Holoparasitic Orobanchaceae, which include the familiar broomrapes of the genus Orobanche as well as genera such as Cistanche, Phelipanche, Phelypaea, Aphyllon, Hyobanche and Lathraea, are achlorophyllous plants that draw all their water and nutrients from the roots of their hosts through specialised organs called haustoria. Because they cannot photosynthesise, they appear above ground only as fleshy, often brilliantly coloured flowering shoots, and many are rare, endangered or, in agricultural settings, notorious weeds. Until now, knowledge of the animals that visit, feed on, shelter in or develop inside these plants has been scattered across isolated reports, mostly concerning a handful of pest insects and occasional pollinator sightings.

The new database shows that arthropods dominate the associated fauna, accounting for roughly 91 percent of recorded species. Within this group, Hymenoptera, the order containing bees, wasps and ants, is by far the largest, with 198 species recorded, followed by Diptera with 72, Coleoptera with 115, Hemiptera with 70, and spiders with 50. Beyond insects, snails and slugs of the order Stylommatophora make up about 4 percent of species, while mammals, birds and reptiles contribute small but ecologically striking numbers of records. The plants most frequently exploited were Orobanche, Phelipanche and Cistanche, which together attracted the richest and most diverse visitor assemblages.

Pollination emerges as a central theme. Bees, particularly bumblebees of the genus Bombus and sweat bees of the genus Lasioglossum, are the primary pollinators across most of the family’s range, visiting tubular, bilabiate flowers that offer nectar deep within the corolla. The study also documents more surprising pollination systems. In southern Africa, red-flowered species of Phelypaea are pollinated by glaphyrid beetles of the genus Pygopleurus, apparently lured by dark spots on the petals that mimic beetle elytra, a likely case of deceptive sexual mimicry. Hawkmoths of the genus Hyles pollinate Cistanche in the Mediterranean and southwest Asia, and on the oceanic Bonin Islands of Japan the endemic Orobanche boninsimae is pollinated by passerine birds, a rare shift from insects to birds within the genus.

Herbivory is equally pervasive. The monophagous fly Phytomyza orobanchia mines stems and seed capsules of dozens of broomrape species and can reduce seed production by 30 to 80 percent, making it one of the most effective biological control agents against invasive broomrapes, though it also attacks rare and endangered relatives. Hoverfly larvae of the genus Eumerus burrow into the massive tubers and stems of Cistanche species in desert and semi-desert habitats, sometimes devastating populations of endangered endemics such as Cistanche armena. Aphids, thrips, beetle larvae and moth caterpillars all feed on the succulent tissues, and florivorous caterpillars can destroy large proportions of flowering populations, as observed with Ammoconia senex on Phelypaea coccinea in Georgia.

The plants also function as hunting grounds and shelters, creating multitrophic webs that extend well beyond simple plant-insect pairs. Crab spiders of the family Thomisidae ambush flower visitors, orb-weavers anchor their webs to stiff inflorescence shoots, and mildly venomous spiders of the genus Cheiracanthium build silken retreats inside the large red flowers of Phelypaea. Dense glandular trichomes trap small flies and aphids, providing carrion for predators, a phenomenon the authors suggest may be a widespread indirect defence strategy in these plants. Ants are ubiquitous visitors, tending aphids for honeydew on both above-ground and underground plant parts, and in some cases nesting in tunnels excavated by mining larvae in the fleshy stems of Cistanche.

Seed ecology adds another layer of complexity. Holoparasitic Orobanchaceae produce some of the smallest seeds in the plant world, and their dispersal has traditionally been attributed to wind and water. The new synthesis highlights evidence that animals matter too: camel crickets and ground beetles disperse viable seeds of Phacellanthus tubiflorus in Japanese forest understoreys, deer pass viable seeds of Conopholis americana through their digestive tracts, ants may disperse seeds of Lathraea squamaria, the only known elaiosome-bearing holoparasite in the family, and slugs have been shown to swallow and defecate undamaged seeds of the same species. Bears, meanwhile, consume flowering shoots of Conopholis and Boschniakia in North America, with squawroot making up as much as 10 to 15 percent of the diet of bears in the southern Appalachians in spring.

Molecular tools played a key role in the study. The team generated 355 mitochondrial COI barcode sequences from 469 specimens using both Sanger sequencing and Oxford Nanopore technology, assigning them to 141 Barcode Index Numbers, 24 of them unique. DNA barcoding proved indispensable for identifying eggs, larvae and pupae that could not be determined morphologically, and the high proportion of unique BINs in the Caucasus, 19 of 24, hints at substantial undiscovered diversity in this hotspot of holoparasite evolution. The authors note that several divergent lineages within Phytomyza orobanchia may represent distinct species awaiting formal description.

Placing the results in an evolutionary framework, the researchers compared visitor assemblages across the three clades in which holoparasitism arose independently within Orobanchaceae. The oldest and most species-rich clade, Orobancheae, is dominated by hymenopteran visitors and shows the highest taxonomic richness. The intermediate clade Buchnereae, which includes the southern African genera Hyobanche and Harveya, displays the greatest heterogeneity, with substantial contributions from gastropods, birds and mammals, consistent with mixed pollination syndromes and transitions between insect, bird and mammal pollination. The youngest clade, containing only Lathraea, is pollinated almost exclusively by bumblebees. These patterns suggest that pollination evolution in holoparasites may have been non-synchronous and linked to shifts in host plants, habitats and phenology.

The study also carries conservation implications. Most holoparasitic species are completely dependent on their hosts and on specific pollinators, making them vulnerable to environmental change, and pollinator declines worldwide threaten the reproduction of species that rely on bumblebees and other insects. At the same time, the authors identify major knowledge gaps: nearly 60 percent of holoparasitic species have no recorded animal associates, and entire genera such as Eremitilla, Gleadovia and Mannagettaea remain unstudied. By demonstrating that these leafless parasites sustain pollinators, herbivores, predators, parasitoids, detritivores and even large mammals, the research establishes holoparasitic Orobanchaceae as keystone components of terrestrial ecosystems whose protection requires safeguarding not just the plants and their hosts, but the intricate animal networks they support.

Subject of Research: Global diversity of animal interactions with holoparasitic plants of the family Orobanchaceae

Article Title: A multiverse of trophic networks and coevolutionary trajectories among holoparasitic Orobanchaceae and their animal associates: a global perspective

Article References: Piwowarczyk, R., Wiśniewska, K., Rewicz, T., Olbrycht, T., Salata, S., Fateryga, A. V., Nicewicz, Ł., Depa, Ł., Zając, K., Masarovič, R., Celary, W., Mielczarek, Ł., & Mátis, A. (2026). A multiverse of trophic networks and coevolutionary trajectories among holoparasitic Orobanchaceae and their animal associates: a global perspective. PhytoKeys, 275, 209-297. https://doi.org/10.3897/phytokeys.275.192014

Image Credits: AI Generated

DOI: 10.3897/phytokeys.275.192014

Keywords: Orobanchaceae, holoparasitic plants, broomrapes, pollination, herbivory, coevolution, DNA barcoding, plant-animal interactions, Phytomyza orobanchia, bumblebees, seed dispersal, biodiversity

The selection of Gentiana asclepiadea for this comparative study was driven by two primary factors. First, the research team had previously collected detailed data on this specific plant and its pollinators in the 1990s, providing a robust baseline for comparison. Second, as a montane species growing at altitudes between 1500 and 1900 meters, it was hypothesized to be less exposed to the immediate threats of habitat destruction and agricultural chemicals that plague lowland pollinators. The plant is a perennial with thick, branched rhizomes and straight, non-branched stems that can reach up to 80 centimeters in height. Its funnel-shaped flowers, which are not capable of spontaneous self-pollination, rely heavily on specific insect vectors for reproduction, making them an ideal indicator species for assessing pollinator health.

