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View as a webpage ARS News Service ARS News Service Heavily infested tree-of-heaven leaves.
Heavily infested tree-of-heaven leaves. (Photo by Javid Kashefi, ARS).

ARS Scientists Discover a Promising Biological Control Agent for Tree-of-Heaven in France  For media inquiries contact: Jessica Ryan, (301) 892-0085 WASHINGTON, December 1, 2021

United States Department of Agriculture (USDA), Agricultural Research Service (ARS) scientists and collaborators confirmed the presence of a newly described Eriophyid mite, a potential biological control agent for the invasive tree-of-heaven, in France. The study, published in Phytoparasitica, showed that this was the first record of the mite species in the country, and the species could be a solution for managing tree-of-heaven infestations in Europe and the United States. “In Europe, this Eriophyid mite is considered one of the most promising biological control agents of tree-of-heaven,” said Javid Kashefi, senior support scientist at the European Biological Control Laboratory (EBCL) near Montpellier, France. “This finding provides encouraging evidence that the geographic occurrence of this species is expanding in the continent.” In May 2020, Kashefi conducted weekly field observations at a park in Colombes, France, near Paris, to identify natural enemies of the tree-of-heaven. He discovered trees displaying leaf rolling associated with Eriophyid mite infestation. Four more populations were then found in different localities in southern France in August and September 2020. Through barcoding mite population samples and comparing them to reference barcode sequences from an Eriophyid mite population from the Biotechnology and Biological Control Agency in Italy, EBCL researchers confirmed the species’ original identification made by a taxonomy expert in Serbia. Eriophyid mites are microscopic in size and form dense populations mainly under the young leaves, causing leaves to curl upwards or downwards and turn yellowish in color. Once a plant is infested by these mites, the plant’s growth is reduced. While some mites could be problematic pests, many Eriophyid mites have proved to be host-specific — something researchers look for when studying biological control agents of an invasive species. “The presence of this species in France is indicative of their dispersal and establishment abilities, two key factors for a successful, future biological control program,” said Kashefi. Native to northeast and central China, the tree-of-heaven was introduced in U.S. and Europe in the 1700s. Despite its angelic name, the tree is invasive in both continents due to its abilities to crowd native species in different climates. The tree can also damage pavement and building foundations in urban areas. To manage invasive populations, researchers are studying natural enemies as biological control agents. Natural enemies can be more environment-friendly, sustainable and cost-effective alternatives to mechanical weed control and chemical herbicides. These alternatives are especially important for countries where herbicide usage is prohibited or the extension of the invasion of the weed is so vast that no other control method could be feasible. 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 archive U.S. DEPARTMENT OF AGRICULTURE
Agricultural Research Service

Kenyan scientist warns for impact ToBRFV on African growers

Tomato farmers in Africa have been urged to be on the lookout for the ToBRFV virus that has been causing havoc in most tomato-growing countries. Speaking during African Seed Trade Association (AFSTA) Congress in September this year, Dr. Isaac Macharia, General Manager, Phytosanitary Services at the Kenya Plant Health Inspectorate Service (KEPHIS), said countries in Africa are encouraged to report the occurrence of the disease to ensure other countries prepare.

“This virus is more severe on young tomato plants and can result in 30-70% yield loss. The unique thing about this virus is that it doesn’t infect the embryo of the seed but instead contaminates the seed coat,” he added. “Its rapid spread demonstrates that ToBRFV has become a worldwide threat to tomato production. The continent needs to prepare for the negative impact of the disease in tomato production,” he said.

“There is a need to ensure we prevent the introduction of this virus in most of our countries. We can achieve that if we embrace pre-shipment testing of all imported tomato, capsicum, and eggplant seeds, regardless of their origin, using an appropriate method such as real-time Polymerase Chain Reaction,” he said. He added that there was a need to sensitize importers of tomato/capsicum seed and commercial growers to ensure early reporting of cases.

Breeders also need to work towards the development of varieties with durable resistance genes since phylogenetic analysis shows the genomic sequence of ToBRFV differs from both ToMV and TMV.  “There is also need to invest in laboratory diagnosis for diseases, including tomato diseases. This will help countries carry out continuous tests for a proportion of seed and seedlings for ToBRFV,” he added.

