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Huanglongbing-sniffing dogs

WFP_Todd_Fitchette_Scenic_California_Citrus-6.jpg Todd Fitchette
While the discovery of Huanglongbing in commercial California citrus groves continues to elude detection, some growers are using dogs as an early detection tool to try to stay ahead of a disease many believe is “inevitable.”

Disease-sniffing dogs alert on Ventura County citrus

Citrus growers cite concerns over Huanglongbing in adjacent counties as reason to employ trained dog teams as early detection tool

Todd Fitchette | Sep 14, 2019

In an abundance of caution, some commercial citrus growers in Ventura County, Calif. elected to remove numerous trees after dogs from Florida trained to detect the presence of the bacterium responsible for Huanglongbing (HLB) alerted on over 200 trees.

The dogs are owned by a private company and are trained to sniff for signs of Candidatus Liberibacter asiaticus (CLas), a bacterium believed by researchers to be the cause of the citrus disease responsible for greatly reducing Florida’s citrus production and for infecting residential trees in southern California.

To date HLB has not been confirmed in commercial citrus groves in California. The disease is present in residential citrus throughout southern California, prompting the state to remove trees that test positive for the bacterium to control its spread.

John Krist, chief executive officer of the Ventura County Farm Bureau, said growers in his county remain concerned with the proximity of the disease to their groves and the length of time it takes for trees to be formally diagnosed with the disease through a scientific process known by the industry simply as “PCR.”

The Polymerase Chain Reaction (PCR) test is a scientific method used to amplify DNA and remains the only regulatory-approved means to declare whether a citrus tree has the disease. It can take years for a tree infected with the bacterium to elicit symptoms or contain enough bacteria to test positive.

Dogs as early detection

The trained dogs are considered by some as a viable early detection tool to aid growers in determining whether their trees are infected. Nevertheless, the dogs are not a government-approved option to declare presence of the bacteria. For growers, this means that even a positive “alert” by dog teams will not otherwise open them to quarantine restrictions.

Earlier this year the Ventura County Farm Bureau contracted with F1K9 in Florida to scout commercial groves in the county for HLB, according to Krist. Similar teams of dogs were previously used in California to scout citrus trees in the University of California’s research grove at Riverside, and at the UC Research and Extension Center at Lindcove in Tulare County. In those instances, several trees at UCR were alerted on by dogs while none of the trees at Lindcove were alerted on by the dogs.

To date UCR has not removed those trees from its research grove. Instead, the trees are covered with netting to prevent access by the Asian citrus psyllid (ACP), the tiny insect believed to be solely responsible for the spread of HLB. Those trees are said to be the subject of ongoing testing and research.

In late July and early August, four dogs, along with their handlers, scouted commercial groves in Ventura County, inspecting about 3,500 trees on 20 properties, according to Krist. Out of that the dogs alerted on 211 trees. Those trees have since been removed and destroyed by their owners.

The genesis of the Ventura dog inspection came from an understanding of research led by Dr. Timothy Gottwald, a plant pathologist with the U.S. Department of Agriculture.

The Gottwald research points to the ability of trained dogs to detect the CLas bacterium. These dogs, which a Gottwald article says have been evaluated in laboratory and field experiments, can detect CLas over 95 percent of the time in commercial groves, and over 92 percent of the time in residential citrus. Perhaps more importantly, these dogs can do this well before a PCR test could result in a positive diagnosis.

That is essentially why the Ventura County Farm Bureau, at the request of local citrus growers, requested the dogs. Krist says they cannot afford to wait for the state to find and declare HLB in commercial citrus through regulatory testing.

Krist is concerned that ongoing state efforts to find HLB appear targeted at residential citrus, with little focus on commercial groves.

“They need to start doing a more systematic survey of commercial citrus than they’ve been doing up to now,” Krist says of CDFA efforts.

Response

News of the dogs’ findings rippled through the commercial citrus industry in California.

Victoria Hornbaker, director of the California Citrus Pest and Disease Prevention Division, a new division within the California Department of Food and Agriculture, says there are no confirmed cases of HLB in Ventura County. Moreover, she said the state was not involved in the dog inspection there.

Krist says the goal never was to have the trees PCR tested because growers believe the tests would be negative due to the inability of the PCR test to definitively detect CLas infection in all cases.

California Citrus Mutual President Casey Creamer said that while dogs can be an effective tool, he and others in the industry became concerned by a published news article that implied HLB was found in the commercial groves when that determination cannot be made solely by a dog.

