New defense in fight against crop pathogens


Credit: CC0 Public Domain

A team of researchers at the University of Toronto has successfully tested a new strategy for identifying genetic resources critical for the ongoing battle against plant pathogens such as bacteria, fungi, and viruses that infect and destroy food crops worldwide.

“As much as 40 per cent of global crop yield annually is lost to pests and pathogens such as bacteria, viruses and other disease-causing microorganisms,” said David Guttman, a professor in the Department of Cell & Systems Biology (CSB) at the University of Toronto and co-author of a study published in Science. “In Canada, pathogens of the top five cause annual losses of approximately CDN $3.2B, even with no significant outbreaks.”

By focusing on the near limitless arsenal of disease-associated genes available to pathogens, and the defences available to plants, they not only uncovered new insights into the ways plants survive relentless attacks, they developed a blueprint that could one day be used to protect the health of any species grown for food production.

“We wanted to know how relatively long-lived plants defend themselves against very rapidly evolving disease-causing pathogens, why disease is so uncommon even while plants are under continual attack by these highly diverse pathogens, and why domesticated crop species are so much more susceptible to pathogen attacks than ,” said Guttman.

Guttman and fellow CSB professor Darrell Desveaux, who co-led the study, addressed these questions by specifically asking how a single plant is able to fight off the attacks of a common, bacterial, crop pathogen. They did this by first characterizing the global diversity of an important class of pathogen proteins, called effectors.

“Effectors play key roles in disease since they evolved to enhance the ability of pathogens to attack and infect their hosts. Fortunately, plants have evolved counter-defenses in the form of immune receptors that can recognize certain effectors,” said Desveaux. “A plant is able to mount an ‘effector-triggered’ that usually stops the infection, if it carries a specific immune receptor that recognizes a specific pathogen effector. This effector-receptor interaction has been called gene-for-gene resistance, and is the basis for nearly all agricultural resistance breeding.”

The team started by sequencing the genomes of approximately 500 strains of the bacteria Pseudomonas syringae (P. syringae), which causes disease on nearly every major crop species.

“From these bacterial genomes we identified approximately 15,000 effectors from 70 distinct families,” said Guttman. “We then reduced this complexity by identifying 530 effectors that represent their global diversity.”

The researchers next had all of these representative effectors synthesized and put into a particularly harmgul strain of P. syringae that causes disease when infecting the plant Arabidopsis thaliana (A. thaliana), a common weed widely used in plant biology studies. By doing infections with each individual effector they saw how many of the 530 effectors elicited an effector-triggered immune response that protected the plant.

The results were unexpected.

“We found that over 11% of the effectors elicited immune response, and that almost 97% of all P. syringae strains carry at least one immune-eliciting effector,” said Desveaux. “We also identified new plant immune receptors that recognize these effectors, and found that almost 95% of all P. syringae strains can be blocked by just two A. thaliana immune receptors.”

The results shed new light on how survive relentless pathogen attack. They also provide an exciting new approach for identifying new plant immune receptors, which is a genetic resource in short supply in agricultural breeding.

“While wild plant species have a diverse array of immune receptors, most domesticated crop species have lost much of this immunodiversity due to intensive artificial selection,” said Guttman. “Our approach enables the rapid identification of new immune in wild relatives of crops that can then be moved into elite agricultural lines by traditional breeding, ultimately creating new varieties with greater ability to resist agricultural .”


Plants can skip the middlemen and directly recognize disease-causing fungi


More information: Bradley Laflamme et al, The pan-genome effector-triggered immunity landscape of a host-pathogen interaction, Science (2020). DOI: 10.1126/science.aax4079

The invasive knotweed scourge | Global Plant Protection News


We are only beginning to understand knotweed’s ecological impacts. Animation by Lisa Larson-Walker. Photos by Chris Clor/Getty Images, Image Source/Getty Images

It’s been nearly four years since I bought hypodermic needles at a CVS, squatted in my backyard, and drew them full of glyphosate. I’d done my best to build a little garden in Brooklyn, only to see the ground begin to vanish beneath the fastest-growing plant I had ever seen. It sprouted in April with a pair of tiny, beet-red leaves between the flagstones, and poked up like asparagus through the mulch. By May the leaves were flat and green and bigger than my hands, and the stems as round as a silver dollar. My neighbor’s yard provided a preview of what was coming my way: a grove as thick as a cornfield, 10 feet high, from the windows to the lot line. I had to kill the knotweed.

I tried a few different approaches: Yanking it out stalk by stalk was a sweaty, summer-long game of whack-a-mole—a thankless full-time job. Then a friend and I spent one long night digging a 10-by-4-foot trench, lining it with black contractor bags, and refilling it with dirt. It looked like we were trying to bury something, and in a way we were: the knotweed rhizomes—the plant’s creeping rootstalks—under our feet, searching for a ray of light.

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“If it’s growing close to your house, there’s a potential it could send its rhizomes and break through your foundation,” says Jatinder Aulakh, an assistant weed scientist at the Connecticut Agricultural Experiment Station. Photo from Japanese Knotweed Solutions, Ltd.

I was facing twin threats. The knotweed would kill my plants within months and prevent anything else from growing. But spraying the yard with Round-Up, Monsanto’s powerful herbicide, would kill everything in days. Which is why I bought the needles. The idea, which was tested in the journal Conservation Evidence, was to inject the plant’s hollow, jointed canes with weedkiller, shooting herbicide into its roots but sparing innocent neighbors from the deadly spray.

In the moment, this felt absurd, a demented instruction from the Wile E. Coyote guide to gardening. This was before I knew that two full-time knotweed fighters had, in 2004, shot glyphosate into more than 28,000 knotweed stems along Oregon’s Sandy River. Or that in the United Kingdom, it has been a crime to plant or transport unsealed knotweed since 1990. Or that right here in New York City, more than 200 acres of parkland have been overtaken by the plant.

Anyway, it didn’t work.

Japanese knotweed has come a long way since Philipp Franz von Siebold, the doctor-in-residence for the Dutch at Nagasaki, brought it to the Utrecht plant fair in the Netherlands in the 1840s. The gold-medal shrub was prized for its “gracious flowers” and advertised as ornament, medicine, wind shelter, soil retainer, dune stabilizer, cattle feed, and insect pollinator. The stems could be dried to make matchsticks, or cut and cooked like rhubarb. It crested in the dog days of summer with tassels of tiny white buds. Oh, and it grew with “great vigor.”

In 1850, von Siebold shipped a bundle of knotweed plants to Kew Gardens. From there, carried by gardeners, contractors, and floods, knotweed conquered the British Isles and dug its roots deep into the English psyche. In 2008, the novelist Jeffrey Archer released a best-selling revenge novel in which the protagonist crafts a strategy to sabotage an enemy via knotweed propagation. Archer believed knotweed had undermined the foundation of his own family home. The plant has worked its way into British vernacular—in 2018, a group of parliamentarians called Theresa May the “Japanese knotweed prime minister”; in April 2019, soccer legend Gary Neville berated losing Manchester United players as knotweed in the locker room, “attacking the foundations of the house”—and has sprouted an industry of knotweed removal specialists, lawyers who chase their vans, and a tabloid press that can’t get enough of the invasive shrub and the human conflict it creates.