Since Kenya imports most tomato, capsicum, and eggplant seeds from different countries, including those where ToBFRV has been reported, Macharia says it is now mandatory for all imported tomato seeds to be tested using real-time PCR. So far, about 192 imported seeds lots have been tested since February 2021, and no positive samples have been registered so far.

A field survey was also done in 2019 and 256 leaf samples were analyzed (245 tomatoes, 10 capsicums, 1 black nightshade) and all samples tested negative. Despite the negative results, emergency measure on ToBRFV was issued to all-out trading partners and import conditions for tomato and capsicum were amended to include pre-shipment testing and upon importation. 

“We will continue to conduct continuous surveillance to ensure this virus doesn’t get to our country. We are also going to develop contingency plans to prevent spread in case of introduction,” reveals Macharia.

Read the complete article at www.standardmedia.co.ke

Publication date: Wed 17 Nov 2021

Bees deliver organic fungicide to crops while pollinating flowers

Sustainable farming technology company Bee Vectoring Technology (BVT) has created a natural fungicide powder that eliminates mold on growing fruits. The preventative measure is delivered by bees doing what they do best – pollinating flowers. They take it directly to the flower, rather than spreading it all over the plants and soil as a traditional spraying system does. This bee-based system has been dubbed ‘natural precision agriculture’.

The fungicide is dispensed through the openings of the hives. As bees leave the hive, they move through the powder, picking up a thick coating on their legs and wings. When they land on a flower to collect pollen, the powder naturally falls off.  

With bee populations all over the world declining in number, lessening environmental pollution is a necessity for their survival. As the bees deliver the fungicide, they are reducing the need for chemicals. Growers can rent or buy hives of bees for a season or full-time, and beekeepers monitor hive health and the needed volumes of fungicide for each crop. The fungicide is available as a single ingredient or a stackable mix of powders, depending on what crop is being protected.

“Spraying products onto crops is inherently inefficient. Only a small amount of what is sprayed on an acre of farm lands on the crop flower,” explains Ashish Malik, CEO of BVT. “On the other hand, bees only visit flowers, and so all of what they are carrying can be used to inoculate the crop with a beneficial microbe to help it fight diseases and pests.”

A number of innovations are focusing on ways to help improve the resilience of hives, with Springwise spotting several new designs. These include a hive that mimics the shape of a tree, and another made from mycelium that helps repel deadly mites. 

For more information:
Bee Vectoring Technologies International 
T: (647) 660-5119
info@beevt.com
www.beevt.com

Biocontrol: How strawberry growers are leading the way

According to Dr. Surendra Dara of the University of California Cooperative Extension, 90-95% of strawberry growers in California use predatory mites to manage two-spotted spider mites. But how did this pest control method get so widely adopted? What can growers of other crops learn from this experience? 

Lane Stoeckle, a certified crop advisor and pest control advisor (PCA) based in Southern California, discusses this topic in this article. Together with his father Lee, Lane owns an independent consulting business that provides scouting, plant protection, fertility, and irrigation recommendation to both conventional and organic strawberry growers as well as to a growing number of blackberry growers.

Lane explains that in agriculture, change does not happen unless there is a catalyst that prompts that change. Those catalysts can either be “push” motivated such as evolving regulations, changing environmental and/or pest conditions, or “pull motivated” such as the benefits offered by emerging technology. “In the 1980s, the go-to miticide in strawberry was called Plictran. Eventually, chemical resistance for that product built up to a point where the spray didn’t work at all. It was like spraying water.” 

The primary catalyst which motivated forward-looking growers such as Richard Nelson and Tom Jones to start using the predatory mite Phytoseiulus persimilis as their main control method was the rise of chemical resistance. Later on, in the 1990s, people such as Lane’s father, Lee Stoeckle, started to widely commercialize P. persimilis in Southern California. 

Read the complete article at www.freshfruitportal.com.

Publication date: Mon 29 Nov 2021

ToBRFV in Saudia Arabia & Iran

In Iran, symptoms resembling those of tomato brown rugose fruit virus were first observed in August 2021 in tomato plants (Solanum lycopersicum) grown in a greenhouse in Isfahan province. The plants had been grown from imported seed. The identity of the virus was confirmed by RT-PCR. All plants were removed and destroyed

In Saudi Arabia, symptoms resembling those of tomato brown rugose fruit virus (Tobamovirus, ToBRFV – EPPO A2 List) were first observed in January 2021 in tomato plants (Solanum lycopersicum) grown in several greenhouses in Riyadh region. The identity of the virus was confirmed by RT-PCR and partial nucleotide sequence. ToBRFV was identified in 25 out of 45 samples taken (Sabra et al., 2021).

