New fungus is the oldest disease-causing species found to date

New fungus is the oldest disease-causing species found to date

by Natural History Museum

Artistic rendition of the Rhynie Chert in the Early Devonian period. Credit: Victor O. Leshyk

The earliest disease-causing fungus has been discovered within the Natural History Museum’s fossil collections. The new fungal plant pathogen, Potteromyces asteroxylicola, which is 407-million-years-old, has been named in honor of celebrated Tales of Peter Rabbit author, and fungi enthusiast, Beatrix Potter.

The paper, “A fungal plant pathogen discovered in the Devonian Rhynie Chert,” has been published in Nature Communications

Beatrix’s drawings and study of the growth of fungi, which were in some cases decades ahead of scientific research, have garnered her a reputation as a significant figure in mycology.

Potteromyces was discovered in fossil samples from the Rhynie Chert, a crucial geological site in Scotland. The site is known for a remarkably preserved Early Devonian community of plants and animals, including bacteria and fungi.

The new study, completed in collaboration with mycologists at the Royal Botanic Gardens, Kew, suggests that disease-causing fungi, such as ash die-back currently decimating the UK’s native ash trees, and fungi which can circulate nutrients that plants and other organisms depend on to survive, have a historical precedent in Potteromyces.

Dr. Christine Strullu-Derrien, Scientific Associate at the Natural History Museum and lead author of the study describing the new species, says, “Although other fungal parasites have been found in this area before, this is the first case of one causing disease in a plant. What’s more, Potteromyces can provide a valuable point from which to date the evolution of different fungus groups, such as Ascomycota, the largest fungal phylum.”

“Naming this important species after Beatrix Potter seems a fitting tribute to her remarkable work and commitment to piecing together the secrets of fungi.”

Christine found the first Potteromyces specimen in 2015. Its reproductive structures, known as conidiophores, had an unusual shape and formation unlike anything seen before.

Equally unusual was the fact this mysterious fungus was found attacking an ancient plant called Asteroxylon mackiei. The plant had responded by developing dome-shaped growths, showing that it must have been alive while the fungus making its attack.

In order for the team to determine that it was indeed a new species, another case of the fungus needed to be found. This is due to the nature of fungi differing greatly between individuals.

The confirmation was achieved when a second specimen was found in the collections of the National Museums of Scotland in another specimen slide from the Rhynie Chert.

“New technology available to us, such as confocal microscopy, has enabled us to unlock more secrets from fossils housed in museum collections, such as those within the Natural History Museum,” said Christine.

“When I first started work on the Rhynie Chert, it was only meant to take two or three years,” Christine says, “It’s now been 12, and I still think there is a lot to discover from this fabulous site.

More information: Christine Strullu-Derrien et al, A fungal plant pathogen discovered in the Devonian Rhynie Chert, Nature Communications (2023). DOI: 10.1038/s41467-023-43276-1

Journal information: Nature Communications 

Provided by Natural History Museum 

This story is republished courtesy of Natural History Museum. Read the original story here

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‘Toxic bait’ from Indian pitcher plants lures hungry insects to their doom

‘Toxic bait’ from Indian pitcher plants lures hungry insects to their doom

Nectar produced on and around the traps is laced with a neurotoxin that may drug ants in addition to drawing them in

Nepenthes khasiana produces a sweet nectar on its traps that attracts insects.MICHAEL DURHAM/MINDEN PICTURES


Pitcher plants in the genus Nepenthes thrive in places where they shouldn’t. There’s very little nitrogen in the Southeast Asian and Australian soils where they grow—but they do just fine, thanks to a macabre source for this essential nutrient: the dissolved flesh of small animals, mostly insects, that slip into their bulbous traps.

A new study suggests why Nepenthes is so effective at catching its victims: It produces a sweet nectar containing a potent neurotoxin that could make them lose their balance at the pitcher’s edge. The work, published as a preprint on bioRxiv this month, is the first known example of nectar acting both as a lure and a poison.

The finding is intriguing, says University of Bristol researcher Ulrike Bauer, who has studied Nepenthes plants for nearly 2 decades but who wasn’t involved with the research. “The nectar has really been neglected for a long time,” she says, and the idea that it contains compounds that “drug” insects is plausible. Still, she and others would like clearer evidence that the toxin originates from the nectar—and that it really accounts for the unlucky ants’ falls.

Phytochemist Sabulal Baby has been studying carnivorous plants—“the most unique life forms on Earth,” he says—for more than a decade. He and his colleagues at the Jawaharlal Nehru Tropical Botanic Garden and Research Institute had previously discovered that the rims of the Indian pitcher plant Nepenthes khasiana are fluorescent and that newly opened traps emit carbon dioxide—features that attract insects. Because they knew the plants also produce nectar on and around their traps, which acts as a lure, they decided to examine it more closely.

