Resistance of cotton bollworm to insect-killing cotton plants involves more diverse genetic changes than expected, an international research team reports in the journal Proceedings of the National Academy of Sciences. To decrease sprays of broad-spectrum insecticides, which can harm animals other than the target pests, cotton and corn have been genetically engineered to produce toxins derived from the bacterium Bacillus thuringiensis, or Bt.

Bt toxins kill certain insect pests but are harmless to most other creatures including people. These environmentally friendly toxins have been used for decades in sprays by organic growers and since 1996 in engineered Bt crops by mainstream farmers.

Over time, scientists have learned, initially rare genetic mutations that confer resistance to Bt toxins are becoming more common as a growing number of pest populations adapt to Bt crops.

In the first study to compare how pests evolve resistance to Bt crops in the laboratory vs. the field, researchers discovered that while some the of the lab-selected mutations do occur in the wild populations, some mutations that differ markedly from those seen in the lab are important in the field.

Caterpillars of the cotton bollworm, Helicoverpa armigera, can munch on a wide array of plants before emerging as moths. This species is the major cotton pest in China, where the study was carried out.

Bruce Tabashnik, head of the department of entomology at the University of Arizona College of Agriculture and Life Sciences, who co-authored the study, considers the findings an early warning to farmers, regulatory agencies and the biotech industry.

“Scientists expected the insects to adapt, but we’re just finding out now how they’re becoming resistant in the field,” Tabashnik said.

To avoid surprises, researchers have exposed cotton bollworm populations to Bt toxins in controlled lab experiments and studied the genetic mechanisms by which the insects adapt.

“We try to stay ahead of the game,” he said. “We want to anticipate what genes are involved, so we can proactively develop strategies to sustain the efficacy of Bt crops and reduce reliance on insecticide sprays. The implicit assumption is what we learn from lab-selected resistance will apply in the field.”

That assumption, according to Tabashnik, had never been tested before for resistance to Bt crops.

Now for the first time, the international team gathered genetic evidence from pests in the field, enabling them to directly compare the genes involved in the resistance of wild and lab-reared populations.

They found some resistance-conferring mutations in the field were the same as in lab-reared pests, but some others were strikingly different.

“We found exactly the same mutation in the field that was detected in the lab,” Tabashnik said. “But we also found lots of other mutations, most of them in the same gene and one in a completely different gene.”

A major surprise came when the team identified two unrelated, dominant mutations in the field populations. “Dominant” means that one copy of the genetic variant is enough to confer resistance to Bt toxin.

In contrast, resistance mutations characterized before from lab selection are recessive – meaning it takes two copies of the mutation, one provided by each parent, to make an insect resistant to Bt toxin.

“Dominant resistance is more difficult to manage and cannot be readily slowed with refuges, which are especially useful when resistance is recessive,” Tabashnik said.

Refuges consist of plants that do not have a Bt toxin gene and thus allow survival of insects that are susceptible to the toxin. Refuges are planted near Bt crops with the goal of producing enough susceptible insects to dilute the population of resistant insects, by making it unlikely two resistant insects will mate and produce resistant offspring.

According to Tabashnik, the refuge strategy worked brilliantly against the pink bollworm in Arizona, where this pest had plagued cotton farmers for a century, but is now scarce.

The dominant mutations discovered in China throw a wrench in the refuge strategy because resistant offspring arise from matings between susceptible and resistant insects.

He added that the study will enable regulators and growers to better manage emerging resistance to Bt crops.

“We have been speculating and using indirect methods to try and predict what would happen in the field. Only now that resistance is starting to pop up in many places is it possible to actually examine resistance in the field.

I think the techniques from this study will be applied to many other situations around the world, and we’ll begin to develop a general understanding of the genetic basis of resistance in the field.”

The current study is part of a collaboration funded by the Chinese government, involving a dozen scientists at four institutions in China and the U.S. Yidong Wu at Nanjing Agricultural University designed the study and led the Chinese effort.

He emphasized the importance of the ongoing collaboration for addressing resistance to Bt crops, which is a major issue in China. He also pointed out that the discovery of dominant resistance will encourage the scientific community to rethink the refuge strategy.

Tabashnik said China is the world’s top cotton producer, with about 16 billion pounds of cotton per year. India is number two, followed by the U.S., which produces about half as much cotton as China.

