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A Marchantia liverwort, where the defense genes and the production of purple pigment was activated in specific sectors only. Credit: Philip Carella

Scientists at the University of Cambridge have uncovered striking similarities in how two distantly related plants defend themselves against pathogens despite splitting from their common ancestor more than 400 million years ago.

Researchers from the Sainsbury Laboratory at the University of Cambridge compared how two distantly related plants—a common liverwort (Marchantia polymorpha) and a flowering plant, wild tobacco (Nicotiana benthamiana) – defend themselves against an aggressive pathogen (Phytophthora palmivora). This is the first time such a comparison has been undertaken. By studying how these distantly related plants—which split from their roughly 400 million years ago—respond to pathogen infections, the research team discovered a suite of microbe-responsive gene families that date back to early land plant evolution.

Our current understanding of how plants successfully defend against disease-causing pathogens mainly originates from studying economically important crop plants and a small number of closely-related model systems. Very distantly-related plants, such as non-flowering liverworts that are believed to resemble some of the first land plants, are often overlooked. As a result, not much was known about how these plants defend themselves from pathogens or how plant defence strategies have evolved.

Published in Current Biology today, the identification of these evolutionarily conserved genes is shedding new light on the strategies that were likely critical for the expansion of plants onto land.

“We have shown that molecular responses to pathogen infection typical of modern flowering plants are common to very distantly-related land plants and may therefore be more ancient than we previously thought,” says Dr. Sebastian Schornack, who led the research team that undertook the study. “Despite fluctuating environmental pressures over a broad evolutionary timescale, these conserved genes have retained their capacity to confer pathogen protection in plants, including in important agricultural crops.”

Bioinformatics expert, Dr. Anna Gogleva, identified a subset of one-to-one corresponding genes (single-copy orthologs) in the liverwort and wild tobacco and analysed their level of activity during the infection. A number of different genes were activated in both plants, but a set of metabolic genes involved in phenylpropanoid (flavonoid) biosynthesis were highly activated in response to infection.

Liver wort 2
Microscopic image of a liverwort where part of it has accumulated purple pigment (left). The pathogen can be detected as red fluorescence and it only sporulates in green tissues and does not accumulate well in purple tissues with activated defence (right). Credit: Philip Carella

These gene families are often associated with the stress-response in flowering plants, providing increased protection against biotic or abiotic stresses caused by chewing insects, pathogens and nutrient or light stress. However, this was the first time that these genes had been functionally linked to pathogen defence strategies in liverworts.

“Pathogen zoospores germinate on the surface of liverworts and eventually colonise the liverwort tissues, but in some areas we saw an accumulation of a purple/red pigment in the liverwort tissues where the pathogen was rarely detected,” says Dr. Philip Carella, lead author of the study.

“We produced liverwort plants with mosaic pigment patterns—resembling military camouflage fatigues—that allowed us to compare pathogen resistance in pigmented and non-pigmented areas of the same plant and found the pigment provided some resistance to pathogen infection.”

The enormous diversity of traits and species that we see in modern plants today speaks to the millions of years of evolution that enabled plants to survive in dynamic and contrasting environments across the globe.

“The conflict between organisms can be a very powerful selective pressure that guides their evolutionary trajectory,” says Dr. Schornack. “Genes involved in fighting specific can evolve rapidly—both in plants and animals. But we have also now found these broadly-conserved genes responding to pathogen infection in very distantly-related plants, which suggests that land plants have retained a likely ancient pathogen deterrence strategy that is much too useful to lose.

“Fossil evidence shows that plants have engaged in close-interactions with microbial life forms throughout their evolutionary history. Our research has uncovered a common set of pathogen-responsive shared in early-divergent land plants and more evolutionarily young flowering plants, which are all likely to have been critical for the expansion of plants onto land. Further comparative studies focusing on other distantly related land and their aquatic algal predecessors should reveal even more information about the evolution and role of these vital gene families.”

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science development net

04/04/19

Biological weapon against fall armyworm found in Africa

Researchers have identified Telenomus remus in Benin, Cote d’Ivoire, Kenya, Niger and South Africa.

Researchers have identified Telenomus remus in Benin, Cote d’Ivoire, Kenya, Niger and South Africa. Copyright: CABI

Speed read

  • Fall armyworm has devastated millions of hectares of maize and sorghum in Africa
  • Researchers have identified an insect that could curb the spread of the pest in four countries
  • Policymakers must act fast to register it as a biological control strategy, experts say

[LAGOS] Scientists have identified a biological weapon that could help fight the scourge of fall armyworm, a devastating pest that experts say threatens the food security of about 200 million people in Africa.

