Trees vs. disease: Tree cover reduces mosquito-borne health risk

Stanford University

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Study co-author Meghan Howard checks a battery-powered mosquito trap.

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Credit: Erin Mordecai

Protecting trees might not seem like a public health strategy, but new research suggests it could be—especially in the tropics. A Stanford University-led study published May 28 in Landscape Ecology, shows that in Costa Rica, even modest patches of tree cover can reduce the presence of invasive mosquito species known to transmit diseases like dengue fever. The illness often brings flu-like symptoms and can escalate to severe bleeding, organ failure, and even death without proper medical care. The findings can inform land use decisions and tree preservation strategies in rural areas, according to the researchers.

“We already knew that small patches of tree cover support biodiversity for a wide range of plants and animals in this region,” said study lead author Johannah Farner, a Ph.D. student in biology in the Stanford School of Humanities and Sciences. “It turns out to be true for mosquitoes too – and has the upside of keeping out a disease-carrying invasive species.”

“It may sound counterintuitive to suggest that we should protect habitat for mosquitoes. But making sure that the many native mosquito species that do not spread disease can stick around can help prevent dangerous invasive species from moving in.”

Using field observations and satellite data on land cover for a patchwork of forests, farms, and residential areas in southern Costa Rica, the researchers found the presence of the Aedes albopictus mosquito, a dengue vector, decreased in areas with more tree cover while the total number of mosquito species increased. That’s because more species leads to more competition, making it harder for an invasive species to find unoccupied space or resources, such as food or breeding sites. Also, more diverse environments are often more stable and resilient to disturbance, making them less hospitable to fast-spreading, opportunistic invaders like Aedes albopictus.

Costa Rica has numerous mosquito-borne diseases and two invasive mosquito species serving as vectors. The forests surveyed in the study hosted a high diversity of mosquito species, none of which were the dengue vector Aedes albopictus . Residential areas, by contrast, had lower overall diversity and were far more likely to harbor the invasive, disease-spreading species. Agricultural areas fell somewhere in between, with outcomes seemingly tied to the intensity and type of land use.

Natural habitats exist alongside agriculture and development in rural areas throughout the world. In Costa Rica and beyond, these areas can provide pathways to conserving biodiversity. The study’s findings offer a potential win-win strategy: protecting trees can help conserve biodiversity while also reducing the likelihood of disease transmission. That is good news in the face of warmer temperatures, changes in rainfall, and human activity that are enabling the spread of mosquito-borne illnesses to new places often unprepared to deal with them.

The researchers emphasize the need to do more research to understand how other vector species respond to increased tree cover and what factors beyond tree cover contribute to dengue transmission. The study underscores the continued importance of forest reserves, which remain critical biodiversity strongholds and natural buffers against disease. Still, researchers caution that planting trees outside of forests should be viewed as a complement—not a replacement—for conserving larger natural areas.

“We need to know more about what drives dengue in rural tropical areas,” said study senior author Erin Mordecai, an associate professor of biology in the Stanford School of Humanities and Sciences. “This work shows that forests and tree cover can reduce risk, but identifying other land use types that sustain vector populations is the next frontier for controlling this rapidly expanding disease.”

To address this important research gap, Mordecai and Giulio De Leo, a professor of oceans and Earth system science in the Stanford Doerr School of Sustainability, founded the Disease Ecology in a Changing World (DECO) program at Stanford. DECO-affiliated researchers work to identify and mitigate the drivers of rural dengue and other diseases associated with environmental degradation.

Stanford researchers studied mosquito populations in rural Costa Rica.


Credit

Chuck Katz

Mosquitoes in a device that allows researchers to pull insects in through suction.


Stanford biologist Erin Mordecai throws a weighted line up to a tree branch to hoist a mosquito trap into the canopy, while fellow researchers look on.

Credit

Erin Mordecai

Mordecai is also is also a senior fellow at the Stanford Woods Institute for the Environment, member of Bio-X, a faculty affiliate of the Stanford Institute for Human-Centered Artificial Intelligence and the Stanford Center for Human and Planetary Health, and a faculty fellow at the Stanford Center for Innovation in Global Health and the Stanford King Center on Global Development.

This work was supported by the National Institutes of Health, the National Science Foundation (with the Fogarty International Center), the Stanford Center for Innovation in Global Health, the Stanford King Center on Global Development, the Stanford Woods Institute for the Environment, the Ward Wilson Woods Jr. Environmental Studies Fund, the American Philosophical Society, the Bing-Mooney Fellowship, and the ARCS Fellowship.

