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Archive for the ‘Biological control’ Category


ARS News ServiceFirefly on a green leaf

Photo by Maverick Dunavan, USDA-ARSSummer Lights
For media inquiries contact: Autumn Canaday, (202) 669-5480July 9, 2021

We often cherish the small memories of summer and all the joy that those memories bring. Maybe those memories are framed with ocean breezes, laughter, good food and time well-spent with friends or family. Whatever your summer memories include, I’d like to think that the yellow-green flash of the firefly is somewhere on the list.Did you spend the summer evenings of your youth capturing fireflies in a glass jar? Did you try to catch them in your hand? Did you ever wonder where these insects come from and why they are such a huge part of summer evenings? If so, this may be the perfect time to learn. First, it’s worth noting that despite their common name, these insects are not flies. They are actually a part of the Lampyridae beetle family, and they appear in late May or early June, often disappearing around September. But that varies according to species, region, and local weather conditions. Some species also emerge earlier than others. Like all beetles, fireflies have a complete metamorphosis, meaning they develop from eggs, to larvae, to pupae, to adults. Fireflies can spend up to two years as larvae, while their lifespan as adults only lasts a few weeks.Most people may find them flying around their yard, but fireflies prefer damp areas and you will often find them in meadows, woods, backyards or near sources of water. As they develop and grow, the larvae will eat other insect larvae, snails, and slugs. The adult diet is less well known, but research shows most adult fireflies don’t feed at all, and when they do, the diet can vary from species to species, but usually includes nectar, pollen, or other fireflies. During the day, nocturnal Lampyridae can be found resting on vegetation or tree trunks. Once evening falls, they begin mating behavior which results in the spectacular light show that we all know and love. During this time, the males will fly through the air and emit light from specialized organs on their abdomen to get the attention of the females. If the female is interested, she’ll reply with a flash of her own, attracting the male towards her. Each species has a specific flash pattern that differs in number, duration, and intervals between flashes. After mating the female lays her eggs and the adults soon die.Fireflies are actually considered a beneficial predator of garden pests, and sometimes, pollinators. Sometimes they are not quite hospitable to one another, as research shows that some female fireflies mimic the response of a different species to lure in a male firefly before eating him.  As everyone knows, fireflies won’t bite or sting you. So, it’s fine if they land on you while you enjoy a summer evening outdoors.There are now more than 136 species of fireflies in the United States and Canada, but they are currently in decline due to loss of habitat, pesticides, and light pollution. Be sure to enjoy their light show as they move about your backyard and be sure to set them free if they’ve been captured in a jar or your hand.We want them around for a long time.

The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.
Interested in reading more about ARS research? Visit our news archiveU.S. DEPARTMENT OF AGRICULTURE
Agricultural Research Service

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Fungus fights mites that harm honey bees

New fungus strain could provide a chemical-free method to help honey bees

ScienceDaily

Date:May 27, 2021Source:Washington State University

Summary: A new fungus strain bred in a lab could provide a chemical-free method for eradicating mites that kill honey bees. Varroa destructor mites play a large role in Colony Collapse Disorder, which destroys thousands of bee colonies every year. Share:

FULL STORY


A new fungus strain could provide a chemical-free method for eradicating mites that kill honey bees, according to a study published this month in Scientific Reports.

A team led by Washington State University entomologists bred a strain of Metarhizium, a common fungus found in soils around the world, to work as a control agent against varroa mites. Unlike other strains of Metarhizium, the one created by the WSU research team can survive in the warm environments common in honey bee hives, which typically have a temperature of around 35 Celsius (or 95 F).

“We’ve known that metarhizium could kill mites, but it was expensive and didn’t last long because the fungi died in the hive heat,” said Steve Sheppard, professor in WSU’s Department of Entomology and corresponding author on the paper. “Our team used directed evolution to develop a strain that survives at the higher temperatures. Plus, Jennifer took fungal spores from dead mites, selecting for virulence against varroa.”

