Pollen Trap Research Articles

Pollen trapping as Honeybees pollination management and identification of dominant pollinators of Guizotia abyssinica (L.f).

Pollination is one of the most fascinating aspects of insect-plant interactions. Pollen is the male reproductive element of flowering plants, gathered by foraging Honeybees from the male parts of flowering plants called the anther. Guizotia abyssinica (L.f) is an important oilseed crop cultivated in Ethiopia and India, which belongs to the family Asteraceae. Although self-incompatibility is found in Guizotia abyssinica, a higher seed set is experienced in places with an active Honeybees population. Agricultural practices usually focus on inputs such as fertilizer application to improve seed yield of Guizotia abyssinica. However, these practices have little effect on yield if the availability of insect pollination is too low. To fill this gap, an experiment was carried out at Dandi district, West Shao zone, Oromia, Ethiopia to see the effect of Honeybees pollination management as an agronomic input. Pollination management of Honeybees was tested under feeding and non-feeding of colonies management. Pollen was trapped with and without sugar syrup feeding. The results discovered that Honeybees fed sugar syrup collected much more pollen than colonies not fed sugar syrup. The proportion of Guizotia abyssinica pollen collected through sugar syrup feeding of the colony was greater (62.2%), compared to the proportion of Guizotia abyssinica pollen trapped without sugar syrup feeding (37.8%). This indicates that sugar syrup feeding enhances the collection of pollen and probably enhances the pollination efficiency of Honeybees since they visit frequently to fulfill their daily protein requirement of pollen. Therefore, Honeybees pollination services should be included as one of the agronomic inputs with sugar syrup feeding as pollination management that might increase the yield of Guizotia abyssinica since it increases visiting frequency.

Amaranthaceae Pollen Trends in the Air

Understanding the trends of airborne pollen allergens is of great importance given the high prevalence and socioeconomic impact of pollen-related allergic diseases globally. To study the morphological features of Amaranthaceae pollen, assess its contribution to the aerobiological situation in the city of Karakol and identify periods of increased concentration in order to improve the diagnosis and prevention of pollinosis symptoms in patients. Aerobiological sampling using a Lanzoni pollen trap was carried out from April to October over a three-year period (2015–2017) in Karakol city. Pollen identification and differential counting were performed according to current standard methodology and specially developed guides and atlases. Pollen characteristics of 4 Amaranthaceae species were visualized using scanning electron microscopy (Hitachi) to provide a detailed understanding of the surface structure and ornamentation of pollen grains. The decadal curve of Amaranthaceae pollen concentration in Karakol is unimodal, with often overlapping quantitative characteristics: 6615 (2nd decade of August 2015), 1326 (1st decade of 2016), 444 pollen grains / m3 (1st decade of 2017). At the same time, strong interannual variability of atmospheric pollen levels was observed, depending both on the pollen production of the plants themselves and on meteorological parameters, especially temperature and precipitation, changes in the traditional farming system. The response of summer-flowering Amaranthaceae weeds to climate change was demonstrated, which consists in a decrease in the annual pollen index, which corresponds to the global trend. Peak concentrations of Amaranthaceae pollen many times exceeded clinical threshold values in the air. On the surface of the Bassia scopariapollen exine, the ultrastructure study revealed the smallest (1.5-2.0 μm) granules of sporopollenin or orbicules (Ubisch bodies), which play a role in the spread of allergens. The obtained data are important in terms of increasing public awareness of the dominant pollen of the Amaranthaceae family, optimizing diagnostics, treatment and prevention of pollinosis.

Study on the Effectiveness of a Copper Electrostatic Filtration System "Aerok 1.0" for Air Disinfection.