In other plants, such extrafloral nectar isn’t designed to harm insects. The liquid’s high sugar content appeals to ants, whose presence—and aggression—wards off potential herbivores. But when Baby and colleagues teased out the contents of the nectars of N. khasiana and several other pitcher plants growing in their institute’s botanic garden, they found something unexpected. The nectars contained (+)–isoshinanolone—a compound that interferes with the activity of an enzyme called acetylcholinesterase, which prevents the buildup of the neurotransmitter acetylcholine between neurons. Too much acetylcholine in lab animals leads to muscle cramps, weakness, blurry vision, and paralysis.

And indeed when Baby and his colleagues examined ants that had drowned in the pitcher fluid of N. khasiana, they found almost no acetylcholinesterase activity in their tissues. Ants collected on the plant’s exterior showed more of this activity. This indicates that the nectar inhibits the insects’ locomotion, Baby says, making them temporarily clumsy and more likely to tumble into a pitcher. The nectar is a “toxic bait,” he says. “Prey capture by these pitchers is a story of total deception.”

Bauer doesn’t agree that the relationship is that unbalanced. The nectar isn’t so potent that the plants catch every ant that imbibes; many of the insects are able to shrug off its effects and make it home to deliver the sweet treat. “Sugar is an important food resource for ants, because it’s very energy dense,” Bauer notes. Meanwhile, worker ants are relatively expendable. “It’s a good deal for the ant colony to sacrifice some workers, as long as the workers that survive bring in enough sugar to offset that loss.”

It wouldn’t be completely unheard of for nectar to manipulate insects to the plant’s benefit, says Martin Heil, an expert on ant-plant interactions and extrafloral nectar with the Mexican Center for Research and Advanced Studies of the National Polytechnic Institute.

That said, he finds the data provided—that drowned ants exhibited high levels of acetylcholinesterase inhibition—are circumstantial at best. He would like to see experiments examining live ants before and after consuming the nectar to be convinced that the fluid has a real impact on prey capture.

Bauer says that in her work, she hasn’t seen ants with impaired movement after drinking pitcher plant nectar, though others have, and she notes the effect need not be dramatic to benefit the plant. She also hasn’t worked with N. khasiana specifically, and nectar components vary between species—a fact she can personally confirm from tasting the nectars of several pitcher plants.

Bauer notes that the authors’ method for nectar sampling—which involved rinsing cut sections of plant to collect the fluid—could have introduced intracellular compounds. So future work should confirm that (+)–isoshinanolone is in the nectar that the ants consume, not just the plant’s tissues.

Still, she wouldn’t be too surprised if it is. Pitcher plants have “such an amazing diversity of tricks for how to trap insects” that toxic nectar would hardly be the strangest.

doi: 10.1126/science.zzb21md




Christie Wilcox

Christie Wilcox



Christie Wilcox is the Newsletter Editor for Science.

Viruses Shown to Be Effective Biological Control Agents

Viruses Shown to Be Effective Biological Control Agents

Beyond Pesticides

Viruses Shown to Be Effective Biological Control

(Beyond Pesticides, November 30, 2023) Scientists at Minami Kyushu University in Japan have made a groundbreaking discovery of a new biological control for a target insect. They have identified a virus in tobacco cutworms that kills males, creating all-female generations. The discovery was described in a recent issue of the Proceedings of the National Academies of Sciences and The New York Times as evidence that multiple viruses have evolved to kill male insects.

This “male-killing” virus could be added to the growing attempts to control unwanted insects with biological, as distinguished from genetically engineered (GE) solutions. Efforts range from the introduction of natural predators, to radiation-based sterilization of insects, CRISPR-based genetic mutations, and other techniques. While the GE approach has run into controversy because of unanswered questions associated with their release into natural ecosystems, some approaches have also run into resistance problems. Nearly a decade ago, researchers found armyworm resistance to Bacillus thuringiensis (Bt)-incorporated genetically engineered (GE) maize in the southeastern region of the U.S., calling this evolution of insect resistance to a naturally occurring soil bacterium engineered into crops “a serious threat to the sustainability of this technology.”

The general population knows to avoid eating raw eggs because the bacteria salmonella, can live inside chicken eggs. Similarly, scientists have long known that microbes can live in insects’ eggs. One of the scientists, Daisuke Kageyama, PhD, explained that the Wolbachia bacteria, another male-killer, is propagated through females. Dr. Kageyama told the The New York Times, “Males are useless” because they cannot help propagate the microbe, so the bacteria prevents male eggs from hatching.

