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Introduction and objective. The timings of Fraxinus and Betula flowering and pollen release overlap, which may cause increased allergic reactions in sensitive people. The aim of the present study was to characterize Fraxinus pollen seasons in Lublin (central-eastern Poland) and to identify meteorological factors that most determine the occurrence of airborne pollen of this taxon, as well as obtain forecast models for the basic characteristics of the pollen season. Materials and method. The study was conducted in Lublin during the period 2001–2016, employing the volumetric method. The seasons were compared by PCA (Principal Component Analysis). To determine relationships between meteorological conditions and the pattern of pollen seasons, regression analysis was used. Data for the period 2001–2015 were used to create forecast models by applying regression analysis, while the 2016 data served to verify these models. Results. Season end date and seasonal peak date were characterized by the lowest variation. The biggest differences were found for peak value and total annual pollen sum. The average dates of occurrence of ash pollen grains in the air of Lublin were between 13 April 13 – 3 May 3, whereas, on average, the pollen peak date occurred on 23 April. The factor loading values for the PC1 variable indicate that it is most strongly correlated with peak value and total pollen sum, while the PC2 variable correlated with the pollen season start date and season duration (a negative correlation). Regression models were developed for the following pollen season characteristics: season start, end and duration, seasonal peak date, and total annual pollen sum. Conclusions. The fit of the forecast models was at the level of 62–94%. Analysis of the data showed that weather conditions mainly in February were important factors controlling the Fraxinus pollen season. [ABSTRACT FROM AUTHOR]

Pollen monitoring was carried out in Lublin in 2001-2012 by the volumetric method using a Hirst-type spore trap (Lanzoni VPPS 2000). Daily pollen concentrations considerably differed in the particular years. The pollen counts with the biggest variability were observed in the first half of a year when woody plants flowering. The highest annual pollen index were noted for the following taxa: Betula, Urtica, Pinaceae, Poaceae and Alnus. Betula annual total showed the greatest diversity in the study years. The number of days on which the pollen concentration exceeded the threshold values, thereby inducing allergies, was determined for the taxa producing the most allergenic pollen. The above-mentioned taxa primarily included the following: Poaceae, in the case of which the highest number of days with the risk of occurrence of pollen allergy was found (35), Betula (18), and Artemisia (10).The following taxa: Alnus (14 days), Populus (11 days), Fraxinus (10 days), and Quercus (8 days), were also characterized by a large number of days on which their pollen concentrations exceeded the threshold values. The occurrence of periods of high concentration of particular pollen types were also noted. Risk of pollen allergy appeared the earliest at the beginning of February during Alnus and Corylus blooming. High concentrations of other woody plants were recorded from the last ten days of March to about 20 May, and of herbaceous plants from the first/last half of May - beginning of October. [ABSTRACT FROM AUTHOR]

An aerobiological study was conducted to investigate the quantity and quality of pollen in the atmosphere of Lublin in central-eastern Poland. Pollen monitoring was carried out in the period 2001-2012 using a Hirst-type volumetric spore trap. The atmospheric pollen season in Lublin lasted, on average, from the end of January to the beginning of October The mean air temperature during the study period was found to be higher by 1.1 °C than the mean temperature in the period 1951-2000. 56 types of pollen of plants belonging to 41 families were identified. 28 types represented woody plants and 28 represented herbaceous plants. The study distinguished 5 plant taxa the pollen of which was present most abundantly in the air of Lublin, which altogether accounted for 73.4%: Betula, Urtica, Pinus, Poaceae, and Alnus. The mean annual pollen index was 68 706; the largest amount of pollen was recorded in April and accounted for 33.3% of the annual pollen index. The pollen calendar included 28allergenic plant taxa.The pollen of woody plants had the highest percentage in the pollen spectrum, on average 58.4%. The parameters of the pollen calendar for Lublin were compared with the calendar for central-eastern Europe with regard to the start of the pollen season of particular taxa. The pollen calendar for Lublin was demonstrated to show greater similarity to the calendar for Munster (Germany) than to the calendar for Bratislava (Slovakia). [ABSTRACT FROM AUTHOR]

• Aesculus hippocastanum is a valuable ornamental tree present in urban greenery. • Defense strategies of Aesculus leaves against Cameraria ohridella were studied. • Increased polyphenol content was observed in infested Aesculus hippocastanum leaves. • New details of the morphology and behaviour of C. ohridella larvae were provided. • Histochemical tests, fluorescence assays, and scanning electron microscopy were used. Although Cameraria ohridella is a pest mining Aesculus hippocastanum leaves, has been known in Europe for 30 years, there is still no completely efficient method for control of this insect. The defence strategies of A. hippocastanum leaves against infestations by this pest have not been fully elucidated yet. The aim of the present study was to identify the defence strategy adopted by A. hippocastanum against the pest based on anatomical and histochemical analyses of leaves as well as to provide details of the morphology and behaviour of the developmental forms of C. ohridella. The study was carried out using a scanning, light, and fluorescence microscope. It was demonstrated that the response of the A. hippocastanum to C. ohridella larval infestations consisted in enhanced accumulation of phenolic compounds in tissues located at the border of mines and in the thickened layer of the leaf supporting the cocoon. Thorough analyses of the consecutive developmental stages of C. ohridella revealed new previously unknown features of larva L 1 and some details of the mandible structures of feeding larvae L 1 -L 4 and the characteristics of the cocoon structure, which is produced by larvae L 5 and L 6. We have found six stages in the developmental cycle of this pest in the present study. [ABSTRACT FROM AUTHOR]

• Tilia pollen can cause pollen allergy in sensitive people. • In Poland, the risk of allergy to Tilia pollen occurs in June, July, and also in May. • The highest counts of Tilia pollen occur during the T. cordata flowering period. • The acceleration in the pollen season onset was almost 14 days during 18 years. • In 2018, the annual pollen sum increased by more than three times. Lindens belong to valued trees that are frequently planted in urban green areas. Nevertheless, during their flowering they can pose a risk to sensitive people in cities due to their allergenic pollen. This paper presents the results of a 3-year phenological study (2016–2018) and an 18-year aerobiological study (2001–2018) conducted in Lublin (Poland). The flowering phenology data for the following five species: T. americana , T. cordata , T. × euchlora , T. platyphyllos , and T. tomentosa , were compared with the data regarding Tilia pollen seasons. It was shown that the largest amounts of airborne Tilia pollen grains occur during the full flowering period of T. cordata and that the flowering sequence of the linden species studied is constant during the growing season: T. platyphyllos , T. americana , T. cordata , T. × euchlora , and T. tomentosa. We found pollen seasons to start earlier by 14 days and to be extended by 15 days. Throughout the study period, the annual Tilia pollen sum did not change significantly. However, in 2018 in which there was a significant increase in temperature above the average for the previous 17 years, flowering and pollen release distinctly accelerated, and the annual pollen sum increased more than three times compared to the average for the previous 17 years. In central-eastern Poland, the risk of pollen allergy due to the presence of Tilia pollen occurs in May, June, and July. We recorded the highest linden pollen concentrations in June. Due to the acceleration of flowering and pollen release in linden trees as a result of global warming, the incidence of pollen allergy in central Europe can be expected to become more intense already in the second half of May. Therefore, linden plantings in new urban green areas should be planned to be established at some distance from residential estates. [ABSTRACT FROM AUTHOR]