Use of maize pollen by adult Chrysoperla carnea (Neuroptera: Chrysopidae) and fate of Cry proteins in Bt-transgenic varieties

We investigated the use of maize pollen as food by adult Chrysoperla carnea under laboratory and field conditions. Exposure of the insects to insecticidal Cry proteins from Bacillus thuringiensis (Bt) contained in pollen of transgenic maize was also assessed. Female C. carnea were most abundant in a maize field when the majority of plants were flowering and fresh pollen was abundant. Field-collected females contained an average of approximately 5000 maize pollen grains in their gut at the peak of pollen shedding. Comparable numbers were found in females fed ad libitum maize pollen in the laboratory. Maize pollen is readily used by C. carnea adults. When provided with a carbohydrate source, it allowed the insects to reach their full reproductive potential. Maize pollen was digested mainly in the insect's mid- and hindgut. When Bt maize pollen passed though the gut of C. carnea, 61% of Cry1Ab (event Bt176) and 79% of Cry3Bb1 (event MON 88017) was digested. The results demonstrate that maize pollen is a suitable food source for C. carnea. Even though the pollen grains are not fully digested, the insects are exposed to transgenic insecticidal proteins that are contained in the pollen.     

Analysis of airborne allergenic pollen spectrum for 2009 in Timişoara, Romania

The objective of this investigation was to identify the overall pollen types and, more particularly, the allergenic pollen content in the investigated area and then to explore their seasonal variations. The measurement point was located in the Timi?oara city, Romania. A Lanzoni volumetric trap was used for sample collection. Duration of the pollen season of allergenic plants and respective variation in airborne pollen concentration are presented in the pollen calendar for the year 2009. Among the identified pollen of 23 types, 20 were allergenic: Taxaceae/Cupressaceae, Alnus sp., Fraxinus sp., Betula sp., Corylus sp., Carpinus sp., Salix sp., Populus sp., Ulmus sp., Juglans sp., Quercus sp., Pinaceae, Tilia, Poaceae, Urticaceae, Chenopodiaceae/Amaranthaceae, Rumex sp., Plantago sp., Artemisia sp., Ambrosia sp. These species prevail throughout almost the entire pollen season, from February–October, accounting for 87.03 % of the total pollen count. The greatest diversity of pollen types is detected in the months of spring. The summer months were characterized mostly by non-arboreal pollen types. In late summer and early autumn, Ambrosia airpollen was the most abundant in the atmosphere. The relationships between pollen concentrations and nine meteorological parameters are presented too. To analyze the correlation between pollen data and variables, the Spearman rank correlation coefficient was used. The correlation analysis of daily pollen counts and meteorological parameters showed that arboreal pollen and non-arboreal pollen counts were significantly correlated with temperature. The prevalence of pollen sensitization resulted to be very high in our patients with respiratory symptoms.     

石家庄市空气花粉散布规律及与气候因子的关系

石家庄市2007—2009连续两年空气花粉分析表明:受植物花期影响,春季以木本植物花粉为主,夏、秋季以草本植物花粉为主,不同类型花粉通量存在一定年际差异。松属、杨属、胡桃属等当地花粉含量占花粉组合的80.0%以上,桦木属、栎属、虎榛子属等区域花粉含量低于20.0%,显示空气花粉能较好地反映周围植被,但也受区域植被的影响。依据空气花粉通量变化规律,石家庄市主要空气花粉类型通量从高到低排在前5位的依次为:胡桃属、悬铃木属、蒿属、杨属、藜科,均为高致敏类型,花粉过敏症患者在其花期或通量较高时期应早作防范。空气花粉百分含量与气候因子之间的(CCA)分析结果显示,其主要受风速与水汽压影响;不同季节主要花粉类型通量与气候因子的相关分析表明:春季和秋季空气花粉通量主要受气温和水汽压的影响,夏季主要受相对湿度和水汽压的影响,冬季与气候因子相关较弱。     

Better safe than sorry? A Fabaceae species exhibits unfavourable pollen properties for developing bee larvae despite its hidden anthers

