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cambodia seederModifies Machinery, Improves Quality of Rice

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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.

Phys.Org


Researchers discover a novel chemistry to protect our crops from fungal disease

exeterresear
Zymoseptoria tritici, the cause of Septoria tritici in wheat, treated with C18-SMe2+ Credit: University of Exeter

Pathogenic fungi pose a huge and growing threat to global food security.

Currently, we protect our crops against by spraying them with anti-fungal chemistries, also known as fungicides.

However, the growing threat of microbial resistance against these chemistries requires continuous development of new fungicides.

A consortium of researchers from the University of Exeter, led by Professor Gero Steinberg, combined their expertise to join the fight against plant .

In a recent publication, in the prestigious scientific journal Nature Communications, they report the identification of novel mono-alkyl chain lipophilic cations (MALCs) in protecting crops against Septoria tritici blotch in wheat and .

These diseases challenge temperate-grown wheat and rice, respectively, and so jeopardise the security of our two most important calorie crops.

The scientists’ journey started with the discovery that MALCs inhibit the activity of fungal mitochondria.

Mitochondria are the cellular “power-house”, required to provide the “fuel” for all essential processes in the pathogen.

By inhibiting an essential pathway in mitochondria, MALCs cut down the cellular energy supply, which eventually kills the pathogen.

Whilst Steinberg and colleagues show that this “mode of action” is common to the various MALCs tested, and effective against plant pathogenic fungi, one MALC that they synthesised and named C18-SMe2+ showed unexpected additional modes of action.

Firstly, C18-SMe2+ generates aggressive molecules inside the mitochondria, which target life-essential fungal proteins, and in turn initiate a “self-destruction” programme, which ultimately results in “cellular suicide” of the fungus.

Secondly, when applied to crop plants, C18-SMe2+ “alerts” the plant defence system, which prepares the crop for subsequent attack, thereby increasing the armoury of the plant against the intruder.

Most importantly, the Exeter researchers demonstrate that C18-SMe2+ shows no toxicity to plants and is less toxic to aquatic organisms and human cells than existing fungicides sprayed used in the field today.

Professor Steinberg said: “It is the combined approach of Exeter scientists, providing skills in fungal cell biology (myself, Dr. Martin Schuster), fungal plant pathology (Professor Sarah J. Gurr), human cell biology (Professor Michael Schrader) and synthetic chemistry (Dr. Mark Wood) that enabled us to develop and characterise this potent chemistry.

“The University has filed a patent (GB 1904744.8), in recognition of the potential of this novel chemistry in our perpetual fight against fungi.

“We now seek partners/investors to take this development to the field and prove its usefulness under ‘real agricultural conditions’. Our long-term aim is to foster greater food security, in particular in developing nations.”

Professor Steinberg added: “I always wanted to apply my research outside of the ivory tower of academia and combine the fundamental aspects of my work with a useful application.

“The visionary approach of the Biological Sciences Research Council (BBSRC) provided me with this opportunity, for which I am very grateful. In my mind, this project is a strong example of translational research that benefits the public.”

Professor Sarah Gurr said: “This is such a timely and important study. We are increasingly aware of the growing burden of plant disease caused by fungi and of our need to safe-guard our calorie and commodity crops better.

“The challenge is not only to discover and describe the mode of action of new antifungals but to ensure that chemistries potent against fungi do not harm , wildlife or .

“This new antifungal is thus an exciting discovery and its usefulness may extend beyond crops into the realms of fungal disease in humans and, indeed to various applications in the paint and preservative industries. This merits investment!”

The paper, published in the Journal Nature Communications, is entitled: “A lipophilic cation protects against fungal pathogens by multiple modes of action”, authored by G. Steinberg, M. Schuster, S.J. Gurr, T. Schrader, M. Schrader, M. Wood, A. Early and S. Kilaru.