The scientists in Japan discovered the new male-killing virus in tobacco cutworms and called it SIMKV. The New York Times described the discovery of the virus as being very lucky that research technician Misato Terao stumbled upon the caterpillars while cleaning the greenhouse and placed them in Yoshinori Shintani’s lab. Even luckier was the temperature zone that enabled the virus to impact the resulting all-female generation of moths.

Anne Duplouy, PhD, an evolutionary biologist at the University of Helsinki specializing in the study of microbial symbionts in insects, suggests that there is a diminishing window of opportunity for humanity to glean insights from these microbes sensitive to temperature changes. Due to climate change, she said, “we are likely to be losing many of these interactions” before they can be documented.

The authors of the study believe the identification of this male-killing virus in insects has the potential to revolutionize methods for managing agricultural pests and disease-carrying insects. Conventional pest control approaches rely on the use of toxic pesticides, which can adversely affect the environment and human health.

Many scientists believe a “female-killer” virus could be a more ecologically friendly approach to pest control. However, these biological controls do not always consider the entirety of a systems-based organic approach that focuses on the root causes of pest problems. To see a more systematic approach to mosquito control, see the city of Boulder, Colorado’s mosquito management plan, which includes  Living with Mosquitoes and Ecological Mosquito Management.

As scientists delve deeper into the study of the relationships between mosquitos and the interactions of species in an ecosystem, there is the prospect of uncovering novel strategies for pest and disease control that are both more efficacious and less environmentally harmful.

The revelation of the male-killing virus in insects serves as a poignant reminder of the extraordinary biodiversity of life on Earth. As scientists persist in their exploration of biological control, they are bound to reveal many more captivating discoveries that will contribute to a better understanding of the natural world.

As The New York Times wrote in November 2018, “The Insect Apocalypse is Here.” Karen Lipps, PhD, and other scientists and researchers observed the consequences for ecosystems that experience the loss of one species and its cascading impact on other species. Dr. Lipps writes about the massive loss of frogs and other amphibians due to a fungus and its resulting increase in insect populations. This, in turn, decreased snake populations (which would have preyed on the frogs).

In industrial agriculture, the typical approach to addressing pest issues often involves prioritizing the destruction of a single “pest” using a pesticide as the primary solution. This practice results in a cascade of harmful effects throughout the food chain, impacting both prey and predator as they fall victim to the broad-spectrum pesticides. While it intuitively makes sense that pesticides can affect more than just their intended insect targets, the extent of this issue came to light through a study conducted by German researchers and published in PLOS One. Their findings, based on 27 years of trapping flying insects, reveals a staggering 75% decline in overall biomass during the study period.

To learn more about using biological control for your yard and outdoor pest problems, make sure the use of any pest management fits within a broader, structured, ecological approach to pest management. Use Beyond Pesticides ManageSafe webpage to assist your research on biological controls.

All unattributed positions and opinions in this piece are those of Beyond Pesticides.

Source: Male-Killing Virus Is Discovered in Insects

This entry was posted on Thursday, November 30th, 2023 at 12:01 am and is filed under AgricultureAlternatives/OrganicsBiological ControlClimate ChangeEcosystem ServicesMalariaMosquitoesPesticide EfficacyPestsUncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

Spider’s distribution differs by urban habitat

Spider’s distribution differs by urban habitat

Nebraska Today


by Scott Schrage | University Communication and Marketing


A funnel-weaving spider, Agelenopsis pennsylvanica, rests on its web while waiting out the rain.

Welcome to Pocket Science: a glimpse at recent research from Husker scientists and engineers. For those who want to quickly learn the “What,” “So what” and “Now what” of Husker research.

Pocket Science icon


The concept of urbanization rests on the population distribution of human beings, more than 50% of whom now live near large, often densely packed groups of other people. But the consequences of that urbanization — shifts in vegetation, localized fluctuations in temperature and wind, light and sound — can alter the distribution of other animals, too.

Given their limited lifespans, spiders and other arthropods must adapt more quickly than most, making them a valuable proxy for the ecological effects of urbanization. While hard data is hard to come by, arachnologists suspect that the global population of spiders — which eat up to 800 million metric tons of pests in a year — is now falling. Whether urbanization is contributing, and to what extent, remains a subject of some debate.

So what?

In search of factors that might sway the distribution and abundance of city-dwelling spiders, Nebraska’s Brandi Pessman and her colleagues turned to the wide-ranging species Agelenopsis pennsylvanica. The team sought out A. pennsylvanica in two areas of Lincoln: Nebraska U’s City Campus, considered an urban center, and Wilderness Park, an urban forest. As expected, the team found that those habitats differed in ways potentially relevant to the spiders. City Campus featured more artificial light, traffic and engineered surfaces — the latter contributing to higher temperatures — whereas Wilderness Park included more tree cover and plant diversity.