Source: EPPO

Publication date: Mon 29 Nov 2021

Global cooperation fights a potentially devastating banana pandemic

A potentially devastating banana disease (Fusarium TR4) is now spreading across the tropics, threatening the livelihoods of smallholders and large commercial farmers alike, especially growers of Cavendish, the main variety of dessert banana. There have been efforts to understand and control this devastating disease, but a real solution will require international cooperation across many disciplines. In 2020, RTB supported a virtual symposium and a masterclass to share information on how TR4 spreads, how to diagnose it and insights into future control methods.ImageTR4 kills the banana plant by attacking its vascular system. M. Dita (Alliance)

A virulent strain of a soil-dwelling fungus known as Fusarium Tropical Race 4 (TR4) is threatening the world supply of bananas, and the livelihood of millions of farmers. TR4 kills the banana plant by attacking its vascular system. Disease management is complex, as the fungus persists for decades in infected fields and there are no fully effective strategies for managing TR4. 

The pathogen spreads easily through spores, in contaminated soil and planting material. The spores even cling to farmers’ shoes and farming equipment. First identified in Taiwan in 1967, TR4 spread to other Asian countries by the early 2000s. Since 2014, the disease has expanded quickly across the greater Mekong Delta, especially in Laos and Vietnam. TR4 also emerged in 2013 in Mozambique, and was more recently identified on Mayotte, an island in the Indian Ocean. In August 2019, TR4 was reported in organic banana plants in La Guajira, Colombia, while in April 2021, TR4 was spotted in northern Peru, also on an organic banana farm. So far, the Colombians have managed to contain TR4 in the department of La Guajira, although the pathogen has spread from two farms to ten. The Cavendish variety, which dominates the market for dessert bananas, is widely grown as a monocrop, facilitating the spread of the disease. However, TR4 is also starting to gradually spread into smaller-scale, more diversified banana farming systems in various Asian countries.ImageSampling a diseased banana in northern Mozambique. Surveys like this help to map the spread of TR4. G. Blomme (Alliance)

The Alliance of Bioversity and CIAT and the International Institute of Tropical Agriculture (IITA), with the support of RTB, held a two-day virtual mini-symposium which presented a state-of-the-art overview of research on this disease. In addition, a virtual Masterclass for anyone interested in the pathogen, diagnostic tools, control strategies and the impact was organized by The Alliance and IITA in the framework of ProMusa and RTB. 

During the Masterclass, banana researchers from across the globe presented current knowledge on Fusarium spread, epidemiology and control. At the virtual symposium, novel research insights were communicated. For example, how to detect viable Fusarium inoculum from environmental samples, or insights in the survival and treatment of Fusarium in water. In addition, weevils and nematodes were reported to contribute to disease spread and infection intensity. The symposium also presented new tools to detect and map TR4.

The symposium discussed biocontrol approaches, including use of the beneficial fungus Trichoderma to control TR4. The substrate left over after harvesting cultivated mushrooms could be applied to the soil to stop the spread of the disease. Groundcover root flavonoids and phenolic acids may also help stop the fungus in the soil. Researchers in China have identified beneficial bacteria closely related to the well-known Bt. Two of these Bacillus bacteria are now being screened to find the best strains for biological control of TR4. Colombian scientists are testing ammonia-based soil disinfectants to eliminate the pathogen from locations where infected mats had been removed.ImageInternal symptoms of Fusarium wilt, TR4 affecting Cavendish bananas in Colombia. M. Dita (Alliance)

The key option to mitigate the impact of Fusarium is through the use of resistant or highly tolerant germplasm. Some promising genetic material is currently available and is being used, and many other banana types are being screened for resistance. Therefore, conventional breeding, in addition to GM and CRISPR, will most likely widen the pool of resistant germplasm in the years to come. 