Empirical evidence suggests that pollen chemistry plays an important role in shaping the pollen host spectra of many bee species. Although the underlying mechanisms are poorly understood, pollen diets of several plant taxa have experimentally been found to impede larval development of unspecialized bees. The pollen of all plant taxa, for which such a detrimental effect on bee larval development has been observed so far, is freely accessible in the flowers and thus easily harvestable for flower visitors, suggesting that this pollen might be chemically protected in order to reduce its loss to pollen-feeding animals. In the present study, we compared larval performance of five solitary bee species on pollen diets of the two Fabaceae species Onobrychis viciifolia and Lotus corniculatus, which have their anthers concealed inside the flowers, with that on control diets composed of host pollen provisions. As the complex flower morphology of the two Fabaceae species already considerably narrows the spectrum of pollen harvesting bee taxa, which might supersede costly chemical protection of the pollen, we expected bees that usually do not exploit Fabaceae to develop well on Onobrychis and Lotus pollen diets. Larval survival on the Onobrychis pollen diet was successful for all five bee species tested. In contrast, larval survival on the Lotus pollen diet was reduced in three species despite the fact that Lotus flowers are more difficult to exploit for pollen than Onobrychis flowers. We conclude that there is no trade-off between pollen concealment and pollen defence in Lotus and that pollen of morphologically complex flowers with a restricted visitor spectrum is not necessarily an easy-to-use nutritional source.     

Evaluation of pollen tube growth ability in Petunia species having different style lengths

Pollen tube growth is essential for the fertilization process in angiosperms. When pollen grains arrive on the stigma, they germinate, and the pollen tubes elongate through the styles of the pistils to deliver sperm cells into the ovules to produce the seeds. The relationship between the growth rate and style length remains unclear. In previous studies, we developed a liquid pollen germination medium for observing pollen tube growth. In this study, using this medium, we examined the pollen tube growth ability in Petunia axillaris subsp. axillaris, P. axillaris subsp. parodii, P. integrifolia, and P. occidentalis, which have different style lengths. Petunia occidentalis had the longest pollen tubes after 6 h of culture but had a relatively shorter style. Conversely, the pollination experiments revealed that P. axillaris subsp. parodii, which had the longest style, produced the longest pollen tubes in vivo. The results revealed no clear relationship between the style lengths and the growth rate of pollen tubes in vitro. Interspecific pollinations indicated that the styles affected pollen tube growth. We concluded that, in vitro, the pollen tubes grow without being affected by the styles, whereas, in vivo, the styles significantly affected pollen tube growth. Furthermore, interspecific pollination experiments implied that the pollen tube growth tended to be suppressed in the styles of self-incompatibility species. Finally, we discussed the pollen tube growth ability in relation to style lengths.     

Characterization of pollen profile of Apis mellifera L. in arid region of Pakistan

Honeybees rely exclusively on pollen and nectar-producing plants for strengthening their colonies and manufacturing honey. Little is known about the indigenous melliferous flora of arid zones of Khyber Pakhtunkhwa (KPK) which is crucial for honey production and how different pollen assessment techniques effect the identification of indigenous melliferous pollen flora. Visual survey and loads ensnaring through pollen traps were used to identify the botanical profile of melliferous pollen flora of Dera Ismail Khan (DIKhan), Khyber Pakhtunkhwa. The test time extended for two consecutive years 2018 and 2019. The study revealed 56 plant species as pollen flora with 18 significant pollen producing species in visual survey technique while 8 species as predominant flora in pollen trapping technique. The major pollen species found common in both the techniques were Brassica napus L., Brassica campestris L., Trifolium alaxandrinum L., Zea mays L., Acacia modesta L., Citrus aurantium L., Euclyptus spp., and Morus alba L. Pollen interception and palynological analysis of pollen were found to be more reliable techniques as compared to focal observations. More than fifty % differences were found by comparing the results of the visual survey and pollen trapping technique in major flora of DIKhan. Based on the availability, utility status and flowering duration of apiphilic flora, mid-February to mid-May was found to be a significant pollen flow period in the study area. Maximum benefit can be taken in this period through trapping ample amount of pollen and stored for using in artificial diets, selling and feeding bees during dearth period.     