Bioaerosols can represent a danger to health. During SARS-CoV-2 pandemic, portable devices were used in different environments and considered a valuable prevention tool. This study has evaluated the effectiveness of the air treatment device "AEROK 1.0®" in reducing microbial, particulate, and pollen airborne contamination indoors, during normal activity. In an administrative room, airborne microbial contamination was measured using active (DUOSAS 360 and MD8) and passive sampling; a particle counter was used to evaluate particle concentrations; a Hirst-type pollen trap was used to assess airborne pollen and Alternaria spores. Statistical analysis was performed using SPSS 26.0; p values < 0.05 were considered statistically significant. The airborne bacterial contamination assessed by the two different samplers decreased by 56% and 69%, respectively. The airborne bacterial contamination assessed by passive sampling decreased by 44%. For fungi, the reduction was 39% by active sampling. Airborne particles (diameters ≥ 1.0, 2.0 μm) and the ratio of indoor/outdoor concentrations of total pollen and Alternaria spp. spores significantly decreased. The results highlight the effectiveness of AEROK 1.0® in reducing airborne contamination. The approach carried out represents a contribution to the definition of a standardized model for evaluating the effectiveness of devices to be used for air disinfection.

Pesticide Contamination in Native North American Crops, Part II-Comparison of Flower, Honey Bee Workers, and Native Bee Residues in Lowbush Blueberry.

In lowbush blueberry fields, we conducted residue analysis comparing flowers, trapped pollen (honey bee and Osmia spp.), and collected bees (honey bee workers, bumble bee queens, and non-Bombus spp. wild native bees). The study was conducted from 2012 to 2014. The number of pesticide residues, total concentrations, and risk to honey bees (Risk Quotient) on flowers were not significantly different from those determined for trapped honey bee pollen (except in one study year when residues detected in flower samples were significantly lower than residue numbers detected in trapped pollen). The compositions of residues were similar on flowers and trapped pollen. The number of residues detected in honey bee pollen was significantly greater than the number detected in Osmia spp. pollen, while the total concentration of residue was not different between the two types of pollen. The risk to honey bees was higher in trapped honey bee pollen than in trapped Osmia spp. pollen. The analysis of honey bee workers, native bumble bee queens, and native solitary bees showed that although more pesticide residues were detected on honey bee workers, there were no differences among the bee taxa in total residue concentrations or risk (as estimated in terms of risk to honey bees).

Changing with the times: From agricultural potential to spatially explicit reconstructions of past land use

Past land-use reconstructions are a key tool for studying long-term human ecodynamics and addressing pressing questions about the origins and evolutionary dynamics of the Anthropocene. In particular, agricultural landcover reconstructions are vital for understanding long-term human-environment dynamics. Most past agricultural land-use models, however, rely heavily on modelling assumptions, make limited use of known archaeological site locations to constrain or inform their estimates and tend to be limited to general estimates of percentages of plant types within catchments around pollen trapping lakes. The lack of information outside catchment areas and low spatial resolution even within catchments constrain the utility of these models. To address this problem, we propose a new approach that combines archaeological predictive modelling with pollen-based agricultural landcover reconstructions to produce more accurate, spatially explicit past landcover estimates. Here, we present the results of a case study deploying the new approach to produce improved past landcover maps for a region in the Western Taurus Mountains, southwestern Turkey. The study area surrounds Sagalassos, an antique urban centre with a regional settlement history encompassing nine millennia. We produced five archaeological predictive models for the study region using the ‘Locally Adaptive Models of Archaeological Potential’ (LAMAP) method spanning the Hellenistic through Late Ottoman period. We then combined those predictive surfaces with ‘Regional Estimates of VEgetation Abundance from Large Sites’ (REVEALS) pollen landcover reconstructions for the same periods based on pollen from sediment cores extracted from three catchments within the study area. Lastly, we compared the resulting hybrid landcover models to the archaeological record using data not used to make the predictions. We found that the hybrid landcover model aligned very well with the known extents of agricultural land-use from the study area. These results indicate that the proposed approach is a viable way to combine pollen-based landcover models with archaeological data and produce more accurate, empirically-based landcover reconstructions reflecting real human activity in the past.