“The rapid spread of TR4 threatens food security across the tropics on three continents. The banana also creates lots of jobs, including many for women and youth, from farming to packing houses to retail sales. It’s heartening that the world’s experts have been able to start working together to develop the technologies that will solve this crisis,” says James Legg, leader of FP3, which helped to sponsor the symposium.ImageFemale banana exporter in Uganda. (CIP)ImageLeaves turn yellow on a diseased plantain plant. A Fusarium Race 1 affected Bluggoe plant in northern Moza

View as a webpage ARS News Service ARS
News Service Handfeeding a honey bee.
Scientists at the ARS Bee Research Laboratory in Beltsville, Md., use the handfeeding technique to deliver pathogens and medicines to bees.

Natural Products May Be Buzzworthy Solutions for Honey Bees’ Health
For media inquiries contact: Jessica Ryan, (301) 892-0085
November 29, 2021 The buzz about natural products is not just for humans. United States Department of Agriculture (USDA), Agricultural Research Service (ARS) researchers from the Bee Research Laboratory in Beltsville, Maryland, and collaborators found some natural products’ medicinal properties reduced virus levels and improved gut health in honey bees. Among the study’s results, which were recently published in Applied Sciences, researchers found a significant reduction in virus levels in bees fed raw cacao and hesperidin, a plant chemical commonly found in citrus fruits and other fruits and vegetables. There were also lower levels of viruses in bees fed chrysin, curcumin and vanillin. Chrysin is a chemical found in honey and various plants such as passionflower and silver linden. Curcumin is a bright yellow chemical produced by plants and is known for giving turmeric its distinctive color. Vanillin is a chemical compound of the extract of a vanilla bean and major flavor component of vanilla. The results also showed that some natural products had positive impacts on bees’ gut health and immune response. For example, bees fed Vitamin E had significantly decreased levels of Gilliamella, a gut bacterium. In addition, there were also lower levels of Gilliamella in bees fed curcumin, vanillin and hesperidin. While Gilliamella can be beneficial for honey bees, too much of the gut bacterium can negatively impact their health. “Gilliamella is a common bacterium in honey bees―even healthy ones,” said Jay Evans, research entomologist for the Bee Research Laboratory. A gut bacterial imbalance could be bad for bees. If Gilliamella levels are high, then Gilliamella could take the place of other core bacteria. If bee diets or treatments help maintain a good mix of ‘good’ bacteria in bees’ guts, then this seems to help strengthen their immune responses, according to the study’s results. The 20 natural products used in the study included native extracts and individual compounds known to support immunity, have antiviral or antimicrobial properties, and/or control parasites and pests. Scientists researched these natural products as possible safer, cost-effective alternatives to antibiotics and synthetic chemicals. Understanding these natural products’ effects can also help scientists determine better crops and flowers for bees’ diets.   “Many of the natural products tested are recognized as safe components of the food supply and are potentially less expensive to produce,” said Evans. “These results could also inform us on possible, healthier crops and flowers for bees. Bees foraging on crops or non-crop plantings of flowers that provide these benefits could naturally have better health.” 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 archive U.S. DEPARTMENT OF AGRICULTURE
Agricultural Research Service

The world’s largest organism is slowly being eaten by deer

November 23, 2021 9.37am EST Updated November 24, 2021 6.47pm EST

Author

  1. Richard Elton WaltonPostdoctoral Research Associate in Biology, Newcastle University

Disclosure statement

Richard Elton Walton is affiliated with Friends of Pando as a volunteer.

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In the Wasatch Mountains of the western US on the slopes above a spring-fed lake, there dwells a single giant organism that provides an entire ecosystem on which plants and animals have relied for thousands of years. Found in my home state of Utah, “Pando” is a 106-acre stand of quaking aspen clones.

Although it looks like a woodland of individual trees with striking white bark and small leaves that flutter in the slightest breeze, Pando (Latin for “I spread”) is actually 47,000 genetically identical stems that arise from an interconnected root network. This single genetic individual weighs around 6,000 tonnes. By mass, it is the largest single organism on Earth.

Aspen trees do tend to form clonal stands elsewhere, but what makes Pando interesting is its enormous size. Most clonal aspen stands in North America are much smaller, with those in western US averaging just 3 acres.

