Pollen Collection Research Articles

Decreased efficiency of pollen collection due to Sulfoxaflor exposure leads to a reduction in the size of bumble bee workers in late European summer

Bumble bees (Bombus terrestris) are important pollinators of wild and crop plants. Despite their importance in the process of fruit and seed production on crop sites, their activity may be impaired due to exposure to pesticides. This species has a yearly life cycle and colony success may rely on effective foraging of workers on ruderal plants late in summer when most crops are no longer flowering. In the current study, we investigated the effect of chronic exposure to Sulfoxaflor on aspects of the foraging behavior of bumble bees and whether Sulfoxaflor influences the body size of workers of B. terrestris in a crop landscape. We found that 2 weeks of continuous exposure to Sulfoxaflor influenced workers’ foraging dynamics and collection of resources. However, there was no evidence that the 5 ppb dose of the pesticide impacted the ability of bees to handle flowers with different traits. Workers from colonies exposed to Sulfoxaflor were smaller. The effect on worker size may be explained as a consequence of the reduced pollen income per unit of worker foraging. Thus, if the effects of Sulfoxaflor applied directly to crops had the same effect as that observed on commercial bumble bees after our chronic exposure, it might negatively impact colony success due to the impact on pollen collection and the reduction in the size of workers.

Zoophily and nectar-robbing by sunbirds in Gardenia latifolia Ait. (Rubiaceae)

Gardenia latifolia is a semi-deciduous tree species which blooms during the dry season. Its flowers are hermaphroditic, strongly fragrant, nectariferous, and specialized with a narrow corolla tube and concealed deep seated nectar. Thrips act as resident pollinators while bats and carpenter bees act as non-resident pollinators. Sunbirds act as nectar robbers and have no role in pollination. The flowers are milky white and fragrant on days 1 and 2; they cease fragrance and change color to golden yellow on day 3. Bats visit newly open, day 1 fragrant flowers for pollen collection while thrips use day 1 and day 2 flowers. Carpenter bees and sunbirds visit only day 2 flowers. The flower visiting activity of all these foragers indicates that they do not visit non-fragrant, golden yellow colored flowers although they possess nectar. Fruit is an indehiscent berry with seeds placed in pulp inside; the birds are the most likely seed dispersal agents when they break the pericarp and feed on the fruit pulp.

Seasonal variability in physiology and behavior affect the impact of fungicide exposure on honey bee (Apis mellifera) health

Honey bee pollination services are of tremendous agricultural and economic importance. Despite this, honey bees and other pollinators face ongoing perils, including population declines due to a variety of environmental stressors. Fungicides may be particularly insidious stressors for pollinators due to their environmental ubiquity and widespread approval for application during crop bloom. The mechanisms by which fungicides affect honey bees are poorly understood and any seasonal variations in their impact are unknown. Here we assess the effects on honey bee colonies of four-week exposure (the approximate duration of the almond pollination season) of a fungicide, Pristine® (25.2% boscalid, 12.8% pyraclostrobin), that has been commonly used for almonds. We exposed colonies to Pristine® in pollen patties placed into the hive, in either summer or fall, and assessed colony brood and worker populations, colony pollen collection and consumption, and worker age of first foraging and longevity. During the summer, Pristine® exposure induced precocious foraging, and reduced worker longevity resulting in smaller colonies. During the fall, Pristine® exposure induced precocious foraging but otherwise had no significant measured effects. During the fall, adult and brood population levels, and pollen consumption and collection, were all much lower, likely due to preparations for winter. Fungicides and other pesticides may often have reduced effects on honey bees during seasons of suppressed colony growth due to bees consuming less pollen and pesticide.

Optimum time for hand pollination in yam (Dioscorea spp.).