Collection Efficiency of Fresh Pollen under Different Pollen Trapping Frequencies by Apis mellifera L. Colonies in Mustard

The present experiment was carried out at apiary of Krishi Vigyan Kendra, Morena and at beekeeper’s apiary in Morena, M.P. during 2022-23 and 2023-24 to evaluate the consumption pattern of different artificial diets by Apis mellifera L. colonies during dearth periods. Front mounted wooden pollen traps were mounted under five different pollen trapping frequencies as treatments, including control and the amount of pollen collection was recorded per colony per day. The results revealed that, colonies with daily trapping had the highest average pollen collection rate (167.45 and 157.34 g/colony/day) and the lowest average pollen collection rate (13.34 and 12.79 g/colony/day) was observed in weekly trapping across the trapping period of both the consecutive years. However, the control group, with no pollen trapping, was observed with no pollen collection. Additionally, the total pollen collection across the trapping frequencies was highest in daily trapping (1.340 and 1.259 kg/colony) and lowest in weekly trapping (0.107 and 0.102 kg/colony) during 2022-23 and 2023-24, respectively. During the trapping weeks, the lowest amount of pollen (17.89 and 20.67 g/colony/day) was collected in 1st week i.e. during 03 – 09 December at the initiation of the mustard flora. However, the highest amount of pollen collection (101.03 g/colony/day pollen) was recorded in 4th week (24 - 31 December, 2022) while during 2023-24 it was recorded highest in 6th week (8 - 14 January) with 99.24 g/colony/day pollen. The correlation analysis showed that the average amount of collected pollen was significantly negative correlated with wind speed.

A prospective study evaluating the correlation between local weather conditions, pollen counts and pruritus of dogs with atopic dermatitis.

Canine atopic dermatitis (cAD) is a hereditary, generally pruritic and predominantly T-cell-driven inflammatory skin disease, involving an interplay between skin barrier abnormalities, allergen sensitisation and microbial dysbiosis. The individual immunological response is predominantly against environmental allergens, including mite antigens; mould spores; and pollen from grasses, trees and weeds. Airborne pollens show fluctuating patterns during the year. The aim of this prospective study was to evaluate the influence of local pollen concentrations and weather conditions on the clinical signs of atopic dogs, and to investigate any possible correlations with the results of intradermal testing (IDT). Thirty-seven privately owned atopic dogs in Bavaria were surveyed from 1 April to 30 November 2021. Owners were asked to record pruritus using a validated Visual Analog Scale (PVAS) score and the weekly medication of their dog. Furthermore, weather data, including pollen count, rainfall, relative humidity, hours of sunshine and temperature from the dog's location were collected daily. Of the evaluated parameters, only humidity and medication scores correlated positively with the PVAS scores of the atopic dogs. There was no correlation between specific pollen counts and PVAS scores of dogs with positive IDT reactions to that pollen. The outcome of this study highlights the importance of a careful interpretation of positive IDT results in dogs with cAD and questions the validity of airborne pollen trap methodology in representing pollen exposure for dogs at ground level.

Trends in airborne grass pollen in Évora City (Portugal)

Aerobiology could be used as complementary data or proxy for studying phenology, especially in species which usually are not long-distance transported, such as grasses. This 21-year aerobiological study took place in Évora (South Portugal), using a seven-day recording volumetric pollen trap with the aim of analysing the temporal trends of grass pollen seasons. To this end, data were statistically tested for correlation and regression to determine the features and temporal trends of pollen seasons. Main results show that Poaceae pollen has a high representation in pollen spectrum, 20% (min: 7%; max: 44%), with a long season starting in March and lasting till August/September or October. There was an overall, but not statistically significant trend, towards an increase in the annual pollen integral and peak values, and also an overall non-statistically significant trend towards an earlier start and later end of the pollen season. Main and high pollen seasons have been lasting longer, and the days with allergenic potential have been rising in line with the local temperature rising trend. It seems that grass pollen production is being aided by warmer temperatures and increased grassland areas in Alentejo region. This could promote the increase in annual pollen levels and in the number of high pollen days over the years. In clinical terms, it means that grass allergic patients are exposed to longer periods of airborne pollen and to higher counts over a longer time. The climate conditions projected for Alentejo region, including rising temperature, and the changes in local grassland areas may help to clarify the trends of grass pollen seasons in the next decades.

