Lessons Learnt From Ragweed and Birch Studies

Here we review some of the most important aspects of recent work on Ragweed (Ambrosia) and birch (Betula) concerning: 1) sources, 2) trends & phenology and 3) dispersion and transformation. Sources: At Northern latitudes the birch fraction in forests usually exceeds 50% of all broadleaved trees and the abundance of birch decreases with latitude from 5%-20% in many mid-latitude regions and down to 0%-2% in more southern areas. Birches are also commonly found in small woodlands or planted as ornamental trees in urban areas. Ragweeds are herbaceous weed species that are associated with areas of disturbance. Ragweed is native to North America, but considered an invasive species in Europe, Australia and China. In Europe, the four main centres are: The Pannonian Plain, Ukraine, The Po Valley (Italy) and the Rhone Valley (France). Trends & Phenology: Birch pollen seasons have started earlier during the last decades. This trend appears have decreased during recent years despite increasing spring temperatures. Ragweed tends to experience less change in flowering date as ragweed flowering depends on photoperiod. Ragweed is increasing its distribution in Europe, but airborne concentrations of ragweed pollen are not universally increasing, e.g. due to control measures or pest attacks. Dispersion & transformation: The beginning of the birch pollen season is often heralded by episodes of Long Distance Transport (LDT) from the south. Similar LDT episodes are intermittently seen for ragweed, which can reach as far north as Scandinavia. Humidity and air pollution can modify pollen grains during atmospheric transport. This can cause a change in allergenic potential of the pollen grain and is a direction for future research including the effect of co-exposure of air pollution and the transformation of aeroallergens

Interlaboratory proficiency test in aerobiology using virtual slides – feasibility study

Abstract This study examines the use of Virtual Slide Images with the aim of assessing their efficacy and usability in comparison to traditional microscopy with glass slides for the Quality Control of aerobiological samples. Three glass microscopy slides containing samples of airborne pollen were digitised. Six counters from two laboratories examined the glass slides and their data were used to calculate assigned values and acceptable coefficients of variation (CV%) for seven pollen types. A total of 24 analysts from 12 countries examined the virtual slides using specialist OlyVIA software. Data from traditional glass and virtual slides were entered into tests for repeatability and intralaboratory reproducibility following the norm EN 16868:2019. Participants also completed a questionnaire reflecting on the efficacy and usability of Virtual Slide Images for interlaboratory Quality Control. Data from traditional glass and virtual slides were comparable but CV% were generally larger for virtual slides than glass slides. Participants who examined < 10% of the slide were more likely to produce results outside the limits of the study. The use of virtual slide technology is not for everyone and, in the current study, we found that opinion was polarised but it was interesting to note that there were no differences in response based on years of experience. There are advantages and disadvantages of the two methods, and we recommend virtual slides are used as an adjunct to glass slides for use in aerobiology Quality Control and other aspects of palynological training and assessment

Risk of Exposure to Airborne Ambrosia Pollen from Local and Distant Sources in Europe – an Example from Denmark

Background. Ambrosia artemisiifolia L. is a noxious invasive alien species in Europe. It is an important aeroallergen and millions of people are exposed to its pollen. Objective. The main aim of this study is to show that atmospheric concentrations of Ambrosia pollen recorded in Denmark can be derived from local or more distant sources. Methods. This was achieved by using a combination of pollen measurements, air mass trajectory calculations using the HYPLIT model and mapping all known Ambrosia locations in Denmark and relating them to land cover types. Results. The annual pollen index recorded in Copenhagen during a 15-year period varied from a few pollen grains to more than 100. Since 2005, small quantities of Ambrosia pollen has been observed in the air every year. We have demonstrated, through a combination of Lagrangian back-trajectory calculations and atmospheric pollen measurements, that pollen arrived in Denmark via long-distance transport from centres of Ambrosia infection, such as the Pannonian Plain and Ukraine. Combining observations with results from a local scale dispersion model show that it is possible that Ambrosia pollen could be derived from local sources identified within Denmark. Conclusions. The high allergenic capacity of Ambrosia pollen means that only small amounts of pollen are relevant for allergy sufferers, and just a few plants will be sufficient to produce enough pollen to affect pollen allergy sufferers within a short distance from the source. It is necessary to adopt control measures to restrict Ambrosia numbers. Recommendations for the removal of all Ambrosia plants can effectively reduce the amount of local pollen, as long as the population of Ambrosia plants is small

The Long Distance Transport of Airborne Ambrosia Pollen to the UK and the Netherlands from Central and South Europe

Background: The invasive alien species Ambrosia artemisiifolia (common or short ragweed) is increasing its range in Europe. In the UK and the Netherlands airborne concentrations of Ambrosia pollen are usually low. However, more than 30 Ambrosia pollen grains per cubic metre of air (above the level capable to trigger allergic symptoms) were recorded in Leicester (UK) and Leiden (NL) on 4 and 5 September 2014. Objective: The aims of this study were to determine whether the highly allergenic Ambrosia pollen recorded during the episode could be the result of long distance transport, to identify the potential sources of these pollen grains and describe the conditions that facilitated this possible long distance transport. Methods: Airborne Ambrosia pollen data were collected at 10 sites in Europe. Back trajectory and atmospheric dispersion calculations were performed using HYSPLIT_4. Results: Back trajectories calculated at Leicester and Leiden show that higher altitude air masses (1500m) originated from source areas on the Pannonian Plain and Ukraine. During the episode, air masses veered to the west and passed over the Rhône Valley. Dispersion calculations showed that the atmospheric conditions were suitable for Ambrosia pollen released from the Pannonian Plain and the Rhône Valley to reach the higher levels and enter the air stream moving to Northwest Europe where they were deposited at ground level and recorded by monitoring sites. Conclusions: The study indicates that the Ambrosia pollen grains recorded during the episode in Leicester and Leiden were probably not produced by local sources, but transported long distances from potential source regions in East Europe, i.e. the Pannonian Plain and Ukraine, as well as the Rhône Valley in France