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Research paves way for new generation of fungicides


More information: Nature Communications (2020). DOI: 10.1038/s41467-020-14949-y , https://www.nature.com/articles/s41467-020-14949-y

Journal information: Nature Communications

The Guardian

Planting hope: the Syrian refugee who developed virus-resistant super-seeds

Plant virologist Dr Safaa Kumari discovered seeds that could safeguard food security in the region – and risked her life to rescue them from Aleppo

 

 

Dr Safaa  Kumari
Dr Safaa Kumari’s seeds are resistant to the climate-fuelled viruses that have destroyed crops of pulses in Syria. Photograph: Courtesy of Arab Society for Plant Protection

The call came as she sat in her hotel room. “They gave us 10 minutes to pack up and leave,” Dr Safaa Kumari was told down a crackling phone line. Armed fighters had just seized her house in Aleppo and her family were on the run.

Kumari was in Addis Ababa, Ethiopia, preparing to present a conference. She immediately began organising a sprint back to Syria. Hidden in her sister’s house was a small but very valuable bundle that she was prepared to risk her life to recover.

Kumari is a plant virologist. Her work focuses on a quiet yet devastating development crisis. Climate-fuelled virus epidemics affecting fava beans, lentils and chickpeas are spreading from Syria to Ethiopia, gradually destroying the livelihoods of low-income populations. Known as “poor man’s meat”, these pulses are vital for both income generation and food security in many parts of the world.

Finding a cure was urgent, Kumari explains. Hopeless farmers were seeing increasing levels of infected crops turning yellow and black. The cause? “Climate change provides aphids with the right temperatures to breed exponentially and spread the epidemics,” she says.

For 10 years, Kumari worked to find a solution. Finally, she discovered a bean variety naturally resistant to one of the viruses: the fava bean necrotic yellow virus (FBNYV). “When I found those resistant seeds, I felt there was something important in them,” says Kumari from her lab in Lebanon where she now works. Only the fighting in Syria had moved. “I had left them at my sister’s in central Aleppo to protect them from the fighting,” she says.

Determined not to let a war get in the way of her work “for the world’s poor”, Kumari felt it her duty to rescue the seeds in Aleppo. “I was thinking: how am I going to get those seeds out of Syria?

“I had to go through Damascus, and then drive all the way to Aleppo. There was fighting and bombings everywhere.” After two days’ driving along dangerous roads, seeds in hand, Kumari made it to Lebanon, where she now works as a researcher at Icarda (International Center for Agricultural Research in the Dry Areas) in the Bekaa valley, close to the Syrian border. Hassan Machlab, Icarda’s country manager says: “Many of the Syrian scientists we welcomed here have suffered. It is tough.”

But bringing the seeds to safety was only the beginning. Kumari needed to turn them into a sustainable solution.

As crop production collapsed in the region, producers started to rely heavily on insecticides. “Most farmers go to the field and spray it without safety material – masks and appropriate jacket,” she says. “Some are dying, others are getting sick or developing pregnancy issues.”

At first, the sample failed. “So we crossed them with another variety that had a better yield and obtained something that is both resistant and productive,” says Kumari. “When we release it, it will be environment-friendly and provide farmers with a good yield, more cheaply and without insecticide.”

Seed samples in the laboratory.

Seed samples in the laboratory.

Kumari now plans to distribute her super-seeds free to farmers. She has already turned down an offer from a large company for the virus detection technology.

“They wanted to buy our product and then sell it to the farmers, but we refused,” says Kumari. “Ours is free. It’s our responsibility to provide our solutions to people everywhere,” she says.

But, as for many Syrian refugees, the war is never far from her thoughts, “Something she won’t tell you is that it wasn’t easy for her,” says Machlab. “She was working on all this and she didn’t have a clear mind as her family were in Aleppo and her house was destroyed.”