Coauthors of the study also include Meghan Howard, a master’s student in biology at Stanford who spearheaded the field research; Jeffrey Smith of Princeton University; and Christopher Anderson of Planet Labs.

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Journal

Landscape Ecology

Article Title

Local tree cover predicts mosquito species richness and disease vector presence in a tropical countryside landscape

Article Publication Date

28-May-2025

 

New study reveals key to increasing Black women tech founders: startup employment

Strategic Management Society

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A groundbreaking new study published in the Strategic Management Journal uncovers a powerful and practical strategy to address the longstanding underrepresentation of Black women in the tech startup world: working at startups before founding one.

Despite the surge in entrepreneurship across the U.S., diversity remains a critical challenge. While 71% of startup founders are white, just 6% are Black—and a mere fraction of that figure represents Black women. In response to this disparity, researchers from Texas A&M University, Arizona State University, and the University of North Carolina at Chapel Hill examined how employment at a startup can pave the way for underrepresented individuals, particularly Black women, to become founders.

“Previous studies suggest that working in a startup increases one’s likelihood of founding a company,” says lead author Dr. Christopher G. Law, Assistant Professor of Management at Texas A&M. “We wanted to find out if this effect differs across demographic groups—and the answer is yes. In fact, it’s especially powerful for Black women.”

The research team—comprising Law, Travis Howell (Arizona State), Chris Bingham, and Sekou Bermiss (UNC Chapel Hill)—analyzed data from Venture For America (VFA), a nonprofit that places recent college graduates in startup roles through a competitive fellowship. Using application data from over 8,000 individuals between 2013 and 2023, along with LinkedIn career tracking, the team identified clear patterns in startup-to-founder transitions.

Their findings show that individuals with startup experience are 91% more likely to start their own ventures. Even more striking, this effect was disproportionately high for Black women. Through interviews with 39 startup professionals—including 10 Black women founders—the researchers discovered why: the power of representation and exposure.

“Many of the Black women we interviewed never saw themselves as startup founders—until they worked at a startup,” explains Bingham, Phillip Hettleman Distinguished Professor. “Seeing founders up close helped dismantle psychological barriers. It wasn’t about having all the answers—it was about realizing those leading startups were just figuring it out too.”

The implications are profound. As Bermiss, Associate Professor of Strategy, notes, “Black women bring new ideas, questions, and goals to the table. Encouraging their entrepreneurial journeys isn’t just a diversity win—it’s an innovation win.”

The researchers advocate for targeted policies and fellowship programs that connect Black women to early-stage startups as employees, laying the groundwork for future entrepreneurial leadership. This approach not only empowers individuals but also enriches the startup ecosystem with fresh perspectives and untapped potential.

To read the full context of the study and its methods, access the full paper available in the Strategic Management Journal.

About the Strategic Management Society

The Strategic Management Society (SMS) is the leading global member organization fostering and supporting rigorous and practice-engaged strategic management research. SMS enjoys the support of 3,000 members, representing more than 1,100 institutions and companies in more than 70 countries. SMS publishes three leading academic journals in partnership with Wiley: Strategic Management Journal, Strategic Entrepreneurship Journal, and Global Strategy Journal. These journals publish top-quality work applicable to researchers and practitioners with complementary access for all SMS Members. The SMS Explorer offers the latest insights and takeaways from the SMS Journals for business practitioners, consultants, and academics.

Click here to subscribe to the monthly SMS Explorer newsletter.

Click here to learn more about the programs and opportunities SMS has to offer.

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Journal

Strategic Management Journal

DOI

10.1002/smj.3705 

Method of Research

Data/statistical analysis

Subject of Research

People

Article Title

From joiners to founders: Startup employment and underrepresented entrepreneurs

After mild stroke, more sleep or time spent trying to sleep tied to thinking problems

American Academy of Neurology

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MINNEAPOLIS — After a mild stroke or transient ischemic attack (TIA), people who spend more time in bed sleeping or trying to sleep may be more likely to have lower scores on tests of thinking and memory skills and changes in their brains that can lead to dementia or second strokes, according to a study published on May 28, 2025, online in Neurology®, the medical journal of the American Academy of Neurology.

Spending longer in bed—when some of that time can be not sleeping due to difficulty falling asleep, fragmented sleep, poor quality sleep or other problems—can be a sign of a sleep disorder. The study found that both people with longer in-bed times and with longer sleep durations were more likely to have these brain changes.

