Controlling the pinewood nematode: finding the best balance between cost and effectiveness

INRAE - National Research Institute for Agriculture, Food and Environment

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Maritime pines on the east cost of Ile d'Yeu in France

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Credit: INRAE - Jean-Marie BOSSENNEC

The pinewood nematode (Bursaphelenchus xylophilus) is the most devastating parasite of pine forests across Eurasia. To combat the pinewood nematode, European regulation requires that Member States clear-cut all susceptible tree species within a 500 metre radius of infested trees. However, this measure has not made it possible to eradicate the disease in Portugal, and a previous modelling study1showed it was not effective in vast, pine-only forests. In this new modelling study, scientists compare the cost-effectiveness of clear-cutting within a 500 metre radius of the infestation site versus selective felling, where only infested trees that display symptoms of the disease are cut inside the 20 km x 20 km area around the infestation site in a homogenous stand of maritime pines. To do so, scientists simulated different methods and intensities of ground-based and aerial forest monitoring.

A comprehensive model for assessing different methods of controlling the pinewood nematode

This study is based on a dispersal model of the pinewood nematode’s insect vector, Monochamus galloprovincialis (Robinet C. et al. 2019, Robinet C. et al. 2020), and the transmission of the pinewood nematode, with adjustments for the insect’s flight behaviour and the location of pines. The model simulates different monitoring methods and their effectiveness in the Landes forest in southwest France: ground-based visual monitoring from forest roads and paths; ground-based monitoring combined with trapping of the insect vector; and aerial monitoring combined with AI-assisted image analysis. The scientists also incorporated the costs associated with monitoring and analyses to identify the nematode, along with the different types of felling (clear-cutting or selective), and the loss of income linked to the felling of healthy trees. Cost-effectiveness was calculated for several scenarios of nematode introduction (number of dispersing insect vectors), several monitoring methods and intensities, and different proportions of symptomatic trees among infested trees. 

Selective felling offers the best cost-effectiveness, provided monitoring is stepped up 

The results show that aerial monitoring is better than ground surveys. Rapid advances in remote sensing combined with artificial intelligence to detect declining pines should enable even more effective monitoring in the years ahead. For the time being, however, ground surveys remain the only method used. Research is currently under way to make remote sensing more operational (see below).

Whatever the strategy –– selective felling or clear-cutting –– eradication of the pinewood nematode is only possible under optimal conditions for detecting the pinewood nematode: namely, if monitoring is carried out several times by aircraft with high detection efficiency at the times when trees infested by the nematode show symptoms. Under these optimal conditions, selective felling of trees could cost as much as 200 times less than clear-cutting, as it avoids the costs associated with the loss of non-infested trees. 

Under non-optimal conditions, eradication is impossible regardless of the cutting method, in which case the objective is to reduce the impact of the nematode by containing the disease. The selective felling of declining trees still offers the best cost-effectiveness ratio.

These results show that improving monitoring is essential in order to effectively limit the spread of the pinewood nematode. 

Advances and hope in research on remote sensing to monitor forests

Monitoring of the nematode in France currently relies on ground surveys and a network of traps for insect vectors (Mariette et al. 2023). However, research on remote sensing to monitor forests is expanding rapidly. Satellite remote sensing now makes it possible to identify clusters of declining trees fairly well, such as patches of mortality due to spruce bark beetle attacks (the FORDEAD method; Dutrieux et al. 2024). In the case of the pinewood nematode, declining pines are more isolated, scattered across the landscape, and need to be detected individually. For the moment, European satellite images lack the resolution necessary for this. Likewise, drones cannot be used to monitor forest landscapes because the area to be covered is too large. It is therefore necessary to use aircraft or microlights (the method considered in this article), but this detection method is still at the experimental stage. Another important line of research is the processing of these images using AI, which requires a large training dataset and is still under development. Finally, detecting a declining tree does not mean that the cause of its decline is the pinewood nematode. Research is therefore underway to identify the spatio-temporal distribution pattern of symptomatic trees likely damaged by the pinewood nematode. Three of the article’s authors are involved in FORSAID https://forsaid.eu/), a European project aimed at developing a diagnostic tool that combines high-resolution imagery and AI-based analysis.

References

Dutrieux R., Ose K., de Boissieu F., Féret J.-B. (2024). Fordead: a python package for vegetation anomalies detection from Sentinel-2 images. Zenodo. DOI: 10.5281/zenodo.12802456.