According to the UN’s Food and Agriculture Organization (FAO), fall armyworm has already spread across Sub-Saharan Africa since its detection in the region in 2016, affecting millions of hectares of maize and sorghum crops.

The biological weapon, known as Telenomus remus, is an egg parasitoid — an insect that completes its larval development within the body of another insect leading to the death of its host. It is already being used to tackle fall armyworm in the Americas, experts say.

“We hope that by using this parasitoid or other biological control agents, the quantity of synthetic insecticides used against fall armyworm will diminish.”

Marc Kenis, CABI

Now an international team of researchers have used DNA analysis and morphological observations to confirm the presence of T. remus in Benin, Cote d’Ivoire, Kenya, Niger and South Africa, according to a study published in the journal Insects last week (29 March).

T. remus is a vital tool that can fight against the fall armyworm, a pest that has the ability to cause yield losses of up to 20.6 million tonnes per annum in 12 of Africa’s maize-producing countries,” says Marc Kenis, lead author of the study and head of risk analysis at the Centre for Agriculture and Bioscience International (CABI, the parent organisation of SciDev.Net).

Kenis tells SciDev.Net that the main control method currently used is broad-spectrum insecticides, which has serious economic, environmental and health consequences.

Fall Army Worm
The fall armyworm. Copyright: CABI

The use of natural enemies to control a pest, an approach called biological control, is environmentally more sustainable and has no negative effect on human health.

“Many teams in Africa are looking for natural enemies of fall armyworm in several African countries. Of particular interest are parasitoids,” says Kenis. “Our discovery showed that the parasitoid is already in West, East and Southern Africa and can readily be used as a biological control agent.”

Kenis cautions, however, that biological control agents do not fully eradicate pests.

“They just lower their populations and impact below a tolerance threshold,” he says. “We hope that by using this parasitoid or other biological control agents, the quantity of synthetic insecticides used against fall armyworm will diminish.”

The team of scientists say surveys should now be carried out throughout Africa to assess the distribution and impact of Telenomus remus on the continent.

The main challenge will be to develop a production method specific to the African context that will be economically viable for farmers, Kenis adds. He believes African policymakers should facilitate the use of T. remus as a biological control agent by allowing it to be registered.

Tony Wemton, director of Wemton Agricultural Development and Advisory Services in Nigeria, tells SciDev.Net that Nigerian farmers have been using insecticides to tackle fall armyworm, which can cause great harm to farmers and end users of their products.

“With this new biological weapon that can fight against fall armyworm, African governments can help local farmers by making funds available through grants or subsidies so that they can have access to it,” Wemton says.

This piece was produced by SciDev.Net’s Sub-Saharan Africa English desk.

References

Marc Kenis and others Telenomus remus, a candidate parasitoid for the biological control of Spodoptera frugiperda in Africa, is already present on the continent (Insects, 29 March 2019)

Wikimedia commons/Sam Droege [Public domain]

 

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Science

A plantation in West Kalimantan in Indonesia, where oil palms have replaced all but small patches of forest

On a plantation in West Kalimantan in Indonesia, oil palms have replaced all but small patches of forest.

ARROWHEAD FILMS

Courting controversy, scientists team with industry to tackle one of the world’s most destructive crops

IN LIBO ON SUMATRA, INDONESIA—Crickets were chirping one clear morning in April when Anak Agung Aryawan walked under the canopy of a quarter-century-old oil palm plantation here. Suddenly Agung, an agroecologist, stopped. “Look, that’s a Sycanus!” He pointed at a black insect perched on a fern in the forest understory. Known as an assassin bug, Sycanus uses its mouthpart to stab its insect prey, including the fire caterpillar, one of the most important pests of oil palm trees. He soon found more insect killers in the palm grove: a Nephila spider, known for its big, elaborate web, and the bright yellow Cosmolestes, another species of assassin bug.

Agung works for SMARTRI, an oil palm research institute here owned by Sinar Mas, one of Indonesia’s largest business conglomerates. The study plot he was visiting was managed without herbicides or insecticides; plantation workers weeded it by hand, and only in a small circle around each tree. As a result, many tall ferns and shrubs were growing beneath the canopy, creating a home for insects, spiders, and snakes.

Many Indonesian planters would abhor this semiwilderness, worrying the understory would compete with oil palm trees for water and nutrients. Agung sees it differently. Allowing a luxuriant understory to grow in plantations can protect insects and some small mammals, such as the leopard cat—and ultimately benefit the oil palm trees as well. Sycanus and other predators control pests, for example, and other invertebrates improve the soil and pollinate the palms.