The study does not prove that these sleep issues cause these brain changes and thinking problems; it only shows an association.   

“These results show that disturbed sleep may be a marker of adverse brain health, even for people with mild strokes or TIAs,” said study author Joanna M. Wardlaw, MD, of the University of Edinburgh in the United Kingdom. “While many people know that a lack of sleep can lead to health issues, less is known about the effects of sleeping longer at night or spending a long time in bed trying to make up for having trouble sleeping—whether people are doing this consciously or not.”

The study involved 422 people from Edinburgh and Hong Kong with an average age of 66 who had a mild stroke or a TIA, which is also called a “mini stroke.” Within one to three months after the stroke, all participants had brain scans, filled out sleep questionnaires and took cognitive tests.

The participants had an average score of one point on a test where scores of one to four indicate a mild stroke.

People who spent a longer time in bed were more likely to have signs of damage to small blood vessels in the brain, including a greater volume of white matter hyperintensities, or areas in the white matter of the brain where brain tissue has been damaged. They were also more likely to have slightly lower scores on the test of thinking and memory skills.

People who had longer sleep duration were more likely to have small areas of microhemorrhages, or microbleeds, in the brain.

“More research is needed to confirm these findings and also to look at whether prolonged sleep has negative effects on people who have never had a stroke or TIA,” Wardlaw said. “Of course, research is also needed on whether improving people’s sleep patterns after stroke could ward off some of these possible detrimental effects.”

The study was a snapshot in time—it did not follow participants to see changes over time, and researchers did not look at participants’ sleep quality before they had strokes.

The study was supported by the UK Dementia Research Institute at the University of Edinburgh.

Discover more about brain health at BrainandLife.org, from the American Academy of Neurology. This resource also offers a magazine, podcast, and books that connect patients, caregivers and anyone interested in brain health with the most trusted information, straight from the world’s leading experts in brain health. Follow Brain & Life® on Facebook, X, and Instagram.

The American Academy of Neurology is the leading voice in brain health. As the world’s largest association of neurologists and neuroscience professionals with more than 40,000 members, the AAN provides access to the latest news, science and research affecting neurology for patients, caregivers, physicians and professionals alike. The AAN’s mission is to enhance member career fulfillment and promote brain health for all. A neurologist is a doctor who specializes in the diagnosis, care and treatment of brain, spinal cord and nervous system diseases such as Alzheimer's disease, stroke, concussion, epilepsy, Parkinson's disease, multiple sclerosis, headache and migraine.

Explore the latest in neurological disease and brain health, from the minds at the AAN at AAN.com or find us on Facebook, X, Instagram, LinkedIn, and YouTube.

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Journal

Neurology

 

Too much of a good thing: Consequences of overplanting Bt corn in the US

Michigan State University

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Why this matters:

• Too much of a specific type of Bt corn — genetically modified to produce insecticides against corn rootworm — is being planted in places that don’t have a high risk of corn rootworms destroying corn crops.

• This overuse is causing corn rootworms to become resistant, or immune, to Bt insecticides. So Bt corn isn’t working as well now in Corn Belt states where corn rootworm is a serious risk, as rootworms are becoming increasingly pesticide resistant.

• Corn rootworm is one of the worst pests for corn in the U.S. — it can cost over $1 billion in crop damage per year.

EAST LANSING, Mich. – A new study from Michigan State University shows that planting too much genetically modified corn designed to fight off a tough insect — the corn rootworm — especially in the eastern U.S. Corn Belt states may be causing more harm than good.

Bt corn was created to produce natural pesticides, through the introduction of genes from a soil bacterium called Bacillus thuringiensis, or Bt for short. Some varieties of Bt corn kill corn rootworms by making the roots poisonous to them, though the corn is safe for humans and animals. But after years of research across 10 states in the U.S. Corn Belt, scientists have found that the more this corn is planted, the less effective it becomes.

According to study author, Felicia Wu, a John A. Hannah Distinguished Professor at MSU, whose graduated doctoral student Ziwei Ye served as lead author of the study, the U.S. is the largest field corn producing nation in the world, supplying nearly 40% of global corn exports.

“Field corn in the U.S. is used for human food, animal feed and ethanol production. We eat field corn in our cornmeal, grits, corn chips, corn flakes and corn tortillas — not as corn on the cob,” Wu said. “But field corn is plagued by the corn rootworm, which is one of the toughest, most amazing pests that exists. I like to think of the corn rootworm as ‘Loki’ because it’s a trickster — it just keeps evolving resistance to everything we throw at it, not just pesticides or Bt corn, but even crop rotation. And it’s costing farmers billions of dollars.”