The field investigations were conducted at three specific study sites in Mt. Vitosha, a mountain range located near Sofia. Sites one and two were situated in open woodlands within the coniferous forest belt, while site three was located in subalpine meadows just above the tree line. Observations took place during the flowering seasons of August and September in both the 1990-1994 period and the 2017-2020 period. The researchers spent a total of 66 hours over 48 days observing bumblebee activity under various meteorological conditions. To avoid altering the natural behavior of the insects, the team refrained from collecting specimens, relying instead on visual identification and recording of visitation rates and behavior.

Identifying bumblebee species in the field presented certain challenges, particularly for species with similar coloration. For instance, Bombus wurflenii and Bombus lapidarius, though belonging to different subgenera and possessing different ecological niches, are difficult to distinguish with certainty in the field. Similarly, Bombus hortorum and Bombus subterraneus, as well as Bombus lucorum and Bombus terrestris, were often recorded as undistinguished pairs. To maintain scientific rigor while acknowledging these limitations, the researchers used an approximate approach in their data analysis. A pollinator activity index was calculated by dividing the number of pollinators recorded by the minutes of observation, multiplied by 60, providing a standardized metric for comparison across years and sites.

The results indicated that the species composition of bumblebees visiting the Gentiana flowers remained largely consistent between the two study periods. The primary visitors included Bombus pascuorum, Bombus pratorum, and the aforementioned undistinguished pairs. However, a slight but notable decline in overall bumblebee activity was observed in the 2017-2020 period compared to the 1990-1994 baseline. Linear regression analyses, while limited by the significant time gap between the two observation periods, showed decreasing trends in total activity at all three study sites. This decline was not uniform; fluctuations were observed within years and between sites, likely influenced by local colony dynamics, foraging ranges, and the presence of competing floral resources.

The reproductive success of the Gentiana plants mirrored the trends in pollinator activity. The researchers tested free pollination fruit set by monitoring 100 flowers each year for the development of fruit capsules. They also assessed seed set by counting matured seeds and non-fertilized ovules in 10 fruit capsules annually. A slight decrease in both fruit set and seed set was recorded during the final four years of the study. This correlation suggests that the reduction in bumblebee visits directly impacted the plant’s ability to reproduce, highlighting the critical role these insects play in the life cycle of this medicinal species. The data underscores that even minor changes in pollinator abundance can have measurable effects on plant reproductive output.

Several ecological factors may contribute to the observed fluctuations and declines in bumblebee activity. The study notes that the foraging range of bumblebees can extend up to 10 kilometers, meaning that local populations may be influenced by conditions in surrounding areas. Colony failure rates are known to be high, with fewer than 30% of Bombus pascuorum colonies producing new queens, and success rates even lower for other species. At site three, the subalpine meadow, fewer bumblebees were recorded, possibly due to competition from large populations of Epilobium angustifolium and Solidago virgaurea, which are known to attract bumblebees. This competition for pollinators may have reduced the frequency of visits to the Gentiana flowers, further impacting seed set.

Behavioral observations also provided insights into the interactions between bumblebees and the plant. In 1991, high activity of male Bombus hortorum or Bombus subterraneus was recorded in early September, likely due to their phenology and the timing of colony life cycles. In 2017, high activity of Bombus wurflenii at site two was attributed to nectar robbing behavior, where workers extract nectar by making holes in the base of the corolla tube. While nectar robbing can have negative, neutral, or positive effects on plants, in this case, it was considered neutral to slightly positive, as the workers still pollinated the flowers while attempting to access the nectar through the normal route. These behavioral nuances highlight the complex nature of plant-pollinator interactions and the importance of detailed field observations.

The study concludes that the slight decline in bumblebee activity and subsequent reduction in fruit and seed set demonstrate that negative effects on pollinators are detectable even in mountain habitats with fewer direct hazards. This finding aligns with broader research, such as a study showing a 76% decline in insect biomass in German nature reserves between 1989 and 2016. While the specific causes of the decline in the Vitosha Mountains are not definitively established, the authors speculate that urbanization of the foothills and increased agricultural activity in the surrounding lowlands may play a role. Additionally, climate change is a known hazard for certain bumblebee species, potentially driving them to higher altitudes, though the study lacks sufficient data for definitive conclusions on this factor. The research emphasizes the need for continued long-term monitoring of pollinators in diverse habitats to fully understand the drivers of their decline and to develop effective conservation strategies.

Subject of Research: Long-term monitoring of bumblebee pollination and reproductive success in Gentiana asclepiadea in Mt. Vitosha, Bulgaria.

Article Title: Monitoring bumblebee pollinator visits to the medicinal plant Gentiana asclepiadea L. (Gentianacese) – a comparison between the periods 1990–1994 and 2017–2020

Article References: Kozuharova, E., & Simeonov, V. (2022). Monitoring bumblebee pollinator visits to the medicinal plant Gentiana asclepiadea L. (Gentianacese) – a comparison between the periods 1990–1994 and 2017–2020. BioRisk, 17, 317-327. https://doi.org/10.3897/biorisk.17.76577

Image Credits: AI Generated

DOI: 10.3897/biorisk.17.76577

Keywords: bumblebees, pollination, Gentiana asclepiadea, insect decline, montane habitats, Bulgaria, long-term monitoring, ecology, reproductive success, bioindicators, Monitoring, bumblebee

The review followed PRISMA 2020 guidelines, searching Scopus and Web of Science for peer-reviewed studies published within the last 20 years. After screening titles, abstracts, and full texts against strict inclusion criteria, the researchers identified 52 primary studies examining neonicotinoid effects on bumblebees under field-realistic or controlled conditions. The resulting dataset reveals a research field that has expanded rapidly since 2012, with roughly half of all studies published in just the last six years and a peak of six papers in 2021, a surge the authors link to the European Union’s partial ban in 2013, the complete outdoor ban of three compounds in 2018, and the controversial resurgence of virus yellows in UK sugar beet in 2020 that reignited the debate.

Technically, neonicotinoids are systemic insecticides developed in the 1980s to replace older organophosphates and combat rising pesticide resistance. Their small molecular size and high water solubility allow them to be absorbed by plants and transported primarily through the xylem, accumulating in leaves, flowers, and pollen. Once inside the insect nervous system, they bind to nicotinic acetylcholine receptors, or nAChRs, overstimulating neural pathways and effectively paralyzing herbivorous pests such as aphids, whiteflies, and leafhoppers. The compounds fall into three chemical groups: the N-nitroguanidines including imidacloprid, thiamethoxam, clothianidin, and dinotefuran; the nitromethylenes such as nitenpyram; and the N-cyanoamidines including acetamiprid and thiacloprid. Their versatility as foliar sprays, seed treatments, and soil drenches made them suitable for maize, sugarbeet, oilseed rape, fruits, and vegetables, and within two decades they accounted for a third of the global insecticide market.