“Our biggest concern was the messaging,” Creamer said, adding that the jury is still out on the effectiveness of the dogs under California conditions.

Citrus Mutual and others in the industry are said to be working on a public response to what many in the industry agree is the inevitable discovery of HLB in commercial citrus in California.

Hornbaker said that testing of plant materials and insects collected in Ventura County in 2015 and 2016 showed “inconclusive” results, meaning some samples taken revealed levels of bacteria too few to declare a positive result under regulatory rules, but enough bacteria that inspectors could not declare a “negative” result. Since then the USDA changed its testing protocols after researchers determined early tests may have “cross-amplified” multiple forms of bacteria in the samples that could have led to a “false positive.” Testing protocols were ultimately tightened to specifically seek only the CLas bacterium regulators are looking for.

What do we know?

Some scientists now believe that the latency of this disease – the period between first infection by ACP feeding activity and when a PCR test will reveal a positive result – may be much longer than the 2-3 years first thought. It’s this latency that concerns growers and led to the use of dogs as an early detection method. Published information by Gottwald suggests these dogs can detect parts-per-trillion levels of the bacteria, which is more sensitive than most laboratory instruments and certainly more sensitive than the PCR test.

A Gottwald article also states that canines studied under Florida conditions, when using potted citrus trees, were able to detect CLas in some trees as early as two weeks after infected psyllids fed on them.

Dr. Beth Grafton-Cardwell, a University of California entomologist and a collaborator in some of the Gottwald studies, is surveying for the presence of ACP in commercial citrus groves in southern California, to include the Ventura County region. She says those surveys have turned up very few psyllids this year, which she attributes to the weather and amplified efforts by growers to treat their groves in unison with approved insecticides as a best management practice. It is believed that a coordinated treatment of groves in a region is the best method to control psyllid populations.

Grafton-Cardwell is one of those scientists who believes that HLB latency may be longer in some cases as the disease may never go systemic in the entire tree, hence the inability for the PCR test to catch it in all cases.

“Everybody here in Ventura County is staring this epidemic in the face and felt a real need to be proactive,” Krist said of the recent dog visit. “Once the disease takes hold, you’re never going to get in front of it. That was the mistake Florida made.”

Krist says there are plans to bring the dogs back in November and again in January to do more scouting of commercial citrus groves.

From PestNet Community Digest

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Andrew Warren

Genetic ‘road map’ reveals the lost birthplace of a 150-year-old butterfly

Some scientific battles are epic: Think Nikola Tesla and Thomas Edison’s war of currents. Others fly under the radar, like a heated dispute over the origins of Mead’s skipper (above), a 150-year-old butterfly gathering dust on a Harvard University museum shelf. Now, using DNA from the dead insect, scientists have discovered its birthplace: a small mountain town in Colorado. The discovery settles old scores—and it could also help museum curators worldwide trace the origins of their own “lost” species.

When U.S. naturalist Theodore Mead found a tiny skipper butterfly (Hesperia colorado) in 1871, he didn’t label its location—typical for birds, insects, and other animals collected before GPS coordinates were added to most specimen tags in the early 2000s. That failure came back to haunt lepidopterists, one of whom discovered a nearly identical butterfly in the early 1980s. He classified it as a new subspecies. Other butterfly scientists were not so sanguine.

To solve the mystery of Mead’s butterfly, researchers from Texas and Florida started with its DNA. They gently removed the skipper’s abdomen from its pinned, fragile body, and extracted one-quarter of its nuclear DNA—and all of its mitochondrial genome—using a chemical solution to break down the genetic material.

They then sequenced the DNA, along with the DNA of 85 other H. colorado skippers. Next, the researchers compared each sequence to a reference genome of the species, creating a genetic “road map” that shows just how closely each specimen is related. From there, it was easy for the scientists to pinpoint the geographic origin of Mead’s skipper: Twin Lakes, Colorado, they report this month on bioRxiv.

Scientists have been using ancient DNA to trace early human remains to the places they lived for 2 decades, but this may be the first time DNA sequencing has been used to pinpoint the geographic origin of a museum specimen older than 100 years. Experts say it may not be the last. If the method can be replicated, it could soon uncover the origins of many old species that lack collection details.

 

 

From PestNet Community Digest

Science

White-crowned sparrows stop eating after they ingest small amounts of neonicotinoid pesticides.