View across a valley with trees highlighted in green
Aerial outline of Pando, with Fish Lake in the foreground. Lance Oditt / Friends of Pando, Author provided

Pando has been around for thousands of years, potentially up to 14,000 years, despite most stems only living for about 130 years. Its longevity and remoteness mean a whole ecosystem of 68 plant species and many animals have evolved and been supported under its shade. This entire ecosystem relies on the aspen remaining healthy and upright. But, although Pando is protected by the US National Forest Service and is not in danger of being cut down, it is in danger of disappearing due to several other factors.

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Deer are eating the youngest ‘trees’

Overgrazing by deer and elk is one of the biggest worries. Wolves and cougars once kept their numbers in check, but herds are now much larger because of the loss of these predators. Deer and elk also tend to congregate in Pando as the protection the woodland receives means they are not in danger of being hunted there.

Three deer in an aspen forest
Well-disguised deer eating Pando shoots. Lance Oditt / Friends of Pando, Author provided

As older trees die or fall down, light reaches the woodland floor which stimulates new clonal stems to start growing, but when these animals eat the tops off newly forming stems, they die. This means in large portions of Pando there is little new growth. The exception is one area that was fenced off a few decades ago to remove dying trees. This fenced-off area has excluded elk and deer and has seen successful regeneration of new clonal stems, with dense growth referred to as the “bamboo garden”.

Diseases and climate change

Older stems in Pando are also being affected by at least three diseases: sooty bark canker, leaf spot and conk fungal disease. While plant diseases have developed and thrived in aspen stands for millennia, it is unknown what the long-term effect on the ecosystem may be, given that there is a lack of new growth and an ever-growing list of other pressures on the clonal giant.

The fastest-growing threat is that of climate change. Pando arose after the last ice age had passed and has dealt with a largely stable climate ever since. To be sure, it inhabits an alpine region surrounded by desert, meaning it is no stranger to warm temperatures or drought. But climate change threatens the size and lifespan of the tree, as well as the whole ecosystem it hosts.

Although no scientific studies have focused specifically on Pando, aspen stands have been struggling with climate change-related pressures, such as reduced water supply and warmer weather earlier in the year, making it harder for trees to form new leaves, which have led to declines in coverage. With more competition for ever-dwindling water resources (the nearby Fish Lake is just out of reach of the tree’s root system), temperatures expected to continue soaring to record highs in summer, and the threat of more intense wildfires, Pando will certainly struggle to adjust to these fast-changing conditions while maintaining its size.

The next 14,000 years

Yet Pando is resilient and has already survived rapid environmental changes, especially when European settlers began inhabiting the area in the 19th century or after the rise of 20th-century recreational activities. It has dealt with disease, wildfire, and grazing before and remains the world’s largest scientifically documented organism.

Trees at sunset
Pando has survived disease, hunting and colonisation. Lance Oditt / Friends of Pando, Author provided

Despite every cause for concern, there is hope as scientists are helping us unlock the secrets to Pando’s resilience, while conservation groups and the US forest service are working to protect this tree and its associated ecosystem. And a new group called the Friends of Pando aims to make the tree accessible to virtually everyone through 360 video recordings.

Last summer, when I was visiting my family in Utah, I took the chance to visit Pando. I spent two amazing days walking under towering mature stems swaying and “quaking” in the gentle breeze, between the thick new growth in the “bamboo garden”, and even into charming meadows that puncture portions of the otherwise-enclosed centre. I marvelled at the wildflowers and other plants thriving under the dappled shade canopy, and I was able to take delight in spotting pollinating insects, birds, fox, beaver and deer, all using some part of the ecosystem created by Pando.

It’s these moments that remind us that we have plants, animals and ecosystems worth protecting. In Pando, we get the rare chance to protect all three.


This article was updated on November 24 to correct a typo: Pando is estimated to weigh 6 million kilograms not 6 million tonnes. It now reads “6,000 tonnes”.