Jennifer Han, a post-doctoral researcher at WSU, led the breeding program along with WSU assistant research professors Nicholas Naeger and Brandon Hopkins. Paul Stamets, co-owner and founder of Olympia-based business Fungi Perfecti, also contributed to the paper. Stamets is a fungi expert, well-known for using several species in applications ranging from medicine to biocontrol.

Varroa destructor mites, small parasites that live on honey bees and suck their “blood,” play a large role in Colony Collapse Disorder, which causes beekeepers to lose 30-50% of their hives each year. The mites feed on bees, weakening their immune systems and making them more susceptible to viruses.

The main tools beekeepers use to fight varroa are chemicals, such as miticides, but the tiny pests are starting to develop resistance to those treatments, Naeger said.

Metarhizium is like a mold, not a mushroom. When spores land on a varroa mite, they germinate, drill into the mite, and proliferate, killing it from the inside out. Bees have high immunity against the spores, making it a safe option for beekeepers.

Stamets, who did some of the initial testing with Metarhizium that showed the fungus couldn’t survive hive temperatures, was impressed by the work done by the WSU researchers.

“Science progresses through trial and error, and my technique wasn’t economical because of the hive heat,” he said. “But Jennifer did enormous amounts of culture work to break through that thermal barrier with this new strain. It’s difficult to really appreciate the Herculean effort it took to get this.”

Han and Naeger screened more than 27,000 mites for levels of infection to get the new strain.

“It was two solid years of work, plus some preliminary effort,” Han said. “We did real-world testing to make sure it would work in the field, not just in a lab.”

This is the second major finding to come from WSU’s research partnership with Stamets involving bees and fungi. The first involved using mycelium extract that reduced virus levels in honey bees.

“It’s providing a real one-two punch, using two different fungi to help bees fight varroa,” Stamets said. “The extracts help bee immune systems reduce virus counts while the Metarhizium is a potentially great mite biocontrol agent.”

The next step is to seek approval from the Environmental Protection Agency to use Metarhizium on hives used in agriculture. The team must also finalize delivery methods for beekeepers to apply the fungus in hives.

“We hope in 10 years that, rather than chemical miticides, Metarhizium is widely used to control Varroa mites,” Sheppard said. “And that the mite problem for beekeepers has been significantly reduced.”

The team thinks the methods they developed to evolve Metarhizium for varroa control could be used to improve biocontrol agents in other crop systems as well.

The majority of the funding for this work came from private donations from individuals and foundations. Additional funding came from Washington State Department of Agriculture (WSDA) Specialty Crop Block Grant K2531 and the USDA National Institute of Food and Agriculture, Hatch 1007314.


Story Source:

Materials provided by Washington State University. Original written by Scott Weybright. Note: Content may be edited for style and length.


Journal Reference:

  1. Jennifer O. Han, Nicholas L. Naeger, Brandon K. Hopkins, David Sumerlin, Paul E. Stamets, Lori M. Carris, Walter S. Sheppard. Directed evolution of Metarhizium fungus improves its biocontrol efficacy against Varroa mites in honey bee coloniesScientific Reports, 2021; 11 (1) DOI: 10.1038/s41598-021-89811-2

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Misconceptions about biological controls

June 24, 202188

By Ethan Proud
PREVIEW Columnist

For some, biological controls (biocontrols) seem like a silver bullet, capable of removing invasive species without using herbicides. To others, it seems counterintuitive to release a non-native species on an invasive species wreaking havoc on the ecosystem.

Biocontrols, unfortunately, do not eradicate a population, though there are some exceptions and populations can decrease by large margins when an insect herbivore is released into the environment. These biocontrol agents will suppress the population of invasive species and can help slow the spread, though they will not completely eradicate the noxious weed. 

Biocontrols must be released repeatedly to see success and a onetime release will not yield great results. Paired with chemical or mechanical control, an acceptable level of control can be achieved. Release biocontrols in areas that are difficult to reach with a backpack, ATV mounted sprayer or equipment for manual control. It’s easier to hike into a difficult area with a small container of insects than it is to carry a shovel and a bag — especially when the bag is completely full and it is time to hike out. Utilize mechanical and chemical control around the perimeter of the release site and you will have a one-two punch, biocontrols suppressing the heart of the infestation and chemical or mechanical control containing the spread.