Margaret Eng

Common pesticide makes migrating birds anorexic

When birds migrate, timing is everything. Fly too late, and they miss the peak season for finding good food, a good mate, or a good nest site. But that’s just what may happen to migrants unlucky enough to eat pesticide-laced seeds, new research shows. Toxicologists studying white-crowned sparrows have shown that these large, grayish sparrows become anorexic after eating neonicotinoid pesticides, causing them to lose weight and delay their southward journeys. The study might apply to other birds as well—and help explain the dramatic songbird decline of recent decades, researchers say.

Neonicotinoids are the world’s most widely used class of pesticide. They protect seeds—and the plants that grow from them—from insects resistant to other pesticides. But scientists have recently found that they can decimate pollinators like honey bees and bumble bees. Such concerns led the European Union to ban three of these compounds in 2018.

Laboratory studies have shown that neonicotinoids sicken and disorient captive birds, but no data existed on how they affect wild birds, who often swoop into fields to nosh on pesticide-laced seeds. Wondering whether pesticide exposure might explain a massive recent decline in farmland bird species, Margaret Eng, an ecotoxicologist at the University of Saskatchewan in Saskatoon, Canada, and her colleagues got to work.

The researchers caught dozens of white-crowned sparrows (Zonotrichia leucophrys) in southern Ontario province in Canada as the birds migrated from the Arctic to the southern United States. They kept the birds in cages with food and water for 6 hours. About a dozen received low doses of the neonicotinoid imidacloprid—equivalent to what they might ingest had they eaten several seeds from a recently planted field. Another dozen got a lower dose of the pesticide, and control birds received the same handling but no pesticide. After 6 hours, Eng put a tiny radio transmitter on each bird’s back and released it into a 100,000-square-kilometer site in Ontario, where 93 regularly spaced radio towers track tagged animals.

Within hours, birds with the highest pesticide dose lost an average of 6% of their body weight and about 17% of their fat stores, which are key to fueling long flights, Eng and colleagues report today in Science. Over the course of those 6 hours, the birds given pesticides stopped eating, taking in about one-third the food that untreated birds ate, they note.

Nor did the birds recover quickly when released. Half of the high-dose birds stuck around Ontario an extra 3.5 days or longer. “It’s just a few days, but we know that just a few days can have significant consequences for survival and reproduction,” Eng explains. She thinks the birds needed that extra time to get the pesticide out of their systems, start to eat again, and regain their lost fat.

The paper provides “a compelling set of observations” that shows how even low doses of neonicotinoids can affect bird survival and reproduction, says Mark Jankowski, a toxicologist at the University of Minnesota in St. Paul who was not involved with the work. These effects could help explain declines in sparrow populations—and may apply to other birds, says Caspar Hallmann, an ecologist at Radboud University in Nijmegen, the Netherlands. But more work would be needed to prove that, Jankowski adds.

Few researchers think the United States or Canada will have the political will to ban neonicotinoids despite the harms, because they are so protective for plants. But there are workarounds, says Nicole Michel, a population biologist with the National Audubon Society’s Conservation Science Division in Portland, Oregon. For example, rather than treat all seeds before they are planted, farmers could save money and reduce birds’ exposure by applying the pesticide to plants only after an insect outbreak occurs. Jankowski says researchers could also explore other methods to reduce birds’ exposure, including coming up with better ways to bury seeds—and remove those that spill—during planting.

From PestNet Community Digest

The Naked Scientist

What herbaria tell us about crop pathogens

13 September 2019

Herbarium.jpg

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Ever since we domesticated the first plants for food production, humanity has been dragged into the age-old arm’s race that exists between our crops and their pathogens…

The impact of one single crop pathogen on human society can be of a dreadful scale, especially when our crops are not naturally protected against them. The best example to illustrate this is the potato epidemic that caused the Great Irish famine in the mid-19th century. The culprit, an American microbe named Phytophthora infestans, crossed the Atlantic by ship, reached the European continent and wiped out entire potato harvests over various consecutive years. The impact was most devastating in Ireland, where people were highly dependent on one single variety of potato that did not bear strong natural resistance against the pathogen. About a million people died of starvation and another million or more were forced to leave the country. The famine reduced Ireland’s population by 25%, and the country has still not yet recovered to its original population size, even today.