Mariette N., Hotte H., Chappé A.-M. et al. (2023). Two decades of epidemiological surveillance of the pine wood nematode in France reveal its absence despite suitable conditions for its establishment. Annals of Forest Science, 80 :21. https://doi.org/10.1186/s13595-023-01186-8 

Find out more about Pinewood nematod with our overview in 8 questions and answers

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Journal

Journal of Applied Ecology

DOI

10.1111/1365-2664.70318 

Article Title

How to eradicate an invasive forest pest without clear-cutting

Article Publication Date

11-Mar-2026

 

Challenging a 300-year-old law of friction

University of Konstanz

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Schematic of two magnetic layers composed of permanent magnets. The magnets in the upper layer are free to rotate, while those in the lower layer are fixed. When the layers move relative to each other, the upper magnets periodically reorient, dissipating energy and giving rise to contactless friction. By decreasing the distance between the layers, which controls the effective load, the friction does not increase monotonically, in contrast to the prediction of Amontons’ law.
Copyright: Hongri Gu

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Credit: Hongri Gu

Researchers at the University of Konstanz have uncovered a new mechanism of sliding friction: resistance to motion that arises without any mechanical contact, driven purely by collective magnetic dynamics. The study shows that friction does not necessarily increase steadily with load, as postulated by Amontons’ law – one of the oldest and most fundamental empirical laws of physics – but can instead exhibit a pronounced maximum when internal magnetic ordering becomes frustrated.

For more than three centuries, Amontons’ law has linked friction directly to load, reflecting the everyday experience that heavier objects are harder to move; for example, pushing a heavy piece of furniture requires far more effort than sliding a light chair. This behaviour is commonly attributed to tiny deformations of the surfaces in contact under load, which increase the number of microscopic contact points and thereby enhance friction. In most classical situations, these deformations remain small and do not qualitatively change the internal structure of the materials during sliding. It is therefore not clear whether Amontons’ law will also hold when sliding induces much stronger internal reconfigurations, as can occur in magnetic materials where motion can modify the magnetic order.

To explore this regime, the team carried out a tabletop experiment using a two-dimensional array of freely rotating magnetic elements moving above a second magnetic layer. Although the two layers never come into physical contact, their magnetic coupling gives rise to a measurable friction force. By varying the separation between the layers, the researchers could continuously tune the effective load while directly observing how the internal magnetic configuration evolves during motion.

“By changing the distance between the magnetic layers, we could drive the system into a regime of competing interactions where the rotors constantly reorganize as they slide,” says Hongri Gu, who carried out the experiments.

Strikingly, friction is weakest at both small and large separations. At intermediate distances, however, competing interactions dominate: the top layer favours an antiparallel alignment of magnetic moments (parallel, but pointing in opposite directions), while the underlying layer favours a parallel arrangement. This incompatibility forces the system into a dynamically unstable configuration. As the layers slide past each other, the magnets are repeatedly driven to switch between these incompatible states in a hysteretic manner (that means the current state depends on its past history), strongly enhancing energy dissipation and producing a pronounced maximum in friction.

“From a theoretical perspective, this system is remarkable because friction does not originate from a physical surface contact, but from the collective dynamics of magnetic moments,” explains Anton Lüders, who developed the theoretical description. The competing magnetic interactions naturally lead to hysteretic reorientations during motion and, as a result, to a friction force that varies non monotonically with load. In this sense, the breakdown of Amontons’ law is not an anomaly but a direct consequence of magnetization dynamics during sliding.

“What is remarkable is that friction here arises entirely from internal reorganization,” adds Clemens Bechinger, who supervised the project. “There is no wear, no surface roughness and no direct contact. Dissipation is generated solely by collective magnetic rearrangements.”

Because the underlying physics is scale free, the results extend far beyond the macroscopic model system. Similar effects may arise in atomically thin magnetic materials, where even small mechanical displacements can switch magnetic order. The findings therefore open new avenues for probing and controlling magnetism through frictional measurements.

