D. Vokou - Academia.edu (original) (raw)

Papers by D. Vokou

Proceedings of the National Academy of Sciences, 2021

Significance Coexposure to airborne pollen enhances susceptibility to respiratory viral infection... more Significance Coexposure to airborne pollen enhances susceptibility to respiratory viral infections, regardless of the allergy status. We hypothesized this could be also true for SARS-CoV-2 infections. To investigate this, we tested for relationships between SARS-CoV-2 infection rates and pollen concentrations, along with humidity, temperature, population density, and lockdown effects. Our unique dataset derives from 130 sites in 31 countries and across five continents. We found that pollen, sometimes in synergy with humidity and temperature, explained, on average, 44% of the infection rate variability. Lockdown halved infection rates under similar pollen concentrations. As we cannot completely avoid pollen exposure, we suggest wide dissemination of pollen−virus coexposure information to encourage high-risk individuals to wear particle filter masks during high springtime pollen concentrations.

Plant Ecology, 2005

We studied five reproductive attributes (fruit production and volume, seed content and weight, an... more We studied five reproductive attributes (fruit production and volume, seed content and weight, and seed germination) of different populations of Campanula species occurring along the elevation gradient of Mt Olympos, the highest mountain of Greece (2917 m), in order to examine whether and how they change with elevation, and if there are trade-offs among them. We also studied flower and fruit (reproductive) losses and population features in order to estimate whether there might be a threat to the survival of Campanula species on Mt Olympos. The genus is represented by nine species, ranging from cosmopolitan to stenoendemic. All species were found non-autogamous, and hence they depend on pollinators for their sexual reproduction. At the genus level, there is a trade-off between seed content per fruit and seed weight. At the species level, this is manifested only for C. glomerata, which produces the heaviest seeds, far exceeding all other species, and for C. spatulata, represented on Mt Olympos by two elevation distinct subspecies. Changes of the reproductive attributes are not continuous all along the elevation gradient at the genus level nor are they monotonic at the species level. Nevertheless, upland Campanula populations (‡1500 m) produce fewer fruits per individual, containing fewer but heavier seeds than lowland populations. This indicates a transition from 'r' to 'K' strategies, from low to high elevations, respectively. The patterns of change of reproductive attributes indicate prevalence of phylogenetic over environmental constraints. Laboratory tests showed that for many populations germinability is high at 15°C, but there are both inter-and intraspecific differences regarding temperature optima. Ecotypic variation among populations of the same species at different elevations was evident; populations from higher elevations had lower optima and vice versa. Reproductive losses, ranging from zero to over 90%, occurred mainly at the stage of fruit maturation; grazing by sheep and goats was the usual cause. Though such losses might affect the short-lived species (the annual C. sparsa and the biennial C. lingulata), which depend entirely on fruit maturation and seed dispersal for their reproduction, there does not seem to be a serious threat to the survival of Campanula species on the mountain.

Ecography, 2001

... Copenhagen 2001 Pollination ecology of Campanula species on Mt Olympos, Greece George J. Blio... more ... Copenhagen 2001 Pollination ecology of Campanula species on Mt Olympos, Greece George J. Blionis and Despina Vokou Blionis, GJ and Vokou, D. 2001. Pollination ecology of Campanula species on Mt Olympos, Greece. ... 95.4 9 1.4 (9) ¦ Megachilidae (Megachile sp.)

Industrial Crops and Products, 2018

In this study, the changes that essential oils undergo during the decomposition process of the pl... more In this study, the changes that essential oils undergo during the decomposition process of the plants producing them are examined. This was done for peppermint, spearmint, and rosemary, the shoots of which were added as soil amendments at a concentration of 4% (w/w). We sampled at 0, 30 and 60 days after the plants' incorporation into the soil. We distilled the soil mixtures and found the essential oil content to be reduced, in the spearmint and peppermint treatments, by approximately 90% after 30 days. In the rosemary treatment, it was reduced only at the last sampling to about 50% of its initial value. Essential oil composition changed dramatically with time. The relative contribution of monoterpenoids, initially about 90% in spearmint and peppermint, fell to 45% and 20%, respectively, after 60 days. Sesquiterpenes and sesquiterenoids increased both in number and relative contribution. Percent participation of β-caryophyllene increased more than 15-fold in the spearmint and peppermint essential oils, and compounds that were not detected at first appeared at later stages of the decomposition process (after 30 or 60 days). In contrast, monoterpenoids made the bulk of rosemary oil at all sampling times, with only a minor reduction (about 5%) at the end of the experimental period. In a second experiment, where rosemary was let to decompose for one year, quantitative and qualitative analysis confirmed persistence of its oil for long in the soil environment. These results can explain the different effects on crop plants that have been reported for rosemary and spearmint soil mixtures and provide further insight for the potential of aromatic plants to find novel uses in agriculture.