England and Wales are the most dramatic examples of knotweed’s spread in the West, but knotweed endures across the channel, too—as the most expensive invasive plant crisis on the continent, according to a 2009 study. And in recent decades, Japanese knotweed has colonized the Northeastern United States, the spine of the Appalachians, the Great Lakes states, and the Pacific Northwest. Infestation is “rapid and devastating,” one researcher wrote. “The plants are characterized by a strong will to live,” wrote another. In New Hampshire, a knotweed researcher told me he had found knotweed systems—almost certainly just one plant, connected underground—as large as 32,000 square feet, more than half the size of a football field.

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Knotweed rises on the banks of the Bronx River in New York City, where more than 200 acres of parkland is covered by knotweed. Photo by Henry Grabar.

Along streams and rivers, knotweed grows into a wall that hides the water. Along roads, its arching canes can make it hard to see around bends. In Bronx River Forest, knotweed once grew so thick that driving along its paths was “like being in a knotweed carwash,” New York City conservation manager Michael Mendez told me. “There were people living in the knotweed,” he recalled. It was a good place to hide.

Knotweed can grow through cracks in cement, between floorboards, and out from the joints in a stone wall. “You can see it everywhere, along the roadside, in every city,” said Jatinder Aulakh, an assistant weed scientist at the Connecticut Agricultural Experiment Station. In the landscapes it has infested, it is impossible to imagine what was there before—and harder still to foresee a future without it. “There is no insect, pest, or disease in the United States,” Aulakh said, “that can keep it in check.”

* * *

In the summer of 2013, a lab technician in the suburbs of Birmingham, England, beat his wife to death with a perfume bottle before killing himself several days later. In the interim, Kenneth McRae outlined the way he understood his own unraveling in a suicide note. “I believe I was not an evil man until the balance of my mind was disturbed by the fact that there is a patch of Japanese knotweed which has been growing over our boundary fence on the Rowley Regis Golf Course,” he wrote. “It has proved impossible to stop, and has made our unmortgaged property unsaleable. … The worry of it migrating onto our garden and subsequently undermining the structure over the next few years, with consequent legal battles which we won’t win, has led to my growing madness.”

No plant can excuse such violence. But the fear McRae describes, says Mark Montaldo, is not exactly irrational. Montaldo is a lawyer in Liverpool and the head of civil litigation at the firm Cobleys Solicitors. His three most profitable lines of work are personal injury suits, bad landlords, and Japanese knotweed.

When I first spoke to Montaldo, he was riding his bicycle outside the city. It was a pleasant day in early April, and across Great Britain, chalk-white knotweed stems were awakening underground. Montaldo expects the summer will bring his firm hundreds of inquiries from buyers fighting sellers, homeowners fighting contractors, and neighbors fighting neighbors—all over Fallopia japonica. “People are thinking, ‘It could totally make my house worthless,’ ” Montaldo told me. “And it can.”

At the heart of the Great British Knotweed Panic is the fear that knotweed will make your house fall down. The U.K. has made knotweed disclosure mandatory on all deeds of sale. British banks will not issue a mortgage to a property with knotweed on its grounds, or to one with knotweed growing nearby, unless a management plan is in place. In February 2019, HSBC clarified its mortgage policy in a letter to a parliamentary committee, which was committed to addressing knotweed even in the midst of the Brexit chaos. Any knotweed growing within seven meters of a property is “unacceptable security,” said the country’s largest bank. A management plan can be a long and costly ordeal, with a bedroom-size clump of knotweed requiring thousands of dollars of treatment over several years. Homeowners with negligent neighbors or few resources have little recourse at all. In 2016, not far from the Rowley Regis course, a retired butcher named William Jones hanged himself in his home. At an inquest, his wife said he had been troubled by, among other things, the financial implications of knotweed on a piece of land he’d bought. “Bill was a very strong character,” she later told the Telegraph. “But this was something he couldn’t cope with.”

There is some dispute among biologists and engineers over whether the plant poses quite the threat banks and courts say it does. But there is no doubt that knotweed in the U.K. is perceived as an affliction, a shameful outbreak. “It’s a little bit like an STD,” said Mike Clough, a knotweed treatment specialist whose clients sometimes request that he arrive in an unmarked van. “You don’t want to talk about it, you don’t want people to know you’ve had it, you just want to get rid of it.” (Clough told me he routinely sees the plant intrude on inside spaces. “We did one hotel, where on opening day the hotel had lumps in the carpet,” he said. “They rolled it back, and knotweed was coming through.”)

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“The key problem, in contrast to most other invasive plants, is how difficult it is to kill,” says Dan Jones, who runs Advanced Invasives in Cardiff, Wales. Photo from Japanese Knotweed Solutions, Ltd.

How did knotweed become so widespread in the U.K.? Only a female specimen had made the trip from Nagasaki to Utrecht to London to the watersheds of Ireland and Wales, so there were no knotweed seeds in the British Isles, just fragments of the plant’s underground stems. But that was enough. In 2000, biologists Michelle Hollingsworth and John Bailey analyzed 150 samples from across the U.K. and concluded that British knotweed was all a clone of that original plant, now one of the world’s largest. The DNA was identical. Not just one species but a single plant had conquered the entire United Kingdom.

That was possible because of knotweed’s astounding powers of asexual reproduction: A new plant can grow from a fingernail-size piece of root, and a century of building homes, roads, ditches, and levees—and dumping the dirt wherever it was convenient—helped put those fragments everywhere. So did flooding, which carried bits of root downstream. Barriers like walls and roads were no obstacle because knotweed roots can stretch as far as 70 feet from the nearest stem.

Did I mention that it’s really hard to kill?

Dan Jones—Twitter handle Knotweed_Doktor—has a Ph.D. in biology and runs a consultancy firm in Cardiff, Wales, called Advanced Invasives. When we spoke in March 2019, he was preparing to fly to Southern California, whose famous dry climate means it is not a great place for knotweed—which means it is a great place for Jones to take his family on vacation. “I quite like that, and so does my wife, because I’m not spotting it.”

Advanced Invasives is in the business of tamping down knotweed using techniques like digging, cutting, and spraying a cocktail of herbicides. But Jones is forthright about the challenges involved and about the fact that living with knotweed might be your only option. His thesis, published last year in the journal Biological Invasions (less exciting than it sounds), was the most extensive field-based study of treating large knotweed patches. Its conclusion: “No treatment completely eradicated F. Japonica.”

“We did one hotel, where on opening day the hotel had lumps in the carpet. They rolled it back and knotweed was coming through.”
— Mike Clough, knotweed treatment specialist

Consider a new housing development in Wales, where Jones was brought in to assess an infestation that measured about 50 by 60 feet. If Jones had his men dig down enough into the earth to be sure of catching the deepest chunks of root, he was looking at excavating nearly 5,000 cubic yards of soil—almost an entire American football field, dug out three feet deep—which would then have to be placed in a specially designated landfill, since knotweed had been classified by the government as “controlled waste,” the same category as some byproducts of nuclear power plants. The cost for off-site disposal would run into the hundreds of thousands of dollars. Removing knotweed from the site of the London Olympics was estimated to have cost about 70 million pounds.