So, why has ‘Loki’ become increasingly resistant to the built-in protection of Bt corn? Wu and this research team found farmers were planting more Bt corn than they needed, especially in the eastern Corn Belt states — Ohio, Michigan, Pennsylvania — with no added benefit and higher seed costs. These eastern states don’t have nearly as much of a corn rootworm problem as the major corn producers in the West, which include Iowa, Illinois and Nebraska.

“The problem is that farmers in the east Corn Belt states are overplanting Bt corn even though rootworm is not a problem,” Wu said. “So, we’re putting a lot of the Bt corn with roots containing toxins for corn rootworms into the environment. What this means is that the rootworm is going to evolve resistance more quickly, since it is Loki.

“One of the things that we’ve known in agriculture in general, not just for genetically modified crops, is that the more of a particular pesticide or antibiotic you put in the environment, the more quickly the pests or the bacteria evolve resistance to it because of selection pressure — it’s a matter of survival of the fittest. The organisms will find a way to survive.”

It’s already costing farmers more money because these Bt seeds containing proteins to target corn rootworm are more expensive — and unnecessary in the East. Every time a new trait is introduced to protect a crop, it adds an additional cost per seed. The study estimates that reducing the Bt planting rate from 50% to 18% in eastern states could have saved farmers $99 million in one-year benefits and $1.98 billion in lifetime benefits. ​

The study calls for more thoughtful and balanced use of Bt corn, including more seed options, including those that don’t protect for corn rootworm, and better communication with farmers. Wu said that to keep this powerful biotech crop working, we need to avoid overusing it and find a new approach that supports both farmers and the environment.

“We need to be more careful about the way we grow Bt corn,” Wu said. “There are less expensive corn varieties that farmers in the East can use that don’t protect against rootworm but do protect against other pests that they have. If we keep using corn rootworm-protected Bt varieties in the East, all we’re doing is shortening the amount of time before the entire industry is negatively impacted.”

The study was published in the journal Science. It was funded in part by the U.S. Department of Agriculture Natural Resources Conservation Service.

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Michigan State University has been advancing the common good with uncommon will for 170 years. One of the world’s leading public research universities, MSU pushes the boundaries of discovery to make a better, safer, healthier world for all while providing life-changing opportunities to a diverse and inclusive academic community through more than 400 programs of study in 17 degree-granting colleges.

For generations, Spartans have been changing the world through research. Federal funding helps power many of the discoveries that improve lives and keep America at the forefront of innovation and competitiveness. From lifesaving cancer treatments to solutions that advance technology, agriculture, energy and more, MSU researchers work every day to shape a better future for the people of Michigan and beyond. Learn more about MSU’s research impact powered by partnership with the federal government.

For MSU news on the web, go to MSUToday or x.com/MSUnews.

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Journal

Science

DOI

10.1126/science.adm7634 

 

Q&A: What universities can learn about navigating ideological tension from the history of same-sex domestic partner benefits

University of Washington

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As public universities across the U.S. face increasing scrutiny over issues such as diversity initiatives and tenure protections, new research from the University of Washington offers timely lessons on how universities can navigate politically charged issues without abandoning their core commitments.

The study, recently published in Organization Science, examines how public universities decided whether to offer same-sex domestic partner benefits in the early 1990s and 2000s. Researchers found that universities — especially those in conservative states — often strategically adjusted not just whether and when they adopted inclusive policies, but also how they justified those decisions.

“When universities face powerful stakeholders who oppose their values, how they frame their decisions can be as important as the decisions themselves,” said Abhinav Gupta, co-author and professor of management in the UW Foster School of Business.

UW News spoke with Gupta about what universities can learn from this earlier period of cultural and political tension.

Can you tell me about the inspiration for this research?

AG: This project began when I was a doctoral student at The Pennsylvania State University, where my co-authors and I were interested in understanding how institutional change unfolds under ideological pressure. We were especially drawn to the LGBTQ+ rights movement, which has been one of the most successful in recent U.S. history — not only in shifting cultural values, but also in driving tangible changes in workplace policy and practice.

Among those changes, the adoption of same-sex domestic partner benefits by universities stood out as a concrete, measurable outcome with real resource implications. It offered us a focused way to examine how inclusive policies are implemented within institutions that must navigate competing political and economic demands.