But the review’s most striking finding is not what the science says, but where it comes from. Of the 52 studies, 81 percent were conducted in just two countries: the United Kingdom, which produced 54 percent of the research, and the United States, which produced 27 percent. Only single studies emerged from the Netherlands, Belgium, Finland, Israel, Mexico, China, and Canada. This geographic concentration matters enormously because neonicotinoids remain widely used in the roughly 35 percent of countries that lack pesticide legislation, with clothianidin, imidacloprid, and thiamethoxam still dominating the global market. In the United States alone, over 1,000 neonicotinoid-containing products remain registered with the EPA. Meanwhile, East Asia hosts the richest bumblebee diversity on Earth, with more than 50 percent of known species concentrated in China, Mongolia, Japan, and parts of Russia and India, yet virtually no neonicotinoid research has been conducted there.

The taxonomic bias is equally pronounced. Bombus terrestris, its subspecies B. terrestris audax, and the North American commercial staple B. impatiens dominate the literature, while the Mesoamerican B. ephippiatus appears in only a single study. With over 260 known bumblebee species worldwide, native to every biogeographic region except Australia, New Zealand, and sub-Saharan Africa, the review argues that risk assessments relying on commercially convenient species may systematically underestimate the vulnerability of wild populations. Species with smaller colonies, such as B. pseudobaicalensis and B. schrencki, could be far more sensitive to the loss of even a few foragers, while larger-bodied species that travel further when foraging may suffer greater navigation and endurance impairments. Differences in metabolic detoxification rates, floral specialization, and colony activity timing could all shape which species are hit hardest.

On the compound side, imidacloprid was the most studied, appearing in 54 percent of the identified papers, followed by thiamethoxam at 23 percent and clothianidin at 19 percent. Together, these three nitroguanidine compounds were represented in 88 percent of the studies. The authors attribute this skew partly to commercial sales, citing earlier work showing a positive correlation between research volume and global sales, and partly to the strong binding affinity of these compounds for nAChRs, which drives their toxicological risk. In contrast, acetamiprid and thiacloprid, classified as lower-risk cyanoamidines, received far less attention, and dinotefuran and nitenpyram were entirely absent from the bumblebee literature, despite dinotefuran having been implicated in bee mortality events and nitenpyram showing adverse effects on non-target organisms in other contexts.

The behavioral toll documented across these studies is staggering in its scope. Exposed bumblebees exhibit reduced flower visitation rates, altered flower preferences, and decreased foraging motivation. Chronic exposure impairs flight endurance, increases exhaustion rates, and disrupts homing ability, meaning bees literally cannot find their way back to the nest. Learning and memory deficits compound the damage, with impaired associative learning, olfactory conditioning, and spatial memory documented across multiple species. Since bumblebees rely on learned foraging routes to locate and return to high-quality floral resources, these cognitive impairments cascade through the colony, reducing resource intake and impairing colony growth. Exposed bees also show reduced responsiveness to food rewards, decreased sucrose and nectar consumption, and diminished food storage within the colony, while disruptions in essential social behaviors such as nest thermoregulation and brood care further weaken colony cohesion.

Reproductive effects were the second most commonly reported outcome, documented in 40 percent of studies. Exposed colonies produce fewer new queens, limiting their ability to establish future generations. Brood production and overall colony growth are often impaired, with fewer workers and reproductive individuals emerging, and delayed colony development including slower nest initiation and egg laying further compromises population stability. Male reproduction is also affected, with reduced drone weight, disrupted production timing, and impaired sperm viability limiting mating success. Physiologically, neonicotinoids disrupt neurophysiology by interfering with nAChRs, impairing neural development, and altering brain ion transport-related gene expression. Increased acetylcholinesterase expression suggests impaired neurotransmission, while metabolic effects include elevated oxygen consumption and metabolic activity in flight muscles and the brain, potentially leading to hyperactivity and exhaustion. Exposure also upregulates antimicrobial peptide gene expression, which could lead to immune overactivation and long-term susceptibility to pathogens.

Perhaps most concerning is what the review did not find enough of. Direct measures of pollination efficiency and ecosystem impacts were the least observed outcomes, reported in only 11 percent of studies, largely because only five of the 52 studies were performed in the field relative to laboratory conditions. Yet the behavioral and reproductive impairments documented so extensively are inherently linked to pollination performance. Compromised buzz pollination efficiency, with shorter buzzing duration, results in lower pollen deposition and reduced crop yield. Smaller or poorly structured colonies result in fewer foragers, limiting floral visitation and pollen transfer. At a broader scale, exposure disrupts plant-pollinator networks, with altered interactions between bumblebees and wild plants potentially affecting plant reproductive success and overall ecosystem stability. The authors argue that subtle, chronic impairments in behavior and reproduction could undermine colony health long before direct mortality is observed, meaning the true ecological cost of neonicotinoid exposure may be far greater than current regulatory thresholds suggest.

The review also grapples with the agricultural benefits that keep these chemicals in widespread use. As systemic insecticides, neonicotinoids offer high efficacy, targeted action, and ease of application, and their use as seed treatments reduces the need for repeated foliar spraying, lowering labor costs and farmworker exposure. They effectively combat pests resistant to older insecticides, and long-term crop protection benefits crops like sugar beet, which is often harvested before flowering, reducing direct pollinator exposure. However, their persistence in soil, sometimes exceeding 1,000 days, leads to accumulation and prolonged contamination, and they have been detected in non-crop plants like wildflowers at field margins, exposing pollinators even in untreated areas. The phenomenon of delayed toxicity, where lethal effects only appear after prolonged exposure, further complicates environmental risk assessments. The authors call for expanded research into alternative pest management strategies, field-realistic exposures, long-term monitoring, species-specific responses, and broader geographic coverage, arguing that addressing these critical knowledge gaps will be vital to developing ecologically sustainable agricultural systems that protect pollinators like bumblebees while ensuring adequate crop protection for a growing global population.

Subject of Research: Neonicotinoids quietly scramble bumblebee brains, landmark systematic review reveals

Article Title: The effect of neonicotinoids on bumblebees (Bombus spp.): a systematic review

Article References: Dennis, D. J., & Gibbs, A. J. (2025). The effect of neonicotinoids on bumblebees (Bombus spp.): a systematic review. Frontiers in Bee Science, 3, Article 1657493. https://doi.org/10.3389/frbee.2025.1657493

Image Credits: AI Generated

DOI: 10.3389/frbee.2025.1657493

Keywords: neonicotinoids, bumblebees, pollinators, pesticides, systematic review, bee health, colony collapse, agriculture, ecotoxicology, Frontiers in Bee Science, effect, Bombus

The demographic statistics cited in the editorial deserve closer attention because they reveal a structural pattern often described as a leaky pipeline. Women earning roughly half of entomology doctoral degrees in North America while remaining underrepresented in permanent academic and government positions indicates that attrition occurs after training, not before it. The Brazilian case is especially instructive: when women receive the majority of bachelor’s and master’s degrees in a discipline yet occupy fewer permanent research posts, the bottleneck lies in hiring, promotion, and retention rather than in interest or preparation. Similar patterns have been documented across many scientific fields, and the consistency of the finding across countries with different academic systems suggests that the causes are systemic rather than local. Career-stage timing compounds the problem, since the years in which researchers typically establish independent laboratories often coincide with peak caregiving responsibilities, and institutions that fail to accommodate this reality lose trained scientists at precisely the moment their investment matures.