Knotweed removal is even more complicated near streams and rivers, where the plant has found its deepest foothold, and overlapping property claims make large-scale cooperation difficult. Digging is often infeasible because running water is ever-present and likely to sprinkle rhizome fragments down the watercourse. Spraying is fraught because herbicide use is regulated around freshwater streams. Jones showed me side-by-side photos of a farmstead at the headwaters of the River Rhymney in South Wales, one taken in 1984 and the second in 2012. The first shows the confluence of two streams at the crook of the property. The second shows a forest of knotweed.

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The headwaters of the River Rhymney in South Wales in 1984 and 2012. Composite image by Slate. Photos by Gethin Bowes, Dan Jones.

* * *

In the late 1860s, James Hogg was running a nursery on East 84th Street in Manhattan when he received a gift from his brother Thomas, who was working in Japan. James was an acquaintance of the couple that started the New York Botanical Garden, and sometime around the turn of the 20th century, his friends decided to try a new planting in the Bronx.

You know what happened next. Knotweed has flourished in the U.S.—especially in the past few decades, driven by construction and flooding. Experts also believe that climate change plays a role, with disruptions like heavier rainfall, warmer winters, and the desynchronization of native plants and animals all favoring hardy invaders like knotweed. Knotweed is “out of control,” says the New York City Parks Department, which has spent almost $1 million treating just 30 acres of knotweed citywide since 2010.

The first American knotweed lawsuit, as far as I can tell, was decided in 2014, when Cynthia and Alan Inman of Scarsdale, New York, sued the owners of the shopping center next door, alleging the defendants had allowed knotweed to thrive on their property and, from there, undermine the Inmans’ property value. They won $535,000 in damages.

But because knotweed still has a relatively low profile in the United States, landowners can be confused and surprised when they first confront the plant. Carly Reynolds bought an old farmhouse on 13 acres in Rome, New York, in 2016, hoping to turn it into a restaurant and event space. The next spring, she found knotweed growing through the floorboards—offshoots from a thicket along the property boundary. “I was turning into a crazed person, watching it take over the property,” she recalled. Now she and her friends dedicate several days a year to knotweed control just to keep the plant at bay.

Knotweed is one in a long list of invasive plants to have prompted concern in the U.S. Pigweed, which plagues soybean farmers in the Midwest, has developed herbicide-resistant strains that alarm farmers and fascinate scientists. Californians are reckoning with their iconic eucalyptus trees, which are delightfully fragrant, non-native, and highly flammable. The panic over kudzu in the American South, while appealing to writers searching for symbolism in the landscape, turned out to have been quite a bit overblown.

“Frankly, kudzu pales by comparison in its effects to Japanese knotweed,” Robert Naczi, a curator of North American botany at the New York Botanical Garden, told me. “There are plenty of invasives [where] yes, they spread, but they’ve occupied most of the habitat that they will occupy. Japanese knotweed still has a ways to go and it appears it will—unless we do something we’ve not yet discovered—be successful in dominating the state of New York.”

The biggest problem with knotweed, Naczi explained, is that it grows so thickly there is no room for anything else. “I don’t want to ascribe moral agency to the plant,” he says. “It’s not an evil plant. It’s doing what a plant does. But Japanese knotweed is a very serious invasive. A very, very problematic species. One of the worst invasive species in Northeastern North America.”

We are only beginning to understand knotweed’s ecological impacts. Chad Hammer, a graduate student and researcher at the University of New Hampshire who has been traveling New England in search of knotweed, is one of the first people to study the plant’s environmental effects. Last year, he found that 30,000-square-foot infestation in Coos County, New Hampshire. In Vermont, he saw how the devastating floods unleashed by Hurricane Irene had, among other things, sprinkled the state’s watersheds with knotweed rhizomes. But it doesn’t take a hurricane: “When you’re working in a stream after a high-flow event, you’re very frequently seeing Japanese knotweed stems floating past you,” he told me. “They land somewhere else, and they start a new colony over there.”

Hammer has found three changes in infested landscapes. First, knotweed grows so densely that virtually no sunlight hits the ground in a knotweed forest. In the massive Coos County patch, he said, there were no more than two other plant species growing in the knotweed’s shadow. That, in turn, reduces the number of bugs that might live in that landscape. Where there are fewer bugs there are fewer birds, and so on.

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A knotweed infestation in the Bronx, where the riverbanks slough into the stream. Photo by Henry Grabar.

Second, and relatedly, new trees can’t grow in a knotweed monoculture, which is very bad for streams. In a native New England forest, dead branches play an indispensable role in shaping streams. Woody debris feeds bugs who feed trout. Logs create eddies and pools, which enhance stream habitats and provide places for sediment to collect, improving water quality downstream. Fewer trees, fewer pools, fewer bugs, fewer trout.

In knotweed colonies, Hammer also found that the ground was barren of organic material, which increased the likelihood of soil erosion during rainstorms. Sure enough, when Hammer looked at the boulders and cobbles in streambeds near knotweed growth, he found that rocks downstream from the plant were more likely to be coated in silt. That’s bad for fish and invertebrates who use the clean rocks for nesting, he said, and bad for humans whose water, down the line, may be carrying chemicals from fertilized soil that makes its way into the stream.

Hammer’s findings are a reminder that knotweed’s impact goes far beyond rickety floorboards and cracked asphalt. And yet, one thing nobody has learned about the plant is how to economically and effectively eliminate it. “It gives me tremendous frustration to give you the truth,” Naczi told me. “Our understanding is far behind the plant’s ability to expand and invade.”

* * *

Not everyone is as apocalyptic as Naczi. Several ecologists I spoke to argue that lawyers and contractors in the U.K. have sown paranoia over a pesky shrub. “The contractors’ marketing is highly spurious, but you have to give them credit,” says Max Wade, an engineer with the firm AECOM who has argued that knotweed is no more likely to undermine a house than a tree. (Still, you can kill a tree in a day, and you won’t have to tell the guy who buys your house that you did.)  “They’ve done a great job convincing us it’s a demon plant.” Even Jones, the Knotweed_Doktor himself, decries what he calls “hysterical” media coverage, as well as a weed-control industry he thinks has taken advantage of a desperate and ill-informed clientele.

“It’s good for business if everyone’s terrified by it,” says the British biologist John Bailey, who is known to his peers as the God of Knotweed. “But nobody talks about the benefits.” Such as: Knotweed’s late-blooming flowers provide a snack for bees in the waning days of summer and produce a mild-flavored honey. Researchers in the Czech Republic have concluded that knotweed can be effectively processed into briquette biofuels because it grows so fast. Knotweed is rich in resveratrol, the family of molecules present in red wine and thought to be responsible for the health benefits associated with wine consumption. If it’s not growing in contaminated urban soil, it’s edible, with a lemony flavor and juicy crunch. Also, it’s just really interesting.