Hand pollination success rate is low in yam (Dioscorea spp.), due partly to suboptimal weather conditions. Thus, determining the most suitable time for pollination could improve the pollination success in yam breeding programs. We performed continuous hand pollination within flowering windows of D. rotundata and D. alata for two consecutive years to determine the most appropriate month, week, and hours of the day allowing maximum pollination success. In D. alata crossing block, we observed significant differences among crossing hours for pollination success (p = 0.003); morning hours (8–12 a.m.) being more conducive than afternoons (12–5 p.m.). No significant differences existed between crossing hours in D. rotundata, though the mid-day seemed optimal. For both species, the time interval 11–12 a.m. was more appropriate for crossing while 4–5 p.m. was the poorest. However, in vitro pollen germination tests showed that mid-day pollen collection (12 noon–2 p.m.) had better results than both extremes, though there were strong genotypic effects on outcomes. Pollination success rates differed significantly among months for D. alata (p < 0.001) but not for D. rotundata (p > 0.05). Differences in pollination success existed across weeks within flowering windows of both D. alata (p < 0.001) and D. rotundata (p = 0.004). The seed production efficiency (SPE) had a similar trend as the pollination success rate. No clear pattern existed between the pollination time and the seed setting rate (SSR) or seed viability (SV), though their dynamics varied with weeks and months. This study provided an insight on the dynamics of pollination outcomes under the influence of pollination times and allows detecting months, weeks, and hours of the day when hybridization activities should be focused for better results.

Influence of Flowering Characteristics, Local Environment, and Daily Temperature on the Visits Paid by Apis mellifera to the Exotic Crop Phacelia tanacetifolia

The opportunity to introduce Phacelia tanacetifolia is still being debated, even if the species is already employed, as it is often sown in rotational set-aside schemes or to support pollinators. Therefore, we need further evidence on its effects on the environment and its attractiveness towards pollinators. This work aims at confirming its appeal towards the honeybee in a mixed agricultural and urban environment in the north of Italy, during late spring and early autumn flowering. We assessed flowering characteristics and honeybee visitation rates by employing observational plots; we recorded resource preferences and behaviours by focal observations and video records; finally, we annotated other flower visitors. Each plant is characterised by one or more flowering stems on which not all flowers open at the same time: an increased number of flowers is, therefore, due to an increase in the number of available flowering stems. Honeybees were highly interested in lacy phacelia resources, especially in nectar collection: pollen collection may not be sufficiently rewarding for bees to dedicate time to it. The only correlation we found was between visitation rates and temperature. Other insects were recorded visiting the flowers: these were especially Hymenoptera; Coleoptera and Lepidoptera were also abundant, while relatively few individuals of Hemiptera and Diptera were recorded. Our results indicate that the mass-flowering of the species is certainly of interest to local pollinators and can be considered to counteract their decline when sown as a single species or in flower mixtures. However, further studies are needed to assess the competition of this plant with native species and its ability to self-regenerate when not purposely planted.

Access to prairie pollen affects honey bee queen fecundity in the field and lab

Beekeepers experience high annual losses of colonies, with environmental stressors like pathogens, reduced forage, and pesticides as contributors. Some factors, like nutritional stress from reduced flower abundance or diversity, are more pronounced in agricultural landscapes where extensive farming limits pollen availability. In addition to affecting other aspects of colony health, quantity and quality of pollen available are important for colony brood production and likely for queen egg laying. While some US beekeepers report &amp;gt;50% of colony loss due to queen failure, the causes of poor-quality queens are poorly understood. Access to resources from native prairie habitat is suggested as a valuable late-season resource for honey bees that can reverse colony growth declines, but it is not clear how prairie forage influences queen egg laying. We hypothesized that the pollen resources present in an extensive Midwestern corn/soybean agroecosystem during the critical late season period affect honey bee queen egg laying and that access to native prairies can increase queen productivity. To test this, we designed a field experiment in Iowa, keeping colonies in either soybean or prairie landscapes during a critical period of forage dearth, and we quantified queen egg laying as well as pollen collection (quantity and species). Then, using pollen collected in the field experiments, we created representative dietary mixtures, which we fed to bees using highly controlled laboratory cages to test how consumption of these diets affected the egg laying of naive queens. In two out of three years, queens in prairies laid more eggs compared to those in soybean fields. Pollen quantity did not vary between the two landscapes, but composition of species did, and was primarily driven by collection of evening primrose (Oenothera biennis). When pollen representative of the two landscapes was fed to caged bees in the laboratory queens fed prairie pollen laid more eggs, suggesting that pollen from this landscape plays an important role in queen productivity. More work is needed to tease apart the drivers of these differences, but understanding how egg laying is regulated is useful for designing landscapes for sustainable pollinator management and can inform feeding regimes for beekeepers.