Comparison of Alnus,Corylus, Betula pollen seasons in Riga,Moscow and Vilnius

Research characterizes differences and similarities of the seasonal behaviour of Alnus, Betula, Corylus pollen in Riga, Moscow and Vilnius. An important uniting factor dealing with the research is that on the selected territories in spring there are abundance of Alnus, Corylus and Betula airborne pollen. The study is based on the 2004–2011 atmospheric pollen records. Differences and similarities of the analysed territories include the following: (1) the beginning of the Alnus and Corylus pollen season usually coincided in Riga and Vilnius, whereas significantly differed between Riga and Moscow; (2) no significant differences among separate stations have been estimated concerning the beginning of the Betula pollen season; (3) Moscow differed by the shortest period of pollen season, independently of the pollen type; (4) the biennial cycle of Betula pollen is characteristic to Riga only; (5) in the spectrum of spring plants’ pollen, Corylus pollen was found in the least amount (10–23 pgm^?3 per day on the average); (6) average concentration of Betula pollen per day significantly differed in all locations of the survey, in Moscow, the concentration (853 pgm^?3) was twice higher that in Riga and Vilnius; (7) Alnus, Corylus and Betula pollen seasons overlap each other in all locations surveyed, thus creating additional load of pollen; (8) in each of the stations, there were 13–15 days when concentration of Betula pollen exceeded 100 pgm^?3.     

Pollen morphology and taxonomy of the subtribe Diocleinae (Leguminosae: Papilionoideae: Phaseoleae)

The pollen morphology of the thirteen genera currently included in the subtribe Diocleinae is described. Nine pollen types with a number of subtypes are recognized. These are arranged into two main groups. The first comprises the macromorphologically anomalous genera Calopogonium, Herpyza and Pachyrhizus which, although united by some pollen characters, are distinct both from each other and from the rest of the subtribe. The second group, consisting of the remaining genera which can to some extent be distinguished from each other by their pollen morphology, nevertheless appear to make up both macromorphologically and palynologically a more natural Diocleinae. The six pollen types in the second group are further divided into two slightly overlapping subgroups. Luzonia and Macropsychanthus are palynologically somewhat distinct but, together with Dioclea and Canavalia, have generally rather large, oblate pollen grains with a complete or perforate tectum, in contrast with the pollen of the genera Camptosema, Collaea, Cratylia and much of Galactia which is smaller, spheroidal with a reticulate tectum.Dioclea has some species with isopolar pollen and others with heteropolar pollen grains and this more or less correlates with subgeneric divisions within the genus. Galactia from the Caribbean area has similar but much smaller pollen. The taxonomic significance of this parallel between the pollen morphology of Dioclea and Caribbean Galactia is unclear. The pollen of Canavalia appears to show no significant variation.A possible correlation between the pollen subgroups with ecological habitat and pollinators is discussed.     

The relationships between the surface arboreal pollen and the plants of the vegetation in China

This paper attempts to test the relationships between the surface arboreal pollen and the plants across the entire vegetation of China. Twelve genera from major arboreal plants are selected from 680 pollen taxa in a total of 803 surface pollen assemblages for this excise. The pollen data are quantitatively compared with the gridded vegetation map on spatial similarity, direction and distance of pollen dispersal, and pollen accuracy for indicating the plant distribution density.The results show that the distributions of the pollen taxa can reflect the major patterns of the plants. Abies, Larix, Picea, Pinus, Quercus and Betula exhibit high spatial similarities between pollen and source plants. The accuracy for Tsuga, Platycarya, Fagus and Cyclobalanopsis is relatively low, probably due to the low pollen productivities and the absence of samples from southern China. In the disagreement part of the pollen-plant accuracy percentage, the pollen taxa Larix, Platycarya, Fagus and Cyclobalanopsis have high proportions in underestimating plants, likely a “convergent-type” in the pollen deposition; while pollen Tsuga, Quercus, Pinus, Betula and Ulmus have high proportions in overestimating plants, likely a “divergent-type” in the pollen dispersal.Pollen dispersal estimates suggest that southward transportation of the 12 pollen taxa is dominant, and the transport distance can be up to ca. 1000 km. This is mainly caused by several months of persistent north winds from the winter monsoon, particularly in spring seasons in eastern China. The second highest pollen dispersal direction is eastward, which occurs mainly in the boreal or sub-boreal plants of Larix, Abies, Picea, Betula and Acer and is likely influenced by the Westerlies in the mid-latitudes of China. Summer-green and evergreen Platycarya, Fagus and Cyclobalanopsis are mainly dispersed to the north, reflecting the influence of the Asian summer monsoon in eastern and southern China. Results of spatial differentiation analysis using accuracy weighting suggest that the low percentage portion (1-10%) in pollen of Abies, Picea, Betula and Quercus and high percentage portion (>40%) in pollen Pinus are acceptable for the plant representatives.These results, based upon the analyses of surface pollen and modern vegetation types of China, can provide important information for testing the various methods for reconstructing and modelling the environmental or climatic parameters during the recent geological past from palaeovegetation data.     