All the methods devised by man to stop knotweed are too expensive, time-consuming, and inefficient. We need a natural ally.

“It’s a giant natural experiment that allows us to think about how plants are evolving,” says Christina Richards, a biologist from the University of South Florida. Richards is fascinated by how knotweed exhibits diversity without genetic variation. It’s the antithesis of Darwin’s finches, which mated and mutated to suit their new habitats. Some knotweed hybridizes and evolves, but much of it does not change. It’s as at home on the volcanic slopes of Mt. Fuji as it is in New York parking lots and English gardens. It is a globalized super-specimen. “It loves so many types of environments—it’s a dream if you wanted to think about exposing a single individual to billions of different conditions.”

“So what makes it a dream for you is exactly what makes it a nightmare for everyone else?” I asked.

“Yes,” she answered.

One thing that knotweed-loving biologists and knotweed-hating ecologists agree on is that humans have no chance of controlling the plant on a national scale. One of the most successful efforts at wild knotweed control was undertaken on Oregon’s Sandy River from 2001 to 2008, a project that super-scaled some of the techniques I had tried in the battle for my backyard—a battle that is, by the way, ongoing. Digging, cutting, injecting, spraying. Negotiating. Doing it all again, year after year.

It was an ambitious endeavor, run by the Nature Conservancy, with two full-time employees and a squad of volunteers. The team got cooperation from nearly 300 landowners to work on their properties, and some sites had to be accessed by boat. By 2008, stem count was down by 90 percent in the patches that had been treated. And yet: The team was unable to eradicate a single one of the biggest infestations, even after as many as nine treatments.

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A view of the author’s neighbor’s yard. Photo by Henry Grabar.

All the methods devised by man to stop knotweed are too expensive, time-consuming, and inefficient. We need a natural ally.

Enter Aphalara itadori, a sap-sucking psyllid from Japan that eats knotweed for breakfast.* (Itadori is the Japanese word for knotweed—this is the knotweed aphid.) In 2013, the U.S. Department of Agriculture’s Technical Advisory Group for Biological Control Agents of Weeds recommended the insect be evaluated for release in the United States.

This idea—fighting invasive species by introducing their native predators—is called biocontrol, and Roy Van Driesche, an entomologist at the University of Massachusetts–Amherst, believes it is the only approach for fighting knotweed at scale. He has been ready to drop psyllids on knotweed infestations around New England since 2011. Van Driesche has his sites. He has the money. He has watched the itadori bugs munch happily away at potted knotweed, and bred dozens of generations of these tiny critters in captivity, for more than five years. He has been waiting, fruitlessly, all that time, for the Animal and Plant Health Inspection Service of the USDA to grant him a permit. “They can wait you to death,” he said glumly.

The thing is, itadori might not even work, and Van Driesche knows it. Trials in the U.K. have brought mixed results, in part because native anthocorids gulped down the aphid eggs. At best, Van Driesche hopes for some decline in knotweed density a decade after introduction: The idea is not to eliminate the plant, but merely to “moderate its abundance” enough that native species can begin to compete.

* * *

On a cool day in early May, I caught a train north from Grand Central to the East Bronx. I saw knotweed all along the way: out the window at a construction site, on the embankments above the highway, and among the tulips in front yards on Burke Avenue. I was heading to meet Adam Thornbrough of the New York City Parks Department for a walk in the Bronx River Forest. Today, Thornbrough says, after nearly two decades of management, this is a place where the Parks Department has beaten back one of its biggest foes.

Once, knotweed so thrived here that in high summer the asphalt paths became tunnels, dark at noon beneath canes of knotweed bending toward the light. Volunteers spaced 10 feet apart used to march through the forest swinging machetes in each hand. Paths through the bush led to homeless encampments, to what one volunteer called the “knotweed people.”

But now, Thornbrough is feeling optimistic. On the river’s east bank, years of cutting, picking, and spraying have in places reduced the plant to a few wayward, scraggly stalks. (One great thing about a paucity of native plants? It’s easier to spray herbicide.) When I visited, the park was busy with volunteers organized by the Bronx River Alliance. They didn’t need machetes anymore. Groups of high schoolers filled the bed of a pickup truck with contractor bags of knotweed. The conservation crew leader told me she is here five days a week, and knotweed takes up 85 percent of her time, but she can finally see the river.

These clearings in the Bronx River Forest are a testament to the enormous human effort required to tame the plant. Here in one of the most densely populated neighborhoods of America’s biggest, richest city, we have broken knotweed’s hold.

But turn the corner on the river’s west bank, and neither the story nor the forest floor is so sunny. There, on the other side of the river, was more knotweed than I had ever seen in my life. “The Bronx River is one of the worst bodies in the state for knotweed. It’s on all the tributaries, it’s everywhere,” said Thornbrough, as we peered into a field of stalks just over a bridge from the culled fields.

Without the fibrous roots of native plants to anchor them, the riverbanks are sloughing into the stream. “It’s a biological wasteland,” Thornbrough said. We walked for a half-mile. Trees stood overhead; weeds grew underfoot. But in between, the only living thing was knotweed.

Henry Grabar is a staff writer for Slate’s Moneybox.



Kenya: Locust invasion | Global Plant Protection News


NAIROBI, Feb. 12 (Xinhua) — When a swarm of desert locusts invaded Mandera in northern Kenya from neighboring Somalia early January, many farmers in the heartlands thought the ravenous insects would be contained there.

However, despite the national and county governments stepping up efforts to eliminate them through aerial spraying, the voracious insects have been spreading in different parts of Kenya, leaving a trail of destruction.

The insects are raising food security fears as farmers in areas where the locusts have invaded count losses.

In Embu, central Kenya, many farmers have lost their crops planted during the October to December 2019 rain season, which recorded enhanced rainfall to the benefit of producers.

Beatrice Ngari, a farmer in the area is among those who lost their crops to the insects. She had planted cowpeas, beans and green grams capitalizing on the extended rains.

“The crops had done well because of the heavy rains and I was looking forward to a bumper harvest but then the locusts came and ate away my hope,” she recounted recently.

In their thousands, the locusts descended on her farm and the neighboring ones and by the time residents were beating metal cooking pots and making noise to scare them away, the destruction was already done.

The county government stepped in and soon started aerial spraying of the locusts but the measure came a little late, with farmers like Ngari losing their investment.

“I had spent 105,000 shillings (some 1,050 U.S. dollars) on my farm to grow the crops hoping to make at twice that amount but that is now all gone,” said Ngari.

In the neighboring Tharaka Nithi, a semi-arid region, the locusts have destroyed thousands of acres of millet and sorghum leaving farmers devastated.

Residents in the dry region rely on the crops for livelihood, selling the sorghum in particular, to beer makers in Nairobi.

Heavy rains in last year’s October-December season had seen farmers extend acreage under the crop to reap more.

“All our investment is going down the drain. The sorghum and millet crops were about to mature and we would have harvested next month but that now remains a dream,” said Nathan Njiru, a farmer.

From northern Kenya, the locusts spread to eastern Kenya before reaching central Kenya and the latest county to record the locust invasion is Kajiado, located in the Rift Valley and south of the capital Nairobi.