It would, nonetheless, be very wrong to think that the threat of starvation due to crop pathogens is a problem of the past. According to the Food and Agriculture Organization (FAO) of the UN, at least 20% of global food production is lost due to plant disease and over 800 million people are chronically undernourished worldwide. In addition, the globalisation of trade since the Second World War combined with a lack of thorough disease control has allowed the spread of local pathogens to every corner of the world. And now, with the threat of climate change coming nearer and nearer, the future of agriculture in the face of disease becomes more uncertain. Simply eradicating pathogens is, however, practically impossible and ecologically irresponsible. What would provide us with more sustainable ways of combating crop disease and hunger, and equip us better for the changes to come, is a thorough understanding on how plant pathogens spread, colonise and adapt to their hosts in the first place, so that our agricultural systems can always be a step ahead of disease. For that, the history of a crop pathogen and its spread is a great starting point.

Studying the evolutionary history of plant pathogens, and tracking their routes of invasion, has always been difficult, however, because the historical crop disease records are sparse in this respect. Moreover, these records often provide misleading information on the spread of the disease as it can take a long time before the presence of a pathogen becomes apparent. This means that its true arrival time and subsequent adaptation to its new environment might have happened years before historical documents suggest. In recent years though, genetic sequencing technologies have taken a giant leap forward such that it has now become possible to sequence entire genomes of all kinds of organisms – even dead ones –  rapidly, cheaply and accurately. Scientists have developed intricate methods to obtain the remaining DNA from tissues that have been dead for thousands of years and have made astonishing discoveries. For example; through the few micrograms of DNA obtained from a Neanderthal bone, it was discovered that we, Homo sapiens, actually intermixed with this other species of hominid. For decades, such an idea had been thought impossible. And while most ancient DNA studies focused on humans and other animals, more recently scientists have begun to find other applications for this promising field of genetics.

To witness significant evolutionary change in humans – organisms with a long generation span – you need to go deep back in time and study them over a couple of centuries or millennia at the least. Microbes on the other hand, are organisms with much shorter generation spans. In their evolutionary context, time is warped: 100 years of change could be equal to millennia of evolution for us. With this idea in mind, scientists started to retrieve microbial pathogen DNA from the dead, dried leaves of old herbaria tucked away in the dark and dusty libraries of botanical gardens worldwide. Indeed, thanks to botanists from the 17th, 18th and 19th century, we have a magnificent plant collection covering all existing and also many extinct species of plants in all forms: old and young, tall and small, healthy and sick. Sequencing the DNA of historical microbes in herbarium samples revealed information on plant pathogens we couldn’t have obtained in any other way. Pioneer studies mostly concentrated on Phytophthora infestans and tracked down the original strain and the invasion route that brought it to Europe, planting death and despair wherever it went.

Through the University of Montpellier, I had the chance to explore this exciting field of ancient genetics, herbarium specimens and pathogen histories myself. For that, my destination was a very special place: the tiny French island of La Réunion, which lies in the middle of the Indian Ocean. There, a couple of scientists at the Research Institute for Agriculture and Development had started to study infected herbarium samples of citrus plants to find out more about the bacterial pathogen Xanthomonas citri (hereafter Xac). Although absent in Europe thanks to the strict border control and quarantine policies of the EU, this microbe is a nuisance in the rest of the world, causing lesions on the fruits and leaves of citrus plants, and premature drop, which makes the fruits inedible and unsellable. When I arrived on la Réunion, very little was known about this pathogen: its origin was thought to be Asia and it was believed to have spread to the rest of the world in the past century and a half. But how and when it reached those places, including La Réunion itself, was unknown; nor was it clear whether the spread had been facilitated by human trade and transport. And scientists also had no idea how fast it could adapt and evolve. These things are nevertheless documented in its inner “genomic” book, which reveals more than any historical document in the world.

Obtaining the DNA sequence of decades-old dead microbes is not an easy task. I spent the first two and a half months of the project in the lab, desperately trying to avoid contamination from modern Xac samples and testing multiple methods to obtain as much DNA as possible from the dead tissue. After getting the sequences back, we spent a further month trying to clean and organise the heavily-damaged data. In the meantime, I was also enjoying to the full the natural wonder that is La Réunion.