Vibrational response of the male ‘peter’ pistachio branch organs to facilitate artificial pollination

Artificial pollination may be a promising practice to both improve pistachio fruit production by mitigating the losses caused by phenological gaps or by adverse meteorological events and establish new production areas. Artificial pollination requires large quantities of pollen and manual collection is not economically viable. Mechanical capture of pollen, for subsequent storage and application, could achieved in two ways: by releasing mature pollen from the inflorescences and capturing it in the air, or detaching mature male inflorescences for taking pollen in laboratory. In this work, the dynamic behaviour of branches of the male ‘Peter’ variety was analysed under controlled laboratory conditions. A wide range of vibration frequencies was used for branch excitation, and the responses of the stem and its inflorescences were analysed. The stem and inflorescences had clearly differentiated dynamic responses according to the vibration frequency. The stem attained maximum acceleration transmissibility values at specified frequency values (8, 13.5, 20.5–22 Hz). At these values, the vibration applied amplified the stem movement and could clearly contribute to pollen release to the atmosphere. At the highest frequency values (45 Hz), the stem damped the vibration, but the inflorescences amplified the response. In the 54–59 Hz range, the inflorescences amplified the acceleration received by an average 5-fold. In this range, detachment of the inflorescences is facilitated without exciting the stems. Thus, current commercial trunk shakers must be adapted if they are used to collect pollen from pistachio trees owing to the higher transmission values of trees without leaves. • Stem and male inflorescences of the Peter variety have a different dynamic response. • Precise vibration frequency applied to branch enables a selective organ excitation. • Trunk shakers can be adapted for mass pollen detachment. • Absence of leaves during the pollination period may increase damage to shaken trees .

Embryology of Ficus tuerckheimii (subg. Spherosuke, Moraceae) and its relevance in interactions with its pollinator wasps, Pegoscapus sp. (Agaonidae)

• Ficus tuerckheimii has two female floral morphs with dimorphic stigmas. • Both floral morphs form showed cohesive synstigmas. • Wet stigmas are described for the first time within the genus Ficus. • The development of the anther wall in male flowers is a basic type. • Several evidence suggest that F. tuerckheimii is actively pollinated. Species in the Ficus (Moraceae) genus carry an inflorescence called syconium, formed by a fleshy, urn-shaped receptacle. This study aims to i) describe the embryology of Ficus tuerckheimii flowers at different developmental stages and ii) determine whether this species is pollinated actively or passively. The species is monoecious, with protogynous syconia and diclinous flowers. The syconia contain two pistillate floral morphs: one sessile with a long style and a symmetrically bilobed stigma, the other pedicellate with a short style and asymmetrical stigmatic lobes. The ovule of each flower type can develop into a seed or a (parasitic or pollinator) wasp. The gynoecium is pseudomonomerous; the flowers form a cohesive synstigma due to the proximity of the stigmatic papillae, which facilitates pollen concentration and pollen tubes growth in neighboring flowers. The staminate flowers are pedicellate and unistaminate. The anther dehiscence is longitudinal, rotating horizontally to open and release bicellular pollen grains. The syconium includes three different trichome types whose functions remain unknown. The drupelet fruit has a pericarp conformed of a tanniferous exocarp, a parenchymatic mesocarp, and a schlerenchymatic endocarp. We detected the following embryological characteristics that were previously undescribed for the genus and are potentially informative for the systematics of the family: i) wet stigmas, ii) a basic anther wall with a non-persistent epidermis and a multiplicative middle layer, iii) pollen grains that can germinate within the anther, iv) a profuse nucellus that later forms a perisperm, and v) a persistent perisperm. Altogether, the synstigma, the low anther-to-ovule ratio (0.12 SD ± 0.031), the smooth pollen ornamentation, and the specialized pollen collection and transport structures (corbiculae) of its pollinator wasps ( Pegoscapus sp., Agaonidae) suggest that F. tuerckheimii is actively pollinated.