“The swarm of locusts that have roosted in the area is the same destructive breed that was first reported in Mandera. They are in full incubation period and are feeding on all vegetation,” said Kajiado Governor Joseph ole Lenku on Monday.

The governor said the county had procured motorized and knapsack sprayers and hundreds of liters of pesticides to spray the insects as they wait for aerial spraying.

Farmers in the vast dry region inhabited by pastoralists has in recent years recorded a surge in irrigation agriculture, with the food sold in the capital where there is a ready market. They have expressed fear that the voracious insects may wipe out their investment.

“I have five acres under traditional vegetables, onions and tomatoes and if the locusts are not contained in time, then we may lose our crop,” said Bernard Ngunjiri, noting the locusts are not also sparing pasture.

The Food and Agriculture Organization of the United Nations (FAO) warned on Jan. 29 that the desert locusts present an extremely alarming and unprecedented threat to food security and livelihoods in the Horn of Africa.

Keith Cressman, senior locust forecasting officer at FAO, said the outbreak is the worst in decades and is being worsened by new breeding in Kenya, Ethiopia and Somalia, with the insects spreading to Uganda and Tanzania.

Agriculture specialists noted that the desert locusts pile pressure on Kenyan farmers who have been ravaged by climate variability effects in the last years.

“If it is not a lengthy dry spell or extended period of rains that destroy crops, Kenyan farmers are battling diseases like maize necrosis and pests like fall armyworm,”said Beatrice Macharia of Growth Point, an agro-consultancy.

The locusts menace is the latest threat to food production in Kenya and all this is due to climate change because the weather conditions are perfect for the breeding of such pests,” Macharia.

John Wightman responded to the submission ‘FAW – Devastating pest hits Australian mainland’.


From PestNet

Thursday, 20 February 2020 18:46:47

John Wightman responded to the submission ‘FAW – Devastating pest hits Australian mainland’.

Response for submission

FreshPlaza
https://www.freshplaza.com/article/9191224/devastating-pest-hits-australian-mainland/

Fall army worm detected
A potentially devastating crop pest, the fall army worm, has been detected on the Australian mainland. Just weeks after its first sighting in Australia in islands in the Torres Strait, Queensland Department of Agriculture and Fisheries (DAF) officials confirmed there had been a positive identification of fall army worm at Bamaga on Cape York in far north Queensland.

Biosecurity Queensland general manager of plant biosecurity Mike Ashton said a suspect moth collected at Bamaga was tested and confirmed to be fall army worm. He said it highlighted the pest’s ability to move rapidly in clement conditions. “This detection follows recent confirmed detections on two Torres Strait Islands, Erub and Saibai and underlines how quickly this pest can spread.”

The incursion of the pest, which can be damaging to a range of crops from cereals to fruit trees, means government officials will have to formulate a response swiftly to minimise potential impact. Surveillance programs will now be in full swing in northern Queensland, including rich agricultural regions such as the Atherton Tablelands, along with the coastal fringe from Cairns to Mossman.

“Biosecurity Queensland has proposed a response plan that is being considered by the national Consultative Committee on Emergency Plant Pests,” Mr Ashton said. He said farmers needed to consider their own responses. “Growers should have on-farm biosecurity measures in place to protect their crops from pests and diseases.”

In terms of identification Mr Ashton said fall armyworm larvae were light coloured with a larger darker head. “As they develop, they become browner with white lengthwise stripes and also develop dark spots with spines,” he said. In the moth phase he said adult moths are 32 to 40mm in length wing tip to wing tip, with a brown or grey forewing and a white hind wing.

Source: farmweekly.com.au

Publication date: Wed 19 Feb 2020

Response

Well it is not too much of a surprise – FAW has spread so quickly across Africa and then Asia. This species is polyphagous and includes many crop species. CABI identified an original infestation as the R strain which is linked to rice crops, as opposed to the C = Corn strain. Most of the reports of damage come from corn fields.

We need to remember that it brought high levels of multiple insecticide resistance with it from the Americas (= northern Latin America to Canada) meaning that eradication programs based on insecticide application are likely to be futile. Interventions based on insect pathogens (viruses and bacteria) are going to be much more successful. Interception (light) traps are invaluable for monitoring spread and catching moths before they lay eggs. Relevant experience is available in the research and commercial sector Queensland.

There are several closely related pest species in Australia. This means that natural enemies (ladybirds, parasites and birds) are already here. They will almost certainly have an impact on the survival of fall armyworm larvae – the stage that damages the crop. Natural control agents can change the status of this species from ‘pest’ to ‘just another insect’. This prediction is based on experience with S. litura in India and elsewhere in Asia. The key message is ‘don’t panic’.

Reference

John A Wightman 2018 Can lessons learned 30 years ago contribute to reducing the impact of the fall army worm Spodoptera frugiperda in Africa and India? Outlook on Agriculture 2018, Vol. 47(4) 259–269

An opinon piece written for Grahame Jackson after the FAW conference on FAW in Bangkok April 2019 for digestion in the Pacific. Firstly, will FAW get to the Pacific Countries? 

I have once again visited Google Earth, to review my mental model of what has happened since mid-last year when FAW was identified in S India. The seasonal winds have taken it as far as the South of China, with populations detected in NE India, Bangladesh, Myanmar, and SE Asia. The general trend of air movement during this period was SW to NE, starting with S India’s monsoon winds that mark the start of the rainy season in June.   We now have detected  pioneer populations on the fringe of the massive archipelagos of Indonesia and the Philippines. My prediction is that FAW will proliferate around the SE and E Asian pioneer populations. I do not know about the ‘normal’ wind movements that are encountered through this area, beyond an expectation for them to reverse in the second part of the year. Infilling or back filling from pioneer outbreaks can be anticipated.

The zone that extends across SE Asia from the equator to about 15 deg S is well known for its serious cyclones. If FAW moths are caught up in these huge vortices, survivors that come to earth on land covered with plants that they can eat will presumably initiate well scattered pioneer populations.

The cyclone factor means (to me) that it is highly likely that Pacific Islands will be infested in time. The reports from Africa are a testament to the ability of FAW to travel large distances over land and fill in the gaps rapidly as  a result of the potentially high reproduction rate (one female can lay as many as 2000 eggs). But Africa is a contiguous land mass with the sub-Sahel presenting a vast area of bush with a well dispersed matrix of arable land. Clearly, the Pacific countries are dispersed in a vast area of sea which certainly will not favour FAW. The Pacific countries will not be invaded as rapidly as landlocked nations, but they are by no means immune.

If we consider Western Papua/Papua New Guinea to be the eastern fringe of the Pacific, this huge land mass is likely to be colonized first. Whilst there are areas of extensive arable production (e.g. Markham Valley) much of the agriculture is small scale with farming systems that promote biotic diversity. The implication is that if FAW gets a foot hold in an extensive area of gardens (worst case scenario) the endemic predators and parasites will adapt to FAW and restrict its ability to multiply. However the Papuan populations will remain as a large and in essence, inaccessible reservoir of emigrants that will slowly move into the Solomon Islands and points N, E and S.