Being a young island, moulded and shaped by the violence of a fierce volcano, it is a strange little paradise for those who love to wander and hike. The landscape is scarred by the violent natural forces that created it, with slopes climbing up steeply from the coast to reach dizzying 3000m heights and then plummeting into a clover-like calderas that arose when the volcano came to its own brutal end, crashing down half a million years ago. Although the coast has been intensely urbanised, the inner parts of the island still remain wild. The hectic landscape, with razor-sharp cliffs, deep ravines, abrupt peaks and the impressive, straight walls of the calderas has created a lot of opportunity for a fantastic variety of natural communities to settle: grasslands, forests, jungles, rivers and waterfalls – while making it very hard for humans to reach. In the south-eastern end of the island a younger, very lively little brother of the now-extinct volcano sprung up about 500,000 years ago and is now one of the most active volcanoes in the world. Also here, landscapes vary immensely, with cool, green grasslands rolling into vast, red sand plains as you climb higher and higher into the mouth of the dragon. It is surreal to think that one can find himself in the prairies of the Alps, the plains of Tatooine, the forests of Middle-Earth and the jungles of Jurassic Park on the very same piece of land that only just stretches 63 km long.

mountain

The caldera of Cilaos lies in the centre of la Réunion and is the result of the main volcano’s collapse half a million years ago.

Looking back, it is hard to decide which of all the fantastic things I saw in La Réunion struck me most. Was it that humpback whale jumping metres high into the air, or the view of two encircled worlds as I stood on the ridge that separated one caldera from the other? Was it the splendid primary jungle that lies tucked between the calderas, bursting with life, covered in fog; or the view of the milky way from a white-sand beach; or the eerie look of a gigantic blood moon crossing the skies? If I had to pick, I believe it would be the view of streams of lava pouring out of the wounded earth one night in April, when the island’s volcano erupted. The trembling and growling underneath our feet, the sight of deep-cutting, red-glowing crevices from which fiery lava was spitting, and the slowly-growing, red tongues of liquid stone rolling towards the sea made me realise what a strange, powerful force is hidden deep in the Earth, one that can so easily destroy life, and give birth to it at the same time. Even though it was the very same Earth that was being vomited onto the surface before my very own eyes, it was by far the most unearthly and surreal thing I’ve seen and felt in my life.

volcano

The 500 thousand year old volcano in the South-East of La Réunion is one of the most active in the world. Here we see its main crater, le Dolomieu, in the back, and the much smaller and younger crater Formica Leo in front, which is thought to have been formed in the mid-18th century. 

While I was able to witness these spectacular natural scenes on the weekend, I was gradually being absorbed with the wondrous feeling of obtaining scientific results and acquiring a better understanding of our study system, Xac during the week. Once our historical DNA sequences were ready for analysis, we paired them up with DNA sequences of contemporary Xac strains from the entire world. This revealed the genetic relationship between historical and modern strains and lifted a tip of the curtain that covers its history. Our analyses confirmed what historical documents had suggested; that Xanthomonas citri is indeed native to Asia. However, something that historical documents cannot accurately report is the arrival date of a pathogen to a new territory. With a large enough sample size, and the availability of historical genomes, we were able to estimate this for the strains that have colonised the islands of the southern Indian ocean: Comoros, Mayotte, Mauritius and la Réunion itself. Our analyses suggested that the bacterium arrived first in Mauritius and la Réunion around 1850. Curiously, this falls shortly after the abolishment of slavery, which caused a major loss of work force on the sugar cane fields that largely fuel the economy of both islands. To replace the now-freed slaves, the French and British colonists brought large groups of workers from other colonies to the islands: many of them coming from India and China. Although we have no direct proof, one could speculate that it was this big migration wave that brought the first Xanthomonas citri to the Indian Ocean, as the migrants carried plants and seeds with them.

jungle

The primary forest of Bélouve lies on a plateau in between two calderas. The combination of past volcanic activity, a high altitude and humidity brought by fog that builds up here has given rise to this fantastically biodiverse tropical jungle. 

Another surprising finding was the close genetic relationship between Xac strains of La Réunion and another French island, Martinique. Martinique, however, is located in the middle of the Caribbean Sea, half a world away from La Réunion. How then, can it be that the two strains are so closely related? One possibility is that Xac was transported to Martinique through human traffic and trade, which has created a quick connection between the two French islands. Our results thus suggest that human mobility has possibly played a large role in the spread of the pathogen and reconfirms the importance of thorough border controls and quarantine policies for crops.