When it comes to approving a new biocontrol agent, the insects must first be carefully studied through a round of choice and no-choice tests, where it is determined that A) the insect will feed on only the target species and B) the insect will starve to death before finding a new food source. These tests are conducted by the U.S. Department of Agriculture Animal and Plant Health Inspection Service Plant Protection and Quarantine Program, or USDA APHIS PPQ for short. The process of approval takes many years, meaning that new biocontrol agents are not only very exciting, but few and far between.

In short, biocontrol agents need to be paired with another control method to be truly effective and they are not an option for certain weeds. However, they are a great tool for integrated pest management and can reduce our dependency on herbicides.

For more information on biological control agents that can be released in Colorado and are available to landowners, visit the Colorado Department of Agriculture website and click Biocontrols underneath the Conservation Banner.

Archuleta County Weed and Pest is your local resource for managing noxious weed populations and controlling other pests.

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Click Here for Japanese Translation

French ‘bug farm’ thrives on demand for pesticide-free fruit

昆虫ファームが無農薬トマトを後押し フランス

Farmers in western France are doubling down on an unusual crop: breeding millions of tiny predatory bugs and wasps to protect tomato plants without resorting to the insecticides that consumers are shunning.
Here, we’re in one of the greenhouses for a bug that’s called the macrolophus, says Pierre-Yves Jestin, as clouds of the pale green insects swarm around his hands.
Jestin is president of Saveol, the Brittany cooperative that is France’s largest tomato producer, cranking out 74,000 tons a year.
For several years the cooperative has promoted pesticide-free harvests in response to growing concerns about the impact of harsh chemicals on humans and the environment.
It does so thanks to its own bug farm, launched in 1983, that now stretches across 4,500 square metres (just over one acre) outside Brest, where the tip of Brittany juts out into the Atlantic.
Plans are in the works to add 1,200 square metres more this year, producing macrolophus as well as tiny wasps that feed on common tomato pests such as whiteflies and aphids.
Every week the insects are packed up in plastic boxes and shipped to the cooperative’s 126 growers.
This new extension will allow us to increase our breeding of macrolophus, which are increasingly in demand for the pesticide-free range, said Roselyne Souriau, head of the insect programme at Saveol — whose name means ‘sunrise’ in the local Breton language.
At the same time, it will let us develop a new range — at least we hope — better suited to strawberries, with parasitic micro-wasps that feed on aphids, she said.
– ‘A third way’ –
Because the vast majority of Brittany’s tomatoes are grown in greenhouses, they do not qualify for an organic label, which requires plants to be grown under natural conditions in the ground.
That prompted Saveol to team up with two other Brittany cooperatives, Sica and Solarenn, two years ago to promote their pesticide-free offerings.
In 2020, we didn’t use any chemical treatments at all, said Francois Pouliquen, whose eight hectares at the Saveur d’Iroise farm are part of the Saveol network.
Consumers are now looking to eat healthily, he said. Organic produce exists of course, but it isn’t always within reach for people on a budget.
Pesticide-free is an alternative, a third way, for mass production that is still healthy, he said.
Overall, use of predatory insects by French farmers has soared, with regulators approving 330 species as plant pest treatments in the first quarter of this year, up from 257 in 2015, according to the agriculture ministry.
At Saveol’s insect farm, the predatory bugs feast on moth eggs spread over hundreds of tobacco plants, which are in the same family as tomatoes and eggplants.
The broad leaves make it easy when workers cut the tops off the plants and shake the insects into a giant metal funnel for packing.
Some 10 million macrolophus and 130 million micro-wasps are produced each year, and Saveol claims it is the only growers’ cooperative in Europe with its own insect-raising facility.