Northern Australia is susceptible to invasion from Papua and Indonesia, but is not an area of intensive arable production, although small scale intensive enterprises may be at risk. Clearly preparatory action is advisable https://www.abc.net.au/news/2018-07-31/why-doesnt-the-tropical-north-produce-more-agriculturally/10049286.

What to anticipate? I wish I had access to the field details of the pioneer populations detected in SE and E Asia so that I could understand what a new infestation looks like. It could be that the pioneers are scattered over an area as large as say Guadacanal. If that is the case, small populations may survive undetected for many years living on native vegetation and perhaps on crops in farmers’ gardens. Their numbers will be ‘managed’ by the array of predators and parasites that form part of the fauna of diversified (agro) ecosystems. These are unlikely to be of significance. On the other hand they could be in dense patches that will intensify and, if on intensively farmed land will cause problems.

Answer to your ‘simple’ question

All the above is the background to this answer, together with previous report.

Short answer is ‘not too much if the powers that be act wisely’.

If the pest managers of the Pacific nations promote vigilance by putting in place protocols that:

·       Lead to the early identification of this pest in those areas of their islands that are important for food production (monitoring)

·       Play down its importance on the basis that its feeding activity causes little or no yield loss, and

·       Pass on simple non-pesticidal, mitigative protocols to farmers,  which in any case do not encourage insecticide application,

…natural enemies will adapt to this species and reduce its importance to non-pest status. Note that the closely related S. litura is endemic in the Pacific Region and its parasites, predators, and pathogens will probably adapt to FAW (a data-free-observation based on optimism).

 

In addition, quarantine procedures need to be stepped up. Whilst the moths are prestigious flyers they can also be moved around via the surface transport system that serves most island groups.

 

If the powers that be allow or promote the application of conventional pesticides in the belief that they can manage this pest they will exacerbate the situation:

·       FAW is resistant to most of the commonly applied pesticides

·       They will kill the natural enemies and create human health risks, and allow the potential to proliferate to pest status.

 

Corn is not a staple across the Pacific Region, so that the powers that be might be tempted to shrug off the risk posed by this potential invader, in the mistaken belief that this is FAWs only host. This is not a good idea. A) Sugarcane is also preferred host, and B) its host list includes just about every crop grown by the Region’s farmers.

Conclusion

FAW is a world traveler. It is likely to move towards the Pacific through Indonesia and or the Philippines by normal dispersal flights. However, cyclones may vastly extend this dispersal process. The agricultural practices of the Region do not normally include high insecticide applications this is a trend that may in the long run maintain FAW, when it arrives, at ‘just another leaf eater’ status.

Graham Walker responded to the submission ‘FAW – Devastating pest hits Australian mainland’.


Graham Walker responded to the submission ‘FAW – Devastating pest hits Australian mainland’.

From PestNet

Thursday, 20 February 2020 13:38:40

Graham Walker responded to the submission ‘FAW – Devastating pest hits Australian mainland’.

Response for submission

FreshPlaza
https://www.freshplaza.com/article/9191224/devastating-pest-hits-australian-mainland/

Fall army worm detected
A potentially devastating crop pest, the fall army worm, has been detected on the Australian mainland. Just weeks after its first sighting in Australia in islands in the Torres Strait, Queensland Department of Agriculture and Fisheries (DAF) officials confirmed there had been a positive identification of fall army worm at Bamaga on Cape York in far north Queensland.

Biosecurity Queensland general manager of plant biosecurity Mike Ashton said a suspect moth collected at Bamaga was tested and confirmed to be fall army worm. He said it highlighted the pest’s ability to move rapidly in clement conditions. “This detection follows recent confirmed detections on two Torres Strait Islands, Erub and Saibai and underlines how quickly this pest can spread.”

The incursion of the pest, which can be damaging to a range of crops from cereals to fruit trees, means government officials will have to formulate a response swiftly to minimise potential impact. Surveillance programs will now be in full swing in northern Queensland, including rich agricultural regions such as the Atherton Tablelands, along with the coastal fringe from Cairns to Mossman.

“Biosecurity Queensland has proposed a response plan that is being considered by the national Consultative Committee on Emergency Plant Pests,” Mr Ashton said. He said farmers needed to consider their own responses. “Growers should have on-farm biosecurity measures in place to protect their crops from pests and diseases.”

In terms of identification Mr Ashton said fall armyworm larvae were light coloured with a larger darker head. “As they develop, they become browner with white lengthwise stripes and also develop dark spots with spines,” he said. In the moth phase he said adult moths are 32 to 40mm in length wing tip to wing tip, with a brown or grey forewing and a white hind wing.

Source: farmweekly.com.au

Publication date: Wed 19 Feb 2020

Response

FYI, I have seen the damage caused by FAW to corn crops in central Vietnam since it’s arrival there about a year ago. We can’t stop the spread and establishment of the moth because it is such a strong flying moth, no doubt arriving in NZ as well soon. I have some observations on damage and control. It obviously prefers grasses, and will be a major pest of corn and maize, and probably sugar-cane and sorghum. But I am not seeing it as a major pest on other vegetable or fruit crops yet. In central Vietnam, although a new pest, I have only seen it causing major damage on corn crops. Nearby crops, mainly vegetable crops don’t appear to be affected. It obviously prefers corn, and the damage is very obvious. The egg-masses are laid on the leaves and the minor damage caused by small gregarious caterpillars is easy to see, However, larger caterpillars move down into the whorls where they are protected and nearly impossible to control. However, they are cannibalistic so you normally only find small numbers in a whorl. However, large caterpillars can destroy a lot of plant material. Control can be by regularly scouting the crop, and when the egg-masses and masses of gregarious small caterpillars are seen, remove and destroy them. If you leave the crop not monitored, suddenly the foliage and crop may disappear (eaten by large caterpillars).  I don’t know what it might do in rice and sugar-cane crops, and elephant grass yet, because I am working mainly in vegetable crops, with other nearby vegetable crops not affected (as discussed above). No doubt other grasses will be a reservoir where the local populations will build up. FYI, I have produced a simple factsheet with photos from a corn crop in Vietnam that I could make available if useful?

Graham Walker

Sawfly GenUS, Edition 1 – identification of sawflies


I am posting a  message from USDA Forest Service, and Agriculture and Agri-Food Canada on a new the release of Sawfly GenUS, Edition 1.

ITP collaborators: Washington State Department of Agriculture, USDA Systematic Entomology Laboratory, USDA Forest Service, and Agriculture and Agri-Food Canada.

Authors:  Quinlyn Baine, Chris Looney, David R. Smith, Nathan M. Schiff, Henri Goulet, and Amanda J. Redford

Available at: https://idtools.org/id/sawfly/

USDA APHIS Plant Protection and Quarantine’s Identification Technology Program (ITP) is pleased to announce the release of Sawfly GenUS, Edition 1.  Sawflies are a unique group of wasp-like herbivorous insects, many of which are economic pests in North America.  While most sawflies generally maintain low population densities, some species can be prone to outbreaks that cause considerable economic damage. Invasive species are of particular concern to land managers, horticulturists, and farmers, as sawflies can potentially pose a significant threat outside their native range.  Sawflies have been documented entering the U.S. via wood packing material and nursery stock, leading to several established pests.