NOVEMBER 23, 2021

For a fungus, the right ‘accessories’ can make or break a relationship with a plant

by American Phytopathological Society

Plants interact with a diversity of organisms over the course of their lifetime, but even very similar microbes can cause opposite reactions. Two strains of the fungus Fusarium oxysporum (Fo) share a core genome, but one is a beneficial endophyte while the other is a detrimental pathogen causing wilt and death. A new study, published in the Molecular Plant-Microbe Interactions journal, tried to tease apart why these two strains cause such opposite reactions, and more generally how plants respond differently to useful and harmful microbes, by exploring the interaction of these two strains with the model plant Arabidopsis.https://171f00c1a52866b7097ffbff08524c56.safeframe.googlesyndication.com/safeframe/1-0-38/html/container.html

As explained by senior author Li-Jun Ma, “strain-specific interactions with a common host are likely dictated by the accessory chromosomes from each F. oxysporum genome.” Accessory chromosomes are extra pieces of genetic material that are considered to be more plastic in that they move and change based on the lifestyle that the fungus has, unlike the core genome. Like the gadget laboratory in a spy movie, the accessory chromosomes of Fo strains contain tools used to infiltrate the plant and shut down defenses. Using closely related strains that differ in accessory chromosomes “allows a comparative study that minimizes genetic differences between strains to address the underlying mechanism that results in distinct phenotypes (growth promotion or disease or even death),” says leading author Li Guo.

In this study, metatranscriptomic data reveals that most plant genes (about 80%) are expressed similarly in response to both fungal strains across timepoints over four days. By just twelve hours, the most obvious differences in plant response are occurring. Co-first author Houlin Yu explains that “it is important to realize that plants can rapidly react to signals of microbial presence by changing their gene expression.” For example, plant defense-related genes are induced by both the endophytic and pathogenic strains, but the endophyte is better able to suppress these genes. The other host genes that varied include plant growth-related genes that were reduced in expression when the pathogen was present, whereas nitrogen uptake and metabolism genes were increased in expression (upregulated) when the endophyte was present.

The accessory chromosomes are also where a lot of the gene expression changes were seen in the fungal strains. The endophytic strain upregulated genes involved in cell signaling and nutrient transport, while the pathogenic strain unsurprisingly upregulated those enriched for virulence or detoxification roles. Identifying the fungal genes with changes in expression on the accessory chromosomes that correspond to the ultimate outcome of plant health tell researchers what to investigate further to increase disease resistance and promote plant growth. Ma emphasizes that, “This research has a profound effect on plant and perhaps even animal immunology, suggesting that cells have a remarkable flexibility and plasticity in response to microbes of same species but genetically different.”


Explore furtherFungal transplants from close relatives help endangered plants fight off disease


More information: Li Guo et al, Metatranscriptomic Comparison of Endophytic and Pathogenic Fusarium–Arabidopsis Interactions Reveals Plant Transcriptional Plasticity, Molecular Plant-Microbe Interactions (2021). DOI: 10.1094/MPMI-03-21-0063-RJournal information:Molecular Plant-Microbe InteractionsProvided by American Phytopathological Society

November 18, 2021

Enemy of invasive, berry-eating fly found in U.S.

 By Scott Weybright, College of Agricultural, Human, and Natural Resource Sciences

Washington State University

A parasitoid wasp, Ganaspis brasiliensis, is a native of South Korea, but has been found in the U.S. for the first time. The wasp is pictured here laying its eggs into a drosophila larva on a blueberry (photo courtesy of Kent Daane, UC Riverside).

WENATCHEE, Wash. – A parasitoid wasp that is the natural enemy of a fly known as the spotted-wing drosophila could be a good friend to growers. Washington State University researchers recently confirmed the discovery of the potentially beneficial wasp in the United States for the first time. 

The drosophila flies cause major damage to several Washington crops, especially sweet cherries and berries. The wasp, which lays its eggs in the flies, could be a means of controlling their spread. 

“This is really a positive step for the cherry and berry industries,” said Elizabeth Beers, a professor in WSU’s Department of Entomology. “Hopefully this speeds up the timeline to get biological control of the spotted-wing drosophila.”

Beers and her team found the parasitoid, called Ganaspis brasiliensis, this September, in a wild blackberry patch less than a mile from the Canadian border near Lynden, Washington. The tiny wasp was found in western British Columbia in 2019. Paul Abram, a Canadian colleague, asked Beers to watch for wasps crossing the border and provided tips on the best places to find them.

Another parasitoid of the Drosophila pest, Leptopilina japonica, was also found in British Columbia in 2019 and in Washington state in 2020 by Chris Looney of the Washington State Department of Agriculture. But the new parasitoid which is native to South Korea has a major benefit: specificity.

