#CropProtection; #GeneticallyEngineeredDiamondbackMoth; #PestControl
New York, Jan 29 (Canadian-Media): A newly published study reports a successful, first-ever open-field release of a self-limiting, genetically engineered diamondback moth, stating that it paves the way for an effective and sustainable approach to pest control, phys.org/news reports said.
Credit: CC0 Public Domain
The diamondback moth, also known as Plutella xylostella, is highly damaging to brassica crops such as cabbage, broccoli, cauliflower and canola. This new strain of diamondback moth, developed by Oxitec Ltd, is modified to control pest diamondback moth in a targeted manner. The study showed the engineered strain had similar field behaviors to unmodified diamondback moths, with results offering promise for future protection of farmers' brassica crops.
The Cornell study was led by Professor Anthony Shelton in the Department of Entomology at Cornell University's AgriTech in New York and has been published in Frontiers in Bioengineering and Biotechnology.
Oxitec's self-limiting diamondback moth is modified to control its pest counterparts in the field. After release of males of this strain, they find and mate with pest females, but the self-limiting gene passed to offspring prevents female caterpillars from surviving. With sustained releases, the pest population is suppressed in a targeted, ecologically sustainable way. After releases stop, the self-limiting insects decline and disappear from the environment within a few generations.
The field test builds on previously published work in greenhouses by Professor Shelton and colleagues that demonstrated sustained releases of the self-limiting strain effectively suppressed the pest population and prevented resistance developing to an insecticide, a win-win situation for pest control.
"Our research builds on the sterile insect technique for managing insects that was developed back in the 1950s and celebrated by Rachel Carson in her book, Silent Spring," reports Professor Shelton. "Using genetic engineering is simply a more effiicient method to get to the same end."
Male moths as a crop protection solution
Employing field and laboratory testing, as well as mathematical modelling, the researchers gathered relevant information on the genetically engineered strain of diamondback moth, whose wild counterparts cause billions of dollars in damage. The study was the first in the world to release self-limiting agricultural insects into an open field.
"For the field study, we used the "mark-release-recapture" method, which has been used for decades to study insect movement in fields. Each strain was dusted with a fluorescent powder to mark each group before release, then captured in pheromone traps and identified by the powder color and a molecular marker in the engineered strain," explains Shelton.
The researchers were very pleased with the results of this comprehensive study.
"When released into a field, the self-limiting male insects behaved similarly to their non-modified counterparts in terms of factors that are relevant to their future application in crop protection, such as survival and distance travelled. In laboratory studies they competed equally well for female mates" reports Shelton. "Our mathematical models indicate that releasing the self-limiting strain would control a pest population without the use of supplementary insecticides, as was demonstrated in our greenhouse studies."
"This study demonstrates the immense potential of this exciting technology as a highly effective pest management tool, which can protect crops in an environmentally sustainable way and is self-limiting in the environment," says Dr. Neil Morrison, Oxitec's agriculture lead and study co-author.
#EarthSciences; #TidewaterGlaciers; #RoboticKayaks, #GeophysicalResearchLetters
New Jersey (United States), Jan 29 (Canadian-Media): Tidewater glaciers, the massive rivers of ice that end in the ocean, may be melting underwater much faster than previously thought, according to a Rutgers co-authored study that used robotic kayaks, phys.org/news reports said.
An autonomous kayak surveys the ocean in front of the 20-mile-long LeConte Glacier in Alaska. The kayak measures ocean currents and water properties to study the underwater melting of the glacier and track meltwater as it spreads in the ocean. Credit: David Sutherland/University of Oregon
The findings, which challenge current frameworks for analyzing ocean-glacier interactions, have implications for the rest of the world's tidewater glaciers, whose rapid retreat is contributing to sea-level rise.
The study, published in the journal Geophysical Research Letters, surveyed the ocean in front of 20-mile-long LeConte Glacier in Alaska. The seaborne robots made it possible for the first time to analyze plumes of meltwater, the water released when snow or ice melts, where glaciers meet the ocean. It is a dangerous area for ships because of ice calving—when falling slabs of ice that break from glaciers crash into the water and spawn huge waves.
"With the kayaks, we found a surprising signal of melting: Layers of concentrated meltwater intruding into the ocean that reveal the critical importance of a process typically neglected when modeling or estimating melt rates," said lead author Rebecca Jackson, a physical oceanographer and assistant professor in the Department of Marine and Coastal Sciences in the School of Environmental and Biological Sciences at Rutgers University-New Brunswick. Jackson led the study when she was at Oregon State University.