In 2011, farmers worldwide planted 160 million acres of Bt cotton and Bt corn. The percentage of cotton planted with Bt cotton reached 75 per cent in the U.S. in 2011, but has exceeded 90 per cent since 2004 in northern China, where most of China’s cotton is grown.

The researchers report that resistance-conferring mutations in cotton bollworm were three times more common in northern China than in areas of northwestern China where less Bt cotton has been grown.

Even in northern China, however, growers haven’t noticed the emerging resistance yet, Tabashnik said, because only about 2 percent of the cotton bollworms there are resistant.

“As a grower, if you’re killing 98 percent of pests with Bt cotton, you wouldn’t notice anything. But this study tells us there is trouble on the horizon.”

Nanotechnology has developed tremendously in the past decade and was able to create many new materials with a vast range of potential applications. Some of those innovative materials are promising to reduce environmental pollution. For instance, carbon nanotubes and metal nano-particles are great candidate materials for cleaning polluted water and soils.

However, the risk that nano-particles may pose to human and environment health is not yet fully understood. The precautionary principle therefore suggests keeping environmental release of nano-particles minimal until their fate and toxicity is better understood.

“A good understanding of nano-materials is essential to evaluate whether the benefits overcome potential new risks”, explains Thilo Hofmann, dean elected at the Faculty of Geosciences, Geography and Astronomy of the University of Vienna.

Among numerous proposed applications, nanotechnology has the potential to revolutionize agricultural practices and food systems. Research has been extremely active over the past few years to develop new pesticides products based on nanotechnology.

“Nano-pesticide research is emerging at high speed at the agrochemical labs, however, this topic has not reached public awareness or state authorities so far, nor are any products available at the marked.

“Since those nano-pesticides have new or enhanced properties, this will change in near future and will inevitably result in both new risks and new benefits to human and environmental health”, states Thilo Hofmann.

Nano-pesticides encompass a great variety of products, some of which are already on the market. The application of nano-pesticides would be the only intentional diffuse input of large quantities of engineered nano-particles into the environment.

Innovation always results in both drawbacks and benefits for human and environmental health. Nano-pesticides may reduce environmental contamination through the reduction in pesticide application rates and reduced losses.

However, nano-pesticides may also create new kinds of contamination of soils and waterways due to enhanced transport, longer persistence and higher toxicity.

The current level of knowledge does not allow a fair assessment of the advantages and disadvantages that will result from the use of nano-pesticides. As a prerequisite for such assessment, a better understanding of the fate and effect of nano-pesticides after their application is required.

The suitability of current regulations should also be analyzed so that refinements can be implemented if needed. Research on nano-pesticides is therefore a priority for preserving the quality of both the food chain and the environment.

Publication in “Critical Reviews in Environmental Science and Technology” Nano-pesticides: state of knowledge, environmental fate and exposure modeling: Melanie Kah, Sabine Beulke, Karen Tiede and Thilo Hofmann. Critical Reviews of Environmental Science and Technology (2012)

University of Southampton researchers are pioneering a new way of measuring and monitoring the impact of industrial and agricultural development on the environment. Working in collaboration with East China Normal University, the Nanjing Institute of Geography and Limnology and the University of Dundee, the team has created the world’s first long-term record of ecosystem health, which examines the past condition of environmental resources in China’s Yangtze basin region, and helps develop forecasts for the future.

“We have examined what effect modern intensive farming techniques have had on ‘ecosystem services’ – things like food, fuel, soil and clean water – in the Yangtze basin area. From this we get an overview of the condition of these resources, which are essential for the survival of local communities,” says lead researcher Professor John Dearing from the University of Southampton.

The team drilled core samples at two lakes in the region, west of Shanghai, and have made detailed studies of the sediment they retrieved.

Professor Dearing explains, “The data we have compiled came from the analysis of microfossils, geo-chemistry, mineral magnetism, and sediment accumulation rates.

These different analyses give us clues about the past health of the environment – for example, pollen samples tell us about the diversity of plant species at a given time, while metal content can be used to measure air quality. By bringing all the information together, we have been able to track the condition of environmental resources over a 200 year period.”

