Search Results (109)

The obligate mutualism between Ficus and its pollinating wasps provides a suitable system to investigate these dynamics because it encompasses two contrasting pollination modes: active and passive. Here we compared pollen traits in an actively pollinated fig tree, Ficus citrifolia, and a passively pollinated species, F. obtusiuscula, examining pollen both at anther presentation and after deposition on the bodies of their pollinating wasps. Pollen morphology, hydration-related behavior, cytology, and reserve composition were characterized using scanning electron microscopy (conventional and modified), light and transmission electron microscopy, histochemical assays, and viability tests. Across species, pollen traits at anthesis showed broad overlap in morphology, viability and major reserve classes, indicating that these characteristics are not consistently predicted by pollination mode alone. In both species, pollen was bicellular, harmomegathic and highly viable at presentation, consistent with resilience during transport. The main divergence emerged after pollen transfer to the pollinator. In the actively pollinated species, pollen recovered from wasp thoracic pockets exhibited pronounced intracellular remodeling, including vacuolization, starch depletion, lipid redistribution and localized cytoplasmic degradation. By contrast, pollen of the passively pollinated species retained a comparatively stable cytological organization after transport despite changes in reserve distribution. These results suggest that the more pronounced cytoplasmic reorganization observed in the pollen of the actively pollinated species after deposition on the wasp body may represent a preparatory phase for rapid germination following pollination, reflecting the stronger dependence of larval development on successful flower fertilization in actively pollinated figs. More broadly, our study provides the first comparative account of pollen structural and cytophysiological dynamics on fig-wasp bodies, linking pollen cell biology to pollinator-mediated dispersal and highlighting how different pollination strategies may impose distinct selective pressures on male gametophytes. Full article

The impacts of climate change on Mediterranean weed flora were investigated to inform future weed management strategies. Projections indicate that rising temperatures and increased atmospheric CO₂ concentrations are likely to favor ruderal species characterized by rapid phenological development and high dispersal capacity. Enhanced abiotic stressors—such as elevated temperatures, water scarcity, and increased UV-B radiation—are expected to affect crops more severely than weeds, given the latter’s greater evolutionary potential to develop stress-tolerant biotypes. Moreover, the increased frequency and intensity of extreme events (e.g., drought, flooding, and soil salinization) may reduce weed community diversity, potentially leading to dominance by a limited number of highly competitive species and consequently intensifying reliance on chemical weed control. Simplification of weed communities may also increase vulnerability to the introduction and establishment of alien species, particularly those originating from hot and arid regions, some of which may be parasitic, toxic, or allergenic. Climate change-induced phenological mismatches between flowering plants and pollinators are likely to favor wind-pollinated weed species, further compromising the aesthetic and ecological quality of agricultural landscapes. Additionally, increased production of wind-dispersed allergenic pollen, together with the anticipated rise in herbicide applications, may pose significant risks to human health. An effective agronomic strategy to address future weed scenarios should include the genetic improvement in crops to enhance adaptive plasticity, exploiting germplasm from ancestral lines and related wild species. Full article

Plantations of the valuable Chinese timber species, Chamaecyparis hodginsii, established by planting, primarily rely on seed orchards for propagation. Therefore, effective management of the genetic composition of these orchards is essential to ensure a sustainable supply of high-quality seeds. However, the mating system and pollen dispersal mechanisms in its high-generation seed orchards remain unclear, limiting precise genetic management. To address this, we analyzed 30 parental clones and 75 of their open-pollinated progeny from a second-generation seed orchard using 15 polymorphic EST-SSR markers. Compared to reported natural populations of C. hodginsii, both parental and progeny populations maintained high genetic diversity (mean uHe = 0.438 and 0.449, respectively), with a significant excess of heterozygotes (mean Fis = −0.084 and −0.066, respectively). Population genetic structure analysis indicated weak genetic differentiation among the parental genetic groups (mean Fst = 0.012), which was further reduced in the progeny population (mean Fst = 0.003) due to open pollination, reflecting a trend toward genetic homogenization. The mating system was characterized exclusively by outcrossing (tm = 1.000). However, paternity analysis revealed highly skewed paternal contributions, a low effective number of pollen donors (Nep = 8.13), and contributions of S5, S11, and S17 as dominant pollen parents, with 17.33% external pollen flow. These findings elucidate the mechanisms underlying sustained genetic diversity despite unequal paternal contributions and provide a theoretical basis for optimizing parental configuration and pollen management. Full article