Two kinds of underwater melting occur near glaciers. Where freshwater discharge drains at the base of a glacier (from upstream melt on the glacier's surface), vigorous plumes result in discharge-driven melting. Away from these discharge outlets, the glacier melts directly into the ocean waters in a regime called ambient melting.
The study follows one published last year in the journal Science that measured glacier melt rates by pointing sonar at the LeConte Glacier from a distant ship. The researchers found melt rates far higher than expected but couldn't explain why. The new study found for the first time that ambient melting is a significant part of the underwater mix.
Before these studies, scientists had few direct measurements of melt rates for tidewater glaciers and had to rely on untested theory to get estimates and model ocean-glacier interactions. The studies' results challenge those theories, and this work is a step toward better understanding of submarine melt—a process that must be better represented in the next generation of global models that evaluate sea-level rise and its impacts.
Researchers at Oregon State University, University of Alaska Southeast, University of Oregon and University of Alaska Fairbanks contributed to the study.
#RotationOfCrops; #PlantPests; #SwitchingOfEnvironment
Germany, Jan 16 (Canadian-Media): A new computational model presented by Maria Bargués-Ribera and Chaitanya Gokhale of the Max Planck Institute for Evolutionary Biology in Germany in PLOS Computational Biology shows how different patterns of crop rotation—planting different crops at different times in the same field—can impact long-term yield when plant pathogens threaten the crops, media reports said.
Crops being managed in crop rotation. Credit: USDA NRCS Texas
The threat posed to agriculture worldwide by the continual evolution of plant pathogens can be minimized by crop rotation which improves pest control and soil quality. Yet another solution, pointed by other research is switching the environment in which a pathogen grows to limit its reproduction and change its evolution. However, these two concepts have been rarely studied together from an evolutionary point of view.
A computational model of the technique integrating evolutionary theory was developed by Bargués-Ribera and Gokhale to investigate a scenario in which cash crops (grown for profit) and cover crops (grown to benefit soil) are alternated, but are affected by a pathogen that only attacks the cash crops and this leads to a better understanding of how crop rotation can protect against pests.
It was also identified by this analysis that the patterns of crop rotation which maximize crop yield over multiple decades under the given scenario showed that regular rotations every other year may not be beneficial. The suggestions of the findings are that the long-term outcome of crop rotation depends on its ability to both maintain soil quality and diminish pathogen load during harvesting seasons.
"Our model is an example of how evolutionary theory can complement farmers' knowledge," Bargués-Ribera says. "In a world with ever increasing food demand, ecological and evolutionary principles can be leveraged to design strategies making agriculture efficient and sustainable."
The new model could be applied in the future research to specific species to assess crop rotation patterns for specific crops and their pests. The model could also be used to help study the combined effects of crop rotation with other pest control techniques, such as fungicides and use of crops that have been genetically modified for pest resistance.
#YaleUniversityResearchers; #MassExtinctionOfDinosaurs; #Asteriod; #VolcanicEruptions
Yale University (United States), Jan 16 (Canadian-Media): The mass extinction event that killed the dinosaurs was the result slamming of an asteroid into the earth, and not volcanic activity, according to an international, Yale-led team of researchers, media reports said.
Credit: CC0 Public Domain
Yale assistant professor of geology & geophysics Pincelli Hull and her colleagues argue in a new research paper in Science that environmental impacts from massive volcanic eruptions in India in the region known as the Deccan Traps happened well before the Cretaceous-Paleogene extinction event 66 million years ago and therefore did not contribute to the mass extinction.
The fact that mass extinction event, also known as K-Pg, occurred after an asteroid slammed into Earth had been acknowledged by many scientists and that volcanic activity happened around the same time.
"Volcanoes can drive mass extinctions because they release lots of gases, like SO2 and CO2, that can alter the climate and acidify the world," said Hull, lead author of the new study. "But recent work has focused on the timing of lava eruption rather than gas release."
In order to find out the exact timing of volcanic gas emission, Hull and her colleagues compared global temperature change and the carbon isotopes (an isotope is an atom with a higher or lower number of neutrons than normal) from marine fossils with models of the climatic effect of CO2 release.
It was concluded by these researchers that most of the gas release happened well before the asteroid impact—and that the asteroid was the sole cause of extinction.
"Volcanic activity in the late Cretaceous caused a gradual global warming event of about two degrees, but not mass extinction," said former Yale researcher Michael Henehan, who compiled the temperature records for the study. "A number of species moved toward the North and South poles but moved back well before the asteroid impact."
Added Hull, "A lot of people have speculated that volcanoes mattered to K-Pg, and we're saying, 'No, they didn't.'"