Acetolysis modifications to process small pollen samples swabbed from live bees

Abstract Understanding the resources bees use is essential because we depend greatly on their ecosystem services, and this information could help guide conservation efforts. One way to identify the flowers that bees visit is to collect pollen directly from the bee and then identify the pollen with plant taxa. However, the current method for processing such pollen samples, acetolysis, is designed for samples such as those collected across individuals (e.g., pollen trap), bee nests, or, at the very least, from pollen pellets collected from live bees or from the exhaustive removal of pollen from lethally collected individuals. Smaller samples, including those down to just a few pollen grains sampled from live bees, could facilitate additional opportunities for bee-pollen research, if they can be processed effectively. We present a revised acetolysis methodology designed specifically for processing small pollen samples, so that they can then be used for more accurate identification. Using pollen samples from cotton swabs directly applied to live bees in the field, we demonstrate the effectiveness of our methodology for processing small pollen samples, including samples too small to be visually detected. This methodology can permit nonlethal collections in the field from a greater number of bee species.

Surveying, identification and characterization for the potential honeybee (Apis mellifera L.) pollen sources in the arid region of Riyadh-Saudi Arabia

This study was conducted targeting identification and documentation of major honeybee plants as pollen sources and their phenology in the central arid region of Saudi Arabia (Riyadh). Pollen loads were collected using pollen traps and were classified according to their color then traced back to plant species level. Throughout the year, sixteen plant species belonging to 10 plant families has been recorded and investigated by Light Microscopy (LM) and Scanning Electron Microscopy (SEM). Asian mustard (Brassica tournefortii Gouan.) (15.91%), willow wattle (Acacia salicina Lindl.) (15.17%), mesquite (Prosopis juliflora) (Sw.) DC. (21.81%) and cat's head (Tribulus terresetris L. var. terrestris) (15.52%) were the dominant sources of pollen. The period from May to July was found to be a significant blooming period and the scarcity period was from December to March in the study area. Color, size and shape of the potential pollen sources were variable between different species. Beekeepers could trap pollen loads that were collected from these sources during February, April and July, respectively. In conclusion, wise use and rehabilitation of these potentially identified bee plant species shall be considered in attempting beekeeping development.

Variability between Hirst-type pollen traps is reduced by resistance-free flow adjustment

During an international campaign organized in Munich (Germany) in 2021 to test the performance of automatic pollen traps, we ran four manual Hirst-type pollen traps in parallel. All 4 Hirst-type pollen traps were set and monitored on a weekly basis for the entire campaign to 10 L/min using the same standard hand-held rotameter. Afterwards, a hand-held heat-wire anemometer (easyFlux®) was used additionally to obtain the correct flow without internal resistance. Uncorrected pollen concentrations were 26.5% (hourly data) and 21.0% (daily data) higher than those obtained after correction with the easyFlux®. After mathematical flow correction, the average coefficient of variation between the four Hirst traps was 42.6% and 16.5% (hourly and daily averages, respectively) for birch and 36.8% and 16.8% (hourly and daily averages, respectively) for grasses. When using the correct flow of each pollen trap (i.e. the resistance free anemometer measured flow), for hourly values, the median standard deviation across the traps for the eight pollen types was reduced by 28.2% (p < 0.001) compared to the uncorrected data. For daily values, a significant decrease in the median standard deviation (21.6%) between traps was observed for 7 out of 8 of the pollen types, (p < 0.05 or lower). We therefore recommend continuing to calibrate Hirst-type pollen traps with standard hand-held rotameters to avoid changing the impacting characteristics of the instruments, but simultaneously also measure with resistance-free flow meters to be able to apply flow corrections to the final pollen concentrations reported. This method improved the accuracy of the final results.

Introducing Pollenyzer: An app for automatic determination of colour diversity for corbicular pollen loads

Pollen is known to be the only source of proteins and fats for honey bees. Therefore, it is an important component of nutrition, essential for brood care and a good indicator for the availability of resources in a landscape. It is also known that a diverse diet is beneficial for bee health, also in relation to winter losses. In this work, an app is presented that allows to quantify the pollen from a pollen trap and to determine its colour diversity in an automatic way. The colour diversity is closely related to the actual plant diversity. This correlation allows conclusions to be drawn on the apicultural importance of a landscape and on biodiversity in general. In this way, the app provides beekeepers with important information about the nutritional condition of their colonies, while scientists can benefit from aggregated information about local biodiversity. The app is free of use and available as a web app on all devices.