Oil palm (Elaeis guineensis) is one of the most controversial crops today, because the plantations often replace tropical rainforests rich in biodiversity, depriving iconic species such as the orangutan of their habitats. Vast swaths of Indonesia and Malaysia are given over to the crop. But Agung and a growing number of other scientists say it’s time to work with oil palm companies—some of them in the crosshairs of environmental activists—to make the best of a bad situation.

Researchers have accepted industry funding to study habitat fragmentation and advised oil palm companies on how to best manage the surviving wildlife in their concessions. And at SMARTRI, a long-term ecological experiment called Biodiversity and Ecosystem Function in Tropical Agriculture (BEFTA) is testing whether the plantations can host more biodiversity without affecting yield. Finding a way to protect species while satisfying the world’s demand for palm oil is “a vital conservation priority of the modern era,” Edgar Turner, a conservation scientist at the University of Cambridge in the United Kingdom who heads BEFTA, wrote in a 2011 paper.

Anak Agung Aryawan inspects a tree planted in 2018 as part of a study seeking to restore riverbanks in plantations to a more natural state.

DEDY SUTISNA/RIAU IMAGES

Some critics call the approach naïve. By accepting industry funding—and using its giant plantations as laboratories—scientists risk losing their independence, they say, and they legitimize the companies’ business by giving it a veneer of sustainability. “They take a pragmatic approach in the face of a desperate situation,” says David Gaveau of the Center for International Forestry Research in Bogor, Indonesia. “If funding and prestige that comes with access to large data sets lures scientists to a particular direction while ignoring the big elephant in the room, then this is problematic,” says Maria Brockhaus, a forest politics expert at the University of Helsinki.

But scientists working with oil palm companies say they don’t feel constrained scientifically, and they welcome the money. “It’s hard to find long-term funding for research,” says Matthew Struebig, a conservation scientist at the University of Kent in the United Kingdom who has consulted for two plantations owned by Wilmar International, the world’s largest palm oil trader. Moreover, the demand for vegetable oil will only grow, and palm oil is the most efficient way to produce it, Turner says. Biodiversity loss is a “complete tragedy,” but “we need to feed the world,” he says. “We need to produce crops that are very productive … in the smallest area possible. And oil palm is the best.”

Palm oil is used in a staggering number of consumer products, from fast food, chocolate spread, and cereals to toothpaste and dog chow. It is also a source of biodiesel. Some 90% of the global supply comes from Indonesia and Malaysia, where plantations cover 17 million hectares, almost half the area of Germany. Growing demand is pushing the industry into Africa and South America.

Gaveau, a landscape ecologist, has tracked the spread of plantations on Borneo—home of Indonesia’s largest rainforest—in images from NASA’s Landsat and data on oil palm concessions to produce the Borneo Atlas, a new online platform. In the past 2 decades, he found, big oil palm companies have cleared 24,000 square kilometers (km2) of Borneo’s forests—almost five times the area of Bali. (Pulpwood production, smallholder farming, mining, dam construction, and other development consumed another 36,000 km2.)

Policies to stem the tide have not worked very well. In 2011, the Indonesian government issued a moratorium on deforestation, and in 2016 it halted the draining and clearing of peatlands for plantations. In September 2018, President Joko Widodo also stopped issuing new oil palm permits, which for now has stalled deforestation in the province of Papua—another biodiversity mecca—where 1800 km2 have been cleared so far.

Yet banning palm oil would not end biodiversity loss, according to a 2018 report by the International Union for Conservation of Nature (IUCN); it would only displace it to other parts of the globe and possibly worsen it. One hectare of tropical land can produce 4 tons of oil annually, at least four times the yield of 1 hectare of rapeseed, sunflowers, or soybeans planted in temperate regions. Unlike those crops, the oil palm is a tree that can live up to 25 years—enough for a diverse ecosystem to thrive in a plantation, if growers allow it. “It’s actually a good crop for conservation, but it just happens to grow in the most biodiverse parts of the world,” Turner says.

Instead of urging a ban, the IUCN report calls for reining in deforestation and discouraging the use of unsustainable palm oil. (Some 19% of the global output is certified as “sustainable” by the Roundtable on Sustainable Palm Oil, which includes thousands of growers, traders, and manufacturing companies as well as groups such as the World Wildlife Fund and Oxfam. To qualify, a company needs to show it’s not contributing to deforestation and is treating its workers well, among other things.)