“The Ganaspis is very host-specific; it really likes to attack spotted-wing drosophila larvae and generally doesn’t bother other species,” said Beers, who is based at WSU’s Tree Fruit Research and Extension Center in Wenatchee.

The invasive drosophila fly hurts fruit because it doesn’t just nibble on the outside—its larvae burrow down into a raspberry or cherry and ruin the entire thing. That’s where the parasitoid comes into play.

Beers said it’s just possible to see the tiny adult parasitoids flying around drosophila-infested fruit. The female Ganaspis then lay their eggs inside the drosophila larvae. The little parasitoid develops inside the drosophila larva, killing it in the process.

“It’s a bit like the movie Alien,” Beers said. “It’s unpleasant to think about in sci-fi movie terms, but really effective for killing spotted-wing drosophila.”

The Ganaspis parasitoids were recently approved by the U.S. Department of Agriculture Animal and Plant Health Inspection Service to be reared and distributed around the U.S. as a biocontrol.

Leptopilina japonica, left, is another parasitoid of the invasive and damaging spotted-wing drosophila, right (photo Courtesy of Warren Wong, Agassiz R&D Center).

To do that, an entomologist went to the native home of spotted-wing drosophila, found the Ganaspis, and brough back several samples. After significant research in quarantine, it was found to be safe to spread here to fight drosophila.

During that process, the Ganaspis found its own way to North America and is spreading without help. Once an invasive species is found living in a state, the USDA does not regulate it being distributed around that state, making the process easier.

“It’s kind of the best of both worlds,” Beers said. “It’s great that we have a lot of research showing that Ganaspis is very host-specific and safe to spread around. But there are also benefits to it being found here in nature.”

This is the third exotic species that Beers and her lab has found in the last few years. They found a parasitoid of the apple mealy bug, a pest for the apple industry, and the Samurai wasp.

“I never anticipated this, it’s not the main focus of our lab,” Beers said. “We’ve just kind of stumbled across them as part of our research on various pests.”

Post-doctoral researcher Dylan Beal and technician Peter Smytheman led the work collecting and rearing the Ganaspis.

Media Contacts

Monarch butterflies may be thriving after years of decline. Is it a comeback?

The North American species is seeing an exponential increase in California, but the population is far short of normal

A western monarch butterfly lands on a plant iln Pismo Beach, California.
Western monarch butterflies have returned to Pismo Beach in increasing numbers this month. Photograph: Gabrielle Canon/The Guardian

Gabrielle Canon@GabrielleCanonSun 21 Nov 2021 06.00 EST

  • On a recent November morning, more than 20,000 western monarch butterflies clustered in a grove of eucalyptus, coating the swaying trees like orange lace. Each year up to 30% of the butterfly’s population meets here in Pismo Beach, California, as the insects migrate thousands of miles west for the winter.

Just a year ago, this vibrant spectacle had all but disappeared. The monarch population has plummeted in recent years, as the vibrant invertebrates struggled to adapt to habitat loss, climate crisis, and harmful pesticide-use across their western range.

Last year less than 200 arrived at this site in 2020 – the lowest number ever recorded – and less than 2,000 were counted across the California coast.

But ahead of the official annual count that takes place around Thanksgiving, early tallies show monarchs may be thriving once again across California. The rise has sparked joy and relief, but the researchers, state park officials, and advocates say that doesn’t mean the species is safe.

Western monarch butterflies gather in the branches of a eucalyptus tree in Pismo Beach.
Up to 30% of the western monarch butterfly population converges on Pismo Beach each winter. Photograph: Gabrielle Canon/The Guardian

Even with the exponential increase, the population is still far short of once-normal numbers. It’s still unclear whether the butterflies are making a dramatic comeback or will continue to decline.AdvertisementThe New Face of Small BusinessR sundae infused with Black history: howRabia Kamara is changing the dessert worldhttps://imasdk.googleapis.com/js/core/bridge3.489.0_en.html#goog_346656178https://imasdk.googleapis.com/js/core/bridge3.489.0_en.html#goog_370564443https://imasdk.googleapis.com

“The takeaway is that the migration isn’t gone, which some people really feared last year,” says Emma Pelton, the senior conservation biologist for the Xerces Society, an organization dedicated to protecting pollinators and other invertebrates. Between 4 million and 10 million butterflies once graced the California coasts before dropping to just over a million at the end of the 1990s. In the decades that followed, the population plateaued at about 200,000.