The scientific content assembled in the Research Topic also illustrates how methodological diversity strengthens inference in pollination science. Species distribution modeling, as applied by the authors studying Neotropical crops and Amazonian bumblebees, relies on occurrence records, environmental layers, and climate projections to estimate where species can persist under future conditions. Such models carry inherent uncertainties, including assumptions about dispersal ability, biotic interactions, and physiological tolerance, which is why the finding that one bumblebee species may lose more than forty percent of suitable climate area while a close relative faces milder projected losses is best interpreted as a call for species-specific field validation rather than a definitive forecast. The contrast between the two Bombus species underscores a recurring lesson in conservation biology: closely related taxa sharing a region can respond very differently to the same climatic pressures, so conservation planning must be grounded in the ecology of individual species rather than in group-level assumptions.

The treatment of neonicotinoid pesticides across the Research Topic similarly demonstrates the value of complementary approaches. A field-focused study of stingless bees in Brazilian coffee cultivation can capture real-world exposure scenarios in a tropical agroecosystem, while a systematic review of bumblebee studies across Europe and North America can synthesize patterns that no single experiment could reveal. The observation that behavioral and reproductive effects are better characterized than effects on pollination efficiency itself identifies a genuine gap: a bee may survive exposure yet deliver fewer or lower-quality pollination services, with consequences for crop yields that current risk assessments may not fully capture. Stingless bees add another dimension to this question because they are dominant pollinators in many Neotropical systems, manage colonies differently from honey bees, and may experience distinct exposure routes through their nesting materials and food storage practices.

The honey bee contributions in the collection connect laboratory-scale mechanisms to practical beekeeping decisions. Hygienic behavior, the removal of diseased or mite-infested brood from cells, has long been recognized as a heritable colony-level defense, and tools that allow breeders to identify resistant colonies without waiting for natural disease outbreaks can accelerate selection programs. Synthetic semiochemical-based assays are valuable precisely because they standardize a stimulus that varies unpredictably in nature, letting beekeepers compare colonies on equal footing. Resistance to the parasitic mite Varroa destructor matters not only for mite control itself but also for the viral complexes that mites vector, which is why a single behavioral trait can correlate with resilience against RNA viruses, microsporidian parasites, and fungal pathogens. At the same time, the study of competition between managed honey bees and cavity-nesting native bees at the urban-bushland interface in Australia addresses a different side of the same species: the same bee that supports crop pollination can, at high densities, compete with native assemblages for floral resources. Practical recommendations for colony placement and for planting pollen sources used by native bees represent the kind of actionable output that emerges when ecological research is designed with management questions in mind.

The waggle dance research highlights how new instrumentation revitalizes classical questions. Karl von Frisch’s decoding of the dance in the mid-twentieth century established that foragers communicate direction and distance, but modern video capture and network analysis allow researchers to follow individual dancers and followers over time, quantifying how recruitment actually propagates through a colony’s forager workforce. Viewing the dance as one node in a social network rather than as an isolated signal opens questions about which bees attend dances, how information spreads unevenly among colony members, and how collective foraging decisions emerge from many individual interactions. This shift from signal description to network dynamics exemplifies a broader trend in animal behavior research, enabled by affordable high-resolution recording and computational tools that were unavailable to earlier generations.

The historical figures invoked by the editors also merit reflection. Eva Crane’s founding of the International Bee Research Association in 1949 created an institutional home for apicultural science at a time when the field was scattered across national traditions, and her prolific career demonstrated that rigorous synthesis could itself be a scientific contribution. Anna Maurizio’s role in establishing the forerunner of the International Commission for Plant-Pollinator Relationships helped build the pollination biology community that now underpins much of the research described in this collection. These women worked in eras when formal recognition of female scientists was rarer, and their legacies illustrate how infrastructure-building, not only experimental discovery, shapes a discipline’s trajectory. Tracing such lineages matters for contemporary equity efforts because it corrects the perception that women are newcomers to bee science rather than long-standing contributors whose visibility in historical accounts has lagged behind their actual influence.

The international composition of the Research Topic carries its own significance. Bee science conducted in Brazil, Australia, North America, and Europe addresses ecosystems, pollinator faunas, and agricultural systems that differ profoundly, from stingless bee coffee pollination in the Neotropics to honey bee and native bee interactions in Australian bushland. Research agendas shaped primarily in a few wealthy countries risk overlooking questions critical to biodiversity hotspots where pollinator dependence of crops and wild plants is high and monitoring capacity is limited. Editorial platforms that deliberately gather work from multiple regions help distribute scientific attention more evenly and expose readers to study systems and bee taxa they might otherwise never encounter. They also create collaboration opportunities, since global challenges such as climate-driven range shifts and pesticide regulation cannot be resolved within any single country’s data.

Ultimately, the editorial frames a dual commitment that characterizes much of contemporary bee science: addressing urgent applied problems, including pollinator decline, crop pollination security, and sustainable pest management, while pursuing fundamental questions about behavior, genetics, and ecology. The two commitments are mutually reinforcing, because applied urgency attracts funding and public interest that sustain basic research, and mechanistic understanding provides the foundation on which practical tools are built. Whether the demographic gap in research positions narrows in the coming decades will depend on institutional choices in hiring, mentoring, and workload allocation, but initiatives that make contributions visible, document persistent inequities with transparent data, and connect researchers across regions and career stages represent concrete steps toward a community in which the full breadth of talent devoted to understanding and protecting bees can flourish.

Subject of Research: Editorial: Women in bee science

Article Title: Editorial: Women in bee science

Article References: Fahrbach, S. E., Imperatriz-Fonseca, V. L., Nunes-Silva, P., & Wallace, H. M. (2026). Editorial: Women in bee science. Frontiers in Bee Science, 4, Article 1781526. https://doi.org/10.3389/frbee.2026.1781526

Image Credits: AI Generated

DOI: 10.3389/frbee.2026.1781526

Keywords: bee science, women in science, pollination, climate change, neonicotinoids, stingless bees, honey bees, bumblebees, Editorial, Women, science, scientific research

The study focused on two plant species of exceptional importance to late-season pollinators: bramble (Rubus fruticosus) and ivy (Hedera helix). Both are prolific sources of nectar and pollen and both attract enormous numbers of flower-visiting insects when in bloom, making them natural arenas in which competitive dynamics can be observed at scale. The researchers selected five sites, all situated within 300 metres of known honeybee colonies, ensuring that honeybee presence at the flowers was substantial and consistent. Over 93 hours of direct observation spread across two years, the team recorded every instance in which one pollinator disrupted or prevented another from accessing a flower, categorising each encounter according to the species involved and its outcome.