AFP-JIJI PRESS NEWS JOURNAL

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Mushroom growing out of fossilized ant reveals new genus and species of fungal parasite

IMAGE
IMAGE: Oregon State University research has identified the oldest known specimen of a fungus parasitizing an ant, and the fossil also represents a new fungal genus and species. A mushroom is…
view more Credit: George Poinar Jr., OSU

CORVALLIS, Ore. – Oregon State University research has identified the oldest known specimen of a fungus parasitizing an ant, and the fossil also represents a new fungal genus and species.

“It’s a mushroom growing out of a carpenter ant,” said OSU’s George Poinar Jr., an international expert in using plant and animal life forms preserved in amber to learn about the biology and ecology of the distant past.

A mushroom is the reproductive structure of many fungi, including the ones you find growing in your yard, and Poinar and a collaborator in France named their discovery Allocordyceps baltica. They found the new type of Ascomycota fungi in an ant preserved in 50-million-year-old amber from Europe’s Baltic region.

“Ants are hosts to a number of intriguing parasites, some of which modify the insects’ behavior to benefit the parasites’ development and dispersion,” said Poinar, who has a courtesy appointment in the OSU College of Science. “Ants of the tribe Camponotini, commonly known as carpenter ants, seem especially susceptible to fungal pathogens of the genus Ophiocordyceps, including one species that compels infected ants to bite into various erect plant parts just before they die.”

Doing so, he explains, puts the ants in a favorable position for allowing fungal spores to be released from cup-shaped ascomata – the fungi’s fruiting body -protruding from the ants’ head and neck. Carpenter ants usually make their nests in trees, rotting logs and stumps.

The new fungal genus and species shares certain features with Ophiocordyceps but also displays several developmental stages not previously reported, Poinar said. To name the genus, placed in the order Hypocreales, Poinar and fellow researcher Yves-Marie Maltier combined the Greek word for new – alloios – with the name of known genus Cordyceps.

“We can see a large, orange, cup-shaped ascoma with developing perithecia – flask-shaped structures that let the spores out – emerging from rectum of the ant,” Poinar said. “The vegetative part of the fungus is coming out of the abdomen and the base of the neck. We see freestanding fungal bodies also bearing what look like perithecia, and in addition we see what look like the sacs where spores develop. All of the stages, those attached to the ant and the freestanding ones, are of the same species.”

The fungus could not be placed in the known ant-infecting genus Ophiocordyceps because ascomata in those species usually come out the neck or head of an ant, Poinar said, and not the rectum.

“There is no doubt that Allocordyceps represents a fungal infection of a Camponotus ant,” he said. “This is the first fossil record of a member of the Hypocreales order emerging from the body of an ant. And as the earliest fossil record of fungal parasitism of ants, it can be used in future studies as a reference point regarding the origin of the fungus-ant association.”

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Findings were published in Fungal Biology.

Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.

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Unusual prey: Spiders eating snakes

There are spiders that eat snakes; observations of snake-eating spiders have been reported around the world. Two researchers from Basel and the US consolidated and analyzed over 300 reports of this unusual predation strategy

28-Jun-2021 1:35 PM EDT, by University of Baselfavorite_border

Newswise: Unusual prey: Spiders eating snakes

Daniel R. Crook

Juvenile scarlet snake (Cemophora coccinea, Colubridae) entrapped on web of Latrodectus geometricus, observed in a private residence in Georgia, USA.

Newswise — There are spiders that eat snakes. Observations of snake-eating spiders have been reported around the world. Two researchers from Basel and the US consolidated and analyzed over 300 reports of this unusual predation strategy.

Spiders are primarily insectivores, but they occasionally expand their menu by catching and eating small snakes. Dr. Martin Nyffeler, arachnologist at the University of Basel, and American herpetologist Professor Whitfield Gibbons of the University of Georgia, USA, got to the bottom of this phenomenon in a meta-analysis. Their findings from a study of 319 occurrences of this unusual feeding behavior recently appeared in the American Journal of Arachnology.

It turns out that spiders eat snakes on every continent except Antarctica. Eighty percent of the incidents studied were observed in the US and Australia. In Europe, on the other hand, this spider feeding behavior has been observed extremely rarely (less than 1 percent of all reported incidents) and is limited to the consumption of tiny, non-venomous snakes of the blind snake family (Typhlopidae) by small web-building spiders.