Kumari adds: “Last week I saw my family in Turkey. I have five sisters and three brothers, scattered in Germany, Turkey, Syria. The last time we met was in Aleppo in 2012. When I came back someone told me ‘Safaa, you’re looking great today!’ Of course, I had just spent time with my family again!” she says, laughing.

But she adds: “It’s not easy for me, it’s not easy for a woman to work on agriculture (research). It’s not easy, but it’s OK.

“When I’m working, I’m not thinking I am a Syrian or a woman though. But I do feel I sometimes receive funding [from westerners] because I’m a woman,” she says. “Perhaps!”

 

science daily

eDNA provides researchers with ‘more than meets the eye’

Date:
March 24, 2020
Source:
Curtin University
Summary:
Researchers have used next generation DNA sequencing to learn more about the different species of plants, insects and animals present in the Pilbara and Perth regions of Western Australia.
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Researchers from Curtin University have used next generation DNA sequencing to learn more about the different species of plants, insects and animals present in the Pilbara and Perth regions of Western Australia.

Lead researcher Curtin PhD candidate Mieke van der Heyde, from the ARC Centre for Mine Site Restoration said that DNA metabarcoding is a growing field in the biological monitoring space, with the potential to provide fast, accurate, and cost effective assessments of biodiversity.

“Traditionally, biomonitoring has relied on scientists setting traps and visually monitoring a certain area, counting the number of species, and then extrapolating that data to come up with regional analysis,” Ms van der Heyde said.

“Understandably, that method of data collecting is expensive, time consuming and challenging, especially when looking into remote areas of Australia, which often present a harsh climate.

“As animals and organisms interact with their environment, they leave behind traces of their DNA through things like droppings, skin cells, saliva, and pollen. When this DNA is found in the environment, it’s known as environmental DNA, or eDNA.

“Our research looked in to the feasibility of using this eDNA as an additional tool for biomonitoring. Not only to see if this type of analysis could potentially make things a bit easier for biologists out in the field, but as well as providing researchers with more accurate field information then what they can visually identify.”

The study analysed samples of soil, animal droppings, plant and insect material, collectively known as ‘substrates,’ taken from two different areas of Western Australia: The Pilbara, a hot desert climate, and the Swan Coastal Plain, a hot Mediterranean-type climate.

“We tested common environmental substrates including soil, bulk scat, bulk plant material, and bulk arthropods from pitfall traps and vane traps, using four eDNA barcoding assessments to detect a wide range of plants, vertebrates and arthropods,” Ms van der Heyde said

“This study was the first of its kind to systematically test terrestrial substrates for eDNA, and it also was the first time that some of these particular substrates were analysed.

“Results show that bulk arthropods and animal droppings detected the most biodiversity, with at least a third of the biodiversity detected in only one substrate. Soil samples detected the least, and fewer samples had usable DNA, especially in the Pilbara. We believe this is most likely due to the hot climate, which potentially degraded the eDNA.

“Biomonitoring is necessary for effective ecosystem management. Our study shows that eDNA can detect biodiversity in an area, and collecting more substrates will increase the breadth of biodiversity detected.

“However, surveys must be carefully considered, as DNA may come from organisms outside the study area,” Ms van der Heyde said.

This research was completed at the Trace and Environmental DNA (TrEnD) Laboratory at Curtin University’s Perth campus.


Story Source:

Materials provided by Curtin University. Note: Content may be edited for style and length.


Journal Reference:

  1. Mieke Heyde, Michael Bunce, Grant Wardell‐Johnson, Kristen Fernandes, Nicole E. White, Paul Nevill. Testing multiple substrates for terrestrial biodiversity monitoring using environmental DNA metabarcoding. Molecular Ecology Resources, 2020; DOI: 10.1111/1755-0998.13148