In addition, researchers have examined official statistical records and climate models to give trends on land use, population, gross domestic product (GDP), temperature and precipitation. By comparing these statistics with the core sample data they have seen that as GDP in the Yangtze region increased sharply in the 1970s, the quality of ecosystem services suffered a downward trend.

Improved environmental regulation and policies encouraged a partial stabilisation in the 1980s, but the downward trend continued sharply in the 1990s and beyond. The study findings have been published in the journal the Proceedings of the National Academy of Sciences1.

Professor Dearing comments, “Intensive agriculture has lifted many Chinese rural communities out of poverty in the last 30 years, but irrigation, mechanisation and fertilisers that came with it have degraded soils badly and there is already evidence of declining water quality.

“Economic development and an increase in regional wealth are clear trade-offs for the decline in ecosystem services. However, in the long-term, this decline will be a threat to local livelihoods and could reach a ‘tipping point’, becoming irreversible.

“Financial indexes, like the FTSE 100 or Dow Jones, are used to monitor the health of an economy, and this project has led us to consider that palaeoecological records could provide the basis for a regional ‘ecosystem service index’, monitoring the health of a region’s environment.”

Where suitable, researchers hope to use the technique they have developed in China for other areas of the world, with the aim of helping policymakers to prioritise the most urgent environmental problems and identify which strategies work best to tackle them.

A team of NOAA-supported scientists is predicting that this year’s Gulf of Mexico hypoxic zone could range from a low of approximately 1,197 square miles to as much as 6,213 square miles. The wide range is the result of using two different forecast models. The forecast is based on Mississippi River nutrient inputs compiled annually by the U.S. Geological Survey (USGS).

The smaller dead zone forecast, covering an area slightly larger than the state of Rhode Island, comes from researchers from the University of Michigan. Their predicted size is based solely on the current year’s spring nutrient inputs from the Mississippi River which are significantly lower than average due to drought conditions throughout much of the watershed.

The larger dead zone forecast, the equivalent of an area the size of the state of Connecticut, is from Louisiana Universities Marine Consortium and Louisiana State University scientists.

The Louisiana forecast model includes prior year’s nutrient inputs which can remain in bottom sediments and be recycled the following year. Last year’s flood, followed by this year’s low flows, increased the influence of this “carryover effect” on the second model’s prediction.

Hypoxia is caused by excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water.

During May 2012 stream-flow in the Mississippi and Atchafalaya Rivers were nearly half that of normal conditions. This resulted in a decrease in the amount of nitrogen transported by the rivers into the Gulf. According to USGS estimates, 58,100 metric tons of nitrogen (in the form of nitrite plus nitrate) were transported in May 2012 by the Mississippi and Atchafalaya Rivers to the northern Gulf.

The amount of nitrogen transported to the Gulf in May 2012 was 56 percent lower than average May nitrogen loads estimated in the last 33 years.

The two smallest recorded dead zones to date are in 2000 when it measured 1,696 square miles and a 15 square miles dead zone in 1988. Last year’s dead zone measured 6,765 square miles. The largest hypoxic zone measured to date occurred in 2002 encompassing more than 8,400 square miles.

“This forecast is a good example of NOAA, USGS and university partnerships delivering ecological forecasts that quantify the linkages between the watershed and the coast,” said Jane Lubchenco, Ph.D., under secretary of commerce for oceans and atmosphere and NOAA administrator.

“Regardless of the size of the dead zone, we should not lose sight of the ongoing need to reduce the flow of nutrients to the Mississippi River and thus the Gulf.”

“These forecasts are the product of decades of research, monitoring, and modeling on how decisions we make in the vast drainage basin of the Mississippi and its tributaries translates into the health of the coastal zone of the Gulf of Mexico,” said USGS Director Marcia McNutt, Ph.D.

“Comparing the actual hypoxic zone against the predictions will help scientists better understand the multi-year memory of this complex land-sea system, and ultimately better inform options for improving ecosystem productivity.”

The actual size of the 2012 hypoxic zone will be released following a NOAA-supported monitoring survey led by the Louisiana Universities Marine Consortium between July 27 and August 3.

Collecting these data is an annual requirement of the Mississippi River/Gulf of Mexico Watershed Nutrient Task Force Action Plan. Additional NOAA-supported surveys led by the National Marine Fisheries Service and Texas A and M University will also provide an indication of the progression of the dead zone during the year.