One of the lead authors of the IUCN report is Dutch ecologist Erik Meijaard, who runs his own consultancy company from Brunei. Meijaard is a prominent figure in Indonesian conservation science. In 1997, he discovered an orangutan population in a small patch of forest in North Sumatra; a decade later, he and others found that genetic and morphological characteristics set it apart as a separate species, now named the Tapanuli orangutan, after the place they inhabit.

Meijaard feels palm oil is unjustly vilified. There are many other threats to Indonesia’s biodiversity, he notes. “We always assume that the forest would have remained if oil palm plantations had not been developed, but my lesson from Indonesia is that forests that are unmanaged are ultimately cut down, either legally or illegally.”

Meijaard is pragmatic when it comes to collaborating with palm oil companies. In 2011, he decided to accept an offer to advise ANJ Agri on how to manage a patch of forest within the company’s concession in West Kalimantan—an Indonesian province on Borneo—that is home to 150 orangutans. That raised eyebrows among some other conservationists. According to Gaveau’s Borneo Atlas, the company cleared 38 km2 of primary orangutan habitat in West Kalimantan in 2012, a year after the Indonesian moratorium on deforestation began. And Greenpeace included ANJ Agri on a blacklist for clearing forests without permission from local indigenous people in South Sorong in West Papua; it also says the company’s private police beat a Papuan man during a 2017 demonstration.

Conservation scientists Erik Meijaard and Nardiyono at work in the high conservation value area of ANJ Agri’s oil palm concession in West Kalimantan in Indonesia. The area is home to some 150 orangutans.

ARROWHEAD FILMS

Meijaard says that in Kalimantan, the company only cleared second-growth forests, which have less biodiversity than primary rainforest; he declined to comment on the South Sorong accusations. (An ANJ Agri spokesperson in Jakarta says an in-depth investigation showed the beating didn’t happen.) In any case, Meijaard says, the company is serious about protecting the orangutans in its concession. “They worked hard in getting rid of rampant illegal logging and hunting, and invested heavily in forest fire prevention,” he says. “Without the company, that piece of forest would be gone, just like a community forest located nearby.”

Meijaard stresses, “There are plenty of companies I wouldn’t take money from.” When he was invited in 2018 for a “dialogue” by PT North Sumatera Hydro Energy, a company building a hydroelectric dam that threatens the home of the Tapanuli orangutan, his answer was resolute. “There is nothing to discuss or have a dialogue over, apart from the total cancellation of the project,” he wrote to the company.

Yet Gaveau says it’s hard for scientists to know exactly what the companies they work with are doing. In 2018, for instance, Greenpeace accused Wilmar of disguising its de facto ownership of plantations to avoid accountability and buying palm oil from 18 companies that had cleared forests, despite Wilmar’s 2013 adoption of a “no deforestation” policy. (In a press release, Wilmar denied some of the allegations, but the company did adopt a plan to better monitor its suppliers 3 months later.) “We cannot trust the companies blindly,” Gaveau says. “They will seek loopholes to cheat the system for their advantage whenever they can.”

SMARTRI is run by Jean-Pierre Caliman, a French agronomist with a passion for oil palms who moved here from Africa in 1993. Employed by Sinar Mas, he leads a team of 81 Indonesian scientists and has a $10 million annual budget. Until recently, its the institute’s research focused on increasing yield or reducing cost; biodiversity wasn’t really on their radar. Now, SMARTRI scientists are studying the carbon dynamics in plantations and putting a price tag on the ecosystem services provided by hundreds of species living among the oil palms. “How much money do we have to spend if a species disappears?” is a key question now, Caliman says.

The Sumatran barn owl (Tyto alba), for instance, is a scourge of the rats that eat the fruits of the oil palm tree, lowering yield. Without owls, Caliman says, plantation managers would need to buy rodenticides worth up to $4 per hectare annually; to lure the birds, Sinar Mas has installed 26,000 artificial nest boxes on Sumatra.

SMARTRI’s major effort to find a place for biodiversity in palm plantations began in 2011, when William Foster, a Cambridge insect ecologist and Turner’s Ph.D. supervisor, asked Caliman whether he wanted to collaborate on a long-term ecological study. Caliman embraced the idea, which became BEFTA. Turner got some of his ideas for BEFTA while doing research in Sabah in Malaysia. “From walking around plantations [there], it’s quite clear that plantations with a higher level of understory have a high level of biodiversity, and we would like to find out what impact that had on functioning and yield,” he says.