In the long term, this work points toward tunable frictional interfaces without wear. By exploiting magnetic hysteresis, friction could be adjusted remotely and reversibly, enabling concepts such as frictional metamaterials, adaptive dampers or contactless control elements. Potential applications range from micro and nanoelectromechanical systems, where wear limits device lifetime, to magnetic bearings, vibration isolation and atomically thin magnets, where mechanical motion is tightly coupled to internal magnetic order. More broadly, magnetic friction offers a new route to accessing collective spin dynamics through purely mechanical measurements, forging a novel link between tribology and magnetism.

 

Facts: Embargoed until 18 March 2026, 06:00 US Eastern Time (10:00 London Time, 11:00 CET)   Original publication: Hongri Gu, Anton Lüders, and Clemens Bechinger, Nonmonotonic Magnetic Friction from Collective Rotor Dynamics (Nature Materials) DOI: https://doi.org/10.1038/s41563-026-02538-1   Press release: University of Konstanz, supported by AI

 

Note to editors:
You can download an image here: https://www.uni-konstanz.de/fileadmin/pi/fileserver/2026/300_jahre_altes_reibungsgesetz.png

Caption: Schematic of two magnetic layers composed of permanent magnets. The magnets in the upper layer are free to rotate, while those in the lower layer are fixed. When the layers move relative to each other, the upper magnets periodically reorient, dissipating energy and giving rise to contactless friction. By decreasing the distance between the layers, which controls the effective load, the friction does not increase monotonically, in contrast to the prediction of Amontons’ law.
Copyright: Hongri Gu

Further images and videos of the experimental setup and magnetic rotor dynamics are available upon request.

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Journal

Nature Materials

DOI

10.1038/s41563-026-02538-1 

Article Title

Nonmonotonic Magnetic Friction from Collective Rotor Dynamics

Article Publication Date

18-Mar-2026

 

Scientists turn rubber waste into New Materials and capture CO2

Researchers have unveiled two breakthrough techniques for chemically recycling and upcycling nitrile‑rubber products, such as disposable gloves, seals, and industrial parts, into new materials that also capture CO2

University of St. Andrews

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Nitrile Gloves upcycling

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Credit: Amit Kumar/University of St Andrews

Researchers at the University of St Andrews have unveiled two breakthrough techniques for chemically recycling and upcycling nitrile‑rubber products, such as disposable gloves, seals, and industrial parts, into new materials that are also capable of capturing carbon dioxide. 

The development of sustainable methods for the upcycling of plastic waste is one of the most important challenges in achieving a circular economy and can play a significant role in tackling the climate crisis.  

Among various plastics that need to be recycled, nitrile butadiene rubber (NBR) has received comparatively little attention, despite a large market of 36 million tons or $2.5 billion globally per year. NBR has wide applications ranging from disposable gloves to hoses, seals, and circular seals used to prevent leaks. 

NBR is challenging to recycle due to its thermoset nature, with less than 2% currently recycled, often through low-value downcycling.  

However, in a paper published today (19th March) in Angewandte Chemie, researchers from the School of Chemistry at St Andrews, introduce two new ways to chemically recycle NBR and turn it into useful new materials.  

By using a ruthenium catalyst and hydrogen gas, researchers were able to “unlock” the chemical bonds in NBR and convert it into either polyamines or polyols, depending on the reaction conditions. Remarkably, the process to make polyamines works at temperatures as low as 35 °C, while making polyols requires higher temperatures but achieves excellent efficiency. 

Additionally, the resulting polyamines were shown to capture CO₂, with their amine groups binding carbon dioxide to form stable compounds, a process widely employed in industrial carbon-capture technologies. This opens the possibility of using recycled materials to remove CO₂ from emissions or the atmosphere, combining plastic recycling with climate action. 

Sustainable chemical recycling or upcycling routes to convert NBR into valuable chemicals or materials would be a huge leap towards greater sustainability 

Lead author Dr Amit Kumar from the School of Chemistry said: “We are thrilled by this discovery, which lets us turn nitrile glove waste from chemistry labs into valuable new materials. With further development, this technology could tackle two of the planet’s biggest waste problems at once: plastic pollution and carbon dioxide emissions.”     

ENDS 

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Journal

Angewandte Chemie

DOI

10.1002/anie.202525705 

Method of Research

Meta-analysis

Subject of Research

Not applicable

Article Title

Chemical Upcycling of Nitrile Butadiene Rubbers to Polyamines and Polyols by Chemoselective Catalytic Hydrogenation

Article Publication Date

18-Mar-2026