The methodological framework was elegantly simple. Flower visitors were sorted into five categories: honeybees, bumblebees, solitary bees, hoverflies, and an ‘other’ group that included butterflies, beetles and wasps. Each recorded interaction was scored either as a ‘win’, in which one insect gained access to a flower at the direct expense of another, or as a ‘share’, in which both insects fed without conflict. This binary scoring system allowed the researchers to quantify not just the frequency of competitive encounters but also which species consistently emerged victorious, and to correlate those outcomes with the local density of honeybees at each site.

The results were striking. Higher densities of honeybees were associated with both lower numbers of other pollinators and a greater frequency of competitive interactions, with honeybees claiming a disproportionately high share of ‘wins’ in their encounters with other flower visitors. The effect was quantifiable in ways that carry real ecological weight. On bramble, a doubling of honeybee density was associated with a 14 per cent reduction in bumblebee abundance. On ivy, increases in honeybee numbers were linked to declines in solitary bees and hoverflies, two groups that include many species of conservation concern. These are correlational findings drawn from field observation, but their consistency across sites and plant species lends them considerable persuasive force.

What distinguishes this study from earlier work on pollinator competition is its behavioural granularity. Honeybees did not simply outcompete rivals by arriving earlier or in greater numbers; they actively instigated aggressive interactions, winning resources by physically displacing or chasing other insects away from flowers. Other pollinators appeared to recognise the threat: honeybees were actively avoided by their wild counterparts in 28 per cent of interactions on bramble and 36 per cent of interactions on ivy. In at least one in five of the honeybees’ winning outcomes on both plant species, the victory involved physical displacement or pursuit. Crucially, the researchers recorded very few aggressive interactions that were not initiated by honeybees, underscoring the asymmetry of the conflict.

There was, however, one remarkable exception to honeybee dominance. The ivy bee, Colletes hederae, a solitary bee species that is itself a relatively recent arrival to Britain, having first been recorded there in 2001, was the only insect observed contesting encounters with honeybees and winning. Ivy bees were seen defending their food source by displacing and chasing honeybees, turning the usual hierarchy on its head. The study’s lead author, Victoria Buckle, a PhD student at Anglia Ruskin University, noted that this was the first time, to the researchers’ knowledge, that such behaviours had been observed, and that ivy bees appear able to hold their own in direct confrontations with the otherwise dominant honeybee.

The findings arrive at a moment of rapid change in British beekeeping. The number of registered beekeepers in the United Kingdom has risen from approximately 19,000 in 2010 to 47,000 last year, a trajectory that implies a substantial and ongoing increase in managed honeybee hive density. Because honeybee colonies can contain tens of thousands of foragers, even modest increases in hive numbers translate into very large increases in the number of individual insects competing at local flowers. The Cambridge study suggests that this numerical advantage is compounded by a behavioural one: honeybees are not passive competitors but active aggressors that shape the foraging environment for every other species around them.

Climate change adds a further and potentially alarming layer to the picture. The researchers found that periods of higher temperature were associated with an increase in competitive interactions between flower visitors. One plausible mechanism lies in the physiology of the plants themselves: heat stress is known to cause flowers to produce less nectar, shrinking the total forage available and forcing pollinators into more frequent and more intense conflict over what remains. As UK summers warm, this mechanism could operate over ever wider areas and longer seasons, intensifying the very competition the study documents.

Temperature also acts directly on the insects, and here the asymmetry between species becomes starker. Low temperatures favour the foraging capacity of hoverflies and bumblebees, both of which are sensitive to heat, while the opposite holds for honeybees. A previous study cited by the researchers found that a 12°C increase in temperature led to a tenfold increase in the number of honeybees leaving their nests. In a warming climate, then, honeybees are likely to become more active foragers precisely when bumblebees and hoverflies are becoming less able to compete, a combination that the study’s authors warn is only likely to exacerbate interference competition from dominant honeybees under future predicted warming in the UK.

The research team is careful to frame the work not as an indictment of beekeeping but as a contribution to coexistence. Buckle emphasised that the aim of the study was not to discourage beekeeping but to better understand how competition unfolds between wild and managed pollinators, with the goal of helping to conserve wild species that play an essential ecological role in pollinating both crops and wild plants. The practical implications, however, are clear: in locations with high densities of hives, such as urban areas where hobbyist beekeeping has surged in popularity, the pressure on wild pollinators may be greatest. Finding ways to ensure that honeybees and wild pollinators can continue to share the landscape, whether through careful siting of hives, habitat restoration that increases total forage availability, or monitoring of wild pollinator populations near apiaries, will be a central challenge for pollinator conservation in the decades ahead. What this study makes unmistakably clear is that the flowers of Britain are contested ground, and that the contest is neither neutral nor gentle.

Subject of Research: Interference competition between managed honeybees and wild pollinators on bramble and ivy flowers in the UK

Article Title: Honeybees exert flower power over other species

Article References: Honeybees exert flower power over other species. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: honeybees, wild pollinators, bumblebees, hoverflies, ivy bee, interference competition, nectar, climate change, heat stress, beekeeping, Cambridge, Ecological Entomology

The research, published in the British Ecological Society’s Journal of Applied Ecology, is among the most comprehensive field investigations yet conducted into competition between managed honey bees and wild pollinators on temperate heathland. Across a full flowering season running from May to September, the team surveyed plant and pollinator communities at 20 moorland sites spread across Scotland. The design deliberately contrasted plots with and without introduced honey bee apiaries, and compared land that was actively grazed and burned using traditional muirburn practices against land left to regenerate naturally. This paired structure allowed the researchers to separate the effects of beekeeping from the effects of routine livestock and vegetation management, something earlier studies had rarely achieved at this scale.

The sheer volume of data collected gives the findings considerable weight. The team recorded more than 1.6 million individual flowers and documented over 5,000 plant-pollinator interactions, spanning 58 plant species and 405 pollinator species. Ten of the study sites hosted commercial apiaries, each averaging 34 hives, which were monitored during the peak of the heather bloom when beekeepers traditionally bring their colonies onto the moors. This is the moment when ling heather erupts into a mass of purple blossom, offering one of the richest nectar resources in the British uplands and producing the famously aromatic heather honey prized by beekeepers across Europe.

Against expectations, the arrival of these hives produced only a modest signal in the ecological data. The presence of honey bees caused a small change to the structure of plant-pollinator networks, the webs of interactions linking flowers to the insects that visit them, but had no measurable effect on the quantity or quality of pollen collected by bumblebees. In other words, the wild bees did not appear to be going hungry, or gathering poorer food, because honey bees were foraging alongside them. For a research community that has grown increasingly concerned about the potential spillover of competition from managed bees onto wild species, the result is striking.

The grazing story was very different. Spring grazing by sheep removed almost two-thirds, 63 percent, of the vital spring nectar available to bumblebees compared with ungrazed sites. This matters because early spring is a bottleneck in the lives of bumblebee queens emerging from winter hibernation. They must find enough nectar and pollen to fuel the founding of new colonies, and the key resource at this time of year is not heather, which flowers later in the summer, but blaeberry, the delicate pink-bellied flowers of bilberry that carpet the moorland floor. When sheep crop the moor in spring, they strip away these flowers along with the grasses and shoots they were intended to eat, effectively removing the fuel station that wild bees depend on at the most vulnerable moment of their annual cycle.