A more natural plantation

A large-scale ecological experiment on a plantation in Indonesia tested three different understory treatments. It suggests reducing herbicide use can lead to a more diverse understory without affecting yield.

Sinar Mas provides BEFTA with funding—Turner and Caliman declined to say how much—and Turner was given 18 research plots, each measuring 150 by 150 meters, at the plantation. On six of them, researchers used herbicides to remove all of the understory, as well as ferns living on palm trees, which many plantation owners do. In six others, they used standard Sinar Mas practice, which is to spray herbicides only on paths and in a circle around each tree to give plantation workers access, while leaving most of the understory alone. On the last six plots—including the one where Agung found his Sycanus—they used no herbicides at all; workers manually removed plants around the trees and on paths.

Data collection finished last year, and some results have come out. In a paper published in December 2018, the team reported that abandoning herbicides improved the condition of the soil and increased the diversity of soil macrofauna, such as earwigs (Dermaptera) and millipedes (Diplopoda), which break down leaf litter, making nutrients available to other species. Another paper reported that the plantation is home to 69 species of dragonfly, including five never before spotted on Sumatra. And the herbicide-free plots had soil nutrient levels just as high as the chemically treated ones, suggesting worries about competition from the understory are unfounded. As-yet-unpublished findings show that even the most ecofriendly regimen had a negligible impact on yields, Caliman says. He and Turner are optimistic they can persuade Sinar Mas management to adopt the strategy widely.

Although environmentalists are wary of such collaborations, some oil palm experts dismiss the results. Agus Eko Prasetyo, an expert on plant protection at the Indonesian Oil Palm Research Institute in Medan, says scientists have known since the 1980s that most ferns and shrubs don’t decrease palm oil yields. But he says planters do need to control certain species—especially woody plants whose roots suck up more water and nutrients—and doing so manually rather than with herbicides will drive up cost. “I bet Sinar Mas won’t adopt” the ecofriendly regime, Prasetyo says.

Others say that in working with large companies, ecologists are missing worse offenders: smallholder farmers who own 40% of Indonesia’s oil palm plantations and may be less informed about biodiversity and oil palm management. If researchers “focus on large companies to ‘help’ them do a little bit less harm to nature, then who is going to study the unsustainable practices?” Brockhaus asks.

Many planters remove the epiphytic ferns living on oil palm trees. In a large-scale experiment on Sumatra in Indonesia, they are left in place as part of an effort to enhance biodiversity.

DEDY SUTISNA/RIAU IMAGES

The Indonesian government, not industry, should fund oil palm research, Brockhaus says: “The country has the responsibility to ensure independent and critical research to serve the interest of the wider society and not in favor of selected interests.” The government could also study social and economic aspects of the industry, adds Hariadi Kartodihardjo, a forest policy expert at Bogor Agricultural University. Revenues primarily benefit the country’s ruling elite and a small number of tycoons, Kartodihardjo says; meanwhile, millions of plantation workers toil, often on low wages, in isolated places with conflicts over land use and few educational opportunities. “This is something that needs to be solved,” he says.

But government funding for research is scarce; many Indonesian scientists can only dream of the budget SMARTRI has. The Indonesian Oil Palm Estate Fund, a government body that collects taxes on palm oil exports, also funds some research, but most of it is in agronomy and postharvesting processing, not on biodiversity or social and economic issues.

Turner has no qualms about the collaboration with Sinar Mas: “For large experimental trials, you need a lot of resources,” he says. Struebig sees the overall balance as positive as well. Working with companies gives researchers access to sites and data and helps build trust between science and the industry, he says. “To me, working with the industry will lead to bigger improvements in sustainability than working without,” he says.

After a long drive through the plantation, Agung got out of his Land Cruiser and walked toward a narrow stream. The area looked very different; there were no palm trees in sight, only young forest trees and wild shrubs. They formed part of a new long-term experiment by the Cambridge team, launched in 2018 and called Riparian Ecosystem Restoration in Tropical Agriculture.

Under a 2015 government policy, companies can’t plant new oil palms in 50-meter-wide ribbons along rivers in their plantations; the idea is to start to give these zones back to nature. How best to restore them to a more natural state is not clear. The team is now testing four different strategies. In one plot, all palm trees were cleared and replaced with six native tree species. Some were struggling. A young red meranti (Shorea leprosula), an icon of the lowland tropical forest on Sumatra and in Kalimantan, was dying.

