Unlike the Beach Boys musical group of old, Rodrigo Krugner is picking up bad vibrations.
It’s the sounds that glassy-winged sharpshooters make as they seek to find and mate with each other. That’s the focus of research by Krugner, research entomologist with the U.S. Department of Agriculture’s Agricultural Research Service in Parlier, Calif.
Krugner discussed “Mating disruption of the Glassy-Winged Sharpshooter: How does that sound?” at this year’s Grape Day event at California State University, Fresno (Fresno State). The insect can spread the deadly Pierce’s disease in grapevines faster than its smaller sharpshooter cousins, and Pierce’s costs California more than $100 million per year.
Krugner explained how the insects communicate with each other through seismic vibrational signals produced by their abdominal muscles. He is studying the degree at which “courtship signals” sent in call-response fashion can be disrupted.
Right now, the means for combatting the pest include insecticide applications in citrus orchards where they congregate, and releasing egg parasitoids.
Krugner explained that a laser Doppler vibrometer, a technology used in the aerospace industry to listen for vibrations, figured into his research. Both white noise and female calls reduced mating under laboratory conditions, but did not affect insect aggregation.
The efficacy of these and other signals in disrupting GWSS communication is being evaluated under field conditions in collaboration with Fresno State.
Electrodynamic shakers were attached to plant stems to generate disruptive and-or masking signals. The idea is to learn if the playback of selected GWSS signals onto grapevines will determine whether mating behavior is affected by disruptive signals and whether GWSS individuals can be either attracted or repelled by signals.
Krugner said males sometimes naturally mimic females to lure rivals away, and noted the process of mates locating each other often takes up to three hours.
The largest agricultural robot on Earth working in an Arizona energy sorghum varietal trial.
The crop analytic robot is a Volkswagen-sized field scanner measuring crop growth with unprecedented resolution.
Plant data collected by the field scanner will be shared with crop breeders to speed up the breeding process in energy sorghum.
Pedro Andrade, left, University of Arizona, and Jeff White, USDA Agricultural Research Service, based in Maricopa, Ariz., stand in an energy sorghum variety trial where the world’s largest crop analytical robot records critical plant data.
Captain Kirk of Star Trek movie fame would feel right at home operating the controls of Planet Earth’s largest agricultural robot, currently operating in an energy sorghum varietal trial in Maricopa, Ariz.
The crop analytic robot, similar in appearance to a gantry crane, features a Volkswagen-sized field scanner loaded with the latest precision agriculture tools to precisely measure crop growth with unprecedented resolution.
The field scanner which moves east-to-west, north-to-south, and up-and-down above the field is located at the University of Arizona’s (UA) Maricopa Agricultural Center (MAC).
Over time, plant data collected by the field scanner will be shared with commercial and university crop breeders to help speed up the natural breeding process in energy sorghum varieties to boost yields and biomass content. The same tools could one day by use to collect plant data for breeding other types of crops.
Over the long term, improved energy sorghum varieties can help growers increase biofuel production, thus helping reduce this nation’s dependence on foreign oil.
Robot ribbon cutting
At a June ribbon-cutting ceremony for the robot field scanner system, DOE Advanced Research Projects Agency-Energy (ARPA-E) Director Joe Cornelius described the project as “agriculture’s version of the Hubble” (telescope), saying the project’s faster breeding results could place improved varieties in growers’ hands sooner.
The DOE’s Ellen Williams said the project would “revolutionize plant breeding.” She believes the sorghum project could accelerate the plant breeding process by two to three fold.
Shane Burgess, UA Dean of the College of Agriculture and Natural Resources, noted, “This is history in the making.”
Led by the Donald Danforth Plant Science Center in St. Louis, Mo., the field scanner robot project includes specialists from several universities, the federal government, and the private sector.
In the first year of the four-year project, the sorghum trial is largely funded by the U.S. Department of Energy (DOE). The project budget is about $8 million, not including the field scanner.
The UA receives about $1.6 million to cover the costs to construct the site and for its day-to-day operation.
John Innes Centre scientists disable infectious bacteria by removing key protein
John Innes Centre
<Scientists at the John Innes Centre and the University of East Anglia have made an exciting discovery that could provide a new way to prevent bacterial infections in both humans and plants without triggering multi-drug resistance in bacteria.