Recent work on the Deccan Traps, in India, has also pointed to massive eruptions in the immediate aftermath of the K-Pg mass extinction. These results have puzzled scientists because there is no warming event to match. The new study suggests an answer to this puzzle, as well.
"The K-Pg extinction was a mass extinction and this profoundly altered the global carbon cycle," said Yale postdoctoral associate Donald Penman, the study's modeler. "Our results show that these changes would allow the ocean to absorb an enormous amount of CO2 on long time scales—perhaps hiding the warming effects of volcanism in the aftermath of the event."
#NASA, #NOAA; #2019AnnualAssessmentOfGlobalTemperatures
Washington, Jan 10 (Canadian-Media): Climate experts from NASA and the National Oceanic and Atmospheric Administration (NOAA) will release their annual assessment of global temperatures and discuss the major climate trends of 2019 during a media teleconference at 12:15 p.m. EST Wednesday, Jan. 15, NASA reports said.
NASA and NOAA are two keepers of the world's temperature data and independently produce a record of Earth's surface temperatures and changes. Shown here are 2018 global temperature data: higher than average (1951-1980) temperatures are shown in red, lower than normal temperatures are in blue. Credits: NASA Earth Observatory
The briefing will take place at the 100th American Meteorological Society Annual Meeting in Boston.
The teleconference participants are:
Media can participate in the teleconference by calling 800-369-2090 (toll-free in the United States and Canada) or 1-203-827-7030 (international) and use the passcode CLIMATE. Audio of the briefing with supporting graphics will stream live at:
The supporting graphics will also be available at:
NASA and NOAA are two keepers of the world's temperature data and independently produce a record of Earth's surface temperatures and changes based on historical observations over oceans and land.
For more information about NASA's Earth science programs, visit:
#PlantLifeExpandingInHimalayanRegion; #DeclineOfTemperatureLimitedAreas; #MountEverest; #HimalayanEcosystems; #GoogleEarthEngine
Cornwall (England), Jan 10 (Canadian-Media): Plant life is expanding in the area around Mount Everest, and across the Himalayan region, new research shows, phys.org/news reports said.
View towards Khumbu and Cholatse from below Ama Dablam at about 4,900 m showing typical subnival vegetation in the foreground. Credit: Karen Anderson
Scientists used satellite data to measure the extent of subnival vegetation--plants growing between the treeline and snowline—in this vast area.
Little is known about these remote, hard-to-reach ecosystems, made up of short-stature plants (predominantly grasses and shrubs) and seasonal snow, but the study reveals they cover between 5 and 15 times the area of permanent glaciers and snow.
Using data from 1993 to 2018 from NASA's Landsat satellites, University of Exeter researchers measured small but significant increases in subnival vegetation cover across four height brackets from 4,150-6,000 metres above sea level.
Results varied at different heights and locations, with the strongest trend in increased vegetation cover in the bracket 5,000-5,500m.
Around Mount Everest, the team found a significant increase in vegetation in all four height brackets. Conditions at the top of this height range have generally been considered to be close to the limit of where plants can grow.
Though the study doesn't examine the causes of the change, the findings are consistent with modelling that shows a decline in "temperature-limited areas" (where temperatures are too low for plants to grow) across the Himalayan region due to global warming.
View towards Nuptse-Lhotse Ridge from below Ama Dablam at about 4,900 m showing typical subnival vegetation. Credit: Karen Anderson
Other research has suggested Himalayan ecosystems are highly vulnerable to climate-induced vegetation shifts.
"A lot of research has been done on ice melting in the Himalayan region, including a study that showed how the rate of ice loss doubled between 2000 and 2016," said Dr. Karen Anderson, of the Environment and Sustainability Institute on Exeter's Penryn Campus in Cornwall.
"It's important to monitor and understand ice loss in major mountain systems, but subnival ecosystems cover a much larger area than permanent snow and ice and we know very little about them and how they moderate water supply.
"Snow falls and melts here seasonally, and we don't know what impact changing subnival vegetation will have on this aspect of the water cycle—which is vital because this region (known as 'Asia's water towers') feeds the ten largest rivers in Asia."
Dr. Anderson said "some really detailed fieldwork" and further validation of these findings is now required to understand how plants in this high-altitude zone interact with soil and snow.
Scrubby vegetation near the Nepalese village of Dingboche about 4,400 m above sea level. Credit: Karen Anderson
Dominic Fawcett, who coded the image processing, said: "These large-scale studies using decades of satellite data are computationally intensive because the file sizes are huge. We can now do this relatively easily on the cloud by using Google Earth Engine, a new and powerful tool freely available to anyone, anywhere."
