It’s possible that I shall make an ass of myself. But in that case one can always get out of it with a little dialectic. I have, of course, so worded my proposition as to be right either way (K.Marx, Letter to F.Engels on the Indian Mutiny)
Saturday, May 10, 2025
Generalist pests cause more damage, specialists kill more trees
Foundational insights for classifying pests by tree damage and mortality
The hemlock woolly adelgid, a nonnative invasive insect and specialist, has killed millions of hemlock trees in the U.S., highlighting the potential threat and impact such pests can have on our forests.
A recent study in the journal Forests highlights the critical need for understanding and managing nonnative forest specialist and generalist pests.
“We classify pests for easier management; it’s just a matter of which we should focus on first, given limited labor and funding,” says Qinfeng Guo, a research ecologist with the USDA Forest Service and lead author of the study.
The hemlock woolly adelgid, introduced accidentally in the 1950s, remains a major tree-killer in the U.S. In Japan, its population is controlled by natural predators and host tree resistance, but in the eastern U.S., where it's invasive, these controls are absent, causing significant damage. The National Park Service reported a loss of 80-90% of eastern hemlocks at some sites. The hemlock woolly adelgid is one of 66 nonnative species analyzed by researchers in this study.
“Invasive insects are the biggest threat to forests. This study aims to shed light on the best methods for defining and confronting this vulnerability,” says Kevin Potter, second author of the study.
Specialist and generalist classifications are used frequently in the field of forest management. Specialist pests are those that consume one or very few host species, believed to take more of a toll on their hosts, while generalists usually infest more species and sometimes across multiple genera or even families.
The key finding of this study was that specialists caused more tree deaths than generalists. However, contrary to expectations, generalists inflicted more nonlethal damage due to their broader impact across multiple species. The study also found that newer nonnative pests caused more tree mortality than older ones, possibly because older pests have already killed the most vulnerable trees, spread to larger areas, and allowed host trees to adapt over time.
Guo and Potter stress the importance of better classification. As it is now, there is no standard approach to differentiating specialists from generalists, especially when it comes to assessing which is more damaging. Depending on the way the damage is measured, different conclusions can be drawn, leading to conflicting findings.
In their study, Guo and Potter analyze damage from 66 nonnative pest species, looking for differences between nonnative generalist and nonnative specialist pests. They do this using two approaches: the binary approach (each pest is either a generalist or a specialist) and the specialist-generalist continuum.
Of the two approaches explored, the specialist-generalist continuum approach made for clearer findings given the limited data available.
“If you have enough species to form a gradient or continuum from specialists to generalists, you can examine host responses along the gradient in terms of infestation and impacts,” Guo comments, reiterating the importance of clear classifications and a need to fill the current gaps in data.
In order to understand current infestations and predict and prepare for future challenges, it’s important that we further efforts to understand the dynamics of invasive pest infestations and how to best manage them.
“Unfortunately, invasive pests are here to stay, and we need to understand how to manage them,” says Potter.
A UW-led team has developed a system, called ProxiCycle, that logs when a passing car comes too close to a cyclist (four feet or less). A small, inexpensive sensor plugs into bicycle handlebars and tracks the passes, sending them to the rider’s phone. Here the team tests how well the system estimates the distance of a passing car. The line on the left is a meter for scale.
While things like rain or hills can keep people from cycling, a major impediment is the risk of getting hit by a car. It’s hard to identify the safest routes to ride, especially for beginner cyclists, and a key way to flag dicey streets involves time and injury: waiting until cars have hit several cyclists at a given location.
A University of Washington-led team has developed a system, called ProxiCycle, that logs when a passing car comes too close to a cyclist (within four feet). A small, inexpensive sensor plugs into bicycle handlebars and tracks the passes, sending them to the rider’s phone. The team tested the system for two months with 15 cyclists in Seattle and found a significant correlation between the locations of close passes and other indicators of poor safety, such as collisions. Deployed at scale, the system could support mapping or navigating cyclists on safer bike routes through cities.
“Experienced cyclists have this mental map of which streets are safe and which are unsafe, and I wanted to find a simple way to pass that knowledge down to novice cyclists,” said lead author Joseph Breda, a UW doctoral student in the Paul G. Allen School of Computer Science & Engineering. “Cycling is really good for your health and for the environment. Getting more people biking more often is how we reap those rewards and increase safety in numbers for cyclists on the roads.”