Accuracy of a hand-held resistance-free flowmeters for flow adjustments of Hirst-Type pollen traps

The Hirst-type pollen trap (1952) is the most common device for aerobiological measurements of pollen and fungal spores in ambient air. In the 1960s the in-line flowmeter was removed and studies since then showed considerable variability in the airflow pumped through the instrument when using hand-held rotameters with an internal airflow resistance to adjust flowrates. To avoid this problem, our study compared the variability of airflow rates of Hirst-type traps when using commercially-available low-resistance airflow meters (heat anemometers) at various timescales. Experiments were conducted in Munich (Germany) and Payerne (Switzerland), using 4 different easyFlux® instruments and 6 Hirst-type pollen traps. Measurements were taken on an hourly basis from dawn to dusk at both locations, and in addition at Payerne, weekly observations over a period of one year. When using the common hand-held rotameters (with airflow resistance) the flow was 28.3% lower than with resistance-free flowmeter (i.e., measured 10 L/min which was in reality 12.8 L/min). The coefficient of variation between the four easyFlux® devices ranged from 0.32% to 1.55% over one day and from 2.88% to 8.17% over an entire year. Some of the traps showed surprising flow variations during the day. Furthermore, flowrates deviated more when measurements were made at the point where the double-sided tape is behind the orifice than elsewhere on the drum. The measurements away from this point are representative of the flow rates for most of the period of operation and flow calibration should thus be carried out away from this point, contrary to the current procedure.

Investigation of spatial and temporal variations of airborne Poaceae, Myrtaceae and Cupressaceae pollen and Alternaria spores in Sydney, Australia, 2017–2020

There is a need for information on pollen exposure to assess allergy risk. Monitoring of aeroallergens in a city is usually limited to the use of a single trap for the whole area. While a single trap provides enough information on background pollen concentration for the area, varying pollen exposure across different urban environments, however, is not considered. In this study, we analysed aerobiological data of three pollen seasons (2017–2020) recorded with a volumetric pollen trap in Sydney, Australia. In order to assess spatial differences in pollen exposure across the city, we installed ten gravimetric traps recording pollen deposition for eight weeks during the summer of 2019/2020. We considered the influence of meteorological variables, land use, urbanisation and distance to the sea. Our results showed differences in pollen season characteristics across the three analysed seasons and correlations with meteorological parameters. Considering all years, we found for Poaceae and Alternaria the strongest positive correlation with mean temperature and for Myrtaceae and Cupressaceae with maximum temperature. Likewise, there were negative correlations with humidity (Myrtaceae, Cupressaceae, Alternaria) and precipitation (Myrtaceae, Cupressaceae). Days with medically relevant pollen and spore concentrations varied between years and we recorded the highest amount in 2017/2018 for Poaceae and Alternaria and in 2019/2020 for Myrtaceae. In addition, we found spatial and temporal variations of pollen deposition. However, we did not detect significant correlations between pollen deposition and land use, which can be attributable to drought conditions prior to the sampling campaign and the temporal setting in the pollen season. This study highlights the importance of continuous volumetric aerobiological monitoring as well as the assessment of pollen exposure at several locations across a large urban area.

Assessment of palynological spectrum of air in Kazan

This article presents the results of a palynological air monitoring study in Kazan during the period of plant dusting from 2019 to 2022. The aeropalynological spectrum was assessed using a Lanzoni pollen trap. The data obtained during the monitoring demonstrates a rich spore-pollen composition in the air. Twenty-five different plant taxa, as well as two fungal taxa, were identified. Betula and Poaceae have been identified as dominant taxa. The variability in pollen concentrations confirms the need for timely information for the pollen-sensitive population.