When bacteria infect either a plant or a human they first have to move across the surface to a likely site of infection. Without this migration, the bacteria find it difficult to get inside the host and are far less able to cause infection.
The research team, led by Dr Jacob Malone from the JIC and UEA’s School of Biological Sciences, was curious about why there were high levels of a particular protein in bacteria when they came into contact with plants. Upon investigating this protein further they discovered it is an important, high-level controller of bacterial movement during plant and human infection. This protein could become a new target against which to develop anti-infective drugs and because the bacteria aren’t killed outright, also reduces the likelihood of the bacteria evolving to develop resistance to the drugs.
Dr Malone and his team study a type of bacteria called Pseudomonas, of which there are dozens of different species, including the pathogen P. aeruginosa, which causes around 7% of hospital acquired infections in the UK and is a major cause of mortality in cystic fibrosis patients. Understanding these bacteria is medically very important.
They have found that the ability of Pseudomonas to cause infection is compromised at an early stage when one key protein is removed from the bacterium.
The key protein is called RimK, and is present in hundreds of species of bacteria, including several important human pathogens, but its biological function has remained largely unknown.
Dr Malone’s team discovered a completely new function for RimK. When they removed it from bacteria, those bacteria weren’t able to move properly, which in turn affected their ability to initiate infections. When scientists examined the effect of RimK deletion on plants they found that spraying a plant with RimK deleted bacteria resulted in milder disease symptoms compared to when wild type bacteria were sprayed on the plant. However, if the early stages of infection were bypassed, for example, by injecting or forcing the bacteria into plant tissue, the RimK mutant bacteria were able to infect normally. This suggests that RimK is important during the early stages of (plant) infection only. Similar results were seen for both plant and human pathogenic Pseudomonas, suggesting a common mechanism for RimK activity in both types of bacteria.
In their paper published in PLoS Genetics, Dr Malone’s team showed that RimK works to control the way that many other proteins are made within bacteria. The research suggests that when a bacterium senses that it is in a new place to grow, such as on a plant leaf or on a human cell, it adapts to that environment by changing the production of hundreds of proteins. The RimK protein controls this change, making sure that the bacteria are able to move around and thrive in their new environment. When bacteria are modified in the laboratory so they don’t contain a RimK protein, this process doesn’t work properly and the bacteria are out of sync with their surroundings, meaning they don’t migrate when they should.
Dr Malone said:
“We have found a completely new way in which bacteria control their responses to the environment: by modifying their production of proteins. This affects how a bacteria that grows on humans and plants can infect its host – if you disrupt that process, they find it difficult to start an infection.”
Dr Malone’s team hope that their insight into how the RimK-regulatory process works will influence future medical and plant research, by targeting this protein to help prevent both human and plant diseases.
Dr Malone said: “This information will be extremely useful for researchers working on plant and human diseases. Many people will have heard about the emergence of multidrug resistant bacteria – if we can target a protein that specifically controls infection rather than killing the bacteria outright, the bacteria are less likely to evolve and become resistant. This finding could give scientists a new target against which to develop anti-infective drugs.”
A juvenile root-knot nematode penetrates a tomato root. Photo by William Wergin and Richard Sayre. Colorized by Stephen Ausmus.
Nematodes, or roundworms, are the most numerous animals on earth, parasitizing most plants and animals. These infections are responsible for many of the most common neglected tropical diseases, causing significant morbidity and mortality. Soil-dwelling nematodes also put food security at risk by attacking agriculturally important plants. While the human response to dealing with parasite infection has been thoroughly researched; it has only recently been discovered that plant-parasitic nematodes not only activate defensive responses in plants, but also provide nematode-mediated immunity to subsequent attack by pathogens and viruses.
Despite more than 4,100 species of plant-parasitic roundworms being identified, two major groups of nematodes are responsible for most agricultural plant damage. The root-knot nematodes, Meloidogyne spp. damage plants by producing galls on roots; whereas, the cyst nematodes, Heterodera and Globodera spp., by the formation of root cysts.
Soil-dwelling nematodes are ubiquitous and rich arable soil may contain up to 3 billion worms per acre. It therefore comes as no surprise that infected crops result in over $100 billion worth of agricultural damage globally per annum. For British crops alone, damage by cyst nematodes, Globodera rostochiensis and G. pallida, account for an estimated £50 million damage each year.