Prior to this tool, there was no comprehensive, up-to-date resource to help identify native and exotic sawfly fauna in North America.  Sawfly GenUS is designed for identification of all sawfly genera found in the United States and Canada and it includes a variety of resources to support screening and identification for experts and non-specialists alike. The first edition covers genera in ten sawfly families, as well as the species of Sirex.

Please find the attached PDF announcement to see an overview of ITP’s newest identification tool for PPQ and its partners. Please also feel free to forward this email or the attachment to your colleagues.

Sawfly GenUS can be accessed at: https://idtools.org/id/sawfly/.  

Visit our website to learn more about ITP’s tools and mobile apps.

Interested in assisting ITP with tool development by being a beta reviewer for an upcoming ITP tool?  We are seeking to increase our pool of beta reviewers for a variety of pest groups.  Beta reviewers can be experts or non-specialists.  Please contact us at [email protected]

If you did not receive this email directly from ITP, and you would like to be included in future ITP announcement emails, please send a request to [email protected]. You can also unsubscribe from the list by emailing us.

Cheers, Amanda

Amanda Redford

USDA APHIS PPQ S&T

Biological Scientist | Identification Technology Program

2301 Research Blvd, Suite 108 | Fort Collins, CO 80526 | p 970-490-4477

[email protected] | https://idtools.org

Cambodia: A machine that plants rice seeds and sprays biopesticides.


This post is written by Sara Hendery, Communications Coordinator for the Feed the Future Innovation Lab for Integrated Pest Management. 

Outside his home in Battambang, Cambodia, In Soun leans against a thin metal wheel almost as tall as he is. One after another, he gathers parts and pieces in a myriad of shapes—curled-up connectors, big and small containers, cylindrical plastic tubes. Many of them are attachments Soun has commissioned local manufacturers to make for the Eli Rice Seeder he leans against, a machine that plants rice in uniform rows instead of the traditional, labor-intensive method of manual transplanting or broadcasting by hand.

Soun is the first farmer in his village to use a mechanized tractor — now, he can add innovator to his list of titles as well.

Soun learned about Agri-Smart, the Eli Seeder developer, at a trade fair organized by the International Rice Research Institute (IRRI) and Feed the Future Innovation Lab for Integrated Pest Management (IPM IL). The quarterly event aims to increase access to productive resources by introducing farmers to private sector companies selling integrated pest management (IPM) tools and offering discounts for on-site purchases.

Utilizing air pressure, the Eli Seeder shoots seeds into the ground in straight rows that are not overconcentrated and easy to weed between. The process reduces seed rates, fertilizer use, pesticide use, and labor time. A low seed rate encourages farmers to buy more expensive, but better quality seeds, which garner higher prices at the market.

After using the seeder in his fields, Soun began thinking of other ways it could contribute to rice production. He added modifications such as new wheels, more productive seed vessels, and a sprayer for diffusing Trichoderma, an IPM IL-promoted biopesticide that boosts plant defense mechanisms against pests and disease. His Trichoderma modification alone has reduced his fungicide spraying rate to zero. Spraying it by hand used to take Soun 2 hours per hectare, but his modified sprayer requires just 20 minutes.

“My neighbors used to say ‘don’t bring the tractor through my field’,” Soun said, “but now they want to follow what I’m doing.”

Soun earns an additional $37 per hectare for using the Eli Rice Seeder in his neighbors’ fields, who are following his low seed rate.

Using the Eli Seeder has reduced Soun’s seed rate from 300kg per hectare to 80kg per hectare and has significantly decreased fertilizer rates. Excess fertilizer can make plants more susceptible to pests and disease—if Soun increased his seed rate by just 10kg, he’d have to add an entire bag of fertilizer to his inputs, which would be costly.

In Cambodia, and many developing countries, poor seed quality is a major contributing factor to food insecurity. Farmers use recycled seeds from previous seasons, which means planting excessive amounts and planting old weed seeds as well, which farmers combat with pesticides. In addition to pests and disease, exposed rice seeds also face the threat of being eaten by rats and birds or whisked away by drought and flooding.

“The quality of the grain is now better,” Soun said. “When a trader comes to buy it, they have no complaints or questions.

Cambodia: Rodent control in rice


. Farmer Leng Nget in a rice field.

Four years ago in Takeo, a southern province of Cambodia, farmer Leng Nget was sleeping next to his rice. He was listening for the sound of feet and wires — the quiet, scurrying sound of rodents and potential failure of the electrical system meant to capture them.

Rats significantly impede rice growth and threaten food security in Cambodia by feeding on germinating seeds and maturing plants. In Takeo, recent estimates of rodent damage in rice fields has climbed up to 22 percent. Farmers rely on rodenticides and electric fences, but the management techniques have dangerous downsides. The electrical system needs to be checked regularly in the evenings as it often short circuits, and there are incidents of farmers getting shocked by the electricity as well.

In 2015, the International Rice Research Institute (IRRI), in collaboration with the Feed the Future Innovation Lab for Integrated Pest Management (IPM IL), began testing a locally adapted barrier system to both protect rice from rodents and decrease labor time in Cambodian fields.

“When we used electricity,” Nget said, “we had to sleep in the fields the whole night for three months. When we use the plastic barriers and traps, we just check the traps in the mornings. It saves us time and we now have higher yields too.”

The trap barrier system requires a plastic barrier either around a trap crop or simply across a rodent’s typical pathway, as well as wire cages that trap rats. Once caught, rodents can be sold or eaten. Results from trials of the barrier system have been extremely positive: rodent damage decreased to just 6 percent, rice yields increased by up to 32 percent, and farmer income increased by up to 169 percent.

Rodenticide use has significantly decreased due to the system. Nget sprays his fields with IPM IL-promoted Trichoderma and Beauveria to help boost plant defense mechanisms against additional threats like insect pests and disease.

Nget said he “sees no challenges with the system” most likely because he combatted any inital challenges head-on and early. When he observed that the original recommended traps were too expensive and too large to fit along the edge of the field, he created a more compact, cheaper version. He is now commissioned to make traps for other farmers, who catch several rats every night with the modified versions.

“The extra money helps us pay for special family social events, like weddings and funerals, and contribute to village donations,” Nget said.

Additionally, in a study conducted in Cambodia by Women and Gender in International Development at Virginia Tech, initial results suggest women were generally not involved in conventional rodent management that involved electric fences, but with the use of the trap barrier system, women are more active in the process of setting traps and collecting trapped rats, which reduces the labor burden on just one farmer.

“Following the recommend practices has saved my husband time,” one female farmer from the study remarked. “He has more to time to go check on another rice field. It has made my work easier too. Now I just check the traps.”

Nget no longer listens for scurrying feet and wires at night. In fact, he listens for an entirely different sound, the sound of a full house—the greatest benefit of the trap barrier system, he said, is less time on the field, more time with family.