Birch Pollen Deposition and Transport along an Altitudinal Gradient in the Bavarian Alps—A Case Study Using Gravimetric Pollen Traps in the Pollen Season 2020

There is only little and partially contradicting knowledge on the variation of pollen abundance at different altitudes in mountainous regions. The aim of this work is to gain new insights on the influence of wind and surrounding trees on the deposition and transport of birch (Betula spec.) pollen in the Bavarian Alps, Germany. Data on birch pollen deposition were collected at five sites using gravimetric traps along an altitudinal gradient from Garmisch-Partenkirchen (720 m a.s.l.) to the Environmental Research Station Schneefernerhaus (2650 m a.s.l) in the pollen season 2020. We compared these data with birch pollen concentration derived from a volumetric trap at Schneefernerhaus and with phenological data, i.e., flowering onset times observed at 21 birch trees at different altitudes. Wind data were gathered directly at or near each pollen trap and surrounding birch trees were mapped in the field. Whereas the pollen load was lowest at the highest location, substantially higher values were measured at medium altitudes (1300–1600 m a.s.l.). This can be explained by the pronounced mountain-valley wind system, which ensured the transport of pollen to the corresponding altitudes. We conclude that pollen levels are influenced by topography, local wind systems and the availability of pollen. Pollen levels in complex mountainous environments are therefore not substantially affected by the occurrence of birch trees in the immediate vicinity.

Stimulation role of pollen grains in the initial development of Botrytis cinerea: The importance of host compatibility, cultivation status and pollen size

AbstractPlant pollens and fungal spores are massively produced in natural habitats and large‐scaled agricultural areas, and the airborne transported biomass can be accumulated on relatively large crop surfaces. A pollen grain contains a specific chemical composition in quantity and quality, highly varied among plant species. So, the accumulated pollens could provide a species‐specific nutrient supply for the initial fungal development in a pollen trap. Thus, this could increase the variation of the pathogen infection risk in certain plants due to selection mechanisms such as host–pathogen coevolution, crop breeding or pollination type. However, the role of the pollen‐stimulated spore germination and the species‐specific differences in the pollen‐spore interferences is still less understood. Therefore, we performed a multispecies experimental comparison (including 20 plant species) to test the role of the taxon‐specific attributes (i.e. host–pathogen compatibility, cultivation, pollination type and pollen size) in the dose and temporal response of the spore germination in Botrytis cinerea. We found a strong pollen‐stimulating effect on spore germination; however, the triggering effect highly varied among plant species and differed between specific functional categories across temporal and concentration gradients. Specifically, the B. cinerea hosts, the non‐cultivated plants and species with larger pollen size, increased the spore germination's stimulation effects, but not the pollination type. The systematic taxonomic and functional differences might reflect indirectly the diversity of the pollens' chemical profile (i.e. composition matrix or specific trigger molecules) which different selection mechanisms might shape. In the crop–pathogen interactions, the pollen‐stimulation effect could play an essential role in early fungal development.

Invasive Growth of Ailanthus altissima Trees is Associated with a High Rate of Sensitization in Atopic Patients

PurposeAilanthus altissima is one of the world’s most invasive species with a globally problematic spread. Pollen is dispersed locally and partially airborne. We aimed at investigating if (i) A. altissima pollen can be detected in relevant quantity in the air and if (ii) sensitization to A. altissima can be detected in patients with seasonal exacerbation of atopic diseases.Patients and MethodsWe recorded distribution of A. altissima in Leipzig, Germany. In 2019 and 2020, pollen was collected with a Hirst-type pollen trap placed on the roof of the University Hospital. Specific IgE investigations were performed in children and adults with history of atopic diseases with deterioration between May and July. We analysed specific IgE for A. altissima, Alternaria sp., birch, grasses, profilins, polcalcins and crossreacting carbohydrates.ResultsWe found abundant growth of A. altissima and pollen was detected from early June to mid-July with a maximum pollen concentration of 31 pollen/m3. Out of 138 patients (63 female, 69 children/adolescents), 95 (69%) had seasonal allergic rhinitis, 84 (61%) asthma, and 43 (31%) atopic dermatitis. Sensitization to A. altissima was shown in 59 (42%). There were no significant differences between age groups. In 59% of patients sensitized (35/59), there was no sensitization to possibly cross-reacting structures.ConclusionSensitization to A. altissima pollen could be detected in 42% of our patients with atopic diseases, suggesting allergenic potential of this neophyte. In the context of further spread with climate change, eradication strategies and population-based sensitization studies are needed.