Allergic rhinitis and asthma remain major public-health challenges, with airborne pollen serving as a key environmental driver. This study investigates the temporal association between aeroallergen exposure, patient healthcare utilization, and allergy medicine consumption at the MNIT Jaipur dispensary from 2015 to 2020, focusing on Holoptelea integrifolia pollen as a primary allergen. Patient visit data and medicine issuance records were analyzed to evaluate seasonal co-trends using descriptive time-series and statistical tests, including Pearson correlation and Mann–Whitney U. The analysis revealed consistent peaks in both patient visit and medicine issuance during February–April, corresponding with H. integrifolia pollen release, and secondary peaks during August–September and October, coinciding with Amaranthus spinosus, Parthenium hysterophorus, and monsoon mold activity. A moderate positive correlation (r = 0.58, 95% CI: 0.22–0.79, p = 0.007) and significant differences between high- and low-patient months (U = 107.5, p = 0.043, 95% CI of difference: 1323–3620 units) indicating that increased healthcare utilization coincides with seasonal aeroallergen exposure. These findings highlight the potential of medicine consumption data as a cost-effective proxy for allergen surveillance, aiding early warning and preparedness for seasonal allergy management. Integration of such pharmaco-epidemiological insights with dispersion models may strengthen predictive frameworks for pollen exposure and public-health response. Full article

Ambrosia artemisiifolia (ragweed) is a highly invasive species that produces large amounts of allergenic pollen. This poses a serious health risk to allergy sufferers. The “Ragweed Finder” is an Austrian citizen science platform (website and app) that enables the public to report occurrences of ragweed, which are then verified by experts. Over 90% of reports are confirmed as positive, with most originating from eastern Austria, where ragweed is widespread. The number of reports has generally increased over time, except in 2020 during the pandemic. Report frequency does not directly correlate with daily pollen concentrations, but peaks before and during pollen season. Most observations occur along traffic routes, likely due to seed dispersal by vehicle airflow or easier accessibility for users. Verified observations are displayed on an interactive map, helping allergy sufferers to avoid exposure and informing local authorities of the need for targeted control actions. The data are also used to raise awareness among policymakers and help to enact the first law for the control and prevention of ragweed in Burgenland (Austria), in 2021: the “Burgenland Ragweed Control Act”. This demonstrates the success of the “Ragweed Finder” as an important tool for monitoring this invasive species in Austria. Full article

Many plant species depend on pollen flow to maximize reproduction and maintain genetic variability. Pollinators mediate this process, but distance between individuals can influence its benefits. Proximity may cause inbreeding depression, while extreme distances can mix locally adapted genotypes, leading to outbreeding depression and reduced fitness. Vereda palm swamps, shaped by the water table, are important habitats in the Cerrado, but they face anthropogenic changes that can affect reproduction, pollinators, and genetic diversity. This study examined how pollen dispersal distance influences the reproductive success of spiral ginger (Costus spiralis, Costaceae), a vereda self-compatible rhizomatous herb pollinated by hummingbirds. Hand pollinations were carried out between plants ranging from 10 to 2000 m distant, and the resulting fruit-set and seed quality traits were evaluated. Fruit set did not vary significantly with distance, with no hint of either inbreeding or outbreeding depression. Nevertheless, seeds resulting from shorter pollination distance (10 m) were heavier, while germination rates were up to five-fold higher at greater pollination distances than at shorter pollination distances. These distinct seed traits are possibly related to main hummingbird pollinators of C. spiralis, which show distinct foraging strategies. The results suggest that C. spiralis is adapted to various modes of pollen dispersal, ensuring reproduction via either territorial or traplining hummingbirds. Full article

Cannabis is usually dioecious, with male and female flowers on separate plants. Cultivators prioritize the use of female plants because their flowers contain a higher density of glandular trichomes, the primary source of cannabinoids, compared to male flowers. Feminized seeds, which give rise exclusively to female plants, are highly valued in the cannabis industry. These seeds are produced by crossing a natural female plant with another female plant that has been masculinized to generate pollen. Masculinization is achieved by inhibiting ethylene and/or applying gibberellins prior to flower initiation in female plants. Currently, silver thiosulfate (STS) is the most common treatment used in the cannabis industry, though environmental concerns arise from silver applications. This study compared STS with three other ethylene-inhibiting agents: aminoethoxyvinylglycine (AVG), cobalt nitrate (CBN), and 1-methylcyclopropene (1-MCP). Some STS and CBN treatments also included gibberellic acid as a synergist. STS-treated plants displayed the most effective masculinization and pollen dispersal, compared to plants treated with AVG. Only STS and AVG generated sufficient pollen for collection. This pollen was initially tested for germination potential and subsequently stored for up to five weeks at 22.2 °C, 7.2 °C, or 1.1 °C.Germination rates ranged from 2.2% to 5.8%, underscoring the influence of storage conditions and highlighting the need to refine preservation methods to enhance agricultural viability. Pollen from plants treated with AVG remained viable for three weeks at 1.1 °C, although there were concerns about a high risk of phytotoxicity. STS-treated pollen also remained viable for three weeks at the same temperature. Neither CBN nor 1-MCP treatments were effective in inducing masculinization. No clear synergistic effect of gibberellic acid combined with STS or AVG was observed; however, growth stunting led to increased mortality. Due to pollen viability and phytotoxicity problems with AVG, STS remains the best treatment to masculinize female cannabis plants when breeding for feminized seeds. Full article