The average of impacted waters over the past five years is approximately 6,000 square miles, much larger than the 1,900 square miles which is the target goal set by the Gulf of Mexico/Mississippi River Watershed Nutrient Task Force.

The hypoxic zone, that form each spring and summer off the coast of Louisiana and Texas, threaten valuable commercial and recreational Gulf fisheries. In 2009, the dockside value of commercial fisheries in the Gulf was $629 million. Nearly three million recreational fishers further contributed about $10 billion to the Gulf economy, taking 22 million fishing trips

This year’s forecast is just one example of NOAA’s growing ecological forecasting capabilities, supported by both NOAA and USGS science, which allow for the protection of valuable resources using scientific, ecosystem-based approaches.

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Malware Gets Snoopy

By Mark Gibbs, NetworkWorld

via PCWorld.com

Selenium is an inexpensive element that naturally belongs in the body. It is also known to combat bacteria. Still, it had not been tried as an antibiotic coating on a medical device material. In a new study, Brown University engineers report that when they used selenium nanoparticles to coat polycarbonate, the material of catheters and endotracheal tubes, the results were significant reductions in cultured populations of Staphylococcus aureus bacteria, sometimes by as much as 90 percent.

“We want to keep the bacteria from generating a biofilm,” said Thomas Webster, professor of engineering and orthopaedics, who studies how nanotechnology can improve medical implants. He is the senior author of the paper, published online this week in the Journal of Biomedical Materials Research A.

Biofilms are notoriously tough colonies of bacteria to treat because they are often able to resist antibiotic drugs.

“The longer we can delay or inhibit completely the formation of these colonies, the more likely your immune system will clear them,” Webster said. “Putting selenium on there could buy more time to keep an endotracheal tube in a patient.”

Meanwhile, Webster said, because selenium is actually a recommended nutrient, it should be harmless in the body at the concentrations found in the coatings. Also, it is much less expensive than silver, a less biocompatible material that is the current state of the art for antibacterial medical device coatings.

Webster has been investigating selenium nanoparticles for years, mostly for their possible anticancer effects. As he began to look at their antibiotic properties, he consulted with Hasbro Children’s Hospital pediatrician Keiko Tarquinio, assistant professor of pediatrics, who has been eager to find ways to reduce biofilms on implants.

Studying selenium
For this study, Webster and first author Qi Wang grew selenium nanoparticles of two different size ranges and then used solutions of them to coat pieces of polycarbonate using a quick, simple process. On some of the polycarbonate, they then applied and ripped off tape not only to test the durability of the coatings but also to see how a degraded concentration of selenium would perform against bacteria.

On coated polycarbonate – both the originally coated and the tape-tested pieces – Wang and Webster used electron and atomic force microscopes to measure the concentration of nanoparticles and how much surface area of selenium was exposed to interact with bacteria.

One of their findings was that after the tape test, smaller nanoparticles adhered better to the polycarbonate than larger ones.

Then they were ready for the key step: experiments that exposed cultured staph bacteria to polycarbonate pieces, some of which were left uncoated as controls. Among the coated pieces, some had the larger nanoparticles and some had the smaller ones. Some from each of those groups had been degraded by the tape, and others had not.

All four types of selenium coatings proved effective in reducing staph populations after 24, 48, and 72 hours compared to the uncoated controls. The most potent effects – reductions larger than 90 percent after 24 hours and as much as 85 percent after 72 hours – came from coatings of either particle size range that had not been degraded by the tape. Among those coatings that had been subjected to the tape test, the smaller nanoparticle coatings proved more effective.

Staph populations exposed to any of the coated polycarbonate pieces peaked at the 48-hour timeframe, perhaps because that is when the bacteria could take fullest advantage of the in vitro culture medium. But levels always fell back dramatically by 72 hours.

The next step, Webster said, is to begin testing in animals. Such in vivo experiments, he said, will test the selenium coatings in a context where the bacteria have more available food but will also face an immune system response.

The results may ultimately have commercial relevance. Former graduate students developed a business plan for the selenium nanoparticle coatings while in school and have since licensed the technology from Brown for their company, Axena Technologies.