Transport of airborne Picea schrenkiana pollen on the northern slope of Tianshan Mountains (Xinjiang, China) and its implication for paleoenvironmental reconstruction

The understanding of airborne pollen transportation is crucial for the reconstruction of the paleoenvironment. Under favorable conditions, a considerable amount of long-distance-transported pollen can be deposited far from its place of origin. In extreme arid regions, in most cases, such situations occur and increase the difficulty to interpret fossil pollen records. In this study, three sets of Cour airborne pollen trap were installed on the northern slope of Tianshan Mountains to collect airborne Picea schrenkiana (spruce) pollen grains from July 2001 to July 2006. The results indicate that Picea pollen disperses extensively and transports widely in the lower atmosphere far away from spruce forest. The airborne Picea pollen dispersal period is mainly concentrated between mid-May and July. In desert area, weekly Picea pollen began to increase and peaked suddenly in concentration. Also, annual pollen indices do not decline even when the distance increased was probably related to the strong wind may pick up the deposited pollen grains from the topsoil into the air stream, leading to an increase of pollen concentration in the air that is irrelevant to the normal and natural course of pollen transport and deposition. This, in turn, may lead to erroneous interpretations of the pollen data in the arid region. This study provided insight into the shift in the Picea pollen season regarding climate change in arid areas. It is recorded that the pollen pollination period starts earlier and the duration became longer. The results also showed that the temperature of May and June was positively correlated with the Picea pollen production. Furthermore, the transport of airborne Picea pollen data is useful for interpreting fossil pollen records from extreme arid regions.     

Effects of pollen dilution on infection of Nosema ceranae in honey bees

Multiple stressors are currently threatening honey bee health, including pests and pathogens. Among honey bee pathogens, Nosema ceranae is a microsporidian found parasitizing the western honey bee (Apis mellifera) relatively recently. Honey bee colonies are fed pollen or protein substitute during pollen dearth to boost colony growth and immunity against pests and pathogens. Here we hypothesize that N. ceranae intensity and prevalence will be low in bees receiving high pollen diets, and that honey bees on high pollen diets will have higher survival and/or increased longevity. To test this hypothesis we examined the effects of different quantities of pollen on (a) the intensity and prevalence of N. ceranae and (b) longevity and nutritional physiology of bees inoculated with N. ceranae. Significantly higher spore intensities were observed in treatments that received higher pollen quantities (1:0 and 1:1 pollen:cellulose) when compared to treatments that received relatively lower pollen quantities. There were no significant differences in N. ceranae prevalence among different pollen diet treatments. Interestingly, the bees in higher pollen quantity treatments also had significantly higher survival despite higher intensities of N. ceranae. Significantly higher hypopharyngeal gland protein was observed in the control (no Nosema infection, and receiving a diet of 1:0 pollen:cellulose), followed by 1:0 pollen:cellulose treatment that was inoculated with N. ceranae. Here we demonstrate that diet with higher pollen quantity increases N. ceranae intensity, but also enhances the survival or longevity of honey bees. The information from this study could potentially help beekeepers formulate appropriate protein feeding regimens for their colonies to mitigate N. ceranae problems.     

Modern pollen and land-use relationships in the Taihang mountains, Hebei province, northern China—a first step towards quantitative reconstruction of human-induced land cover changes

Studies of the modern relationship between pollen, vegetation and land-use are essential to infer past human impact on vegetation from pollen records. Nevertheless, such investigations are relatively few in China. We present here a study of pollen assemblages from sediment samples collected from irrigation pools in the Tuoliang and Qipanshan catchments in northern China. Pollen and spores from natural vegetation such as Artemisia, Chenopodiaceae, Pinus and Selaginella sinensis dominate the pollen assemblages, while pollen types which could be from crops such as cereals, Brassicaceae, Fabaceae, Solanaceae, Apiaceae and Cucurbitaceae are common but not abundant. Pollen percentages of Artemisia and Chenopodiaceae become less with decreasing altitude, while Pinus and S. sinensis percentages increase, indicating that saccate Pinus pollen and S. sinensis spores are transported further than non-saccate Artemisia and Chenopodiaceae pollen, and differential sorting of pollen is occurring during transport in river water. Proportions of pollen from farmland and crops increase with decreasing altitude, showing that pollen percentages of crops might be a good indicator of the extent of farmland. A linear correlation analysis between pollen percentages and vegetation proportions shows that pollen percentages of crops are positively correlated with proportions of farmland, while correlation between pollen percentages of trees, shrubs and herbs and proportions of woodland, scrubland and grassland respectively is poor. This study indicates that the relationship between pollen percentages and vegetation proportions can be explained by the differences of pollen productivity, dispersal and deposition, and might be the basis for a modelling approach to infer past vegetation cover in northern China.     