 

science daily

Bats depend on conspecifics when hunting above farmland

Date:
March 25, 2020
Source:
Forschungsverbund Berlin
Summary:
Common noctules — one of the largest bat species native to Germany — are searching for their fellows during their hunt for insects above farmland. Scientists show that bats forage on their own in insect-rich forests, but hunt collectively in groups over insect-poor farmland.
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Common noctules — one of the largest bat species native to Germany — are searching for their fellows during their hunt for insects above farmland. Scientists from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) show in a paper published in the journal Oikos that bats forage on their own in insect-rich forests, but hunt collectively in groups over insect-poor farmland. They seem to zoom in on places where conspecifics emit echolocations during the capture of insects, an inadvertent clue that reveals high-yielding areas to others. However, “listening” to their hunting companions to find food only works when sufficient numbers of bats forage in the same area. If numbers continue to decline, density could fall below a critical level and joint hunting could become difficult or impossible. This could pose an additional threat to the survival of species such as the Common noctule.

Human activities have massively changed the face of the earth over the past centuries. While Central Europe was covered by dense primeval forests in ancient times, today farmland, meadows and managed forests dominate the countryside. Humans have transformed natural landscapes into cultural landscapes and many wild animals disappeared, while others found new ecological niches. Bats were particularly successful in the latter process. As so-called cultural successors, many species were able to survive in modern environments, finding shelter in buildings and feeding above arable land and managed forests. But what is the secret of their success? Are they particularly efficient hunters?

To verify this, a research team from Leibniz-IZW equipped two groups of the Common noctule with sensors that recorded the both spatial position and echolocations calls at the place of the tagged bat. From acoustic recordings of special hunting calls, so-called “feeding buzzes,” the authors deduced when and where the bats preyed on insects. In addition, the recording of the acoustic environment made it possible to determine whether conspecifics were present. Individuals of the first population hunted for insects in an area north of Berlin, which is characterized by large wheat, rape and corn fields. Individuals of the second population went in search of food southeast of Berlin over an area dominated by pine forest. In both areas, bats showed two flight patterns — commuting flight and the small-scale search flight, in which the animals zigzagged around in above a small area. When hunting over the forest, the bats regularly emitted feeding buzzes, both during commuting flight and during small-scale search flight, regardless of whether other bats were around. Apparently, they were successful as individual hunters. Above farmland, however, commuting bats did not emit feeding buzzes. Only after encountering a conspecific, they switched to the small-scale search flight, which was accompanied by many hunting calls.

The conclusion of the scientists: Above farmland, prey is presumably rare and only found in larger numbers at a few places — for example, on hedges or ditches. This is why bats eavesdropped on their conspecifics when foraging above farmland. When they recognized a successful hunt by the feeding calls of their neighbor, they joined the group of hunting conspecifics and switched to small-scale search flights in order to effectively feed on the swarm of insects they had tracked down. Over forests, on the other hand, there is likely to be more prey, which may also be more evenly distributed. Here the animals were successful even without eavesdropping on conspecifics.

“Community hunting makes it possible for the bats to find food even above farmland with low prey density,” says Christian Voigt, head of the Department of Evolutionary Ecology at Leibniz-IZW. “However, this only works if the population is sufficiently large. Due to insect mortality and collisions with wind turbines, the populations of the Common noctule and other species could decline further. These populations could fall below the critical population density, so that joint hunting may no longer be possible. Local populations that are dependent on this form of food acquisition would then be on the brink of extinction.”


Story Source:

Materials provided by Forschungsverbund Berlin. Note: Content may be edited for style and length.


Journal Reference:

  1. Manuel Roeleke, Torsten Blohm, Uwe Hoffmeister, Lara Marggraf, Ulrike E. Schlägel, Tobias Teige, Christian C. Voigt. Landscape structure influences the use of social information in an insectivorous bat. Oikos, 2020; DOI: 10.1111/oik.07158

Forschungsverbund Berlin. “Bats depend on conspecifics when hunting above farmland.” ScienceDaily. ScienceDaily, 25 March 2020. <www.sciencedaily.com/releases/2020/03/200325154056.htm>.

