A new study of ants in Fiji – involving genomic sequencing of over 4,000 ant specimens from museum collections – shows that most native species have been in decline since humans first arrived in the archipelago 3,000 years ago. Meanwhile, recently introduced ant species have expanded. The findings underscore how human activity has and continues to reshape fragile island ecosystems. Insects, which make up much of Earth’s biodiversity, provide crucial ecosystem services, including pollination, soil health, and natural pest control. Recent reports of dramatic declines in insect abundance and diversity – sometimes referred to as the “insect apocalypse” – have raised global concern. Although factors such as habitat destruction, agricultural intensification, climate change, pesticide use, and light pollution are frequently implicated, the scale and universality of these declines remain debated because most studies rely on relatively short-term data or historical collections spanning only decades to centuries, leaving long-term trends largely unexplored. Advances in genomic techniques now allow scientists to reconstruct historical population trends over thousands of years, however, providing insight into how both recent and ancient human activities have shaped insect communities.

 

Here, Cong Liu and colleagues examined long-term trends in abundance, diversity, and ecological roles of ants in the Fijian archipelago. Ants – abundant and functionally important – serve as indicators of broader biodiversity patterns, making them ideal for such studies. And islands like Fiji, with high numbers of endemic species, are especially vulnerable to human impacts. Liu et al., applied a community genomics approach, which used high-throughput genomic sequencing on over 4,000 ant specimens from Fijian museum collections, to estimate long-term community assembly and demographic trends of ants on the islands. Fiji’s ant fauna was shaped by at least 65 colonization events, they say. Some arrived millions of years ago, which led to endemic Fijian species. Regional Pacific colonizations also impacted Fiji’s ant fauna, as did more modern introductions of ant species by humans through global trade. Notably, population modeling revealed stark differences between endemic and non-endemic species. About 79% of endemic ants – mostly confined to high-elevation, intact forests – have declined, with reductions beginning after humans first settled Fiji ~3,000 years ago and accelerating in the past 300 years alongside European contact, industrial agriculture, and species introductions. In contrast, widespread Pacific species and recent human-introduced invasive ants, which are more tolerant or adapted to human-dominant habitats, have generally expanded their populations, particularly in disturbed lowland habitats. These divergent trajectories reflect how ecological traits, habitat preference, and biogeographic context determine which species “win or lose” in the Anthropocene, Liu et al. say.

 

For reporters interested in the novelty of the methods and collections used in this study, study coauthor Evan Economo notes; “Community genomics refers to approaches that infer patterns and processes from genomic data across many species living together (i.e. an ecological community), rather than one or a few species at a time.  In this case, by analyzing many species in parallel, we were able to infer patterns of population change across the community to recover general trends. In principle, approaches like this have a lot of potential to analyze communities of any taxon, whether it is to look for evidence for declines or other ecological dynamics of interest. In this project, we recovered genomic data from museum collections, and this is an example of how such specimens are a continual source of insight as new technologies come online.  Collections are not just some old stuff we store in the attic, they become more valuable over time as the information they contain is unlocked in ways that may have been unimaginable to the people who originally collected the specimens decades or centuries ago.  Furthermore, we cannot fully anticipate how biodiversity collections can be used by humanity in the future, and this is why it is critical to invest in stewarding and growing collections for future generations.”

According to a new study, most climate models exploring wildfires’ impacts on air quality overlook the effect of heat from a fire in one location on altering weather patterns – and in turn air quality – in locations farther afield. The authors of this study report that wildfires in the western United States are worsening air quality in the West but, paradoxically, may be improving it in the East. Over recent decades, wildfires in the western United States have become more frequent and intense, releasing vast amounts of smoke, which can greatly degrade air quality both locally and in regions far downwind. Often assumed to worsen when wildfire smoke drifts eastward from the West, fine particulate pollution (PM2.5) from wildfires has long been a major health concern in the eastern United States, potentially contributing to thousands of premature deaths each year. While this conventional wisdom has long informed air quality and fire management policies nationwide, the intense heat released by fires, which is capable of altering air temperatures, destabilizing the atmosphere, and driving strong convection, isn’t fully understood. Because wildfire heat can alter large-scale atmospheric circulation, its role in shaping distant air quality has been underappreciated. Most climate models consider only smoke emissions and not fire heat, which may explain why they tend to overestimate wildfire-driven pollution in the East.

 

Using both observational data and climate model simulations that incorporate daily heat measurements, Qihan Ma and colleagues found that, during extreme wildfires in the West, PM2.5 actually declines in the East, not only during extreme events but also throughout the fire season. This occurs because the intense heat released by large fires drives strong convection, which changes weather patterns, suppresses eastward smoke transport, and promotes rainfall that helps cleanse the air. However, while fire heat can improve air quality in the East, wildfires still worsen pollution in the West. According to Ma et al., ignoring fire heat in current climate models leads to inflated nationwide health and economic impact estimates – by about 1,200 premature deaths and $3.3 billion in damages – highlighting the need for policies that recognize its role in shaping regional air quality and environmental equity. “The differential impacts of wildfires necessitate the more appropriate allocation of resources and policy intensity for fire management and regional pollution control,” write the authors. “With greening in a warming world, the accumulation of fuels will lead to increased fire heat release when wildfires occur. It is imperative to consider fire heat in the Earth system when conducting comprehensive climate simulations and wildfire risk assessments.” In a related Perspective, Yun Qian discusses the study and the implications of its findings in greater detail.

Understanding the strategies and unmet needs of caregivers managing medications for people with Alzheimer’s disease or related dementias may improve the lives of both caregivers and patients. A recent study describes the strategies and the unmet needs of caregivers managing medications for people with Alzheimer’s disease or related dementias. The researchers identified three distinct caregiver personas: “Checklist Cheryl,” “Social Sam,” and “Responsive Rhonda.” Each persona embodies a different approach to medication management, varying in organization, technology use, collaboration and response to challenges. These nuanced personas can guide the design of customized caregiver support and digital health tools.

To harness the full potential of new medical technologies, a new white paper calls for significant FDA reforms to streamline clinical trials, provide greater certainty for innovators and speed game-changing treatments to more patients.

About The Study: In this prospective study of the Adolescent Brain Cognitive Development (ABCD) Study cohort, modifiable parental factors in early adolescence were associated with specific adolescent sleep outcomes 4 years later, with screen use and emotional regulation serving as mediators. Adolescent sex moderated the association between parental warmth and sleep chronotype. These findings highlight potential targets for evidence-based interventions to improve adolescent sleep health.

About The Study: In this economic evaluation estimating effects of the possible health care policy changes on HIV transmission, findings suggest that even modest reductions in pre-exposure prophylaxis (PrEP) coverage would result in thousands of avoidable HIV infections and billions of dollars of increases in net health care costs.