Pollen collection by honey bee hives in almond orchards indicate diverse diets

Almond is one of the world's most economically valuable crops and many varieties require cross pollination for optimal fruit set. For this reason, western honey bee (Apis mellifera L.) hives are often placed in almond orchards. However, little is known about the usage of almond and other pollen sources by individual hives during almond bloom. Here, we investigated the timing, identity and quantity of pollen collection associated with almond floral abundance and spatial location of individual hives by sampling 440 individual pollen tray samples and counting 45,072 pollen grains from 13,200 pollen pellets collected from 80 individual hives across the flowering season in Victoria, south-eastern Australia. A large proportion of hives collected non-almond pollen in addition to almond pollen (63/80 = 79%). The weight of almond pollen collected by the hives at each sampling time was positively related to the number of concurrently open almond flowers. However, non-almond pollen richness and abundance was not related to the number of almond flowers but had a positive relationship with the weight of almond pollen collected. There was no relationship between the distance among hives and identity of pollen collected. Yet, three plant families in the study area were found to account for a high percentage of the non-almond pollen collected, Euphorbiaceae, Fabaceae and Asteraceae. Understanding crop and non-crop pollen collection could inform honey bee diet needs and identify the plant species of importance to inform best practice bee management during almond flowering.

Annual Development Performance of Fixed Honeybee Colonies Linked with Chemical and Mineral Profile of Bee Collected Pollen.

Climate change affects plant phenology and, as a result, can damage nectar and pollen sources, which are the basic needs of bees during flowering. This situation creates nutritional stress for bee colonies in the region. Changing climatic conditions, the use of agricultural lands adversely affects honeybees and beekeepers. The aim of this study is to determine the annual development performance of fixed honeybee colonies linked with the chemical and mineral profile of bee collected pollen. According to the research findings, in terms of colony development parameters, the number of bee frames (9.17) was found to be at the highest level in May, and in terms of brood area (4652.35 cm2 ) in April (P<0.05). March, April, and May are the most abundant months in terms of pollen collection of the colonies (P<0.05). The pollen samples collected are rich in potassium, sodium, calcium, magnesium, silicon, and iron. There are differences between months in terms of pollen sources and mineral levels. Especially in stationary beekeeping, additional feeding is required during critical periods. The existing flora is insufficient for the future of the honey bee. In periods when the flora is weak, important plants for the honey bee should be grown in the region.

Issue Information

Left: Justicia betonica inflorescence showing completely opened bilabiate flowers. Photo by Prakash KarmakarTop‐right: Potter wasp (Anterhynchium abdominale) collecting nectar. By Mrinmoy MiddayBottom‐center: Black and White Cuckoo bee (Thyreus) searching for nectar. By P. KarmakarBottom‐right: Sweet bee (Halictus acrocephalus) gathering pollen. By M. MiddayThe photographs are taken adjacent to the Vidyasagar University Campus, West Bengal, India.Karmakar P et al. (2022) Floral biology, breeding system and pollination ecology of Justicia betonica L. (Acanthaceae): an assessment of its low reproductive success in West Bengal, India. Plant Species Biology, 278–293. https://doi.org/10.1111/1442-1984.12380image

Differences in olfactory sensitivity and odor detection correlate with foraging task specialization in honeybees Apis mellifera