Diabrotica virgifera virgifera Le Conte, 1868 (Coleoptera: Chrysomelidae), known as the western corn rootworm, is one of the most important alien insect pests affecting maize crops globally. It causes significant economic losses by feeding on the roots, which affects plant stability and nutrient absorption, as well as by attacking essential aerial organs (leaves, silk, pollen). Since its accidental introduction into Europe, the species has expanded its range across maize-growing regions, raising concerns about future distribution under climate change. This study aimed to estimate the risk of pest establishment across Europe over three future time frames (2034, 2054, 2074) based on geographic coordinates, climate data, and maize distribution. Spatial simulations were performed in QGIS using national centroid datasets, risk classification criteria, and temperature anomaly maps derived from Copernicus and ECA&D databases for 1992–2024. The results indicate consistently high risk in southern and southeastern regions, with projected expansion toward central and western areas by 2074. Risk zones showed clear spatial aggregation and directional spread correlated with warming trends and maize availability. The pest’s high reproductive potential, thermal tolerance, and capacity for human-assisted dispersal further support these predictions. The model emphasizes the need for expanded surveillance in at-risk zones and targeted policies in areas where D. v. virgifera has not yet established. Future work should refine spatial predictions using field validation, genetic monitoring, and dispersal modeling. The results contribute to anticipatory pest management planning and can support sustainable maize production across changing agroclimatic zones in Europe. Full article

AtmoHub, the Greek Copernicus National Collaboration Programme (NCP) gateway, delivers daily air quality forecasts aligned with the EC Air Quality Directives and provides in situ measurements for key pollutants (NO₂, O₃, PM10, PM2.5, SO₂), as well as insights into environmental phenomena such as pollen dispersion, smoke, volcanic activity, and dust transport. To address a previous lack of coordinated atmospheric services in Greece, it utilizes the WRF-Chem model for downscaling CAMS data. Offering hourly forecasts at 5 km resolution, AtmoHub supports researchers, authorities, and the public, promoting climate resilience and informed air quality management through a centralized, accessible platform. Full article

In many regions, the El Niño Southern Oscillation (ENSO) cycle is a key factor in modulating climate processes that can influence seasonal variability in the production and dispersal of allergy-triggering pollen. However, the impacts on allergy health are not well known. We compare grass pollen seasons between the major modes of the ENSO cycle in Auckland, New Zealand’s largest city, within a region that is highly sensitive to quasi-predictable meteorological oscillations of the ENSO cycle. We find no clear difference in the timing of onset of the pollen seasons, but season length was shorter, by >30 days, and less severe during the La Niña phase than for the other phases. The difference in pollen season length may be explained by the greater summer rainfall typically experienced in Auckland and elsewhere in northern New Zealand during La Niña phases, which tend to suppress grass pollen abundance when excessive. As grass pollen is the principal source of allergenic pollen in New Zealand and in many other countries, these results have wider implications for allergy management. With ENSO forecasting offering the prospect of several month’s lead time, there is potential for improving community preparedness and resilience to inter-annual dynamics of the grass pollen season. This work points to the need to better understand the influence of short-term climate cycles on seasonal variability in pollen allergy, while we also emphasise that the strong geographical heterogeneity in ENSO cycle climate impacts necessitates a region-specific approach. This work also further underscores the need for standardised, local–regional pollen monitoring in NZ and the risk of relying upon static, nationwide pollen calendars for informing allergy treatment. Full article

The volumetric Hirst method is considered a golden standard in aerobiology for determining particle number concentrations of bioaerosols. Using Hirst-type pollen and spore traps on mobile platforms (i.e., aircraft, cars, motorbikes, bicycles or carried by pedestrians) is anticipated to significantly enhance the spatial and temporal granularity of data for bioaerosol monitoring. Mobile sampling promises to enhance our understanding of bioaerosol dynamics, ecological interactions and the impact of human activities on airborne biological particles. In this article, we present the design and test of an airborne Hirst-type volumetric sampler. We followed a structured approach and incorporated the fundamental principles of the original design, while optimizing for size, weight, power and cost. Our portable Hirst-type volumetric sampler (FlyHirst) was attached to an ultralight aircraft, together with complementing instrumentation, and was tested for collection of atmospheric concentrations of pollen, fungal spores and hyphae. By linking the temporal resolution of the samples with the spatial position of the aircraft, using flight time, we calculated the spatial resolution of our measurements in 3D. In six summer flights over Denmark, our study revealed that the diversity of the recorded spores corresponded to the seasonal expectance. Urtica pollen was recorded up to 1300 m above ground (a.g.l.), and fungal spores up to 2100 m a.g.l. We suggest that, based on this proof-of-concept, FlyHirst can be applied on other mobile platforms or as a personal sampler. Full article