Phys.Org


The discovery of Xyella fastidiosa in European olive trees in 2013 caught European researchers off-guard. Credit: Sjor/Wikimedia commons, licenced under CC BY-SA 4.0

A plant disease spread by sap-sucking insects has been devastating olive and fruit orchards across southern Europe, but scientists are inching closer to halting its spread with the help of insect repelling clays, vegetative barriers and genetic analysis.

In the late summer harvest of 2013, olive farmers in the Puglia region of southern Italy noticed that the leaves on several of their trees were turning brown and their shoots withering. The problem spread from one orchard to another, as more olive farmers found their trees were drying out and beginning to die.

Genetic testing confirmed them to be infected with Xyella fastidiosa, a originally found in America. Soon outbreaks appeared throughout the Mediterranean, even briefly as far north as Germany in 2016.

The bacteria is mainly spread by sap-sucking insects known as spittlebugs and sharpshooters. As the insects feed, the bacteria is able to infect the vessels that transport water and nutrients around the plant, known as the xylem. As the bacteria destroy the xylem, it slowly chokes the plant.

“We are dealing with a very severe situation in southern Italy,” said Dr. Maria Saponari, based at the Institute for Sustainable Plant Protection in Bari, Italy. Europe’s researchers were caught off-guard by the epidemic, she explained. “When the bacterium was discovered here, there wasn’t any research centre in Europe working specifically on this pathogen. We were starting from zero.”

The can infect a wide range of plants, including shrubs like the myrtle-leaf milkwort and rosemary, oak trees, and important crops like lavender. Food crops including cherry trees, plum trees and are among the species considered to be at high risk.

In particular, the outbreak has amplified problems in Italy’s strained olive oil sector. In 2018, the country reported a 57% drop in its olive harvest compared to 2017—a 25-year low. Researchers blamed a frosty spring followed by a summer drought, which weakened the olive trees and left them even more susceptible to infection.

The intense summer weather in southern Italy may also have made it easier for the disease to spread among olive trees as insects carrying the bacteria sought out food in the dry conditions. “Here in summer, olives are the only green plants that we see,” said Dr. Saponari. “Olive canopies, for them, (are) like a refuge to survive.”

While the disease has been found in a number of EU countries, it appears ‘the strains that have been imported in Corsica or in Spain are much less aggressive than the strain spreading in Puglia,” added Dr. Saponari.

In response, Dr. Saponari is leading one of several Europe-wide projects seeking ways to curb this new threat to Europe’s olive crops, and monitor its spread. Her XF-actors project is examining olive trees’ genetics to see if some of the plants have natural resistance to Xyella fastidiosa that can then be used to breed crops that are more resilient against the disease.

Border plants

Researchers on the project are also conducting field experiments to look at natural strategies to combat the disease, such as using kaolin clay as an insect repellent. Others are experimenting with ‘border plants’ that can be grown around olive groves and other important crops to draw the bacteria-carrying insects away from the crops, and ‘sentinel plants’ such as the myrtle-leaf milkwort which show symptoms of bacterial infection sooner, allowing action to be taken quickly to contain an infection.

It is also hoped it may be possible to contain the disease by chopping down infected plants, using more insecticide, or planting crops that are less susceptible to the bacterial strain.

The project team’s priority lies in assisting the early detection and containment of the disease. Field inspections and new imaging technology developed by the XF-actors project can already predict how the bacteria may spread, and how to contain it. For example, a combination of thermal images, fieldwork, and spectroscopy can now detect infection in plants and trees before any symptoms appear.

All this information can then be put together to give the authorities a better idea of in which areas the disease is more likely to spread, and so where to send their inspectors next.

To date, monitoring and predicting outbreaks has proven difficult. Even tracking the disease-carrying insect vectors involves hours of sweeping trees and shrubs with entomological nets, and scientists still have to unravel exactly how the bacteria passes from the insects to the plants.