Division of labor is central to the ecological success of social insects. Among honeybees foragers, specialization for collecting nectar or pollen correlates with their sensitivity to gustatory stimuli (e.g. sugars). We hypothesize that pollen and nectar foragers also differ in their sensitivity to odors, and therefore in their likelihood to show odor-mediated responses. To assess foragerś sensitivity to natural odors, we quantified the conditioning of the proboscis extension reflex (PER) to increasing concentrations (0.001; 0.01; 0.1; 1 M) of linalool or nonanal. Furthermore, we compared electroantennogram (EAG) recordings to correlate bees’ conditioned responses with the electrophysiological responses of their antennae. To further explore differences of the antennal response of foragers in relation to task-related odors, we registered EAG signals for two behaviorally ‘‘meaningful’’ odors that mediate pollen collection: fresh pollen odors and the brood pheromone (E)-β-ocimene. Pollen foragers performed better than nectar foragers in PER conditioning trials when linalool and nonanal were presented at low concentrations (0.001, 0.01 M). Consistently, their antennae showed stronger EAG signals (higher amplitudes) to these odors, suggesting that differences in sensitivity can be explained at the periphery of the olfactory system. Pollen and nectar foragers detect pollen odors differently, but not (E)-β-ocimene. Pollen volatiles evoked EAG signals with hyper and depolarization components. In pollen foragers, the contribution of the hyperpolarization component was higher than in nectar foragers. We discuss our findings in terms of adaptive advantages to learn subtle olfactory cues that influence the ability to better identify/discriminate food sources.

Establishing Honey Bee Floral Calendar in West Arsi and East Shewa Zones of Oromia, Ethiopia

Adequate knowledge about honey bee flora is important for beekeeping this study was under taken to identify and document honeybee plants in West Arsi and East Shoa Zone using melissopalynological analysis of honey samples, pollen collection, plant inventory, structured questionnaires and field observation. Eighteen honey samples were collected from different parts of the zones. Out of 18 samples, 14 were identified as monofloral honeys and 4 as multifloral honeys. This indicated that there is high diversity of honeybee plant species in 4 honey samples that give flowers in the same season contributing for production of multifloral honey and 14 samples were dominated by few major honeybee plants due to their abundance in addition to their quality for honey production. Fifty eight (58) plants species were identified as honey source plants based on melissopalynological analysis of honey. Of 58 species, Guizotia scarba (89.7%). Eucalyptus (69.2%) Eucalyptus camadulensis (66.2%) Acacia tortolis (60.9%) Schefflera Abyssinia (70.2%) and Croton macronstachys (57.2%) provided mono-floral honey. The flowering calendar of the zone indicated two major honey flow periods from April to June and September to November. The scarcity of honeybee forages were observed in July to mid of August and January to February and mid of March. In many districts of the zone, herbaceous honeybee forage species were the dominant honey source plants in September to November. While, in March to May majority of honey source plants were trees and shrubs due to the phonological patterns of plants. To apply seasonal honeybee colony management, beekeepers should manage honeybee colonies following phonological pattern of honeybee plants. Beekeeping based agro forestry practices on cultivated rain fed land, and selection of plant species that can resist drought and bear (set) flower for a long season should be introduced in all land use types.

Phylogenetic analysis of Starmerella apis in honey bees (Apis mellifera).

Honey bees are among the most effective pollinators that promote plant reproduction. Bees are highly active in the pollen collection season, which can lead to the transmission of selected pathogens between colonies. The clade Starmerella comprises yeasts that are isolated mainly from bees and their environment. When visiting plants, bees can come into contact with Starmerella spp. The aim of this study was to determine the prevalence and phylogenetic position of S.apis in bee colonies. Bee colonies were collected from nine apiaries in three regions. Ten colonies were sampled randomly from each apiary, and pooled samples were collected from the central part of the hive in each colony. A total of 90 (100%) bee colonies from nine apiaries were examined. Starmerella apis was detected in 31 (34.44%) samples, but related species were not identified. The 18S rRNA amplicon sequences of S.apis were compatible with the GenBank sequences of Starmerella spp. from India, Japan, Syria, Thailand, and the USA. The amplicon sequences of S.apis were also 99.06% homologous with the sequences deposited in GenBank under accession numbers JX515988 and NG067631.This is the first study to perform a phylogenetic analysis of S.apis in Polish honey bees.