To start, researchers surveyed 389 people in Seattle. Respondents of all cycling experience levels ranked the threat of cars as the factor which most discouraged them from cycling, and said they’d be very likely to use a map that helps navigate for safety. But a key factor preventing this is limited data on road safety.
The team then built a small sensor system that plugs into a bike’s left handlebar. The system, which costs less than $25 to build, consists of a 3D printed plastic casing that houses a pair of sensors and a Bluetooth antenna. The antenna transmits data to the rider’s phone, where the team’s algorithm susses out what’s a passing car rather than a person, or another cyclist, or a tree.
The team validated the system both by testing it in a parking lot, with a car passing at different distances, and with seven cyclists riding through Seattle with GoPro cameras on their handlebars. Researchers watched the footage from these rides and compared this to the sensor output.
The team then recruited 15 cyclists through the newsletter of Seattle Neighborhood Greenways, a local advocacy group. Each got a ProxiCycle sensor, a custom Android application and instructions. The cyclists took 240 bike rides over two months and recorded 2,050 close passes. Researchers then compared the locations of close passes with riders’ perceived safety at different locations in the city — which they measured by showing cyclists images of locations and having them rate how safe they felt at those locations (referred to as “perceived safety”) — and with the locations of known automobile-to-bike collisions in the last five years.
The team found a significant correlation between close passes and both other indicators of cycling risk. They also found that this measure of close passes was a better indicator of actual safety than the surveyed perceived safety, which is the current standard used by policymakers to study safety when collisions aren’t enough.
In the future, researchers hope to scale the study up and potentially account for other risk factors, such as cyclists being hit by opening car doors, and deploy ProxiCylce in other cities. With enough data, existing bike mapping apps, such as Google Maps or Strava, might include safer route suggestions for cyclists.
Some of those routes involve only minor adjustments.
“One study participant, who was living down by Seattle Center, was biking down Mercer all the time,” Breda said. “It’s this busy, multi-lane road. But just before the study, they found out that there’s a great bike lane on a quieter street, just one block north.”
Keyu Chen, an applied science lead at Gridware, and Thomas Ploetz, a professor at Georgia Institute of Technology, are also co-authors on this paper. Shwetak Patel, a UW professor in the Allen School, is the senior author.
ProxiCycle: Passively Mapping Cyclist Safety Using Smart Handlebars for Near-Miss Detection
A UW-led team has developed a system, called ProxiCycle, that logs when a passing car comes too close to a cyclist (four feet or less). A small, inexpensive sensor plugs into bicycle handlebars and tracks the passes, sending them to the rider’s phone. Here is the sensor on a table.
Credit
Breda et al./CHI ‘25
Women non-smokers still around 50% more likely than men to develop COPD
Findings challenge idea that heightened vulnerability to cigarette smoke is to blame
Women’ are around 50% more likely than men to develop COPD, the umbrella term for chronic lung conditions, such as emphysema and bronchitis, even if they have never smoked or smoked much less than their male counterparts, suggests observational research, published in the open access journal BMJ Open Respiratory Research.
The findings challenge the widely held belief that women’s increased vulnerability to cigarette smoke likely explains this disparity, conclude the researchers.
Smoking is the principal cause of COPD. But despite significant falls in cigarette smoking over the past 50 years, it remains a leading cause of death in the USA, with the prevalence of COPD in women approaching that of men, say the researchers.
Women with COPD tend to have more severe symptoms, and at a younger age, than their male counterparts, prompting the suggestion that the explanation may lie in a heightened susceptibility to the effects of cigarette smoke, explain the researchers.
To clarify the associations between gender, cigarette smoke, and COPD, and to update previous estimates of the prevalence and impact of COPD, the researchers drew on a large nationally representative US survey of adults from the 2020 National Health Interview Survey (NHIS).
Respondents (12,638 women and 10,390 men aged at least 40) were asked about their smoking history, what tobacco products they used, and whether they vaped.
Women reported lower rates of both current and former cigarette, cigar, and pipe smoking, and smokeless tobacco use than men, but similar rates of vaping.
The prevalence of COPD was just under 8% for women and 6.5% for men. Women with COPD were more likely to have never smoked cigarettes than men with COPD (26.5% vs just over 14%), and less likely to use other tobacco products except for e-cigarettes (26.5% vs 20%).