But Agung’s face lit up in another plot, where the researchers had left the oil palm trees in place and had planted native trees between them. Here, a red meranti was thriving; maybe it needed to be shaded by the aging palm trees early in life, Agung speculated. Another native forest tree, Peronema canescens, which the team had planted last year, was already taller than Agung. He stood next to it to take a selfie, ignoring a weaver ant crawling on his neck. “I just can’t wait to see the plot in a few years,” he said. “It’s going to look like a forest.”

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Science News

Tiny glasses help reveal how praying mantises can see in 3-D

Newfound nerve cells in the insects’ brains play a role in depth perception

By
10:00am, July 12, 2019
praying mantis

LIFE IN 3-D  Colored filters let a praying mantis watch a 3-D video of a moving disk while researchers studied the nerve cells that contribute to the insect’s depth perception.

A praying mantis depends on precision targeting when hunting insects. Now, scientists have identified nerve cells that help calculate the depth perception required for these predators’ surgical strikes.

In addition to providing clues about insect vision, the principles of these cells’ behavior, described June 28 in Nature Communications, may also lead to advances in robot vision or other automated systems.

So far, praying mantises are the only insects known to be able to see in 3-D.  In the new study, neuroscientist Ronny Rosner of Newcastle University in England and colleagues used a tiny theater that played praying mantises’ favorite films — moving disks that mimic bugs. The disks appeared in three dimensions because the insects’ eyes were covered with different colored filters, creating minuscule 3-D glasses.

As a praying mantis watched the films, electrodes monitored the behavior of individual nerve cells in the optic lobe, a brain structure responsible for many aspects of vision. There, researchers found four types of nerve cells that seem to help merge the two different views from each eye into a complete 3-D picture, a skill that human vision cells use to sense depth, too.

SPOT IT In the optic lobe of a praying mantis’s brain, this nerve cell, called a TAOpro neuron, has three elaborate fan-shaped bundles (two shown with a colored stain) that receive incoming visual information. This cell helps compute objects’ depths from information from the insect’s eyes.

Newcastle University, UK

 

One cell type called a TAOpro neuron possesses three elaborate, fan-shaped bundles that receive incoming visual information. Along with the three other cell types, TAOpro neurons are active when each eye’s view of an object is different, a mismatch that’s needed for depth perception.

The details of the various types of nerve cells, and how they might receive, combine and send visual information, suggest that these insects’ vision may be more sophisticated than some scientists had thought, the team writes. And the principles guiding praying mantis depth perception may be useful to researchers working on improving machine vision, perhaps allowing artificial systems to better sense the depths of objects.

Citations

R. Rosner et al. A neuronal correlate of insect stereopsis. Nature Communications. Vol. 10, June 28, 2019. doi: 10.1038/s41467-019-10721-z.

Further Reading

L. Sanders. Vision cells can pull double duty in the brain, detecting both color and shape. Science News Online, July 1, 2019.

A. Dance. Bat brain signals illuminate navigation in the dark. Science News. Vol. 192, September 30, 2017, p. 22.

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NewsWise

Effectiveness of using natural enemies to combat pests depends on surroundings

15-Jul-2019 4:05 PM EDT

Cornell University


  • newswise-fullscreen Effectiveness of using natural enemies to combat pests depends on surroundings

    Credit: Ricardo Perez-Alvarez

    A spined soldier bug nymph eats a cabbage looper larvae on a cabbage plant.

Newswise — ITHACA, N.Y. – When cabbage looper moth larvae infest a field, sustainable growers will often try to control the pests by releasing large numbers of predators, such as ladybugs. That way they can avoid spraying expensive and environmentally harmful insecticides.

Still, farmers have mixed results when they supplement their fields with beetles or other predators.

A new study of cabbage crops in New York – a state industry worth close to $60 million in 2017, according to the USDA – reports for the first time that the effectiveness of releasing natural enemies to combat pests depends on the landscape surrounding the field.

“The landscape context can inform how to better use this strategy in field conditions,” said Ricardo Perez-Alvarez, the paper’s first author and a graduate student in the lab of co-author Katja Poveda, associate professor of entomology. Brian Nault, an entomology professor at Cornell AgriTech, is also a co-author.

The paper, “Effectiveness of Augmentative Biological Control Depends on Landscape Context,” was published in the journal Nature Scientific Reports. It showed that releasing pest predators led to fewer pests, less plant damage and increased crop biomass on farms surrounded by more forest and natural areas and less agricultural land. But on farms predominantly surrounded by other farms, the reverse was true, with more pests and plant damage and reduced crop biomass in spite of added predators.