Black widows are particularly successful

Incidents of snake predation by spiders have never been reported from Switzerland. A possible explanation is that Switzerland’s native colubrids and vipers are too big and heavy even when freshly hatched for Swiss spiders to subdue them.

The data analysis also showed that spiders from 11 different families are able to catch and eat snakes. “That so many different groups of spiders sometimes eat snakes is a completely novel finding,” Nyffeler emphasizes.

Black widows of the family Theridiidae were the successful snake hunters in about half of all observed incidents. Their potent venom contains a toxin that specifically targets vertebrate nervous systems. These spiders build webs composed of extremely tough silk, allowing them to capture larger prey animals like lizards, frogs, mice, birds and snakes.

Big catch

Another new finding from the meta-analysis: spiders can subdue snakes from seven different families. They can outfight snakes 10 to 30 times their size.

The largest snakes caught by spiders are up to one meter in length, the smallest only about six centimeters. According to the statistical analysis done by the two researchers, the average length of captured snakes was 26 centimeters. Most of the snakes caught were very young, freshly hatched animals. That some spiders are able to subdue oversized prey is attributable to their highly potent neurotoxins and strong, tough webs.

Possible insights into the effect of spider venom

Many spider species that occasionally kill and eat snakes have venom that can also be lethal to humans. That means the venom of various spider species has a similar effect on the nervous systems of snakes and humans. For this reason, observations of vertebrate-eating spiders can also be important for neurobiology, as they allow conclusions to be drawn about the mechanisms by which spider neurotoxins affect vertebrate nervous systems.

“While the effect of black widow venom on snake nervous systems is already well researched, this kind of knowledge is largely lacking for other groups of spiders. A great deal more research is therefore needed to find out what components of venoms that specifically target vertebrate nervous systems are responsible for allowing spiders to paralyze and kill much larger snakes with a venomous bite,” says Martin Nyffeler.

The captured snakes are anything but helpless themselves: about 30 percent are venomous. In the US and South America, spiders sometimes kill highly venomous rattlesnakes and coral snakes. In Australia, brown snakes (which belong to the same family as cobras) often fall prey to redback spiders (Australian black widows). Martin Nyffeler says, “These brown snakes are among the most venomous snakes in the world and it’s really fascinating to see that they lose fights with spiders.”

Additional information

Storage of energy reserves

When a spider catches a snake, it will often spend hours or days feasting on such a large prey. Spiders have an irregular feeding pattern. When a lot of food is available, they eat in excess, only to go hungry for long periods again afterward. They store excess food as energy reserves in their body and use it to tide them over longer periods of starvation.

Still, a spider often eats only a small part of a dead snake. Scavengers (ants, wasps, flies, molds) consume what remains.

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The company is working hard so that the product is available in 2022

Koppert is developing a biological solution against “Nezara viridula”

Over the last decade, the green bug (Nezara viridula) has plagued pepper, aubergine, and cucumber greenhouses in southern Europe and its presence is growing in state-of-the-art and heated greenhouses in the north, east, and central parts of Europe. The elimination of chemicals in combination with climate change has increased the pressure of this pest in greenhouses.


The green bug (Nezara viridula) on a pepper plant.

The fight against the green bug is a great challenge, and to date, it can only be done with chemical products. However, these products affect the population of the natural enemies of thrips, spider mites, aphids, and whiteflies that keep these pests under control. There is the possibility of manually removing the green bug from the crop, but this is only feasible if the pressure of the pest in the crop is low; therefore this technique has had little success.

The Nezara problem was identified early by Koppert. In 2018 the company began research with this pest’s most effective natural enemy: a wasp that parasitizes its eggs. The first field trials are promising and show that Nezara can be fought well in practice. Large-scale trials in different countries are expected to confirm these results later this year.