Nematode control therefore is a serious business; however, following the current tightening of legislation, withdrawal from use of inorganic pesticides (the primary source of pest and disease management over the past decades) and a lack of resistant plant varieties, there is an urgent need to understand more about plant natural defenses to promote resistance to nematodes and other invaders.
Plant defenses against pathogens
Plant defenses can be broadly grouped into constitutive (continuous) defenses and inducible defenses. Toxic chemicals or defense-related proteins are typically only produced after pathogens are detected due to the high energy costs associated with their production and maintenance. To allow detection of, and rapid response to, potentially harmful pathogens plants have evolved several layers of highly developed surveillance mechanisms to try and circumvent serious damage.
The first line of defense consists of inducible defenses, which are mounted when plant cells recognize microbe-associated molecular patterns (MAMPs), such as lipopolysaccharides, flagellin, peptidoglycan and other compounds commonly found in microbes. Plant cells then become fortified against attack, conferring protection from the invading pathogen. Although MAMP’s have been well characterized, up until recently, it remained unclear as to whether plants could detect conserved molecular patterns derived from plant-parasitic animals, such as soil-dwelling nematodes.
‘Nematode-associated molecular patterns’
A number of studies have previously shown that, in response to plant-parasitic nematode infection, plants quickly activate defense pathways similar to those induced by other pathogens. Although these findings were very promising, what the nematode-derived signals actually were remained a mystery.
Following the discovery that non-parasitic soil nematodes can also induce plant defenses, a conserved nematode signature molecule appeared to be a likely trigger for activating the plant defense response. Ascarosides are pheromones exclusive to nematodes that are used to regulate development and social behaviours. Ascarosides represent an evolutionarily conserved family of signalling molecules, of which more than 200 different ascaroside structures from over 20 different species have been identified. Due to the highly conserved nature of these molecules, it seemed plausible that plant hosts and nematode-associated microorganisms may have evolved the means to detect and respond to this ancient nematode molecule. A recent study published in Nature Communications investigated whether ascarosides can be detected by plants, and whether detection of the molecules induced the plant-defence response.
Profiles of ascarosides from adult and juvenile stages of a number of agriculturally relevant species of plant-parasitic nematodes were characterised using mass spectrometry (MS) to analyse the metabolome excreted into media supernatant. MS analysis of exo-metabolome samples revealed excretion of similar sets of ascarosides in all analysed species; however, ascr#18 was identified in all plant-parasitic nematodes as the most abundant molecule.
In order to determine whether ascr#18 could be perceived by plants and influence plant-defensive responses to different pathogens, the ascaroside was applied in various concentrations to Arabidopsis roots 24 h prior to leaf innoculation with pathogens. By monitoring expression of MAMP-triggered immunity (MTI) markers and defense-related genes in leaves at different time points after root treatment with ascr#18, characteristic defense responses such as MAMP-triggered immunity were shown to be induced. Interestingly, local and systemic defenses were also shown to be activated by ascr#18 application to leaves.
Detection of ascr#18 by plants increased resistance to viral, bacterial, oomycete, fungal and nematode infections in Arabidopsis, as well as tomato, potato and barley. Additionally, three other ascarosides applied to different plants showed defense responses were induced by structurally diverse ascarosides, but that this varied in a structure- and species-dependent manner.
Plant crops suffer considerable damage every year from parasites and pathogens, putting food security at great risk. The ability to activate plant immune responses as and when required by using signalling molecules, such as ascarosides, is an exciting discovery that could contribute to improving the economic and environmental sustainability of agriculture. One potential application could be spraying of ascr#18 on crop leaves; as although plants primarily encounter ascarosides via their roots, leaf exposure to low ascr#18 concentrations was also effective at inducing the defense responses to confer fortification against attack.
One of the leading pests of rice, brown planthoppers can grow up to have either short or long wings, depending on conditions such as day length and temperature in the rice fields where they suck sap. The hormone insulin controls the switch that tells young planthoppers whether to develop into short- or long-winged adults, finds a new study. Photo by Chuan-Xi Zhang of Zhejiang University in China
Insulin tells young planthoppers whether to develop short or long wings
DURHAM, NC – Each year, rice in Asia faces a big threat from a sesame seed-sized insect called the brown planthopper, Nilaparvata lugens. Now, a study reveals the molecular switch that enables some planthoppers to develop short wings and others long — a major factor in their ability to invade new rice fields.