Mechanical damage to pollen aids nutrient acquisition in Heliconius butterflies (Nymphalidae)

Neotropical Heliconius and Laparus butterflies actively collect pollen onto the proboscis and extract nutrients from it. This study investigates the impact of the processing behaviour on the condition of the pollen grains. Pollen samples (n = 72) were collected from proboscides of various Heliconius species and Laparus doris in surrounding habitats of the Tropical Research Station La Gamba (Costa Rica). Examination using a light microscope revealed that pollen loads contained 74.88 ± 53.67% of damaged Psychotria pollen, 72.04 ± 23.4% of damaged Psiguria/Gurania pollen, and 21.35 ± 14.5% of damaged Lantana pollen (numbers represent median ± first quartile). Damaged pollen grains showed deformed contours, inhomogeneous and/or leaking contents, or they were empty. Experiments with Heliconius and Laparus doris from a natural population in Costa Rica demonstrated that 200 min of pollen processing behaviour significantly increased the percentage of damaged pollen of Psychotria compared to pollen from anthers (P = 0.015, Z = ?2.44, Mann–Whitney U-test). Examination of pollen loads from green house reared Heliconius butterflies resulted in significantly greater amounts of damaged Psiguria pollen after 200 min of processing behaviour compared to pollen from flowers (P < 0.001, Z = ?4.583, Mann–Whitney U-test). These results indicate that pollen processing functions as extra oral digestion whereby pollen grains are ruptured to make the content available for ingestion.     

Bombacaceae pollen from the Indian Tertiary sediments and its bearing on evolution and migration

Several pollen species recovered from the Indian Tertiary sediments have close similarities with pollen of extant Bombacaceae. These morpho species are included in the morphogenera Lakiapollis Venkatachala and Kar, Dermatobrevicolporites Kar, Bombacacidites Couper, Tricolporocolumellites Kar and Retitribrevicolporites Kar. Nine species are re-described on the basis of original type material or other specimens. The fossil pollen belongs to the Bombax- and Durio-types. The small-sized Bombax-type pollen (e.g., Eriotheca pollen) has been documented in India from the early Palaeocene to the Miocene while large-sized pollen similar to that of Bombax appeared in the Oligocene and continued up to the Present. The lobed variety of the Bombax-type is rare and occurs only in the Pleistocene. Palynological evidence suggests a migration of Bombacaceae producing Bombax-type pollen to India from Africa. Durio-type pollen appeared in the late Palaeocene and continued to dominate until the early Eocene. In southern India, this pollen remained frequent during Oligocene/Miocene times, whereas in other areas, it became rare at the end of the Eocene. The earliest (late Palaeocene) record suggests an origination of Bombacaceae producing Durio-type pollen in India and a subsequent migration to Southeast Asia.     

Influence of temperature on the in vitro pollen germination and pollen tube growth of various native Iranian almonds (Prunus L. spp.) species

Pollen germination and pollen tube growth was quantified among various native Iranian wild almonds (P. dulcis (Mill.) D. A. Webb, P. eleaegnifolia Mill., P. orientalis Mill., P. lycioides Spach, P. reuteri Bioss. et Bushe, P. arabica Olivier, P. glauca Browick and P. scoparia Spach in order to identify differences in the tolerance of pollen to temperature variations. Pollen germination and pollen tube growth were observed after incubation in darkness in a germination medium for 24?h at 10?C50°C at 5°C intervals. Maximum pollen germination of the wild almond species and specify that 60% was obtained for P. orientalis pollen and 98% for P. scoparia. Pollen tube length ranged from 860???m was obtained in P. lycioides and 1490???m in P. scoparia. A modified bilinear model best described the response to temperature of pollen germination and pollen tube length. Almond species variation was found for cardinal temperatures (T _min, T _opt and T _max) of pollen germination percentage and pollen tube growth. Mean cardinal temperatures averaged over eight almond species were 14.7, 24.2, and 43.7°C for maximum percentage pollen germination and 14.48, 25.3, and 44.4 °C for maximum pollen tube length. The principal component analysis (PCA) identified maximum percentage pollen germination and pollen tube length of the species, and T _max for the two processes as the most important pollen parameters in describing a species tolerance to high temperature. PCA also classified Prunus L. spp. into four groups according to the tolerance of pollen to temperature variations. The T _min and T _opt for pollen germination and tube growth, rate of pollen tube growth were less predictive in discriminating species for high temperature tolerance.     