“The damage caused by Nezara is enormous and often leads to early removal of crops. The fight against this pest is complicated, and the only remedy is to use chemicals. That’s why we are pleased that we’re close to being able to provide a natural solution to our customers. Our international team is dedicated body and soul to offering a suitable solution against Nezara as soon as possible,” stated Bart Sels, Head of Koppert Belgium.

For more information:

Koppert 
C/ Cobre 22
Pol. Industrial Ciudad del Transporte del Poniente
04745 La Mojonera, Almería (España)
Tel.: +34 950 554 464
Fax: +34 950 553 905
www.koppert.es

Publication date: Mon 28 Jun 2021

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Futureco Bioscience obtains European patent for new biopesticide

“These formulations will be valuable tool for grower who wants to apply biological control”

Futureco Bioscience has obtained, as officially communicated in the Bulletin 20121/16 of the European Patent Office, the European Patent No. EP3607048, with the title “A strain of Pseudomonas putida and its use in the control of diseases caused by bacteria and fungi in plants”.

The subject of this patent is the production and commercial use of Pseudomonas putida strain B2017. This strain has been evaluated in different vegetable crops (tomato, lettuce, cucumber, courgette, potato) as well as in vineyards and fruit trees. Pseudomonas putida B2017 has shown great potential for the control of a broad spectrum of agricultural diseases including fungi causing powdery mildew, downy mildew, rots, sclerotinia, pox, and bacterial diseases.

“We are always excited to discover and characterize strains with such high biocontrol potential,” says Carolina Fernandez, Research and Development Director at Futureco Bioscience. “The efficacy of strain B2017 is very consistent, and I am convinced that our formulations will soon be a very valuable tool for any farmer who wants to apply biological control strategies.”

“The granting of this patent reinforces the alignment of Futureco Bioscience’s mission and vision with the needs expressed by stakeholders. Farmers, consumers, and legislators are willing to promote more sustainable agriculture, put in practice programs like the European ‘Farm to Fork’ strategy, and to align with ONU Sustainable Development Goals and the global transition to sustainable agri-food systems,” says Jose Manuel Lara, Technical Director of Futureco Bioscience.

Read the complete article at www.agribusinessglobal.com.

Publication date: Mon 28 Jun 2021

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Acoustical Society of America (ASA)

Acoustical Evolution Increases Battle Between Predator, Prey

Moth wing structure, composition absorb bat echolocation calls.

4-Jun-2021 2:30 PM EDT, by Acoustical Society of America (ASA)favorite_border

Newswise: Acoustical Evolution Increases Battle Between Predator, Prey

Thomas Neil, University of Bristol

Newswise — MELVILLE, N.Y., June 9, 2021 — In the evolutionary battle between hunter and hunted, sound plays an integral part in the success or failure of the hunt. In the case of bats vs. moths, the insects are using acoustics against their winged foes.

During the 180th Meeting of the Acoustical Society of America, which will be held virtually June 8-10, Thomas Neil, from the University of Bristol, will discuss how moth wings have evolved in composition and structure to help them create anti-bat defenses. The session, “Moth wings are acoustic metamaterials,” will take place Wednesday, June 9, at 1 p.m. Eastern U.S.

Nocturnal moths are under intense selection pressure by the bats that hunt them. Some moths have developed a form of acoustic camouflage by evolving structures on their bodies and wings to absorb ultrasound. This decreases the strength of the bat’s echo return and gives the insects a better chance of survival.

“The wings of a moth will produce strong echoes to a hunting bat owing to their large size,” Neil said. “As such, it is important the moth cloaks the wing with sound-absorbing material, so it matches the acoustic camouflage brought about by the fur on the body. The only way to create the much thinner sound absorber allowed on the wings is by developing a resonant absorber, and we discovered moth wings have evolved this approach.”

The scales covering moth wings allow as much as 70% of the sound hitting them to be absorbed. More amazingly, these scales are individually tuned to different frequencies, forming an array of resonant absorbers, which together create broadband absorption by acting as an acoustic metamaterial — the first known in nature.