Lodged in the stalks of rice plants, planthoppers use their sucking mouthparts to siphon sap. Eventually the plants turn yellow and dry up, a condition called “hopper burn.”
Each year, planthopper outbreaks destroy hundreds of thousands of acres of rice, the staple crop for roughly half the world’s population.
The insects have a developmental strategy that makes them particularly effective pests. When conditions in a rice field are good, young planthoppers develop into adults with stubby wings that barely reach their middles.
Short-winged adults can’t fly but they’re prolific breeders. A single short-winged female can lay more than 700 eggs in her lifetime.
“The short-winged ones have great big fat abdomens. They’re basically designed to stay put and reproduce,” said biologist Fred Nijhout of Duke University, who co-authored the study with colleagues at Zhejiang University in China.
But in the fall as days get shorter and temperatures begin to drop — signs that the rice plants they’re munching on will soon disappear — more planthopper nymphs develop into slender adults with long wings. Long-winged planthoppers lay fewer eggs but are built for travel, eventually flying away to invade new rice fields.
Until now, scientists did not know exactly how the shorter days and cooler temperatures triggered the shift between short and long wings, or which hormones were involved.
To find out, the researchers used a technique called RNA interference (RNAi) to silence the genes for two different insulin receptors — regions on the cell membrane that bind to the hormone insulin — and measured the effects on the animals’ wings.
“Previously it had been assumed that all insects only had a single insulin receptor gene. We discovered that brown planthoppers have two,” Nijhout said.
When the researchers silenced the first insulin receptor, short-winged adults emerged. Silencing the second receptor produced adults with long wings.
Further study revealed that long wings are the default design. But when planthoppers secrete a particular type of insulin in response to changing temperatures or day length, the second insulin receptor deactivates the first receptor in the developing wings, leading to short-winged adults.
“The second insulin receptor acts by interfering with the first one, therefore shutting down the signal,” Nijhout said.
It’s too early to say whether the findings could lead to techniques to treat planthopper populations so they are unable to invade new rice fields, Nijhout says.
But the researchers have found similar mechanisms in other planthopper species, and are now trying to find out if insulin plays a similar role in other insect pests with flying and flightless forms, such as aphids.
This research was supported by the National Basic Research Program of China (973 Program, no. 2010CB126205) and by the National Science Foundation of China (no. 31201509 and no. 31471765).
The Colorado potato beetle, also known as an international super pest, munches on a potato plant leaf. Credit: MPI for Molecular Plant Physiology and MPI for Chemical Ecology
Insecticides: Researchers stop the Colorado potato beetle in its tracks by preventing the insect from synthesizing essential proteins
By Sarah Everts
Department: Science & Technology
News Channels: Biological SCENE, Environmental SCENE
The Colorado potato beetle, also known as an international super pest, munches on a potato plant leaf.
Credit: MPI for Molecular Plant Physiology and MPI for Chemical Ecology
The Colorado potato beetle costs the agricultural industry billions of dollars per year and devours so many crops around the world that the insect has been branded an “international super pest.” Because the pest has become resistant to all major classes of insecticides and has few natural enemies, crop scientists are seeking a strategy to rein in the beetle’s feeding frenzies.
A team of researchers led by Ralph Bock at the Max Planck Institute for Molecular Plant Physiology, in Potsdam, Germany, now reports that it has found a way to protect crops from the Colorado potato beetle with a new insecticidal tool: RNA interference, or RNAi (Science 2015, DOI: 10.1126/science.1261680).
To use RNAi against the pest, the researchers first identified a gene the insect can’t do without—one that encodes a cytoskeleton protein vital to maintaining a cell’s shape. Researchers then engineered vulnerable plants to produce a custom double-stranded RNA. As the insect pest dines on the plant, the double-stranded RNA gets converted into small interfering RNA. These fragments prevent the insect’s ribosome from reading the messenger RNA for the essential protein. The obstruction blocks production of the essential protein, and the insect dies.
The inspiration to use RNAi to kill pests dates back nearly a decade, says Jiang Zhang, the study’s first author.