‘(Nets are) the best way to catch them,” said Professor Alberto Fereres, an entomologist based at Spain’s Institute of Agricultural Sciences in Madrid. “They are not very much attracted to sticky-colour traps. They communicate by sound—they don’t use colours as visual cues to find their host plants.”

Prof. Fereres works on the XF-actors project while also leading another project aimed at tackling pest-spread pathogens in Europe, called POnTE. Prof. Fereres and his team are hoping to understand how insects transmit bacterial diseases like Xyella fastidiosa.

Their research is providing some early clues for strategies to stem the transmission of the disease. One involves introducing other non-harmful bacteria into the insects that make it harder for Xyella fastidiosa to spread.

“These can do two things—they can try to suppress the replication of the (Xyella) bacteria, (and) they can also compete with the bacteria in the vector for binding sites,” explained Prof. Fereres.

‘(This) binding site is the precise place where the virus or bacteria binds inside the insects mouthparts,” said Prof. Fereres.

His team is also experimenting with antimicrobial peptides—short bits of protein—and chemicals that can interfere with the bacteria’s ability to remain inside insects’ bodies.

The project is trying to prove which insects can pick up the bacteria from a plant and which are able to successfully transfer it to other plants as they feed.

The team are conducting laboratory experiments that place infected insects on plants in controlled environments so they can pinpoint what exactly needs to happen for insects to transmit the bacteria to other plants—do they need to bite into the xylem specifically or just into other parts of the plant, for example.

The bacteria could also affect each plant species differently.

“We don’t know the genetic determinants which lead to the infection of some plant species and not other ones… that are genetically close,” says Dr. Anne Sicard of the Institut National de la Recherche Agronomique (INRAE) in Montpellier, France.

Dr. Sicard leads the XYL-EID project, a joint effort between INRAE, the University of California Berkeley, US, and Italy’s National Research Council, which is analysing the bacteria’s DNA to find out why such differences occur.

Outbreak origins

The project is searching for genes involved in helping the bacteria adapt to new environments, and in particular what happened in the outbreak in Puglia. They have analysed 74 bacteria samples collected from infected olive trees from across the affected area by sequencing each of their genomes.

This work is already offering some promising insights into the origin of the outbreak. All samples are genetically very similar to one another, confirming that the outbreak in Puglia is the result of the introduction and subsequent establishment of a single strain of Xyella fastidiosa. They also had a genetic similarity to a strain of the bacteria found in coffee in Costa Rica.

But while this research may ultimately provide new ways of fighting the disease, it is unlikely to eradicate it, added Prof. Fereres.

“We will have to learn how to live with Xyella, but we will have to also develop ways to contain the disease as much as possible and to avoid situations as in the south of Italy.”


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France reports first case of fatal olive tree bacteria


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Australia: Fall armyworm reaches Bowen and the Burdekin

The fall armyworm is continuing to spread across North Queensland and has now been detected as far south as Bowen. The pest was first detected in Australia on two Torres Strait islands in January, before reaching the mainland at Bamaga in February. It was then detected on a property in the Gulf country, and in South Johnstone, Tolga and Lakeland.

Last week, it was confirmed that the pest had been found in the Burdekin, with the latest detection being recorded at Bowen.

The animal has the potential to wipe out agricultural crops, and at the larval stage feeds on more than 350 plant species including cultivated grasses such as maize, rice, sorghum, sugarcane and wheat, as well as fruit and vegetable and cotton crops.

Bowen-Gumlu Growers Association president Carl Walker said fall armyworm had made it to the region over a week ago, but its presence was only confirmed in recent days. Walker urged growers to be vigilant in checking their crops: “We are taking it seriously, the biggest concern with these new pests or diseases from overseas is that they may already have resistance to the chemicals we rely on. Growers need to remember not to overuse their chemicals, as the misuse of chemicals can cause resistance.”