How else can these fundamental studies benefit society, you might ask? Apart from creating a historical record on crop disease, such phylogenetic studies can have direct applications. We were, for example, not only able to date the arrival of Xanthomonas citri to the Southern Indian Ocean, but also to estimate a mean mutation rate for its genome. This is a measure for the pace at which mutations occur in the Xac genome, and therefore also for the speed at which it is able to evolve. Such measures are incredibly useful when designing strategies to combat the disease: it gives us an idea how quickly it could adapt and overcome a pesticide, for example. Thanks to such knowledge, we can make sure we’re always a step ahead of the pathogen in the eternal arms race we have found ourselves locked in since our hunter-gatherer ancestors started growing the first crops.

landscape, mountain

Sunrise view over the highest mountain of la Réunion, the Snowpeak, and the surrounding calderas. In front, smaller, extinct craters from times long-gone spring up across the landscape. The picture was taken from the grassy, rural plains that lie at the foot of the volcano. Here, cows graze and oaks grow, as if it were a little piece of Europe brought to this remote island. 

Five months after my arrival in La Réunion, I was on my way again to the airport, with the scientific report of my project and a fantastic collection of unforgettable memories as extra luggage. More than anything, I felt extremely lucky that I had been given the chance to travel there and explore the island’s beauty and magical phenomena, while also learning so much on the evolution of crop pathogens and the unimaginable potential that lies hidden in the millions of herbarium samples across the world. Now that we have the tools to genetically study them, an entire new world of adaptation and evolution has opened up to us, that will certainly provide answers and applications when we face agricultural crisis due to pathogens, climate change or anything else. Most to thank are all those botanists from centuries past which, although oblivious of the true value of their work, knew how to treasure the accumulation of basic, fundamental knowledge about the world that surrounds us. That was one of the key lessons learned while staying in la Réunion; collecting information and knowledge about the natural world just for the sake of curiosity is never in vain, for one can never know what applications we may find for it in the future. And in that aspect, the potential of herbarium libraries is unmeasurable. If only a few historical strains were able to elucidate key aspects of Xanthomonas citri’s evolution and spread, can you imagine what we can learn from the immense natural library that all those botanists from centuries ago left us?

From PestNet Community

bbc-blocks-dark

by Jonathan Amos

9 September 2019

zombie fungus

Frenchman Frank’s remarkable photo was taken in the Peruvian amazon, near Iquitos, at the Madre Selva biological station.

“At first, I was wondering what could be this weird thing,” he said. “Then, I got closer and I was really impressed by this sight and the perfect symmetry of the fungus,” he told BBC News.

Frank had seen some other parasitised beetles, but none in quite so photogenic a pose.

Parasitism, where one organism adapts its whole mode of living around the exploitation of another, is one of the great marvels of evolution. And on occasions, it can become wonderfully sophisticated.

In this case, the fungus spreads inside the poor weevil, taking chemical control of the creature and compelling it to climb. When it reaches a suitable height – for the fungus – the insect will lock down on the stem and die. Look and you can see the glaze has gone from its eyes.

Meanwhile, fuelled by the weevil’s insides, the fungus will start to grow those exquisite fruiting bodies. The capsules at the top will eventually burst and release countless tiny spores to infect new prey.

“The perfect symmetry made me think to photograph the beetle from the front to get sharp the whole fungus and the head of the beetle both,” said Frank.

“Furthermore as the beetle was dead and immobile, I tried a long exposure under daylight, avoiding the sun to reduce the contrast of the background.”

Now in its 55th year, WPY has become one of the most prestigious competitions of its kind anywhere in the world. Nearly 50,000 entries were received for this year’s event.

Frank Deschandol’s picture was Highly Commended in the Plants and Fungi category. A number of other Highly Commended images are shown below.

 

From PestNet community Digest

Sunday, 15 September 2019 11:46:00

Grahame Jackson posted a new submission ‘The ‘pathobiome’ — a new understanding of disease’

Submission

The ‘pathobiome’ — a new understanding of disease

7th space
http://7thspace.com/headlines/968421/the_pathobiome____a_new_understanding_of_disease.html

Cefas and University of Exeter scientists have presented a novel concept describing the complex microbial interactions that lead to disease in plants, animals and humans.

Microbial organisms and viruses cause many diseases of plants and animals.

They can also help protect from disease, for example the complex communities of microbes in the human gut, which are very important for our health.

However, very little is known about these microbes and how they cause and prevent disease.

The pathobiome concept opens a door on this unexplored world of microbial diversity and how it controls all other organisms on the planet.