Although the RNAi strategy was implemented in plants years ago, it failed as a powerful insecticide because the pests didn’t all die, explains Steve Whyard, at the University of Manitoba, in Winnipeg, in an associated commentary (Science 2015, DOI: 10.1126/science.aaa7722). Bock, Zhang, and their colleagues, however, have now made a “clever modification” to the earlier, partially successful strategy, Whyard notes, by inserting the instructions to make the double-stranded insecticidal RNA into plant cells’ chloroplasts, instead of into their nuclei. The result of putting the insecticidal RNA into chloroplasts, a plant’s photosynthesis hot spot, was full crop protection from the Colorado potato beetle.
Previous attempts probably didn’t work well because the cytoplasm within plant cells has machinery that metabolizes double-stranded RNA before pests such as the Colorado potato beetle can consume it. Conversely, chloroplasts have no machinery to metabolize double-stranded RNA, allowing the insecticidal molecules to accumulate and be stored until a pest dines on the plant.
One general benefit of the RNAi approach, Zhang says, is that researchers can selectively target specific insect pests by targeting species-specific gene sequences; this avoids the blanket destruction of other insect species seen with many insecticides, he explains.
Whether the new approach will work on other insect pests is an open question, comments Niels Wynant, who studies pest control at KU Leuven, in Belgium. And it remains to be seen how quickly pests will develop resistance mechanisms to the RNAi insecticides. That being said, Wynant adds, the findings could have a “significant impact” on pest control strategies and should be further investigated by agricultural companies.
Pesticides just got a whole lot smaller. Is that a good thing?
By Liz Core on 22 Jan 2015
Nanoparticles are basically the X-Men of the molecular world, in that they are unpredictable, elusive, and come in a dizzying array of forms.
So it should come as no surprise that scientists are now researching a new type of nanotechnology that could revolutionize modern farming: nanopesticides. Recent studies have suggested that the nano-scale pesticide droplets could offer a range of benefits including raising crop durability and persistence, while decreasing the amount of pesticide needed to cover the same amount of ground. But they’re also looking at the hefty potential for trouble: No one knows if the nanopesticide particles will seep into water systems, and, if they do, if they will harm non-pests like bees, fish, and even humans.
As we’ve written before, nanotechnology involves engineering particles that are tinier than the tiniest tiny. (More technically, we’re talking anything measured in billionths of a meter.) Scientists find this useful, since most substances behave much differently at that scale. Already, nanotechnology has changed the medical world, with nanoparticles used to purify water, protect against UV rays, and detect contamination.
The same could be true in farming. By shrinking the size of pesticide droplets down to nano-scale, scientists could help decrease overall pesticide use in U.S. agriculture. Which is a big thing — although we’ve come down a bit from the pesticide heyday of the 1980s, we still poured out 516 million pounds of pesticides in 2008 alone. Yipes. Here’s more on the potentially game-changing tech, from Modern Farmer:
By shrinking the size of individual nanopesticide droplets, there is broad consensus — from industry to academia to the Environmental Protection Agency — that the total amount of toxins sprayed on agricultural fields could be significantly reduced. Smaller droplets have a higher total surface area, which offers overall greater contact with crop pests. As well, these tiny particles can be engineered to better withstand degradation in the environment, offering longer-lasting protection than conventional pesticides.
Because many pesticides have been linked to birth defects, nerve damage, and cancer, scientists are pretty damn jazzed about the idea of using less of them.
But wait! Before we all lose our heads over the extreme tinification of agricultural chemicals — scientists still believe there could be a dark side to spraying our food and land with untested substances unknown to nature and immune to the usual kinds of breakdown (whaaa?! no way!).
So researchers across the world are slipping into lab coats and digging in. One project, led by Oregon State researcher Stacey Harper, is currently looking into how the compounds interact with their environment in “nano-sized ecosystems.” The research is still in its beginning stages, but the findings are slated to be published by the end of the year.
There is an obstacle and, surprise, it’s money. Scientists need more — more even than the $3.7 billion the the U.S. has invested through its National Nanotechnology Initiative to date — to assess fully the possible risks and rewards of nanotechnology.
Meanwhile, we giants here in the macro-world will continue enjoy the benefits of nanotechnology in our sunscreen, clean water, and scrumptious caramelly treats — even if invisible to us. As long as they don’t start manipulating magnets …