The reasons behind this phenomenon are complex, and depend on interactions between local predators and those that are added, which can vary on a case-by-case basis.

“Landscape composition influences how predator species interact with one another and thereby mediates the potential consequences for biological pest control,” Perez-Alvarez said.

The study focused on cabbage crops and three cabbage pests (the larvae of the cabbage white butterfly, the diamondback moth and the cabbage looper moth), and their natural enemies. In central New York, there are 156 native predator species and seven parasitoid wasps that prey on these pests. Among these, two generalist predators are commonly used to augment fields with additional pest enemies: the spined soldier bug and the convergent ladybird beetle. These two generally complement each other well because soldier bugs feed on larvae and ladybugs feed on eggs.

In the study, the researchers set up experimental plots on 11 cabbage farms in central New York, which together represented a range of surrounding landscapes from agricultural lands to natural areas.

Each farm had two cabbage plots: one that was left alone so it was exposed to the naturally occurring predators, and another where soldier bugs and ladybugs were added. The researchers then collected a wide range of data that included surveys of pest and predator abundances, plant damage and final crop yields. They also conducted lab experiments to better understand the relationships between predators and how those interactions impact pest control.

Given how complex these predator-predator and predator-pest interactions and their relationships to pest control can be, more study is needed to make specific recommendations to growers. Still, the paper is a first step toward understanding how landscapes influence the effects of augmenting farms with predators for pest control.

The study was funded by National Institute of Food and Agriculture at the United States Department of Agriculture.

For additional information, see this Cornell Chronicle story.

Cornell University has dedicated television and audio studios available for media interviews supporting full HD, ISDN and web-based platforms.

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western farm press

GL0711-USDA-SLF1_BT_Edits.jpg Lance Cheung/USDA
Spotted lantern flies are a threat to several high-value crops, including grapes.

Growers brace for pest’s ‘inevitable’ arrival

Grape growers preparing for spotted lantern fly, which has created havoc on the East Coast and is likely headed west.

Lee Allen | Jul 10, 2019

California grape growers and other farmers are proactively responding to what experts say is the inevitable arrival of the latest in a long line of pests, the spotted lantern fly (SLF).

Already a scourge abroad and in eastern states such as Pennsylvania, where it was discovered in 2014, the pest – Lycorma delicatula – is known to spread rapidly. It moved from Pennsylvania to nearby states like New York and Delaware in 2017, expanding its range into New Jersey, Maryland, and Virginia in 2018.

With a wingspan of only 1 ½ inches, its flying talents are limited to a few hundred feet, but it’s learned how to be a great hitchhiker and that’s how it’s expected to travel across the country.

“It’s inevitable, but manageable,” says Mark Hoddle of the University of California, Riverside, who is working with Kent Daane of UC, Berkeley on a newly-funded project, “Proactive Biological Control of Spotted Lantern Fly.”

“California’s wine, table, and raisin grape industries take invasive pests like these very seriously and have a long track record of supporting integrated pest management and bio-control,” says Daane. “The difficulty here is the wide host range of SLF that increases avenues for invasion into western vineyards.”

The project will piggyback on work already being conducted in the eastern U.S. and overseas.

“This project, supported by a $544,000 grant from the California Food and Agriculture Department, will be a fantastic opportunity to get ahead of such an invasion,” Daane says.

“We hope that statewide quarantine measures in place will deter or prevent the pest’s arrival and if small numbers are found, the state will act quickly in an eradication attempt as was done for the European grapevine moth.”

The mission of the Proactive Integrated Pest Management Solutions grant program is to anticipate which exotic pests are likely to arrive in California and to identify and test strategies that can be implemented rapidly if pests become established.

Threat to crops

SLF is worrisome on a lot of fronts, particularly for several of the state’s high-value crops like grapes, avocados, walnuts, and pistachios.

The lantern fly causes damage by secreting what Hoddle, director of UC, Riverside’s Center for Invasive Species Research, calls “copious amounts of honeydew, a juicy waste product that attracts undesirable foraging insects like ants, wasps, and hornets that start eating the fruit which then encourages sooty mold and fungal pathogens to move in – all the while damaging a plants ability to grow.”

The researchers are worried the impact could hit California and extend well beyond – bad news for a state cited as the 4th largest wine producer in the world as well as for neighboring states like Washington and Oregon.

“About 44 percent of invasive insects that come to California – the brown marmorated stink bug, Asian citrus psyllid and the palm weevil, for example – have established somewhere else in the U.S. before they arrive here,” says Hoddle.