Then, in 2017, the numbers crashed to fewer than 30,000 butterflies at the annual counts. Monarchs are resilient and adaptive but they continue to face challenges. This year’s uptick is small when put in perspective with past population levels, but “the good news is that it is not too late”, Pelton adds.

A remarkable migration

There’s still a fair amount of mystery surrounding the western monarchs and their incredible annual migration. Each year, they follow a celestial compass and head west from the Rocky Mountains to the coast. Remarkably, each generation of butterflies often returns the same groves along the coast each year, sometimes even a particular tree, without ever having been there before.

Generally, they arrive in California around November and disembark in the spring, heading east as the weather warms. A separate population of monarchs spends the winter in Mexico, coming from Canada and the eastern United States.

Stephanie Little, a scientist with California state parks, uses binoculars to look up in the trees and count butterflies in Pismo Beach.
Stephanie Little, a scientist with California state parks, counts butterflies in Pismo Beach. Photograph: Gabrielle Canon/The Guardian

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Their dedication to routine makes them easier to count each year. But the process isn’t exactly simple, especially when the numbers are low and they are harder to spot. In the Pismo Beach grove, which usually hosts the largest gathering, there are three state parks officials tasked with tallying them before the Thanksgiving count that relies on help from volunteers.

Armed with binoculars, butterfly counters estimate the numbers based on clusters that can be seen in the branches, roughly 50ft (15 meters) from the ground. California state parks has partnered with advocacy organizations to produce a welcoming environment for them. That means planting more of the non-native eucalyptus trees, which the butterflies love to roost in.

The reasons behind this sharp increase remain a mystery. Monarchs that live in the west tend to have three or four generations each year, each with a different role to play in the migration that can span thousands of miles, and there are opportunities at each stage for big shifts.

Monarch butterflies gather in the branches of a eucalyptus tree, roughly 50 ft from the ground.
Monarch butterflies gather in the branches of a eucalyptus tree, roughly 50ft from the ground. Photograph: Gabrielle Canon/The Guardian

But what’s driving their precipitous decline is clear. Their historic habitats in grassland ecosystems across the US are being destroyed. Commercial agriculture is eating away at their range which is increasingly laced with deadly pesticides. And, susceptible to both fluctuations and extremes in temperatures, monarchs are vulnerable to climate change. That’s partly why they are considered a so-called “indicator species” revealing the devastating toll taken on other insects and ecosystems.

“The butterflies are just very adaptable and strong,” David James, an entomologist at Washington State University who has spent decades studying the species says. “But they are giving us a warning too – and we need to take heed of that,” he adds. “Their decline is going to affect other organisms.”

‘There’s still time to act’

The butterflies have also felt the impact of extreme heat, fires, and drought, as well as the severe winter storms on the California coast where they spend the winter. “Some of those storms have ripped the trees out and thrown butterflies to the ground,” James says.

But he also believes last year’s extremely low numbers may have been the result of dispersion, not necessarily death.

“When we only had 2,000 overwintering at the traditional sites, at the same time there were many reports inland in San Francisco and the LA area of monarch butterflies reproducing in people’s backyards and parks and gardens throughout the winter,” he says, noting that this spread makes them tricky to count.

But even if last year’s low numbers can be attributed to behavior changes, that’s still a sign climate crisis is causing problems. “They are indicating to us that things are going wrong,” James says.

Visitors look for butterflies at the Pismo Beach Butterfly Grove.
Visitors look for butterflies at the Pismo Beach Butterfly Grove. Photograph: Gabrielle Canon/The Guardian

Individuals can make a difference by planting native nectar plants, including the milkweed that monarchs lay their eggs on and limiting the use of pesticides. Members of the public can also volunteer to monitor monarchs across the west. And, according to Xerces’ Emma Pelton, the promising numbers show that small changes can have a big impact.

“The main message to me is that there’s hope,” she says, noting the way monarchs have inspired the public to reimagine how they see insects and the role that everyone can play in their conservation. “The insect apocalypse narrative and the very real biodiversity crises that we are facing, those can feel really dark” she says. “But the issue is not intractable and we can make a difference. There is still time to act.”