Dr Maisie Brett, the study’s lead author, captured the surprise at the heart of the findings. We expected honey bees to be the main threat to wild bees and other heathland pollinators, she said, but it turns out how we manage these habitats may matter far more. Managing livestock with pollinators in mind could be more impactful than restricting beekeeping. The comment reframes a debate that has often focused narrowly on the ethics and ecology of migratory beekeeping, pointing instead toward the everyday decisions that shape what actually flowers on the moor and when.

The timing of the research gives it particular policy relevance. Scotland’s Wildlife Management and Muirburn Act, passed in 2024, now restricts heather burning, a practice long used to create fresh young shoots for grouse and grazing animals. At the same time, the current Scottish Pollinator Strategy does not currently address the potential impact of managed honey bees on wild pollinators. The new findings suggest that both frameworks may need to look more closely at livestock management, and that the conversation about protecting pollinators on moorland cannot be settled by regulating beekeepers alone. Dr Brett noted that the findings are particularly timely given these recent legislative and strategic developments.

The recommendations that flow from the study are pragmatic rather than punitive. The researchers suggest carefully managing or avoiding sheep grazing on heathland in spring, precisely when blaeberry and other early flowers are in bloom, so that emerging bumblebee queens can access the nectar they need. They also recommend that honey bee hives be introduced only during the peak heather flowering period, when the moor’s nectar supply is at its most abundant and competition pressure is likely to be lowest. Finally, they highlight the value of maintaining a patchwork of habitat types across the landscape, a mosaic that careful grazing can actually help to create, ensuring that different pollinator species find resources throughout the season rather than in a single concentrated burst.

That last point carries an important nuance. Grazing is not inherently harmful to moorland ecosystems; traditional low-intensity grazing has shaped these habitats for centuries and can prevent scrub encroachment while creating the structural variety that many invertebrates require. The problem identified by the Bristol team is one of timing and intensity. Sheep turned onto the moor in spring, when blaeberry is flowering, undo the seasonal nectar supply at its most critical point, whereas grazing patterns adjusted to the flowering calendar could retain the habitat benefits while sparing the pollinators. It is a reminder that in ecology, the question is often not whether a practice should happen, but when and how much.

The study was funded by UKRI and BBSRC and was carried out in collaboration with landowners and beekeepers across east Scotland, a partnership that reflects the practical realities of moorland management. Any change to grazing calendars or apiary siting will require cooperation among farmers, sporting estates, beekeeping associations and conservation bodies. What the research offers all of them is a clearer evidence base: on Scotland’s moorlands, the fate of wild pollinators appears to rest less with the hives that arrive in summer than with the sheep that graze in spring, and with the human choices that determine whether the moor blooms when the bees need it most.

Subject of Research: The impact of sheep grazing and managed honey bee hives on wild pollinator communities in Scottish heathland moorlands

Article Title: Sheep grazing may pose greater threat to Scotland’s wild pollinators than honey bees

Article References: Sheep grazing may pose greater threat to Scotland’s wild pollinators than honey bees. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: Scotland, heathland, bumblebees, honey bees, sheep grazing, pollinators, ling heather, muirburn, Journal of Applied Ecology, nectar availability, land management, blaeberry

The study, published in Ecology and Evolution, took advantage of an extraordinary dataset gathered at the Lijiang Forest Ecosystem Research Station. Over the 2012 flowering season, researchers conducted nine censuses at two-week intervals in four alpine meadows spread along an elevation gradient from 2,725 meters to 3,910 meters above sea level. Across 320 hours of observation, they recorded 5,369 pollination events linking 101 plant species with 335 insect pollinator species, each insect identified through a combination of morphology and DNA barcoding. Crucially, the team filtered out insects carrying no pollen, ensuring the network represented genuine pollination rather than mere flower visitation.

What makes the analysis novel is its treatment of time. Rather than slicing the season into disconnected snapshots, the researchers built temporal multilayer networks, a framework borrowed from network science in which each two-week census forms a layer and species are connected both to their interaction partners within a layer and to themselves across adjacent layers. The weights of these interlayer links reflect changes in abundance and phenology, effectively encoding how strongly a species persists from one period to the next. This architecture allowed the team to ask questions that static networks cannot answer: which species hold the community together through time, and what biological traits make them capable of doing so?

The first major finding concerns modularity. Ecological networks are typically organized into modules—clusters of species that interact strongly with one another but weakly with outsiders—and in static networks this modularity is thought to buffer disturbances. Using the Infomap algorithm, which compresses the description of flows through a network to detect its natural divisions, the researchers confirmed that all four temporal networks were significantly modular compared with randomized null models. But the modules themselves were startlingly ephemeral. No single module persisted across all nine time layers at any site, and at three of the four meadows, roughly 60 to 69 percent of modules lasted only one or two census periods. Early-season and late-season modules became entirely distinct communities.

Yet the turnover of species with different flowering and flight phenologies turned out to be only half the story. On average, 47.6 percent of pollinator species changed their module affiliation at least once during the season, a property the authors call adjustability. More striking still, the number of modules a pollinator occupied was tightly correlated with the number of time layers in which it remained active, with Spearman correlations ranging from 0.67 to 0.90 across sites. Long-persisting species do not simply sit in a stable niche; they actively track floral resources as the plant community shifts, rewiring their interactions and migrating between modules. The bumblebee B. friseanus exemplified this flexibility, occupying up to six different modules at the highest-elevation sites.

The second pillar of the analysis is versatility, measured through multilayer PageRank centrality—the same algorithm that underlies Google’s search rankings, adapted to rank species by their importance across the entire temporal structure. Most pollinators scored low, but a select few stood out: between 4 and 14 species per site, or roughly 5 to 15 percent of the local pollinator fauna, showed versatility significantly exceeding random expectation. These super-generalists were dominated by Diptera and Hymenoptera, with hoverflies and anthomyiid flies taking center stage at high elevations, consistent with the established importance of flies in cold, alpine environments. Intriguingly, a hemipteran of the genus Nysius emerged as highly versatile at two sites, hinting that true bugs may be underappreciated pollinators in alpine meadows.

Having identified the network’s temporal linchpins, the researchers turned to the mechanistic question: what makes these species versatile? Their hypothesis drew on classical niche theory, which holds that species exploiting a broader range of resources and conditions persist better in fluctuating environments. They quantified each pollinator’s trophic niche space as the volume of floral trait space—corolla depth, flower units per plant, and plant height—spanned by the plants it visited, and its environmental niche space as the volume of temperature and humidity conditions under which it foraged, using convex hull volumes in multivariate trait space. Body traits likely to underpin these niches were also measured: proboscis length, head width, and forewing index.