Italian Ragweed Pollen Inventory

This study provides the first spatially detailed and complete inventory of Ambrosia pollen sources in Italy – the third largest centre of ragweed in Europe. The inventory relies on a well tested top-down approach that combines local knowledge, detailed land cover, pollen observations and a digital elevation model that assumes permanent ragweed populations mainly grow below 745m. The pollen data were obtained from 92 volumetric pollen traps located throughout Italy during 2004-2013. Land cover is derived from Corine Land cover information with 100m resolution. The digital elevation model is based on the NASA shuttle radar mission with 90m resolution. The inventory is produced using a combination of ArcGIS and Python for automation and validated using cross-correlation and has a final resolution of 5km x 5km. The method includes a harmonization of the inventory with other European inventories for the Pannonian Plain, France and Austria in order to provide a coherent picture of all major ragweed sources. The results show that the mean annual pollen index varies from 0 in South Italy to 6779 in the Po Valley. The results also show that very large pollen indexes are observed in the Milan region, but this region has smaller amounts of ragweed habitats compared to other parts of the Po Valley and known ragweed areas in France and the Pannonian Plain. A significant decrease in Ambrosia pollen concentrations was recorded in 2013 by pollen monitoring stations located in the Po Valley, particularly in the Northwest of Milan. This was the same year as the appearance of the Ophraella communa leaf beetle in Northern Italy. These results suggest that ragweed habitats near to the Milan region have very high densities of Ambrosia plants compared to other known ragweed habitats in Europe. The Milan region therefore appears to contain habitats with the largest ragweed infestation in Europe, but a smaller amount of habitats is a likely cause the pollen index to be lower compared to central parts of the Pannonian Plain. A low number of densely packed habitats may have increased the impact of the Ophraella beetle and might account for the documented decrease in airborne Ambrosia pollen levels, an event that cannot be explained by meteorology alone. Further investigations that model atmospheric pollen before and after the appearance of the beetle in this part of Northern Italy are needed to assess the influence of the beetle on airborne Ambrosia pollen concentrations. Future work will focus on short distance transport episodes for stations located in the Po Valley, and long distance transport events for stations in Central Italy that exhibit peaks in daily airborne Ambrosia pollen levels

Mesoscale Atmospheric Transport of Ragweed Pollen Allergens from Infected to Uninfected Areas

Allergenic ragweed (Ambrosia spp.) pollen grains, after being released from anthers, can be dispersed by air masses far from their source. However, the action of air temperature,humidity and solar radiation on pollen grains in the atmosphere could impact on the ability of long distance transported (LDT) pollen to maintain allergenic potency. Here, we report that the major allergen of Ambrosia artemisiifolia pollen (Amb a 1) collected in ambient air during episodes of LDT still have immunoreactive properties. The amount of Amb a 1 found in LDT ragweed pollen grains was not constant and varied between episodes. In addition to allergens in pollen sized particles, we detected reactive Amb a 1 in subpollen sized respirable particles. These findings suggest that ragweed pollen grains have the potential to cause allergic reactions, not only in the heavily infested areas but, due to LDT episodes, also in the regions unaffected by ragweed populations

Supplementary data for article: Kostić, A. T.; Barać, M. B.; Stanojević, S. P.; Milojković-Opsenica, D. M.; Tešić, T. L.; Šikoparija, B.; Radišić, P.; Prentović, M.; Pešić, M. B. Physicochemical Composition and Techno-Functional Properties of Bee Pollen Collected in Serbia. LWT - Food Science and Technology 2015, 62 (1), 301–309. https://doi.org/10.1016/j.lwt.2015.01.031

Supplementary material for: [https://doi.org/10.1016/j.lwt.2015.01.031]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/1680

Pollen Nightmare: Elevated Airborne Pollen Levels at Night

High airborne pollen concentrations are generally associated with daylight hours when it is sunny and warm and plants release pollen into the air (Alcázar et al. 1999; Dahl et al. 2013). In contrast, cooler night-time periods are usually considered to be the time of low-allergy risk. This opinion is often reflected in pollen allergy avoidance strategies presented by the media, where the most commonly repeated recommendation is to stay indoors during the day and plan outdoor activities for the evening. However, there is evidence to suggest that elevated concentrations of airborne pollen might also occur during the evening (e.g. Norris-Hill and Emberlin 1991). So, is the night really a time of low-allergy risk? We present the results of the comparative analysis of pollen concentrations during daytime and night-time hours for five allergenic pollen types (Burbach et al. 2009), i.e. alder (Alnus sp.), birch (Betula sp.), grasses (Poaceae), mugwort (Artemisia sp.) and ragweed (Ambrosia sp.)