Journal of Geophysical Research: Atmospheres, 2010

The long-range transport of particulates can substantially contribute to local air pollution. The... more The long-range transport of particulates can substantially contribute to local air pollution. The importance of airborne pollen has grown due to the recent climate change; the lengthening of the pollen season and rising mean airborne pollen concentrations have increased health risks. Our aim is to identify atmospheric circulation pathways influencing pollen levels in three European cities, namely Thessaloniki, Szeged, and Hamburg. Trajectories were computed using the HYSPLIT model. The 4 day, 6 hourly three-dimensional (3-D) backward trajectories arriving at these locations at 1200 UT are produced for each day over a 5 year period. A k-means clustering algorithm using the Mahalanobis metric was applied in order to develop trajectory types. The delimitation of the clusters performed by the 3-D function "convhull" is a novel approach. The results of the cluster analysis reveal that the main pathways for Thessaloniki contributing substantially to the high mean Urticaceae pollen levels cover western Europe and the Mediterranean. The key pathway patterns for Ambrosia for Szeged are associated with backward trajectories coming from northwestern Europe, northeastern Europe, and northern Europe. A major pollen source identified is a cluster over central Europe, namely the Carpathian basin with peak values in Hungary. The principal patterns for Poaceae for Hamburg include western Europe and the mid-Atlantic region. Locations of the source areas coincide with the main habitat regions of the species in question. Critical daily pollen number exceedances conditioned on the clusters were also evaluated using two statistical indices. An attempt was made to separate medium-and long-range airborne pollen transport.

Biological an d bioch emical parameters distin gu ish in g soil microsites u n der differen t Med... more Biological an d bioch emical parameters distin gu ish in g soil microsites u n der differen t Mediterran ean sh ru b species.

Life

Sustainable farming practices aim to replace agrochemicals with plant-based alternatives to incre... more Sustainable farming practices aim to replace agrochemicals with plant-based alternatives to increase productivity and soil quality. To evaluate the potential use of aromatic plants as soil amendments in tomato seedbeds, in a greenhouse experiment, we used spearmint, peppermint, and rosemary, separately, as soil amendments, in pots sown with tomato, and studied their effect on seedling growth, soil nutrients, and the soil nematode community in terms of trophic and functional structure, metabolic footprint, and genera composition. Non-amended soil was used in the control pots. We further explored the dynamics of the plant–soil–nematode interactions by using aromatic plants at different stages of decomposition (0, 28, and 56 days). Incorporating aromatic plants into the soil led to the proliferation of free-living nematodes, especially of the opportunistic kind, resulting in vigorous and enriched soil. This was more pronounced in the case of the spearmint and peppermint, which also inc...

III WOCMAP Congress on Medicinal and Aromatic Plants - Volume 1: Bioprospecting and Ethnopharmacology, 2005

The germplasm of oregano has been gathered from indigenous populations and examined in the field ... more The germplasm of oregano has been gathered from indigenous populations and examined in the field collection. Infraspecific variability of oregano has been identified at phenotype level by morphometric and chemical methods. ANOVA indicated significant differences for majority of variables. On the basis of morphological characters, the accessions of oregano have been attributed to O. vulgare subsp. vulgare L. The essential oil isolated from aerial parts was analysed by GC and GC-MS. The accessions varied highly in essential oil content (0.25-1.51%). The results of essential oil analysis show rich composition and high variation of oil compounds. The populations of oregano found in Lithuania could be defined as sabinene-β-ocimene-β-caryophyllene-germacrene D chemotype. One can expect that the germplasm of O. vulgare is a potentially important source of genetic variation. Indigenous populations of oregano might be interesting for breeding of winter hardy varieties of this species.