Structural equation modeling revealed a consistent hierarchical pathway across all four meadows. Trophic niche space exerted a significant positive effect on versatility at every site, with standardized coefficients climbing from 0.31 at the lowest meadow to 0.51 at the highest. Environmental niche space acted both directly on versatility at the lower sites and indirectly, through its strong positive association with trophic niche space, at all sites—suggesting that pollinators tolerant of a wide range of microclimatic conditions also access a wider variety of flowers. Trait effects were more context-dependent: proboscis length broadened the trophic niche at the lowest site and the environmental niche at mid-high elevation, while head width showed a negative direct effect on versatility at one site, possibly because smaller-bodied insects can access more floral morphologies. The models explained between 23 and 48 percent of the variation in versatility.

The team took considerable care to rule out statistical artifacts. Because richer communities naturally offer larger interaction pools, they resampled the networks 100 times with fixed species richness and confirmed that the observed path coefficients generally fell within the null distributions, indicating genuine ecological signal rather than richness-driven inflation. A parallel resampling that standardized the number of individuals per pollinator species showed that the niche-versatility relationships were not merely a byproduct of abundant taxa accumulating more records. The consistency of the results across a 1,200-meter elevation gradient, spanning meadows with 58 to 169 pollinator species, strengthens the case that niche breadth is a general determinant of temporal network roles.

The implications reach well beyond Yulong Mountain. As climate change disrupts phenology and drives mismatches between flowering times and pollinator activity, the species most capable of holding ecosystems together may be precisely these broad-niched, module-switching generalists. The authors argue that highly versatile pollinators, by sustaining interactions across shifting temporal and ecological contexts, are likely to persist in changing environments and should be treated as priority candidates for conservation and further research into their functional replaceability. The multilayer framework itself invites extension to other interaction types—seed dispersal, herbivory, predation—and to temporal scales from hours to years, offering a general lens for understanding how ecological networks endure, reorganize, and sometimes collapse in a rapidly changing world.

Subject of Research: Temporal dynamics of plant-pollinator networks and the traits driving pollinator versatility across seasons

Article Title: Trophic and Environmental Generalists Maintain Pollinator Network Functional Continuity by Switching Modules Through Time

Article References: Li, H.-D., Zhao, Y.-H., Holyoak, M., Tao, Z., Xu, K., Wu, Z., Wang, H., & Li, D.-Z. (2026). Trophic and Environmental Generalists Maintain Pollinator Network Functional Continuity by Switching Modules Through Time. Ecology and Evolution, 16(9), Article e74263. https://doi.org/10.1002/ece3.74263

Image Credits: AI Generated

DOI: 10.1002/ece3.74263

Keywords: pollination networks, multilayer networks, modularity, versatility, niche breadth, bumblebees, alpine meadows, phenology, structural equation modeling, ecological networks, Himalaya-Hengduan Mountains, pollinator conservation

The research team, led by Gwen Kühn and Heike Feldhaar of the University of Bayreuth’s Bayreuth Center of Ecology and Environmental Research, designed a fully crossed factorial experiment on buff-tailed bumblebees, Bombus terrestris. In such a design, every possible combination of the three stressors—ozone, heat, and microplastics—is tested, including each stressor alone, every pairwise pairing, and all three together. This rigorous architecture allowed the scientists to disentangle the individual effect of each hazard from the effects that emerge only when hazards collide, a distinction that is critical because wild insects never experience stressors in isolation. In the field, a foraging bumblebee on a hot summer afternoon may simultaneously breathe ozone-laden air and carry microplastic particles on its body and in its gut.

The ozone levels used were environmentally relevant concentrations rather than extreme laboratory doses. Ground-level ozone is a secondary pollutant formed when nitrogen oxides and volatile organic compounds react in sunlight, and its concentrations are expected to rise in many regions as temperatures climb. Heat exposure likewise reflected realistic warming scenarios. The microplastics were low-density polyethylene particles, one of the most common plastics in the environment, generously provided and characterized by Daniel Wagner under the supervision of Professor Seema Agarwal within the Collaborative Research Centre 1357 Microplastics, a flagship German research program dedicated to understanding this pervasive pollutant.

To probe what the stressors were doing inside the bees, the team turned to proteomics—large-scale analysis of the proteins expressed in the fat body, the insect organ that serves as a combined liver, fat store and immune hub. The protein signatures told a clear and mechanistically revealing story. Ozone exposure triggered an oxidative stress response, consistent with ozone’s chemistry as a powerful oxidant that damages tissues and consumes antioxidants. Heat stress reshaped the bees’ metabolism, reflecting the energetic cost of maintaining physiological balance at elevated temperatures. Microplastics, remarkably, induced signatures of tissue damage and detoxification, suggesting the particles were physically harming internal structures and mobilizing the bees’ cellular defense machinery.

When the researchers turned from proteins to survival, the pattern became even more striking. Among the single stressors, microplastics alone had the strongest effect on mortality—a sobering result given the quiet, continuous accumulation of plastic particles in terrestrial ecosystems. Yet ozone and heat, which on their own did not significantly increase mortality in this setup, became lethal partners when microplastics entered the equation. Only in combination with microplastics did ozone, heat, and both of them combined significantly raise death rates. In other words, plastic particles appeared to lower the bees’ resilience, opening the door for environmental conditions that would otherwise be survivable.

The most alarming result emerged when all three stressors acted together. For that triple combination, the observed effect on mortality exceeded what would be predicted from simply adding up the individual and pairwise effects, indicating true synergistic interaction. Synergy is the word toxicologists reserve for combinations that are more dangerous than the sum of their parts, and it is exactly the kind of nonlinearity that single-stressor studies miss. The authors propose one plausible mechanism: microplastic exposure may reduce heat resistance in bumblebees, so that temperatures a healthy bee could tolerate become deadly for a plastic-burdened one. If the particles damage gut or fat body tissues and drain detoxification resources, the physiological reserves needed to survive heat waves may simply no longer be there.

Why does this matter beyond the laboratory? Pollinators already face pesticide exposure, habitat loss, parasites and shifting flowering seasons. This study adds a troubling layer: the very pollutants generated by industrial society—plastics and photochemical smog—do not just coexist with climate warming, they chemically and physiologically collaborate with it. Rising temperatures do not only stress bees directly; they also drive the photochemical reactions that produce more ground-level ozone, while the global accumulation of microplastics continues essentially unchecked. The Bayreuth team’s conclusion is blunt: the progressive environmental buildup of microplastics, rising temperatures, and the ozone increases they bring could pose a serious health risk to pollinators in the near future.

The technical sophistication of the work deserves emphasis. By combining a fully crossed factorial mortality assay with fat body proteome analysis, the study links whole-organism outcomes to molecular mechanisms, moving the field beyond the simple observation that ‘pollution is bad for bees.’ The proteome data provide concrete, testable hypotheses—for instance, that oxidative damage from ozone compounds the tissue injury caused by plastic particles, or that metabolic reprogramming under heat leaves exposed bees with diminished capacity to repair microplastic-induced damage. Such mechanistic insight is essential for building realistic risk models that regulators and conservationists can actually use.

For conservation policy, the implications are uncomfortable but actionable. If microplastics sensitize pollinators to ozone and heat, then reducing plastic emissions into soils and airways, curbing the nitrogen oxide pollution that feeds ozone formation, and protecting bees from compound exposures during heat waves become intertwined goals rather than separate agendas. The study, funded by the German Research Foundation through CRC 1357 and published with open access support, arrived as an accepted manuscript that is fully citable and carries a permanent DOI. Its timing could hardly be more pointed: as summers grow hotter and plastic pollution spreads to every ecosystem on Earth, the humble bumblebee may be sounding an early alarm about the hidden arithmetic of combined environmental stressors—where one plus one plus one can equal far more than three.

