for Dominic Reisig, an associate professor of entomology at NC State and an extension specialist at the Vernon James Research & Extension Center in eastern North Carolina. Reisig divides his time between conducting research and helping farmers deal with problems related to insect . Recently, Reisig began to wonder: How many growers aren’t planting sufficient refuge crops? Do growers understand the rationale behind refuge crops? What can influence whether growers plant refuge crops? And what factors affect a grower’s willingness to plant refuge crops?

To address these questions, Reisig talked with several hundred corn growers in more than a dozen counties in eastern North Carolina.

Reisig found that approximately 40 percent of corn growers who used Bt corn would not plant refuge crops in the next growing season, while another 25 percent weren’t sure. However, a majority of growers did understand the value of refuge crops – and felt they should be planting them.

Reisig also found that there was a high correlation between how much land was devoted to corn, cotton and soybeans in a county, and how likely farmers in that county were to plant refuge crops. The more land being devoted to crops, the more likely farmers were to plant refuge.

“Some of the resistance to planting refuge may be due to a lack of understanding about how important refuge crops are,” Reisig says. “But it’s also likely to be a function of the fact that many of the farms in counties with low refuge crop compliance are smaller operations. Growers may simply be trying to get more crop yield from their acreage – though there is little evidence of short-term benefit, and ample evidence of long-term risk from Bt-resistant pests.”

Reisig also found that better enforcement and peer pressure from other farmers weren’t seen as making farmers more likely to plant refuge crops. Instead, growers said that financial incentives – such as rebates on non-Bt seed – would make them more likely to plant crops, as would the availability of high-yield non-Bt seed.

“This study is really a starting point,” Reisig says. “We know this is a problem. I’m looking for partners in the social sciences to help me figure out how we can help growers make informed decisions and protect the long-term viability of their crops.”

Explore further: Armyworms develop resistance to Bt corn

More information: Dominic D. Reisig. Factors Associated With Willingness to Plant Non-Bt Maize Refuge and Suggestions for Increasing Refuge Compliance, Journal of Integrated Pest Management (2017). DOI: 10.1093/jipm/pmx002

Read more at: https://phys.org/news/2017-04-ways-refuge-resistance-bt-crops.html#jCp

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PHYS ORG

March 23, 2017

Novel virus breaks barriers between incompatible fungi
SsMYRV4-mediated enhancement of horizontal transmission between different VCGs effectively prevents and controls Sclerotinia diseases. Credit: Wu S, et al. (2017)

Scientists have identified a virus that can weaken the ability of a fungus to avoid pairing with other incompatible fungi, according to new research published in PLOS Pathogens. By promoting fungal pairing, the virus could aid transmission of additional unrelated viruses between fungi.

Fungi, like all other organisms, can recognize foreign substances; such non-self recognition can help protect against pathogens. Some also use non-self recognition to avoid pairing and sharing genetic material with incompatible strains. The fungus Sclerotinia sclerotiorum, which infects hundreds of plant species worldwide, employs this strategy, which is known as vegetative incompatibility.

While studying S. sclerotiorum, Jiatao Xie of Huazhong Agricultural University, China, and colleagues discovered a they named Sclerotinia sclerotiorum mycoreovirus 4 (SsMYRV4). To better understand this novel virus, they grew infected S. sclerotiorum alongside other vegetatively incompatible strains and investigated the molecular effects.

The researchers found that SsMYRV4 decreased expression of S. sclerotiorum genes that promote vegetative incompatibility. Vegetative incompatibility is a molecular process that normally causes when two incompatible strains touch each other; in this study, Xie’s team found a reduction in the amount of cell death that normally occurs in intermingled colonies of incompatible strains.

S. sclerotiorum infected with SsMYRV4 successfully made connections with incompatible by fusing filamentous structures known as hyphae. To investigate the consequences, the scientists grew SsMYRV4-infected fungi alongside fungi infected with other unrelated viruses. They found that the unrelated viruses were able to pass through the fused hyphae, crossing between fungal pairs.

Vegetative is considered a significant obstacle to using viruses to effectively control fungal diseases. These new findings could point to a new strategy that uses SsMYRV4 to weaken barriers between fungi. They could also improve understanding of virus ecology and evolution.

Explore further: Potential biological control agents found for fungal diseases of soybean

More information: Wu S, Cheng J, Fu Y, Chen T, Jiang D, Ghabrial SA, et al. (2017) Virus-mediated suppression of host non-self recognition facilitates horizontal transmission of heterologous viruses. PLoS Pathog 13(3): e1006234. DOI: 10.1371/journal.ppat.1006234

Read more at: https://phys.org/news/2017-03-virus-barriers-incompatible-fungi.html#jCp

https://cm.g.doubleclick.net/push?client=ca-pub-0536483524803400&srn=gdn

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US EPA Approves Three Varieties of GE Potatoes

The U.S. Environmental Protection Agency approved the planting of three types of genetically engineered potatoes that resist the pathogen that caused the Irish potato famine. According to EPA, the GE potatoes are safe for the environment and safe to eat.

The GE potatoes were developed by J.R. Simplot Co. According to Simplot, the GE potatoes only contain potato genes and that the resistance to late blight trait originated from an Argentine potato variety that naturally exhibited defense against the pathogen.

The decision by EPA is consistent with the safety clearance given by Food and Drug Administration in January 2017.

Read more from AP. View the notices (for Y9 and X17) from the EPA website.

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