Development and Testing of the A1 Volumetric Air Sampler, an Automatic Pollen Trap Suitable for Long-Term Monitoring of eDNA Pollen Diversity.

Airborne pollen surveys provide information on various aspects of biodiversity and human health monitoring. Such surveys are typically conducted using the Burkard Multi-Vial Cyclone Sampler, but have to be technically optimized for eDNA barcoding. We here developed and tested a new airborne pollen trap, especially suitable for autonomous eDNA-metabarcoding analyses, called the A1 volumetric air sampler. The trap can sample pollen in 24 different tubes with flexible intervals, allowing it to operate independently in the field for a certain amount of time. We compared the efficiency of the new A1 volumetric air sampler with another automated volumetric spore trap, the Burkard Multi-Vial Cyclone Sampler, which features shorter and fewer sampling intervals to evaluate the comparability of ambient pollen concentrations. In a sterile laboratory environment, we compared trap performances between the automated volumetric air samplers by using pure dry pollen of three species—Fagus sylvatica, Helianthus annuus and Zea mays—which differ both by exine ornamentation and pollen size. The traps had a standard suction flow rate of 16.5 L/min, and we counted the inhaled pollen microscopically after a predefined time interval. Our results showed that though we put three different pollen types in the same container, both the traps inhaled all the pollens in a statistically significant manner irrespective of their size. We found that, on average, both traps inhaled equal an number of pollens for each species. We did not detect any cross-contamination between tubes. We concluded that the A1 volumetric air sampler has the potential to be used for longer and more flexible sampling intervals in the wild, suitable for autonomous monitoring of eDNA pollen diversity.

Where Does Honey Bee (Apis mellifera L.) Pollen Come from? A Study of Pollen Collected from Colonies at Ornamental Plant Nurseries.

Simple SummaryPollen is the main source of protein, fats, and many micronutrients for honey bees, and it also has the potential to be a major route of exposure to pesticides. The objective of this study was to quantify to what extent honey bee colonies use ornamental nursery plants as sources of pollen over the season. We put honey bee colonies at two large commercial ornamental plant nurseries and used a pollen-trapping device to collect pollen from foraging honey bees as they returned to the hive. Pollen was collected each week from June until September in 2015 and 2018. Samples from the pollen collected were identified to genus by a pollen specialist. By counting and measuring the pollen grains, we could quantify how much of the pollen came from what plant source. We found that most of the pollen in July and August was collected from plant genera not grown at the nursery, including clover (Trifolium), maize (Zea), buckwheat (Fagopyrum), and jewelweed, and related species (Impatiens). Genera grown at the nurseries and found in the honey bee-collected pollen in June and early July included roses (Rosa), sumac (Rhus), and hollies (Ilex), but each of these genera also include native or naturalized species that are abundant in the surrounding area, so the pollen probably came from both the nursery and the surroundings.Ornamental nursery plants are both a major agricultural industry in the U.S. and a major feature of the urban and suburban landscape. Interest in their relationship with pollinators is two-fold: the extent to which they provide a nutritional benefit to pollinators, and the extent to which they have the potential to harm pollinators by exposing them to pesticide residues in nectar and pollen. We identified plant genera as sources of trapped pollen collected by honey bee colonies located at commercial ornamental plant nurseries in Connecticut in 2015 and 2018 and quantified the percentage of pollen volume collected from each genus for each weekly sample over two seasons. Plant genera grown at these nurseries, particularly Rosa, Rhus, and Ilex, contributed substantially to pollen volume during weeks 23–27 of the year. Among the genera not grown in nurseries, Toxicodendron was also important during weeks 23 and 24, and Trifolium was important in both frequency and quantity throughout the season. Zea was a major component of pollen volume from weeks 28–36 in both sites, even though cropland was not over 11% of land cover at either site.