Portrait of Brandi Pessman


A sampling expedition identified 131 funnel webs constructed by A. pennsylvanica, 64 of which brought forth spiders when the team stimulated the webs with a toothpick affixed to an electric toothbrush. City Campus boasted substantially more of those webs, and more spiders, than did Wilderness Park. Less distance separated the webs of the urban center than in the urban forest. And webs built on campus generally resided closer to the ground. Those findings suggest that differences between the urban environments could be motivating the real estate chosen by A. pennsylvanica, whose varied diet may help it adapt to human-disturbed areas that are less hospitable to pickier predators.

Yet the team also found that, even within City Campus, A. pennsylvanica webs were fewer and farther apart in spaces adjacent to roads or highways. The vibrations that propagate when rubber meets road might be to blame: Like many spider species, A. pennsylvanica relies on vibratory signals both to hunt and woo mates.

Now what?

Pessman is already conducting follow-up research on A. pennsylvanica in rural versus urban areas, hoping to determine whether environmental vibrations in the latter can limit the spider’s ability to detect prey. She’s also looking into whether the spider could be using webs to dampen disruptive frequencies.





Chloroplasts are a key player in plant immunity

Chloroplasts are a key player in plant immunity

by UC Davis

Experimental seedlings in the laboratory. UC Davis plant biologists have discovered how chloroplasts, responsible for photosynthesis in green plants, also play a key role in plant immunity to infections. Credit: Sasha Bakhter, UC Davis College of Biological Sciences

Scientists have long known that chloroplasts help plants turn the sun’s energy into food, but a new study, led by plant biologists at the University of California, Davis, shows that they are also essential for plant immunity to viral and bacterial pathogens.

Chloroplasts are generally spherical, but a small percentage of them change their shape and send out tube-like projections called “stromules.” First observed over a century ago, the biological function of stromules has remained enigmatic.

Previous studies have shown that chloroplasts produce more stromules when a plant detects an infection. Stromules aid in clustering chloroplasts around the nucleus and function as conduits to transport pro-defense signals from chloroplasts to the nucleus. Despite these findings, researchers have not been able to determine the role of stromules in immunity, as no genes involved with the formation of stromules have been identified.

In the new study, Savithramma Dinesh-Kumar, professor and chair in the Department of Plant Biology, graduate student Nathan Meier and colleagues have identified a key protein involved in stromule biogenesis during immunity. Their findings were published Oct. 25 in Science Advances.

A hidden player in immune defense

In order to test the stromules’ role in immunity, researchers need to switch them off and then observe how stromule-less plant cells fare when faced with a pathogen. However, without knowing which genes are involved with the creation of stromules, researchers have had no way to know which genes to switch off.

To overcome this roadblock, Dinesh-Kumar and his colleagues turned to kinesins, proteins that function as tiny motors that allow molecules and organelles to move around a cell. This intracellular movement usually involves the cell’s cytoskeleton, which is made up of two different types of fiber: large microtubules and smaller actin filaments.

The researchers wanted to investigate a type of kinesin that is unique to plants and capable of binding both microtubules and actin filaments. The researchers found that overexpression of one of these kinesins, KIS1, induced stromule formation in the absence of pathogen infection.

When the researchers manipulated tobacco and Arabidopsis plants so that they could not produce the KIS1 kinesin, they found that neither plant was able to form stromules, and their chloroplasts did not migrate toward the nucleus. This left the plants unable to defend themselves from introduced pathogens.

Secrets of chloroplast movement

To disentangle the roles of microtubules and actin, the researchers engineered one set of KIS1 variants that could only bind to microtubules, and another that could only bind to actin. Expression of these variants in tobacco showed that KIS1 needs to bind to microtubules in order for chloroplasts to form stromules, but in order for chloroplasts to move toward the nucleus, it must also bind to actin.

The team also wanted to know how stromules fit into the bigger picture of plant immunity. By using genetic manipulation to switch different immune signals off, they found that stromule formation is triggered by molecular signaling and that an intact immune signaling system is needed in order for stromules to form.

“If we remove any of the known immune signaling genes, the chloroplasts lose the ability to make stromules, which suggests that these structures are an integral part of the immune signaling pathways that activate defense,” said Dinesh-Kumar.