Developmental temperature predicts body size, flight, and pollen load in a widespread butterfly

Abstract Most of our understanding of the effects of climate warming on insect body size comes from laboratory experiments. Whether these studies predict patterns in nature is largely unknown. Here we examine the relevance of laboratory warming experiments for wild populations of the butterfly Pieris rapae. We tested two predictions: (i) butterflies reared at warmer temperatures in the laboratory should attain smaller adult sizes and have reduced flight ability, and (ii) in nature, this trait combination should lead to smaller butterflies visiting fewer flowers and accumulating less pollen. Overall, we found that warm‐reared butterflies were indeed smaller and flew more slowly compared to colder‐reared conspecifics. Additionally, wild‐caught small butterflies carried fewer, and a lower diversity of pollen grains compared to larger butterflies. Our warming experiments thus largely predicted pollen collection patterns in wild P. rapae. This study demonstrates that increased temperatures will likely have important consequences for butterfly‐plant interactions in nature.

Rose Pollen Management Methods to Improve Productivity

Roses are one of the most highly produced and purchased ornamental plants worldwide. Procurement and preservation of pollen is essential for the production of diverse rose varieties. In this study, we analyzed pollen management conditions, such as the pollen collection stage, drying time, and storage temperature, to determine optimal conditions for rose pollen management. Pollens were stored under different conditions and the pollen vitality and germination rate were investigated through an optical microscope. The vitality of pollen was an essential factor for rose breeding and depended on the storage conditions. Collecting pollen in the seventh flowering stage resulted in a relatively higher pollen yield. Drying the flower for 5 h after the anther opened improved pollen germination. The germination rate of freshly collected pollen was similar to that of pollen stored at temperatures between −20 °C and −72 °C for up to 30 days, indicating the efficacy of pollen storage at sub-zero temperatures. Since the rate of fruiting increases when pollination is performed three times, considering the time and cost of breeding, it is appropriate to pollinate three times to increase the number of seeds. This study provides an efficient pollen management method to collect and store pollen for breeding.

MINIMISATION OF RISKS ASSOCIATED WITH THE USE OF POLLEN-BASED MEDICINES, AT THE STAGE OF POLLEN COLLECTION

The aim of the study is the elaboration of Rules for Harvesting/Collecting of Pollen to minimize the risks associated with the use of pollen-based medicinal products.Materials and methods. The following electronic resources were used in the study: PubMed, Medline, ScienceDirect, Web of Science, Scopus, Google Scholar, eLibrary, World Allergy Organization, Cochrane Database, Stallergenesgreer, Allergenscienceandconsulting, Pharmacopoeia, Fda.gov, fs.usda.gov, Ema.europa.eu. The analysis covered the period from January 1, 2010 until December 31, 2021.Results. Currently, there are some general requirements for the quality of pollen in Russia, but there are no controls or standardised procedures for harvesting, drying, and purification of pollen. The USA and EU also lack established qualification programmes for pollen-collecting companies and/or individual pollen collectors. Regulatory authorities establish requirements only for visual control of raw materials or delegate responsibility to the manufacturer. The analysis of the existing regulatory documentation revealed lack of requirements for collection, storage, and processing of pollen used as the raw material for the production of allergen products. This calls for the elaboration of appropriate regulatory documents. The authors have compiled the Rules for Harvesting/Collection of Pollen, which include 6 parts. The Rules are intended for individuals directly involved in harvesting/collection of pollen, and contain requirements for pollen collectors, the process of pollen collection, documentation, storage, and transportation.Conclusion. The authors have prepared the Rules for Harvesting/Collecting of Pollen, which include 6 parts. The Rules cover the whole process of pollen collection and all related processes. The implementation of this document will improve the process of pollen collection, thus reducing the risks associated with the use of pollen-based medicines. Further studies will assess the impact of the pollen quality on the safety of medicinal products.