Women also reported smoking fewer daily cigarettes than men, averaging around 18 compared with around 22, and to have done so for fewer years. And they were less likely than men to have started smoking before the age of 15:19% vs 28%.
Yet the prevalence of COPD was higher among women who had ever smoked than it was among men: 16% vs 11.5%. And among women who had never smoked the prevalence of COPD was almost twice as high as it was in male non-smokers: just over 3% compared with just over 1.5%.
In further analysis, female gender was associated with a significantly (47%) higher risk of being diagnosed with COPD after accounting for potentially influential factors.
This gender difference in risk persisted, irrespective of smoking history: among those who had never smoked, women were 62% more likely to be diagnosed with COPD, and among those who had ever smoked they were 43% more likely to do so.
The researchers acknowledge that their study relied on self report rather than objectively measured data. And they lacked potentially important information on hormonal influences, family history, or infectious, occupational, and environmental exposures.
But they nevertheless suggest: “These findings should raise questions about whether differing susceptibility to tobacco smoke is the key factor driving the increased COPD prevalence in women in the USA.
“If women were more susceptible to the effects of smoking, we would not expect to see a nearly identical risk per 10 pack-year exposure, nor would we expect to see a similarly increased relative risk among those who had never smoked.”
And they conclude: “Our findings refine prior estimates of COPD among those without a smoking history and re-emphasise the high burden of COPD in women, underscoring the need for thoughtful efforts to prevent, diagnose, and treat their disease.”
Gender, tobacco and chronic obstructive pulmonary disease: analysis of the 2020 National Health Interview Survey
Article Publication Date
8-May-2025
North Korea’s illegal wildlife trade threatens endangered species
The North Korean government engages in unsustainable and illegal wildlife trade, which includes species protected under its own laws and poses a threat to biodiversity recovery in the region, finds a groundbreaking new study by UCL researchers.
Bear bile farms exist in several different countries in Asia. The practice has been criticised for its impact on wild animal populations and the health and welfare of captive animals. Image taken on a bear farm in South Korea.
The North Korean government engages in unsustainable and illegal wildlife trade, which includes species protected under its own laws and poses a threat to biodiversity recovery in the region, finds a groundbreaking new study by UCL researchers.
The report, published in Biological Conservation, found that although North Korea has a regulatory system of protected areas and protected species, these are regularly breached by people hunting and trapping wild animals for personal consumption or black market trade, either domestically or for sale to buyers in China.
Additionally, the North Korean state itself is implicated in, and actively profiting from, harvesting and trade of endangered species protected under domestic or international law. Protected species reported from state wildlife trade include Asiatic black bears, long-tailed gorals and Eurasian otters.
Their study is based on extensive interviews with North Korean defectors, including former hunters, wildlife trade middlemen and buyers, and is the first in-depth assessment of North Korea’s multifaceted wildlife trade, carried out between 2021 and 2022. The study was carried out in collaboration with researchers from the ZSL's Institute of Zoology, Norwegian Institute for Nature Research (NINA) and University of Inland Norway.
The researchers argue that the North Korean government’s compliance with domestic protected species legislation should be an immediate priority. They call on China, as a key market for North Korean wildlife products, to continue efforts to curb domestic demand for illegal wildlife and put diplomatic pressure on its economically dependent neighbour to disengage from state-sanctioned illegal wildlife trade.
Lead author Dr Joshua Elves-Powell (UCL Geography) said: “The widespread harvesting of North Korea’s wildlife, driven by the economic limitations of the North Korean state and the shortages of food, medicine and basic goods experienced by many of its citizens, is an important threat to the biodiversity of North Korea and the wider region.”
China is the primary international market for the North Korean wildlife trade, with notable products including wild meat, furs, and body parts for use in traditional medicine. Some of this trade breaches China’s commitments as a Party to the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) and member of the UN Security Council, for example UN Security Council Resolution 2397, which prohibits the export of food from North Korea.
State wildlife trade
North Korean defectors who took part in the study reported that the North Korean state receives wild animals and their body parts from state-sanctioned hunters and local communities.