New book: Natural Enemies of Insect Pests in Neotropical Agroecosystems


New book: Natural Enemies of Insect Pests in Neotropical Agroecosystems

Biological Control and Functional Biodiversity

  • Brígida Souza
  • Luis L. Vázquez
  • Rosangela C. Marucci
  • Conservation of Natural Enemies and Functional Biodiversity in Neotropical Agroecosystems

  • Bioecology of Natural Enemies Used in Biological Control in the Neotropical Region

    1. Brígida Souza, Terezinha Monteiro dos Santos-Cividanes, Francisco Jorge Cividanes, Ana Luiza Viana de Sousa

      Pages 73-87

    2. Maurício Sergio Zacarias, Erika Carla da Silveira, Leopoldo Ferreira de Oliveira Bernardi

      Pages 89-96

    3. Luis Cláudio Paterno Silveira, Ivana Lemos Souza, Vitor Barrile Tomazella, Heisler Alexsander Gomez Mendez

      Pages 97-109

    4. Vanessa Andaló, Juan Pablo Molina Acevedo, Aldomário Santo Negrisoli Júnior, Viviane Araujo Dalbon

      Pages 111-122

    5. Lorena Barra-Bucarei, Andrés France Iglesias, Carlos Pino Torres

      Pages 123-136

    6. Fernando Hercos Valicente

      Pages 137-150

    7. Fernando Hercos Valicente

      Pages 151-159

  • Mass Production of Biocontrol Agents in Latin America: Rearing Techniques and Releasing Strategies

    1. Front Matter

      Pages 173-173

    1. Brígida Souza, Carlos Eduardo Souza Bezerra

      Pages 175-187

    2. Tiago Cardoso da Costa-Lima, Aloisio Coelho Jr., Alexandre José Ferreira Diniz, Marcus Vinicius Sampaio

      Pages 199-211

    3. Luís Garrigós Leite, José Eduardo Marcondes de Almeida, Julie Giovanna Chacon-Orozco, Clara Yalexy Delgado

      Pages 213-221

    4. José Eduardo Marcondes Almeida, Luís Garrigós Leite, Antonio Batista Filho

      Pages 223-233

    5. Fernando Hercos Valicente

      Pages 235-244

    6. María Elena Márquez Gutiérrez, Deise Maria Fontana Capalbo, Regina de Oliveira Arruda, Rodrigo de Oliveira Moraes

      Pages 245-259

  • Biological Control in Major Crops, Forests, Pasture, Weeds and Plant Diseases in the Neotropical Region

    1. Front Matter

      Pages 261-261

    1. Eliane Dias Quintela, Tiago Cardoso da Costa-Lima, Alexandre José Ferreira Diniz

      Pages 263-275

    2. César Freire Carvalho, Stephan Malfitano Carvalho, Brígida Souza

      Pages 277-291

    3. Cecilia Czepak, Karina Cordeiro Albernaz Godinho, Pablo da Costa Gontijo, Janayne Maria Rezende

      Pages 293-303

    4. Leonardo Rodrigues Barbosa, Juliana Mendonça Campos, Carlos Frederico Wilcken, José Cola Zanuncio

      Pages 305-317

    5. Lenira V. C. Santa-Cecília, Brígida Souza, Kethullyn H. Silva, Ernesto Prado

      Pages 319-328

    6. Rosangela C. Marucci, Simone Martins Mendes, Ivana Lemos Souza

      Pages 329-339

    7. Alessandra de Carvalho Silva, Carolina Rodrigues de Araújo, Luis L. Vázquez

      Pages 341-354

    8. Lívia Mendes Carvalho, Brígida Souza, Ana Luiza Viana de Sousa

      Pages 355-368

    9. Alexander Machado Auad, Sandra Elisa Barbosa da Silva

      Pages 369-382

    10. Bruno Zachrisson

      Pages 383-395

    11. Alexandre de Sene Pinto, Regiane Cristina Oliveira de Freitas Bueno

      Pages 397-412

    12. Alexandre de Sene Pinto, Sóstenes Eduardo Leal Trujillo

      Pages 413-425

    13. Kátia de Lima Nechet, Marcelo Diniz Vitorino, Bruno Sérgio Vieira, Bernardo de Almeida Halfeld-Vieira

      Pages 437-449

    14. Flávio Henrique Vasconcelos de Medeiros, Júlio Carlos Pereira da Silva

      Pages 451-466

  • Experiences in the Integration of Biological Control in Pest Management Programs in Latin America

    1. Front Matter

      Pages 467-467

  • Back Matter

    Pages 535-546

 

 

 

Insects’ Ability to Smell | Global Plant Protection News


 

Newswise — SAN DIEGO, CA – Even though they don’t have conventional noses, insects have adapted to smell odors in nearly every imaginable niche. Mosquitoes find us by our odor molecules binding to odor receptors on their antennae, bees are drawn to flowers the same way, whereas ticks detect an approaching host using receptors on their forelegs. Insects’ ability to smell is uniquely adapted to their needs and habitats and Vanessa Ruta, Associate Professor at Rockefeller University, reveals a key to this versatility in research presented on Monday, February 17 at the 64th Annual Meeting of the Biophysical Society in San Diego, California.

“All animals use large families of olfactory receptors to detect the incredible variety of chemicals that exist around us. Insects evolved a unique molecular solution, the largest and most diverse group of specialized channels in nature, due to the large number of different insect species. And yet, we knew so little about these proteins,” Ruta said. Ruta and colleagues unveiled the structure of a protein for insect scent that provides an explanation for how insects evolved millions of odor receptors suited for a wide range of lifestyles and habitats.

Each insect olfactory unit is a channel comprised of two different proteins: an odor receptor that is opened by a specific scent molecule, and a co-receptor named Orco. While the odor receptors are highly specific to each species of insect, Orco is nearly the same in all of them. “You can take an Orco from one insect and it works with any other insect’s odor receptor,” explains Ruta. How one Orco assembles with hundreds of thousands of odor receptors was a fascinating evolutionary and molecular puzzle for Ruta, and she wanted to look at it in greater detail.

Using cryo-electron microscopy, Ruta and colleagues solved Orco’s structure, which serves as the first structural template to understand this huge protein family. “Orco itself can form an ion channel, unlike any others,” said Ruta. It features a central pore surrounded by four loosely-associated subunits, which explains how it can assemble with so many different odor receptors. “By minimizing inter-subunit interactions, it’s able to accommodate many protein sequences,” Ruta explained, they believe it can assemble with an odor receptor and share a common channel. Orco’s shape may also be crucial for evolution.

When Ruta mapped the sequence of odor receptors onto the Orco channel the similarity was strong in pore, but weak in the four loosely-associated subunits, which may allow those parts to diversify and evolve rapidly. Orco also likely provides a channel that works no matter how much the odor receptor diversifies, since they assemble together.

Most insects rely heavily on smells to navigate the world. And when it comes to insect vectors of disease, like mosquitoes, Ruta says, “this could be a starting point for designing insect repellents or insect confusants, that scramble the olfactory code and prevent them from finding their human hosts.”