We weren’t just curious about whether universities adopted these benefits — we wanted to understand how they managed the politics of those decisions, especially in states where conservative legislatures controlled university budgets. This was an opportunity to study how organizations pursue values-based change pragmatically, often advancing their commitments in ways that are sensitive to the views of key stakeholders.

Over time, we built a comprehensive dataset of top public universities, tracking the progression of this policy between 1990 and 2013. Modeling that process was painstaking, but it allowed us to identify patterns in how universities adopted and framed these decisions — strategically aligning with trusted actors in their environments, such as major local employers, and adjusting their rhetoric to reduce backlash.

Although history doesn’t repeat itself exactly, the same underlying dynamics often resurface. This case offers a narrow but revealing window into how change happens — not through confrontation alone, but through patient, careful work that gradually builds consensus. For anyone interested in advancing equity in complex institutional settings, there are valuable lessons in how the LGBTQ+ movement translated advocacy into durable, systemic shifts.

What patterns did you notice in universities’ decision making?

AG: One of the most striking dynamics we observed was in states where public universities relied heavily on funding from conservative legislatures. In these contexts, university administrators were often deeply concerned about potential backlash. They feared that allocating funds to support same-sex domestic partner benefits could be seen as ideologically out of step with legislative priorities.

We analyzed adoption patterns across major public universities — research powerhouses and flagship institutions throughout the U.S. — and found a clear and systematic pattern. Universities in more progressive states were often early adopters of these benefits, with some acting as early as 1991. In contrast, their peers in more conservative states often waited nearly a decade longer to adopt the same policies.

But what was particularly telling was how these later adopters framed their decisions. Many universities in red states did not lead with social justice arguments. Instead, they took a “business case” approach, aligning their decisions with market-based rationales — emphasizing competitiveness, talent recruitment and employee retention. These institutions typically adopted the policy only after major local employers had done so, effectively using the private sector as cover. This allowed them to present the decision as a practical response to labor market trends rather than an ideologically driven move.

This pattern led us to develop a broader theoretical insight: when organizations anticipate ideological resistance from key stakeholders, they often look to “exemplar organizations” — entities already seen as legitimate by those stakeholders. By emulating the behavior of these exemplars and adopting rhetoric that reflects stakeholder values, they can diffuse opposition and build support without abandoning their goals.

In contrast, universities in more liberal states often cited peer institutions and framed their decisions more explicitly around fairness and inclusion. What this shows is that organizations don’t simply conform or resist in the face of ideological tension — they adapt. They make strategic choices about when and how to act, often tailoring their message and reference points to gain legitimacy in diverse political and cultural environments.

What lessons can universities take from this case study, particularly in the current environment?

AG: We’re living through a time of heightened scrutiny and political tension, and universities increasingly find themselves at the center of it. In many ways, higher education has long enjoyed a degree of autonomy — but that autonomy rests on relationships with a broad set of external stakeholders whose values may not always align with those of university leadership, faculty or students.

This moment raises a fundamental question: What should universities do when their internal priorities come into conflict with the beliefs or expectations of those who hold influence over their resources — such as policymakers, donors or community leaders? Some might argue that institutions should stay true to their values no matter the cost. But our research suggests that universities benefit more when they strategically engage their environment, not ignore it.

This doesn't mean compromising principles. It means understanding the value systems of key stakeholders and learning to speak in ways that resonate. For example, when universities face resistance to inclusive policies, it can be effective to frame those decisions around economic competitiveness, workforce needs or community relevance — themes that often carry bipartisan appeal. The goal is not to dilute the message, but to translate it into language that expands support rather than provokes opposition.

In our research, we also emphasize the value of “exemplar organizations” — trusted institutions that skeptical stakeholders already view as legitimate. When a university can point to respected peers or private-sector leaders who have adopted a similar course of action, it lowers the perceived risk of following suit and frames the decision as pragmatic rather than ideological.

At their best, universities are extraordinary institutions. They create scientific breakthroughs, train healthcare professionals and business leaders, support local economies and open doors for the next generation. Their work benefits people across political, cultural and socioeconomic divides. To continue delivering that value, especially in contentious times, universities need to build broad-based coalitions — not by avoiding disagreement, but by finding common ground wherever possible.

Other co-authors were Chad Murphy of Oregon State University and Forrest Briscoe of Cornell University.

For more information, contact Gupta at abhinavg@uw.edu.

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Journal

Organization Science

DOI

10.1287/orsc.2022.17219 

Article Title

How Ideologically Opposed Stakeholders Influence Organizational Practice Adoption: Theory and Evidence from the Diffusion of Domestic Partner Benefits in Higher Education