Fall armyworm, which is native to tropical and subtropical regions of the Americas, has spread across the globe and since 2016 been detected in Africa, the Indian subcontinent, China and South East Asia.

According to queenslandcountrylife.com.au¸ the Consultative Committee on Emergency Plant Pests has determined that it is not technically feasible to eradicate fall armyworm from Australia as it has never been eradicated anywhere else in the world.

Publication date:

Shahid Siddique Kathy Keatley Garvey/UC-Davis
Shahid Masood Siddique says the success of plant-parasitic nematodes depends on their ability to locate a suitable host in the soil.

UC researchers: How nematodes play hide and seek

What attracts nematodes to their host is largely still a mystery, a team of four scientists writes

Kathy Keatley Garvey | Mar 25, 2020

If you’ve ever played the childhood game of “hide and seek,” in which you try to conceal yourself from others, you know the outcome. “Ready or not, here I come!” eventually leads to “You’re It!”

It’s somewhat like that when plant-parasitic nematodes (microscopic round worms) play “chemical hide and seek” with their plant host, says plant pathologist  Shahid Masood Siddique, an assistant professor in the UC Davis Department of Entomology and Nematology.

“The success of plant-parasitic nematodes depends on their ability to locate a suitable host in the soil,” says Siddique, corresponding author of the newly published Spotlight article, “Chemical Hide and Seek: Nematode’s Journey to Its Plant Host,” in the journal Molecular Plant.

Nematodes can be deadly to plants, not only because of the direct damage they cause (they extract water and nutrients from their hosts such as wheat, soybeans, sugar beets, citrus, coconut, corn, peanuts, potato, rice, cotton and bananas) but the role of some species as virus vectors.

“Plant-parasitic nematodes are among the most destructive agricultural pests, causing more than $100 billion in losses per year in the United States,” Siddique said, noting that nematodes are especially damaging to potato, soybean and wheat crops.

Still an unknown

Although the success of nematodes depends on their ability to locate a suitable host in the soil, what attracts them to their host “has largely remained unknown,” wrote the four-member UC Davis team of Siddique, Natalie Hamada, Henok Zemene Yimer and Valerie Williams. “Recent studies have revealed that host-seeking by nematodes is a complex process that involves multiple stages in the interaction.”

“Most damage is caused by a small group of root-infecting sedentary endoparasitic nematodes including cyst nematodes and root-knot nematodes (RKNs),” the team of UC Davis researchers wrote in their abstract. “Second stage juveniles (J2s) of plant-parasitic nematodes hatch from eggs into the soil and localize to the roots of host plants. The success of these non-feeding J2s depends on their ability to locate and infect a suitable host.”

For eight decades, scientists have researched the attraction of plant-parasitic nematodes to the host root, ever since the pioneering Maurice Blood Linford (1901-1960) of the University of Illinois, Urbana, Ill., observed in 1939 that the larvae of root-knot nematodes congregate in the cell elongation region behind the root cap.

“Both volatile and soluble components in the rhizosphere have been shown to influence nematode movement,” the UC Davis researchers wrote. “Methyl salicylate, a volatile chemical root signal, has been demonstrated to be a strong root attractant for RKN towards several Solanaceous plants (nightshade family). The non-volatile tomato root exudate quercetin was shown to elicit concentration dependent attraction or repulsion effect against Meloidogyne incognita to host root. Three recent studies have revealed that the recognition of and response to hosts by infective juveniles is a complex process that involves multiple stages in the interaction.”

Siddique focuses his research on basic as well as applied aspects of interaction between parasitic nematodes and their host plants. “The long-term object of our research is not only to enhance our understanding of molecular aspects of plant–nematode interaction but also to use this knowledge to provide new resources for reducing the impact of nematodes on crop plants in California.”

Source: University of California Division of Agriculture and Natural Resources, which is solely responsible for the information provided and is wholly owned by the source. Informa Business Media and all its subsidiaries are not responsible for any of the content contained in this information asset.