The Hindu Kush Himalayan region extends across all or part of eight countries, from Afghanistan in the west to Myanmar in the east. More than 1.4 billion people depend on water from catchments emanating here.
The paper, published in the journal Global Change Biology, is entitled: "Vegetation expansion in the subnival Hindu Kush Himalaya."
A new study published by biologists at LMU demonstrates that there are no simple or universal solutions to the problem of engineering plants to enable them to cope with the challenges posed by climate change, phys.org/news reports said.
Adapting crops such as tobacco to climate change is more complex than expected. Credit: Ludwig Maximilian University of Munich
For plants, climate change promises one thing for sure—increased levels of stress. After all, plants put down roots. They don't have the option of moving to where the weather suits them. Wider fluctuations in temperatures and increasing levels of aridity in many regions around the world are already making their lives more difficult. Plants are highly complex and sensitive systems. Even in zones with stable climates today, variations in light levels can reduce growth rates and crop yields. For example, plants have developed sophisticated cellular mechanisms that protect them against the deleterious effects of high light intensities on photosynthesis. In one such photoprotective process, the excess light energy is dissipated as heat before it can damage the photosynthetic apparatus. This depresses yields but it is very much in the plant's interest.
Three enzymes play a key role in this adaptation process, which are referred to as V, P and Z for short. In a paper published in 2016, which drew a great deal of attention, an American research group overexpressed the genes for these three proteins in tobacco plants, thus increasing the amounts of the enzymes produced in the leaves. They subsequently observed, under field conditions, that these "VPZ' lines grew faster rates than did control plants with normal levels of the enzymes. LMU biologists Antoni Garcia-Molina and Dario Leister have now performed essentially the same experiment in the model plant Arabidopsis thaliana (thale cress). Their findings appear in the journal Nature Plants.
Their results confirm that, as in the case of tobacco, higher levels of V, P and Z reduce rates of photosynthesis while enabling the plants to adapt more rapidly (in fact, even faster than tobacco) to fluctuating light levels. Crucially however, the Arabidopsis VPZ lines did not grow faster than control plants. On the contrary, overexpression of the three enzymes resulted in retarded growth. "This clearly shows that it's not quite as easy to produce plants that are better adapted as some research groups have confidently suggested," Leister remarks. "In fact, higher levels of photoprotection may actually interfere with the operation of other mechanisms that are important for plant growth."
For Leister, these data essentially demonstrate that targeted adaptation of plants to facilitate successful adjustment to changing climatic conditions is likely to be a very complicated task. They certainly show that one cannot always expect to confer increased resistance to desiccation or optimize yields under fluctuating light levels simply by adjusting the levels of a few proteins. "The physiological processes in plants are tightly interconnected. This makes it impossible to predict the effects of flipping this switch or tightening that screw," he says. This explains why he and his colleagues approach the problem of targeted adaptation from the perspective of systems biology, which takes a "holistic" view, as he calls it. For example, efforts to increase the yield or biomass by increasing the efficiency of photosynthesis must also ensure that the extra energy available is in fact channeled into increased growth. In principle, enhanced photosynthetic performance should result in the capture of more energy and in higher levels of metabolites. But this extra energy and abundance of chemical compounds must be put to some beneficial use. In the absence of any "added value," increased rates of photosynthesis can prove to be detrimental to plants.
The analysis of complex relationships like this is the raison d'ètre of the Transregional Collaborative Research Center TR175, of which Leister is the principal coordinator. The scientists involved in the project seek to understand how plants react to biotic and abiotic environmental factors, such as drought, light levels and temperature, by analyzing their impact on the concentrations of all measurable metabolites, transcripts and proteins in plant cells. With the help of these data, they hope to identify the key components that allow plants to cope with varying conditions. In the case of crop plants that are indispensable for human nutrition, the mechanisms that underlie trade-offs between growth rates, increases in biomass and yields must also be taken into consideration. "In the context of climate change, the idea is to help plants to adapt to the changing conditions by introducing targeted genetic changes that allow them to handle the altered environmental parameters," Leister explains. Researchers refer to this strategy as "assisted evolution." "In order to have a realistic chance of finding sustainable solutions, we must adopt a systematic approach to the active adaptation of plants to the changing environmental conditions," he says. In this respect, some progress has already been made in certain species of algae that have very short generation times, which permits instances of successful adaptation to be rapidly detected. Such systems can then serve as sources of potentially useful genetic mutations that can be introduced into green plants.