The Lancet Planetary Health, 2019

Background Ongoing climate change might, through rising temperatures, alter allergenic pollen bio... more Background Ongoing climate change might, through rising temperatures, alter allergenic pollen biology across the northern hemisphere. We aimed to analyse trends in pollen seasonality and pollen load and to establish whether there are specific climate-related links to any observed changes. Methods For this retrospective data analysis, we did an extensive search for global datasets with 20 years or more of airborne pollen data that consistently recorded pollen season indices (eg, duration and intensity). 17 locations across three continents with long-term (approximately 26 years on average) quantitative records of seasonal concentrations of multiple pollen (aeroallergen) taxa met the selection criteria. These datasets were analysed in the context of recent annual changes in maximum temperature (T max) and minimum temperature (T min) associated with anthropogenic climate change. Seasonal regressions (slopes) of variation in pollen load and pollen season duration over time were compared to T max , cumulative degree day T max , T min , cumulative degree day T min , and frost-free days among all 17 locations to ascertain significant correlations. Findings 12 (71%) of the 17 locations showed significant increases in seasonal cumulative pollen or annual pollen load. Similarly, 11 (65%) of the 17 locations showed a significant increase in pollen season duration over time, increasing, on average, 0•9 days per year. Across the northern hemisphere locations analysed, annual cumulative increases in T max over time were significantly associated with percentage increases in seasonal pollen load (r=0•52, p=0•034) as were annual cumulative increases in T min (r=0•61, p=0•010). Similar results were observed for pollen season duration, but only for cumulative degree days (higher than the freezing point [0°C or 32°F]) for T max (r=0•53, p=0•030) and T min (r=0•48, p=0•05). Additionally, temporal increases in frost-free days per year were significantly correlated with increases in both pollen load (r=0•62, p=0•008) and pollen season duration (r=0•68, p=0•003) when averaged for all 17 locations. Interpretation Our findings reveal that the ongoing increase in temperature extremes (T min and T max) might already be contributing to extended seasonal duration and increased pollen load for multiple aeroallergenic pollen taxa in diverse locations across the northern hemisphere. This study, done across multiple continents, highlights an important link between ongoing global warming and public health-one that could be exacerbated as temperatures continue to increase.

We examine the extent to which the rich endemic flora of Greece, a country in the Mediterranean h... more We examine the extent to which the rich endemic flora of Greece, a country in the Mediterranean hotspot, and particularly that part facing an extinction risk, is effectively conserved ex situ. We detected 3067 accessions of 523 taxa representing 37.2% of the Greek endemics in 213 botanic gardens (BGs, 439 taxa) and 14 seed banks (SBs, 344 taxa) of 36 countries; 46.7% of these accessions are in Greek institutions. Seeds are available for only 23.8% of the taxa in SBs. Of the 558 threatened and near-threatened endemics, 268 are conserved ex situ. Of these, 44.8% are accessioned in a single BG and 48.9% in a single SB; in the latter, 25% are represented by a single accession number. Based on major concerns, for a taxon to be considered as effectively conserved ex situ, we propose that it be represented by no less than five accessions deposited in two institutions of two countries, at least. This criterion is met by only 6.4% of t...

Bioclimatic variables of sea turtle Regional Management Units.

The species which grow wild and are used as oregano in Greece are Coridothymus capitatus (L.) Rei... more The species which grow wild and are used as oregano in Greece are Coridothymus capitatus (L.) Reichenb. f i l., Satureja thymbra L., Origanum onites L. and 0. vulgare L. Because of their economic importance, we studied their distribution in Greece and their essential oils. By examining various populations from all over the country, intraspecific variability was detected as to essential oil contents and to the carvacrol content of the oils, the main component responsible for their use as oregano. The species were evaluated on the basis of their oil and carvacrol contents. 0. onites proved to be the most stable species, that was always rich in carvacrol, whereas 0. vulgare was the most variable one. 0. vulgare subsp. hirtum (Link) letswaart was very rich in essential oil; in some cases a content of about 8 % was found and a carvacrol content ranging from 2.4 % to 95%. 0. vulgure subsp. vulgare contained only small amounts of essential oil (4.3%) and amounts of carvacrol below 0.1%. Fo...