The obtaining a honey pollen product in apiaries

Due to the fact that consumers are paying more attention to the safety and functionality of food, the authors have developed a functional product based on honey and pollen collected by bees. This product is characterized by high indicators of safety, nutritional and biological value. The problem of bees for its production is that they use old honeycombs, which are not suitable for brood production because of the narrowing of the lumen of the cell due to the fact that each exiting bee leaves behind a cocoon. However, old combs accumulate antibiotics and other veterinary drugs that beekeepers use to treat bees. For the production of this product, which is not inferior in quality to bee bread, the authors used pollen collected in the form of a pollen collector, and honey was extracted from the superstructures of the store, in which brood was never hatched. In other words, the starting material for the product did not come into contact with the nesting frames containing the cells with the cocoons of the emerging bees. Moreover, these nest frames could contain the remains of veterinary drugs. The analysis of the organoleptic indicators of the quality of the honey pollen product and bee pollen showed that, in appearance, the bee bread was a hexagonal strong prism, which repeated the cells of a honeycomb. Its color varied in layers from light yellow to brown. The honey pollen product was homogeneous throughout the mass, ointment-like consistency and orange in color. The smell of all samples is honey pollen. The taste of bee pollen was sweet and sour, slightly bitter, that of the honey pollen product was sweet, that of the honey pollen product with vitamin C was sweet and sour. Comparison of physicochemical parameters of the quality of bee bread and honey pollen product showed that the mass fraction of fat in bee bread was lower by 3.5–3.6%, cholesterol - by 11.2, protein content - above 0.4%. The level of assessment of the production of honey pollen product at a selling price of 4000 rubles/kg, like bee bread, is from 145.8 to 150.0%, while the chemicals associated with the production of the product range from 1600 to 1627 rubles/kg. The profit reached from 2373 to 2400 rubles/kg

Traffic-related NO2 affects expression of Cupressus sempervirens L. pollen allergens.

Traffic pollution has been recognized as directly worsening respiratory symptoms of allergic subjects, although whether urban air pollutants can also directly increase the allergenic potential of pollen has not yet been definitely proven. Therefore, the hypothesis that intra-urban air NO2 variation influences allergens expression in Cupressus sempervirens (Cs) L. pollen was tested. Mature microsporophylls were cut from Cs trees of similar age and height (14-17 m) present in three different sites of Florence (Italy) and processed in the laboratory. Cs pollen allergens amount was determined by a semi-quantitative analysis of electrophoretically separated pollen extracts fractions. NO2 air concentrations were recorded by air monitoring stations located at a distance not exceeding 50 m from each pollen collection site, and the relative annual mean values were acquired by a publicly available database (Tuscan Regional Agency for Environment Protection). Expression of three major Cs pollen allergens was non-linearly correlated with mean annual NO2 concentrations. Expression peak of all major allergens considered was reached at NO2 air concentration (67μg/m3), far below the value at risk for direct effect on the respiratory health (European Union Directive 2008/50/EC). The findings suggest that intra-urban NO2 variations do affect the expression of Cs pollen major allergens, and an apparent low risk NO2 concentration should be regarded as indirectly harmful for increasing the allergenic potential of pollen.

A Comparison of Springtime Pollen and Nectar Foraging in Honey Bees Kept in Urban and Agricultural Environments

Spring is an essential time for honey bee foraging in temperate climates. This is a period of increased brood rearing supporting colony growth and demands access to high-quality pollen and nectar resources. With the expansion of urban and agricultural landscapes, the availability of pollen and nectar producing flowers is declining in many areas. We aim to determine how patterns of spring pollen and nectar foraging differ between colonies surrounded by varying degrees of urban and agricultural intensity, as well as to assess the potential for nectar sampling to serve as a proxy for pollen collection. Thirteen apiaries in Central Ohio, along a gradient of urban and agricultural intensity, were monitored in spring of 2019 through the periodic collection of pollen and nectar samples and continuous colony weight monitoring. We found that spring honey bees in urban and agricultural areas gain comparable amounts of weight and use similar spring resources. Foraging was heavily focused on flowering trees and shrubs including Malus (apple), Salix (willow), and Prunus (cherry), until the beginning of clover bloom (Trifolium spp.). We also identified differences in pollen and nectar foraging within colonies, with nectar containing fewer species collected more evenly than matched pollen samples. These results demonstrate that honey bees in both agricultural and urban environments exhibit similar foraging patterns during the spring, and that plant species important for nectar collection are substantially different from plants important for pollen foraging, though limitations in nectar collection hinder our ability to draw definitive comparisons of pollen and nectar foraging in this region.