It will change the way we approach health and disease control in animals, plants and humans.

Traditional approaches to describe infectious disease in plants, animals and in humans are based on the concept that single pathogens are responsible for the signs or symptoms of disease observed in those hosts.

The pathobiome concept explains that in reality, disease occurrence is much more complex.

Today sees the publication of a paper exploring the pathobiome concept, a novel way of seeking to understand diseases of plants and animals, including humans.

The concept acknowledges that all organisms are in fact complex communities of viruses, microbes and other small organisms (e.g. parasites) which can interact to affect health or disease status at any given time.

These complex communities continually interact with their hosts, sometimes conferring benefits (e.g. “good” bacteria in the human gut microbiome), and at other times causing harm by contributing to disease.

Read on: http://7thspace.com/headlines/968421/the_pathobiome____a_new_understanding_of_disease.html

From PestNet Community Digest

Fall armyworm, destroyer of maize farms, causes concern in India

Source(s):  Mongabay

By Manupriya 

  • After ravaging cornfields of sub-Saharan Africa, the fall armyworm arrived in India in 2018. The pest infestation has already spread to most parts of the subcontinent and has been reported from maize farms in 20 states.
  • A native of America, the fall armyworm has spread through trade routes to Africa and Asia. There is no single solution to get rid of this voracious eater of maize plants, and scientists suggest a multi-pronged approach depending on geographical location and extent of the infestation.
  • Maize monoculture and overuse of pesticides that increase resistance have turned the fall armyworm into a serious pest. A shift towards agro-ecological approaches like organic and natural farming, and multiple cropping systems could help in managing the outbreak.

Maize farmers in many parts of Karnataka were taken by surprise in July last year when an unknown caterpillar attacked their crop. It didn’t take scientists long to identify the new pest. By the second week of July, researchers from the National Bureau of Agricultural Insect Resources (NBAIR), an institute under the Indian Council for Agricultural Research, said the new pest was the Fall Armyworm (FAW).

Spotted in a maize field in Chikkaballapur, some 60 km from state capital Bangalore, the appearance of FAW in India is a cause for serious concern. Native to tropical and subtropical regions of the Americas, the dreaded caterpillar appeared and spread rapidly in Africa in 2016, and has since then devastated millions of hectares of maize crop in all parts of sub-Saharan Africa.

And sure enough, the worm spread very fast through the maize fields of India as well. In a matter of months, more than 14 states in the country reported the infestation last year, seriously compromising the corn harvest. The infestation has since spread even wider this year to 20 states, with the northeastern parts of the country the worst affected.

The caterpillar stage of a moth, the FAW (Spodoptera frugiperda) is a voracious eater of maize plants and has been termed as an invasive species by scientists. It’s not a picky eater though. Besides corn, it likes to feed on the leaves and stems of more than 350 plant species, including rice, sorghum, sugarcane and wheat.

An adult female moth can lay up to a thousand eggs in her lifetime. They are also terrific fliers and can travel up to 100 km in a single night.

Fast spread

The spread of FAW through the Indian subcontinent has been particularly fast. In 2019, the pest has spread as far as Mizoram in the northeast, Uttar Pradesh in the north, Gujarat in the west, Chhattisgarh in central India, and several states in the south. This year, the biggest victims so far have been farmers in the northeastern states, where a cumulative of 10,772 hectares of maize crop has been affected. The pestilence has been reported from 20 states in India.

Scientists are not surprised at the fast transmission of FAW. “We have already seen in Africa that the infestation spread from one country, Nigeria, to almost half of the continent in a matter of two years (2016-2018),” said Malvika Chaudhry, regional coordinator, Plantwise Asia, Centre for Agriculture and Bioscience International (CABI).

The northeastern states with their “high humidity and moderately high temperatures” are suitable for the spread of FAW. Its metabolic rate is well supported in these conditions, sometimes even leading to “intensification of infestation,” said Chaudhry. It means that the pest is able to complete its lifecycle in a shorter period of time, resulting in more pests, more quickly.

Farmers and scientists are now fighting to contain the infestation. Maize is India’s third most important cereal crop after rice and wheat. In 2016, 25.9 million metric tons of maize  was produced in India. In 2017, that number rose to 28.7 million tons. In 2018, however, production fell by 3.2% to 27.8 million tons. It is expected that the net production will decline further in 2019 due to the pest attack.