Annual pollen spectrum in the air of Palma de Mallorca (Balearic Islands, Spain)

This aeropalynological study documented the pollen of 13 taxa with the highest concentration in the air of Palma de Mallorca during the years 2004–2010, using a Hirst-type volumetric spore trap. The taxa were Cupressaceae, Olea europaea, Platanus hispanica, Pinus spp., Parietaria judaica, Urtica membranacea, Quercus ilex, Poaceae, Chenopodiaceae/Amaranthaceae, Plantago spp., Castanea sativa, Pistacia lentiscus and Betula spp. These taxa accounted for 91.85 % of the total annual pollen recorded during the period. The mean annual pollen index was 20,027. The highest pollen counts occurred in February–June, representing 88.74 % of the annual total collected. Every year, there was a substantial increase in the concentration and types of pollen from March to May, followed by a decrease from July to January. The maximum annual total pollen count was recorded in 2005 with 25,870 and the minimum in 2009 with 14,726. The mean daily average pollen concentration count showed a declining trend over the study period. With respect to seasonal phases analysed, the later phase of the pollen season is more variable than the beginning. To observe the overall dynamics of the different pollen types better, a pollen calendar was established for Palma de Mallorca. The pollen calendar had typical Mediterranean features and is a useful tool for allergological and botanical awareness.     

The Role of Arabidopsis ABCG9 and ABCG31 ATP Binding Cassette Transporters in Pollen Fitness and the Deposition of Steryl Glycosides on the Pollen Coat

The pollen coat protects pollen grains from harmful environmental stresses such as drought and cold. Many compounds in the pollen coat are synthesized in the tapetum. However, the pathway by which they are transferred to the pollen surface remains obscure. We found that two Arabidopsis thaliana ATP binding cassette transporters, ABCG9 and ABCG31, were highly expressed in the tapetum and are involved in pollen coat deposition. Upon exposure to dry air, many abcg9 abcg31 pollen grains shriveled up and collapsed, and this phenotype was restored by complementation with ABCG9_pro:GFP:ABCG9. GFP-tagged ABCG9 or ABCG31 localized to the plasma membrane. Electron microscopy revealed that the mutant pollen coat resembled the immature coat of the wild type, which contained many electron-lucent structures. Steryl glycosides were reduced to about half of wild-type levels in the abcg9 abcg31 pollen, but no differences in free sterols or steryl esters were observed. A mutant deficient in steryl glycoside biosynthesis, ugt80A2 ugt80B1, exhibited a similar phenotype. Together, these results indicate that steryl glycosides are critical for pollen fitness, by supporting pollen coat maturation, and that ABCG9 and ABCG31 contribute to the accumulation of this sterol on the surface of pollen.     

A 10-year survey of allergenic airborne pollen in the city of Porto (Portugal)

Airborne pollen calendars are useful to estimate the flowering season of the different plants as well as to indicate the allergenic potential present in the atmosphere at a given time. In this study, it is presented a 10-year survey of the atmospheric concentration of allergenic pollen types. Airborne pollen was performed, from 2003 to 2012, using a 7-day Hirst-type volumetric trap. The interannual variation of the daily mean concentration of the number of pollen grains and the main pollen season was determined as well as the hourly variations and correlation with meteorological parameters. During the study period, 18 different allergenic pollen types were considered based on its representativeness on the total annual airborne pollen concentration. The lowest annual concentrations were sampled in 2006 and the highest in 2007. The highest airborne pollen concentration was found during early spring and early summer. On the contrary, December was the month with the lowest pollen concentration. The major pollen sampled belongs to trees followed by weeds and grasses, being the most representative pollen types in the atmosphere: Urticaceae, Platanus, Poaceae, Pinaceae, Cupressaceae, Acer, Quercus, Castanea, Plantago, Alnus, Olea europaea, Betula, Myrtaceae and Populus. Intradiurnal distribution patterns of the pollen types studied presented differences with some taxa being predominantly sampled in the morning (9–11 a.m.) while others in first night hours (between 9 and 12 p.m.). Significantly correlations were found between the airborne pollen concentration and meteorological parameters.