Subject of Research: Combined effects of microplastics, ozone and heat stress on bumblebee health and mortality

Article Title: Negative effects of increased ozone concentrations and heat stress on bumblebees are exacerbated by microplastics

Article References: Kühn, G., Rupprecht, M. M., Mair, M. M., Stöckl, J. B., Kröger, F., Schieder, A., Nölscher, A. C., Fröhlich, T., & Feldhaar, H. (2026). Negative effects of increased ozone concentrations and heat stress on bumblebees are exacerbated by microplastics. Microplastics and Nanoplastics. https://doi.org/10.1186/s43591-026-00229-x

Image Credits: AI Generated

DOI: 10.1186/s43591-026-00229-x

Keywords: bumblebees, microplastics, ozone, heat stress, pollinators, LDPE, proteomics, fat body, synergistic effects, ecotoxicology, multiple stressors, Bombus terrestris

The study, published in Nature Climate Change, tackles one of the most stubborn problems in conservation science: attribution. Pollinating insects face a gauntlet of modern pressures, from agricultural chemicals to habitat fragmentation to parasites such as the bee-processing pathogen Crithidia bombi and spillover from managed honeybees. When a bumblebee population vanishes from a landscape, which of these culprits deserves the blame? Traditional correlative studies cannot easily answer that question, because climate trends move in lockstep with many other environmental changes. The Belgian-led research team, headed by Bastien De Tandt of the Université Libre de Bruxelles and the University of Mons, sidestepped the problem with a counterfactual design borrowed from the climate attribution community.

Technically, the approach rests on running the same ecological models twice. First, the team trained ecological niche models for forty-seven European bumblebee species using occurrence records drawn from a newly synthesized database of wild bee and hoverfly observations across Europe, combined with climatic variables from the ISIMIP3a reanalysis framework, which reconstructs historical weather conditions from 1901 to 2019. These models, built with boosted regression trees, learn the environmental envelope each species occupies, capturing the temperature and precipitation conditions under which bumblebees persist. Performance was validated with spatially blocked cross-validation and metrics including the area under the receiver operating characteristic curve and a prevalence-calibrated Sørensen index, guarding against the optimism that plagues purely random data splits.

Then comes the counterfactual. Using the ATTRICI method, the researchers constructed a parallel climate dataset in which long-term anthropogenic trends have been removed while natural year-to-year variability is preserved. In this counterfactual Europe, weather still fluctuates and seasons still turn, but the warming fingerprint of industrial society is erased. Feeding both datasets through identical niche models produced two parallel histories of habitat suitability, and their difference isolates the specific contribution of human-caused climate change. It is the ecological equivalent of a clinical trial with a control group, and it gives the results a causal weight that earlier correlational studies of bumblebee decline could not claim.

The verdict is sobering but geographically nuanced. At the continental scale, community-level ecological suitability, a measure averaging suitability across all forty-seven species, fell by roughly five percent under the factual climate relative to the counterfactual one. But that continental average conceals sharp regional contrasts. Southern Europe, already identified as a Mediterranean climate-change hotspot in CMIP5 and CMIP6 projections, suffered the steepest declines, with suitability losses reaching nineteen percent locally. Lowland central regions, including the Carpathian Basin and the surrounding plains, also registered pronounced erosion of suitable conditions. These are areas where summer heat extremes have intensified faster than many climate models simulate, and where bumblebees, evolutionarily adapted to cool temperate conditions, bump against their physiological limits.

Bumblebees are, in a sense, mammals of the insect world: thick-furred, cold-adapted descendants of alpine lineages that struggle when temperatures climb. Laboratory protocols developed to test insect heat tolerance have shown that many Bombus species have critically low thermal maxima compared with other insects, and heat waves have been linked to a ‘scarcity syndrome’ of local disappearances documented in France as far back as the early 2000s. The new results suggest those anecdotal local extinctions are the visible edge of a continent-wide redistribution of livable space. As conditions warm, the suitable zone shifts poleward and upward, and species unable to disperse fast enough accumulate a mounting climatic debt.

The mountain and boreal edges of Europe tell a different story. In the Alpine and Boreal biogeographic regions, gains in suitability at higher altitudes and latitudes partially compensated for losses at lower elevations, yielding minimal net change. Cold-adapted species such as Bombus alpinus have shown hints of uphill shifts in the Alps, and bumblebee elevation ranges have climbed measurably in the Pyrenees over the past century. Yet researchers caution that these apparent refuges are finite. Mountains are truncated worlds: a species can only climb so far before it runs out of summit. The modest boreal gains also reflect expansions of a few generalist species, including the tree bumblebee Bombus hypnorum, rather than a broad story of resilience.

What makes the findings particularly consequential is what they imply for the rest of the century. An earlier analysis by overlapping authors projected steep declines in European bumblebee populations through 2100 under future warming scenarios. The new attribution study confirms that the projected future has, in a quantifiable sense, already begun. Climate change is not a looming threat to these pollinators; it is a pervasive, measurable pressure that has been reshaping their distributions for more than a hundred years, compounding the stresses of intensive agriculture, pesticide exposure and dwindling floral resources. Because bumblebees pollinate a large share of wild flowering plants and numerous crops, including tomatoes, berries and legumes that depend on their distinctive buzz pollination, the erosion of their habitat carries direct consequences for both biodiversity and food production.

The methodological template established here is likely to spread. Counterfactual climate datasets and impact-attribution frameworks of the kind used in the Inter-Sectoral Impact Model Intercomparison Project are increasingly available, and the researchers have released their curated occurrence database, models and R scripts openly through Zenodo and GitHub. Similar attribution exercises could now disentangle climate’s role in the fortunes of other threatened insect groups, from hoverflies to butterflies, where blame has been similarly contested. For conservation planners, the regional maps of climate-driven suitability loss offer a practical tool: southern and central lowland populations emerge as priority targets for habitat restoration, connectivity corridors and thermal refugia, while mountain reserves gain added strategic value as potential stepping stones in a warming race. The study’s authors note that all datasets underpinning the work are freely available, and their results demonstrate unambiguously that climate change is already rewriting the map of Europe’s most beloved wild pollinators.

Subject of Research: Attribution of declines in European bumblebee habitat suitability to human-driven climate change since 1901

Article Title: Declines in European bumblebee habitat suitability attributable to climate change

Article References: De Tandt, B., Serres, K., Pietroiusti, R., Erazo, D., Massonnet, F., Michez, D., Thiery, W., Ghisbain, G., & Dellicour, S. (2026). Declines in European bumblebee habitat suitability attributable to climate change. Nature Climate Change. https://doi.org/10.1038/s41558-026-02734-6

Image Credits: AI Generated

DOI: 10.1038/s41558-026-02734-6

Keywords: bumblebees, climate change, habitat suitability, pollinators, ecological niche modelling, counterfactual climate, attribution, biodiversity loss, Europe, Nature Climate Change, conservation biology, ISIMIP3a