The gene flow rate in rice (Oryza sativa L.) is a critical factor for establishing safe isolation distances between genetically modified (GM) and non-GM varieties and for ensuring varietal purity in rice breeding programs. This study refines existing gene flow models by disentangling two key components of rice pollen dynamics: quantitative pollen competition and genetic competitiveness. We define B as the proportion of GM pollen within mixed pollen, representing quantitative pollen competitiveness. The outcrossing parameter C_b reflects the likelihood of successful fertilization and seed development by foreign pollen, while the hybrid compatibility parameter C_p captures the relative fertilization success of GM versus non-GM pollen within the same pollen pool. Together, C_b and C_p characterize the genetic competitiveness of rice pollen. Our findings reveal a nonlinear relationship between B and the observed GM pollen rate G, which may exhibit either upward or downward curvature. A nonlinear model provides a significantly better fit to this relationship than a linear model, improving R² by 4.1–21.4% and reducing RMSE by 9.9–47.8%. The parameters C_b and C_p play central roles in determining gene flow; higher values correspond to stronger GM pollen competitiveness, resulting in higher gene flow rates and greater dispersal distances. Specifically, C_b sets the range of the B–G curve, while C_p determines its curvature. Full article

Wildfires have had measurable impacts on pollen dispersal in some areas; both facilitation and potential barriers to pollen movement have been reported. These dispersal dynamics in turn affect population genetics and reestablishment of seed-producing plants, at times significantly impacting the successional trajectory of the area in question. However, research on post-fire pollen distribution and occurrence is lacking for the boreal and sub-boreal forests of western Canada, and many communities that have been heavily impacted by wildfire remain concerned about the future forest landscape of these areas. We analyzed post-fire pollen samples from unburned and severely burned sub-boreal spruce stands in north-central British Columbia four years after a major wildfire. We used pollen traps to measure the occurrence and abundance of pollen types from four important plant families: Asteraceae, Ericaceae, Onagraceae, and Pinaceae families, to address specific concerns of the First Nation communities with territories overlapping the Shovel Lake wildfire burned area. Pinaceae pollen was found across all traps and was observed as the most dominant pollen type at all study sites, while pollen belonging to other families was found less frequently. No significant differences in pollen occurrence or abundance were found between burn severities, despite differences in the plant communities; however, plant and pollen abundance were found to be positively correlated to one another. These results may indicate that, as previously noted in other conifer-dominated forests, openings of the forest landscape by wildfire may facilitate rather than hinder pollen movements. Understory species should be studied in more detail as the effect of wildfire on pollen transport may vary between taxa and pollination syndromes. Full article

Himantoglossum metlesicsianum is a threatened orchid with low population numbers and fragmented distribution, present in four of the Canary Islands. This study focused on assessing the genetic variability and population genetic structure of the natural populations known to date, identifying those characteristics of the species that condition the flow and genetic variation. For that purpose, we collected samples from eight sites in its distribution range and developed 14 polymorphic microsatellite markers. Despite its rarity, this orchid presents high levels of genetic diversity and a homogeneous population structure, characterised by a low degree of genetic differentiation and patterns consistent with high genetic connectivity among populations. Our results suggest that the species might show dichotomy in seed dispersal, combining long- and short-distance events. In addition, it is possible that pollen cross-pollination (pollinia) between adjacent sites may also be involved. In conclusion, these findings reveal unexpectedly high genetic diversity and connectivity among populations, despite the species’ rarity and fragmented distribution, highlighting key biological traits that should be considered in future conservation and recovery plans. Full article

We investigated whether a cold front passed on the day when the most cedar pollen was dispersed in each year. When we looked at the 10-year period from 2015 to 2024, and found seven cases in which a cold front passed through the pollen survey area in the Tohoku region. In these cases, extremely large amounts of pollen were dispersed in the hours before and after the front passed. What they had in common was that the amount of pollen dispersion increased significantly at the time the front passed and before and after it. There were 3 cases when a large amount of Japanese cedar pollen was dispersed, even though a cold front did not pass through our Tohoku region. In these cases, large amounts of pollen were dispersed during the time when the warm front was located several hundred to one thousand kilometers south from Tohoku region. The large amount of dispersion continued as long as the fronts moved northward and got closer by several hundred kilometers to the Tohoku region, and the pollen dispersion decreased by the time the front reached the Tohoku region. Full article