Cascading effect

Although corn is not a staple in India, it serves an important role as feed for poultry. The growth in the poultry industry has resulted in a concomitant increase in the area cultivated under maize since the turn of the millennium. The decrease in maize production thus has a cascading effect on the poultry industry.

Earlier in August, poultry farmers in Karnataka and Maharashtra urged Narendra Singh Tomar, India’s farm minister, to urgently import maize to meet a shortfall. Due to the deficit, maize prices have shot up, resulting in an increase in production cost for chicken and eggs.

It’s not just the feed and starch industries that are feeling the heat. Maize farmers maize are too facing additional challenges in continuing to grow the crop. They’ve had to endure crop losses and bear the additional cost of rescuing their crop from FAW and preventing further infestation.

“The input cost of growing maize has gone up,” said Bhagirath Choudhary, founder-director of South Asia Biotechnology Centre (SABC), a New Delhi-based scientific organization. In addition to the usual input cost, farmers have to spend on pheromone traps, safety kits, botanical and biological control methods and more pesticides.

In addition to their price, most of these items attract high taxes to the tune of 18 percent. Only botanical and biological controls are taxed at five to 12 percent. For farmers, especially smallholders, these costs are punitive. “The SABC has submitted a request to the Union Minister of Finance, Nirmala Sitharaman, to either completely exempt GST (Goods and Services Tax), or reduce it to the lowest slab on these items,” said Choudhary.

Worryingly, FAW seems to have spread to crops other than maize as well. For example, scientists noticed FAW infestation on sorghum and bajra (millet) in the fields of an agricultural research station at Ananthapuramu in Andhra Pradesh in October 2018. The researchers noted that the pest was gradually spreading to other millets grown in Ananthapuramu district.

In another report, researchers from Maharashtra noted FAW’s presence in sugarcane and sorghum. A  statement by the Ministry of Agriculture and Farmer Welfare on June 25 confirmed FAW infestation on sorghum and ragi (finger millet). The only consolation of sorts is that the spread in these crops has not been as rapid as than in corn.

Stopping FAW’s march

In 2018, when the pest attack first started, most farmers were unfamiliar with FAW. On Plantix, an AI-based farmer assistance mobile application where farmers can ask questions, farmers in 2018 were mostly asking to identify the pest, according to Sairekha Kadirimangalam, who works for Plantix in Hyderabad. However, as FAW starting spreading in India, the nature of queries changed. Maize farmers are now looking for solutions to stop the pest from damaging the crop, Kadirimangalam said.

There is no silver bullet to stop FAW in its tracks. A good monitoring system and farmer awareness about the pest are the first steps, said Chaudhry. “Sometimes, when confronted with the pest suddenly, farmers tend to panic and spray their fields with an array of chemicals,” she said. “This panic response is not just ineffective but also leads to broad-spectrum resistance in the pest, and should be avoided.”

“The first thing they (farmers) should do is to contact the nearest Krishi Vigyan Kendra (agricultural extension center) or state department’s agriculture officials,” said A.N. Shylesha, principal scientist, Entomology, NBAIR. Based on geography and extent of infestation, ICAR recommends a variety of solutions, which include mechanical, biological and chemical measures. For example, the infestation is in its early stages can be controlled by using bio-control agents like Trichogramma and Telenomus, and providing good nutrition to the plants. It is only when the infestation is severe that chemicals are recommended.

As FAW continues its march across India and other Asian countries, the need for effective protective measures will only grow stronger. “Increasing monoculture of maize around the year and wrong pest management practices with excessive dependence on chemical pesticides, which increased the resistance in the insect to pesticides, have contributed to FAW becoming a serious pest,” said G.V. Ramanjaneyulu, executive director of the Centre for Sustainable Agriculture, which works with smallholder farmers. “Any pest is always a function of practices followed and local weather conditions. Therefore, a shift towards agro-ecological approaches like non-pesticidal management, organic or natural farming, and multiple cropping systems are the ways to manage such pest outbreaks.”

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Editor’s note: There will be two fall armyworm symposia at the International Plant Protection Congreess in Hyderabad, Nov. 10-14, 2019: http://www.ippc2019.icrisat.org
The symposia will be presented by experts from Africa, USA, Europe, South America and Asia. Topics covered include biology and ecology, monitoring, modeling, global movement, agro-ecological approaches to control,chemical, biological and cultural controls and the push-pull system for control.