Aerobiologia, 2016

The European Commission Cooperation in Science and Technology (COST) Action FA1203 ''SMARTER'' ai... more The European Commission Cooperation in Science and Technology (COST) Action FA1203 ''SMARTER'' aims to make recommendations for the sustainable management of Ambrosia across Europe and for monitoring its efficiency and cost-effectiveness. The goal of the present study is to provide a baseline for spatial and temporal variations in airborne Ambrosia pollen in Europe that can be used for the management and evaluation of this noxious plant. The study covers the full range of Ambrosia artemisiifolia L. distribution over Europe (39°N-60°N; 2°W-45°E). Airborne Ambrosia pollen data for the principal flowering period of Ambrosia (August-September) recorded during a 10-year period (2004-2013) were obtained from 242 monitoring sites. The mean sum of daily average airborne Ambrosia pollen and the number of days that Ambrosia pollen was recorded in the air were analysed. The mean and standard deviation (SD) were calculated regardless of the Electronic supplementary material The online version of this article (

Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2016

Abstract This study assesses the current situation regarding the electronic trade of the Cypriot ... more Abstract This study assesses the current situation regarding the electronic trade of the Cypriot endemic plants. We examine the plant material sold over the Internet, prices and vendors, and we explore to what extent this activity complies with national laws and international treaties. Overall, 48 taxa (34% of the Cypriot endemic flora) are traded by 21 nurseries of Europe and North America, belonging mostly to Lamiaceae, Brassicaceae, Iridaceae, Asparagaceae, Fabaceae and Asteraceae. Seeds are the commonest form of sale; prices range from €0.12 to 0.79 per seed and from €0.31 to 2.56 per gram. The price range for live plants is €5.67–30.22 (highest for Quercus alnifolia). Among the traded taxa, two are designated critically endangered, another two endangered, four vulnerable, 12 are globally rare and threatened and 12 are protected at the international level. None of the nurseries surveyed seem to have been granted a permit by the authorities of Cyprus to harvest and sell its wild flora, at least during the last decade. State authorities should extend the current legislative framework so as to cover all endemic and nationally threatened taxa, monitor their wild populations, engage in routine surveillance of their e-trade and regulate access to the country’s genetic resources.

Aerobiologia, 2016

We explored the temporal and spatial variations in airborne Alternaria spore quantitative and phe... more We explored the temporal and spatial variations in airborne Alternaria spore quantitative and phenological features in Europe using 23 sites with annual time series between three and 15 years. The study covers seven countries and four of the main biogeographic regions in Europe. The observations are obtained with spore traps of the Hirst type providing time series with daily records. Site locations extend from Spain in the South to Denmark in the North and from England in the West to Poland in the East. The study is therefore the largest assessment ever carried out for Europe concerning Alternaria. Aerobiological data were investigated for temporal and spatial patterns in their start and peak season dates and their spore index. Moreover, the effects of climate were checked using meteorological data for the same period, using a crop growth model. We conclude that local climate, vegetation patterns and management of landscape are governing parameters for the overall spore concentration, whilst the annual variations caused by weather are of secondary importance but should not be neglected. We find that the start of the Alternaria spore season varies by several months in Europe, but the peak of the season is more synchronised in central-northern Europe in the middle of the summer, while many southern sites have peak dates either earlier or later than northern Europe. Use of a crop growth models to explain the start and peak of season suggests that such methods could be useful to describe Alternaria seasonality in areas not covered by observations.

Allergenic Pollen, 2012

Airborne plane tree (Platanus hispanica) pollen distribution in the city of Cordoba, southwestern... more Airborne plane tree (Platanus hispanica) pollen distribution in the city of Cordoba, southwestern Spain and possible implications on pollen allergy.

Allergy, 2014

Background: The EC-funded EuroPrevall project examined the prevalence of food allergy 35 across E... more Background: The EC-funded EuroPrevall project examined the prevalence of food allergy 35 across Europe. A well-established factor in the occurrence of food allergy is primary 36 sensitization to pollen. 37 Objective: To analyse geographic and temporal variations in pollen exposure, allowing 38 investigating how these variations influence the prevalence and incidence of food allergies 39 across Europe. 40 Methods: Airborne pollen data for two decades (1990-2009) were obtained from 13 41 monitoring sites located as close as possible to the EuroPrevall survey centres. Start dates, 42 intensity and duration of Betulaceae, Oleaceae, Poaceae and Asteraceae pollen seasons 43 were examined. Mean, slope of the regression, probability level (p) and dominant taxa (%) 44 were calculated. Trends were considered significant at p < 0.05. 45 Results: On a European scale Betulaceae, in particular Betula, is the most dominant pollen 46 exposure, 2-fold higher than to Poaceae, and > 5-fold higher than to Oleaceae and 47 Asteraceae. Only in Reykjavik, Madrid and Derby was Poaceae the dominant pollen, as was 48 Oleaceae in Thessaloniki. Weed pollen (Asteraceae) were never dominant, exposure 49 accounted for > 10% of total pollen exposure only in Siauliai (Artemisia) and Legnano 50 (Ambrosia). Consistent trends towards changing intensity or duration of exposure were not 51 observed, possibly with the exception of (not significant) decreased exposure to Artemisia 52 and increased exposure to Ambrosia. 53 Conclusions: This is the first comprehensive study quantifying exposure to the major 54 allergenic pollen families Betulaceae, Oleaceae, Poaceae and Asteraceae across Europe. 55 These data can now be used for studies into patterns of sensitization and allergy to pollen 56 and foods.