New light on plant immunity

This study is the first evidence of a plant kinesin directly involved in plant immunity. It’s also the first time that scientists have identified a gene—KIS1—involved in chloroplast stromule biogenesis, which opens the door to understanding the role of chloroplast stromules and why chloroplasts cluster around the nucleus during plant immune defense.

“If we can better understand at the cellular level how organelles like chloroplasts help cells to defend themselves, we could help to engineer resistance to the pathogen,” Dinesh-Kumar said.

More information: Nathan Meier et al, Calponin-homology domain containing kinesin, KIS1, regulates chloroplast stromule formation and immunity, Science Advances (2023). DOI: 10.1126/

Journal information: Science Advances 

Provided by UC Davis 

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Monday, 20 November 2023 12:05:05

Grahame Jackson posted a new submission ‘TOMATO BROWN RUGOSE FRUIT VIRUS – MOROCCO: FIRST REPORT’




Source: European Plant Protection Organisation (EPPO) Reporting Service 10/2023/235 [summ. Mod.DHA, edited]
The NPPO [National Plant Protection Organisation] of Morocco recently informed EPPO of the occurrence of _Tomato brown rugose fruit virus_ (_Tobamovirus_, ToBRFV – EPPO A2 List) on its territory. During the production season 2022-2023, about 10 outbreaks have been confirmed on tomato (_Solanum lycopersicum_) grown in glasshouses for fruit production. The sources of the outbreaks are infected imported seed.

ToBRFV has been a priority quarantine pest in Morocco since 2018, and official measures are taken in case of findings. They include the destruction of infected plants, restriction on cultivation of host plants and hygiene measures. In 2023, yield losses were observed, as well as increased management costs.

Communicated by:
[_Tomato brown rugose fruit virus_ (ToBRFV) was identified as a new member of the genus _Tobamovirus_ (type member _Tobacco mosaic virus_, TMV) in Jordan and soon after in Israel (see links below). Since then, it has also been reported from Europe and the Mediterranean region, where it continues to spread (see links below), as well as from China and North America, but so far not from South America. The virus was shown to affect also capsicum and has been detected in both plants and seeds of both crops. ToBRFV symptoms on tomato vary depending on host cultivar but may include chlorosis, mottling, mosaic, crinkling (rugosis) on leaves; necrotic spots on petioles and calyces; yellowish mottling, brown spots and rugosis on fruit to make them unmarketable. On capsicum, leaf symptoms are similar; fruits may be deformed with yellow mottling or green stripes. Almost 100% incidence was reported for some outbreaks in tomato, but not every fruit on an infected plant may show symptoms.

ToBRFV (like many tobamoviruses) is seed transmitted and can also be spread by mechanical means, contaminated equipment, as well as with plant or other materials. It is very stable and can remain infectious for months outside a host. Bumblebees, which are used widely as commercial pollinators in glasshouse tomato production, have been shown to be effective vectors of ToBRFV (see link below). Volunteer crop plants and solanaceous weed species are likely pathogen reservoirs. The Tm-22 resistance gene used in some tomato cultivars to protect from other tobamoviruses (such as _Tomato mosaic virus_) does not appear to be effective against ToBRFV. Disease management relies mainly on exclusion but may include phytosanitation (disinfecting tools, removing crop debris) and control of virus reservoirs. Use of certified clean seeds or crop transplants is crucial. Research on possible seed treatments to eliminate the virus is being carried out (see link below). Tomato seeds are traded widely and are known to pose a risk of spreading viruses and other pathogens internationally (e.g., ProMED post 20140122.2222560).

Coinfection of ToBRFV with _Pepino mosaic virus_ (genus _Potexvirus_) and _Tomato spotted wilt virus_ (TSWV; genus _Orthotospovirus_) has been found in tomato (ProMED posts 20191029.6751082, 20200507.7307615), as well as with TSWV in capsicum (see link below). It is thought that the respective symptoms may have been due to either virus or synergism. Further research is needed to clarify a potential role of ToBRFV in coinfections and to determine whether its presence in coinfections may have led to earlier cases of misdiagnosis and delayed identification of this new virus.
ToBRFV on tomato:×0/4137.jpg and×0/4138.jpg
ToBRFV symptoms on capsicum:

Information and characterisation of ToBRFV: (with distribution and host list), (Jordan), (Israel), (TSWV co-infection, capsicum) and via
ToBRFV spread: (new reservoir hosts) and (by pollinators)
Tomato resistance breeding:, and
ToBRFV seed treatment:
Recent ToBRFV updates. Europe:, in-sardinia,, (1st report Slovakia, ex Austria) and (first at seed production and breeding site)
International spread of tobamoviruses by seeds (review):
Virus taxonomy via:
EPPO A2 quarantine list:
– Mod.DHA