The study found this includes species which are legally protected in North Korea, including long-tailed gorals – hoofed mammals resembling a goat – and Eurasian otters. These species have been used domestically, for example furs in the manufacture of winter clothing, but they are also reported to be used as a tradable resource.
This is in keeping with North Korea’s use of natural resources such as timber and coal, but also illegal trade in weapons and narcotics, to generate revenue.
The study also details that the North Korean state operates wildlife farms, including animals such as otters, pheasants, deer, and Asiatic black bears. North Korea is believed to have first started farming bears for their bile in the 20th century, before the practice spread to China and South Korea. Bear bile has been used in various traditional Asian medicines, including traditional Korean medicine and traditional Chinese medicine.
Bear bile farming has been widely condemned by conservationists and animal welfare campaigners for perpetuating demand for endangered species and the unnecessary suffering of farmed animals.
Economic hardship drives black market trade
In addition, the report identifies economic hardship as a major driver of black market wildlife trade in North Korea. A wide range of animals are reported to be hunted and trapped for meat, for use in traditional medicine, to protect crops or domestic livestock, or for sale on the black market.
When North Korea’s economy collapsed in the 1990s, preceding a major famine which is believed to have killed between 600,000 and one million people, the country’s informal economy grew rapidly, as ordinary citizens turned to buying and selling goods, including wildlife, to provide essential food resources and generate income.
While economic conditions in North Korea have since improved, the researchers found no evidence that black market trade in wildlife has halted.
Dr Elves-Powell said: “A hunter might simultaneously engage in both state-sanctioned and black market trade. For example, the skin of an animal like a red fox might be submitted to the state, but it might equally be sold to North Korean middlemen to smuggle across the North Korea-China border. The hunter could keep the animal’s meat - a valuable food resource - for their family, or try to sell it locally.”
Impact on biodiversity
North Korea’s extensive harvesting of wildlife has serious consequences for the country’s wildlife populations, with evidence that almost all native mammal species larger than half a kilogram have been targeted in some capacity.
The sable, a native species of marten, was highly sought after by North Korean hunters for its fur but is now likely to be functionally extinct in the country. There are similar concerns regarding Amur tigers and Amur leopards, while deer populations are also thought to have been severely reduced due to overhunting.
The researchers warn that if exploitation in North Korea continues to pose a risk to wildlife populations, it could threaten biodiversity recovery throughout the region.
In recent years, Amur tiger populations have started to recover along North Korea’s border with China, but are likely to be targeted by hunters if they cross into North Korea. North Korea could also act as a barrier to the movements of native terrestrial species between the Korean Peninsula and mainland Asia.
Notes to Editors
For more information or to speak to the researchers involved, please contact Michael Lucibella, UCL Media Relations. T: +44 (0)75 3941 0389, E: m.lucibella@ucl.ac.uk
Joshua Elves-Powell, Jan C. Axmacher, John D.C. Linnell, Sarah M. Duranta, ‘Unsustainable and illegal wildlife trade during periods of extreme hardship threatens biodiversity in North Korea’ will be published in Biological Conservation on Friday 9 May 2025, 00:01 UK time and is under a strict embargo until this time.
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Unsustainable and illegal wildlife trade during periods of extreme hardship threatens biodiversity in North Korea
Article Publication Date
9-May-2025
Bear bile farms exist in several different countries in Asia. The practice has been criticised for its impact on wild animal populations and the health and welfare of captive animals. Image taken on a bear farm in South Korea.
The biodiversity of North Korea and the threats it faces are poorly known. The Korean Demilitarized Zone (DMZ), which divides North and South Korea, is home to a wide range of species and is an important over-wintering site for migratory species like cranes.
The biodiversity of North Korea and the threats it faces are poorly known. The Korean Demilitarized Zone (DMZ), which divides North and South Korea, is home to a wide range of species and is an important over-wintering site for migratory species like cranes.
Water deer
The Korean Peninsula is home to a globally important population of water deer. Deer were one of the animals most often reported to have been eaten as wild meat in North Korea.
Water deer II
The Korean Peninsula is home to a globally important population of water deer. Deer were one of the animals most often reported to have been eaten as wild meat in North Korea.
Long-tailed gorals, here photographed in a restoration programme in South Korea, are restricted to the Korean Peninsula, China and Russia and are considered vulnerable to extinction. They are listed under Appendix I of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES), the highest level of protection afforded by the convention.