Neil said the strategies identified in moths have already been partially explored from a theoretical and technical standpoint. The advantages of using a metamaterial design for sound absorption is the absorbers can be much thinner than the wavelength of the sound they absorb. In the case of the moths, their absorbers are 100 times thinner than the wavelength of a bat’s cry.

“In theory, we could take inspiration from the moths and build sound absorbing panels made from lots of differently tuned resonating paddles, with the goal of achieving sound absorption that is on par with traditional sound absorber panels but being just a fraction of the width,” Neil said. “With this approach, we would be getting close to a much more versatile and acceptable sound absorber wallpaper rather than the typically bulky absorber panels we use today.”

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Scientists breed fungus that fights Varroa mites

USDA ARSWFP-ARS-varroa-mite.jpgScientists have found that a strain of the fungus Metarhizium anisopliae is deadly to Varroa mites, such as this one on an adult worker honey bee’s thorax. Team from Washington state uses ‘directed evolution’ to develop natural tool against honeybee nemesis.

Tim Hearden | May 28, 2021

Farm Futures Summit and Boot Camp 2021

A team of West Coast scientists thinks it has developed a chemical-free way of neutralizing Varroa mites, which are largely blamed for honeybee die-offs that decimate up to half of hives nationwide each year.

Washington State University entomologists joined forces with an Olympia, Wash.-based business and others in a two-year effort to breed a strain of Metarhizium, a common beneficial fungus found in soils, to work against the mites.

Metarhizium anisopliae has been used for decades to combat numerous soil-dwelling pests around the world, including the sugarbeet root maggot and the Japanese beetle, according to the USDA’s Agricultural Research Service. But it doesn’t survive in higher temperatures.

So post-doctoral researcher Jennifer Han and the other scientists used “directed evolution” to develop a strain that could survive in hives that typically get as hot as 95 degrees, said Steve Sheppard, professor in WSU’s Department of Entomology. Sheppard was a corresponding author of the paper on the research published this month in Scientific Reports.

Related: Scientists follow bees to study colony survival

“Importantly, in an era of declining honey bee health, the strains of Metarhizium created in these experiments were able to control Varroa mites and may provide beekeepers with an alternative to chemical acaricides,” the scientists wrote. “Additionally, it is possible that the methods presented here could be applied to fungi or other biocontrol agents targeting other arthropod pests.”

The team’s next tasks will be to develop delivery methods for beekeepers to apply the fungus in hives and get approval from the U.S. Environmental Protection Agency to use it in agriculture, according to the university.

Mites feed on bees

Varroa mites feed on honeybees, weakening their immune systems and making them more susceptible to viruses, the scientists explain. The mites are considered a major cause of colony collapse disorder, an annual phenomenon in which beekeepers have lost nearly half their hives in some winters.

The average loss per beekeeper nationwide in 2020 was 35.5%, down from 43.5% in 2019 and a record 50.2% in 2018, according to the Bee Informed Partnership.

WSU scientists say Metarhizium is like a mold, not a mushroom. When its spores land on a Varroa mite, they germinate, drill into the mite and proliferate, killing it from the inside out, the university explains. The fungus won’t harm bees, which have a high immunity to the spores.

Related: Coalition seeks to scale up pollinator protection efforts

Han took fungal spores from dead mites and selected for virulence, creating a strain that survives at the higher temperatures, Sheppard said. She and assistant research professors Nicholas Naeger and Brandon Hopkins screened more than 27,000 mites for levels of infection to get the new strain.

“It was two solid years of work, plus some preliminary effort,” Han said. “We did real-world testing to make sure it would work in the field, not just in a lab.”

Expert consulted

The team also worked with Paul Stamets, co-owner and founder of Olympia-based business Fungi Perfecti, who previously helped the university in a research project that used mycelium extract to reduce virus levels in honeybees.

The projects will provide beekeepers with natural alternatives to chemical treatments, such as miticides, for which the pests are starting to develop a resistance, the scientists wrote.

“It’s providing a real one-two punch, using two different fungi to help bees fight Varroa,” Stamets said. “The extracts help bee immune systems reduce virus counts while the Metarhizium is a potentially great mite biocontrol agent.”

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