Allergenic Pollen, 2012

The onset, duration and intensity of the period when pollen is present in the air varies from yea... more The onset, duration and intensity of the period when pollen is present in the air varies from year to year. Amongst other things, there is an effect upon the quality of life of allergy sufferers. The production and emission of pollens are governed by interacting environmental factors. Any change in these factors may affect the phenology and intensity of the season. Readiness to flower in a plant, and the amount of pollen produced, is the result of conditions during an often long period foregoing flowering. When a plant is ready to flower, temporary ambient circumstances e.g., irradiation and humidity, determine the timing of the actual pollen release. In order to understand variation between years and to be able to safely predict future situations, not least due to the ongoing climate change, it is necessary to know the determinants of all related processes and differences between and within species, here reviewed.

Proceedings of the National Academy of Sciences, 2021

Plant Ecology, 2005

Ecography, 2001

Industrial Crops and Products, 2018

Journal of Geophysical Research: Atmospheres, 2010

Life

III WOCMAP Congress on Medicinal and Aromatic Plants - Volume 1: Bioprospecting and Ethnopharmacology, 2005

The Lancet Planetary Health, 2019

Bioclimatic variables of sea turtle Regional Management Units.

Aerobiologia, 2016

Plant Biosystems - An International Journal Dealing with all Aspects of Plant Biology, 2016

Aerobiologia, 2016

Allergenic Pollen, 2012

Allergy, 2014

Allergenic Pollen, 2012

In M. Sofiev and K.-C. Bergmann (eds.) Allergenic Pollen, 2014

The section about monitoring covers the development of phenological networks, remote sensing of t... more The section about monitoring covers the development of phenological networks, remote sensing of the season cycle of the vegetation, the emergence of the science of aerobiology and, more specifically, aeropalynology, pollen sampling instruments, pollen counting techniques, applications of aeropalynology in agriculture and the European Pollen Information System. Three data sources are directly related with aeropalynology: phenological observations, pollen counts and remote sensing of the vegetation activity. The main future challenge is the assimilation of these data streams into numerical pollen forecast systems. Over the last decades consistent monitoring efforts of various national networks have created a wealth of pollen concentration time series. These constitute a nearly untouched treasure, which is still to be exploited to investigate questions concerning pollen emission, transport and deposition. New monitoring methods allow measuring the allergen content in pollen. Results from research on the allergen content in pollen are expected to increase the quality of the operational pollen forecasts. In the modelling section the concepts of a variety of process-based phenological models are sketched. Process-based models appear to exhaust the noisy information contained in commonly available observational phenological and pollen data sets. Any additional parameterisations do not to improve model quality substantially. Observation-based models, like regression models, time series models and computational intelligence methods are also briefly described. Numerical pollen forecast systems are especially challenging. The question, which of the models, regression or process-based models is superior, cannot yet be answered.

In M. Sofiev and K.-C. Bergmann (eds.) Allergenic Pollen, 2013

A progressive global increase in the burden of allergic diseases has affected the industrialized ... more A progressive global increase in the burden of allergic diseases has affected the industrialized world over the last half century and has been reported in the literature. The clinical evidence reveals a general increase in both incidence and prevalence of respiratory diseases, such as allergic rhinitis (common hay fever) and asthma. Such phenomena may be related not only to air pollution and changes in lifestyle, but also to an actual increase in airborne quantities of allergenic pollen. Experimental enhancements of carbon dioxide (CO) have demonstrated changes in pollen amount and allergenicity, but this has rarely been shown in the wider environment. The present analysis of a continental-scale pollen data set reveals an increasing trend in the yearly amount of airborne pollen for many taxa in Europe, which is more pronounced in urban than semi-rural/rural areas. Climate change may contribute to these changes, however increased temperatures do not appear to be a major influencing factor. Instead, we suggest the anthropogenic rise of atmospheric CO levels may be influential.