“One of the things we’ve learned from invasion biology is that if something appears on a crop somewhere else,” he says. “It’s likely to be a pest for you if you grow the same crop, and the spotted lantern fly likes grapes.”

Hoddle says he will jump start his biological program by borrowing on work already done by the USDA on the East Coast, setting up a proactive rather that reactive system ready to intervene when the unwanted visitors finally arrive.

“It takes several years for programs like this to start up and gain momentum and we’re hoping to eliminate that lag time to be ready when needed,” he says.

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TAGS: Insects

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The Guardian

Nearly half of all child deaths in Africa stem from hunger, study shows

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Almost 60 million children deprived of food despite continent’s economic growth, in what is ‘fundamentally a political problem’

Schoolchildren in the Amboasary-South district of Madagascar eat lunch provided by the World Food Programme.
Schoolchildren in the Amboasary-South district of Madagascar eat lunch provided by the World Food Programme. Photograph: Rijasolo/AFP/Getty Images

One in three African children are stunted and hunger accounts for almost half of all child deaths across the continent, an Addis Ababa-based thinktank has warned.

In an urgent call for action, a study by the African Child Policy Forum said that nearly 60 million children in Africa do not have enough food despite the continent’s economic growth in recent years.

A child dies every three seconds globally due to food deprivation – 10,000 children every day – but although figures show an improvement in child hunger at a global level, it is getting worse in some parts of Africa, where the problem is largely a question of political will.

Nine out of 10 African children do not meet the criteria for minimum acceptable diet outlined by the World Health Organization, and two out of five don’t eat meals regularly. Liberia, Congo and Chad are at the bottom of the chart when it comes to children aged six to 23 months receiving sufficient and diverse food with a healthy frequency. They are followed by Zimbabwe, Guinea-Bissau, Gambia and the Democratic Republic of the Congo.

“Child hunger is fundamentally a political problem,” said Assefa Bequele, ACPF’s executive director. “It is the offspring of the unholy alliance of political indifference, unaccountable governance, and economic mismanagement. Persistent and naked though the reality is, it remains a silent tragedy, one that remains largely unacknowledged and tolerated, perhaps because it is a poor man’s problem.”

Bequele added: “It is completely unacceptable that children are still going hungry in Africa in the 21st century. The statistics are truly alarming. Child hunger is driven by extreme poverty, uneven and unequal economic growth, gender inequality and a broken food system. Although Africa now produces more food than ever, it hasn’t resulted in better diets.”

Hunger impairs growth and cognitive development of children, but also hits the economic performance of the country they come from. Child hunger can cost African countries almost 17% of their GDP, according to the report. The continent’s present GDP is estimated to have been reduced by 10% because of stunting alone.

Annually, child hunger costs Ethiopia 16.5% of its GDP. The rate for Rwanda is 11.5%. The report says “for every dollar invested in reducing stunting, there is a return of about $22 (£17) in Chad, $21 in Senegal, and $17 in Niger and Uganda”, and if the investment is made early in the child’s life, the return rates can be even higher: up to $85 in Nigeria, $80 in Sudan and $60 in Kenya.

Africa could have one billion undernourished, malnourished and hungry children and young people by 2050 if current levels continue unabated. More than half of African countries are currently off course to meet targets required in the African regional nutrition strategy (2015-2025). Just nine countries will meet the target of reducing stunting by 40% by 2025.

Mauritius and South Africa are among the states with fewer children suffering from hunger, while Central African Republic and Chad are the worst child-friendly nations, according to ACPF. Child hunger has been in sharp contrast with economic growth seen in countries such as Kenya, which has had a 2% average growth in GDP per capita but also a 2.5% increase in stunting.

Child rights campaigner Graça Machel said at last month’s International Policy Conference on the African Child: “Women and girls, along with children from poor and rural backgrounds, suffer the most from hunger. In some countries, stunting rates are twice as high among rural children as among their urban counterparts.”

Graça Machel, founder of the Foundation for Community Development.

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Graça Machel, founder of the Foundation for Community Development. Photograph: Nic Bothma/EPA

Conflict and the climate crisis have exacerbated child hunger in Africa, with three out of four of the continent’s stunted children under the age of five living in countries turned into war zones. In areas experiencing protracted conflicts, the rate of undernourishment in children is about two to three times higher.

In 2017, more than eight million people in Ethiopia, five million in Malawi, four million in Zimbabwe and three million in Kenya were affected by acute food insecurity caused by issues relating to the climate crisis.

 

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