Pollen Source Research Articles

Pollinator spillover: Hay cutting of grass with white clover, Trifolium repens, displaces bees and increases their abundance in adjacent patches of bramble, Rubus fruticosus

White clover, Trifolium repens, is a legume used widely in agriculture due to its ability to fix atmospheric nitrogen and improve soil fertility. Due to increasing cost of artificial fertiliser and concern over environmental impact, growing white clover in permanent grassland or in rotation with arable crops can potentially reduce cost and impact while maintaining productivity. White clover is also a source of pollen and nectar for pollinators and may contribute to alleviating floral resource shortages, which is one cause of pollinator decline. However, recent work has shown that agricultural plants grown in dense patches or monocultures can affect competition for floral resources by causing pollinators to aggregate and spillover into surrounding areas. Pollinator spillover can occur spatially by affecting density in nearby areas, or temporally, by affecting pollinator abundance at different times in relation to flowering. Here we examine whether growing and cutting of white clover in fields causes local pollinator spillover by surveying insects in landscapes around three fields planted with white clover and perennial ryegrass per summer over two years. Pollinator abundance was quantified in the fields and on bramble (Rubus fruticosus) in areas which were adjacent (<20 m) or distant (>1 km) before and after the fields were cut for hay. Honeybees and bumblebees, the main pollinators foraging on white clover, were 147% more abundant in adjacent survey areas after hay cut, indicating that mass-flowering of white clover planted with grass can cause spillover of pollinators. Implementing extensive management practices, such as reducing cutting frequency or grazing intensity, will extend the availability of floral resources produced by white clover.

Diet quality influences nutrient retention and reproductive fitness of the biocontrol agent Hadronotus pennsylvanicus (Hymenoptera: Scelionidae)

Diet can have a direct influence on the reproductive success of parasitoid wasps. For synovigenic parasitoids, the nutrients obtained from floral resources, such as nectar and pollen, play a vital role in fueling bodily functions and physiological energy expenditure incurred from reproduction. Insufficient access to nutrient-rich diets can lead to lower rates of reproductive fitness, therefore reducing the efficacy of biocontrol. Here, a study was conducted to evaluate the influence of diet quality on nutrient retention and reproductive fitness of the egg parasitoid Hadronotus pennsylvanicus (Hymenoptera: Scelionidae), a prospective biocontrol agent for the leaffooted bug Leptoglossus zonatus (Heteroptera: Coreidae), a primary pest of almonds and pistachios. Newly emerged parasitoid females were provided host eggs every other day accompanied by diets of varying sucrose concentrations (source of carbohydrates) and pollen (source of lipid and proteins). The sucrose concentration in the diet, regardless of pollen content, significantly increased the survival and lifetime fecundity of female H. pennsylvanicus. While wasps fed high sucrose diets depleted bodily sugars, glycogen, and lipids at a slower rate than wasps fed low sucrose diets, there was no effect on bodily protein levels. Given these findings, further research is now needed to identify floral resources that are compatible, attractive, and nutritionally-sufficient for optimal H. pennsylvanicus reproductive fitness, which could lead to enhanced parasitism of L. zonatus in crop systems.

Bioprospecting of the Telekia speciosa: Uncovering the Composition and Biological Properties of Its Essential Oils

The essential oils (EOs) of Telekia speciosa, a perennial plant native to southeastern Europe and Asia Minor, were analyzed for their composition and biological properties. T. speciosa is an invasive plant in Poland; however, its beauty prompts gardeners to cultivate the plants. T. speciosa serves as a valuable source of nectar and pollen for honey bees. Our results revealed more than 150 compounds in the flower, leaf, and root EOs. Major constituents found in the essential oils from the roots included isoalantolacton (46.2%) and from the flowers nerol (11.9%), while from the leaves, they included (E)-nerolidol (10.1%). T. speciosa flower EO showed significant cytotoxicity against A375 cells, with IC50 values of 7.2, 5.1, and 3.4 μg/mL referring to 24, 48, and 72 h, respectively, indicating its potential as a natural cytotoxic agent. The antimicrobial activity of the essential oils against Staphylococcus aureus ATCC 29213 and Escherichia coli ATCC 25922 was also investigated. The essential oils from the flowers and leaves of T. speciosa demonstrated higher inhibitory activity against S. aureus (MIC: 5.9–7.8 μL/mL) and E. coli (MIC: 7.8–11.7 μL/mL) than the essential oil isolated from the roots of the plant (MICs 31.3 and 62.5 μL/mL against S. aureus and E. coli, respectively).

A sublethal dose of neonicotinoid imidacloprid precisely sensed and detoxified by a C-minus odorant-binding protein 17 highly expressed in the legs of Apis cerana

As a native honeybee species in East Asia, Apis cerana is essential for the stability of local agricultural and plant ecosystems by its' olfactory system for searching nectar and pollen sources. Odorant-binding proteins (OBPs) existing in the insect's olfactory system can recognize environmental semiochemicals. It was known that sublethal doses of neonicotinoid insecticides could still cause a variety of physiological and behavioral abnormalities in bees. However, the molecular mechanism of A. cerana sensing and response for insecticide has not been further investigated. In this study, we found an A. cerana OBP17 gene significantly up-regulated expressed after exposure to sublethal doses of imidacloprid based on the transcriptomics results. The spatiotemporal expression profiles showed that OBP17 was highly expressed in the legs. Competitive fluorescence binding assays showed that OBP17 had the special and high binding affinity to imidacloprid among the 24 candidate semiochemicals, and the KA value of OBP17 binding with imidacloprid reached the maximum (6.94 × 104 L/mol) at low-temperature. Thermodynamic analysis showed that the quenching mechanism changed from dynamic to static binding interaction with the increasing temperature. Meanwhile, the force changed from hydrogen bond and van der Waals force to hydrophobic interaction and electrostatic force, indicating the interaction exhibits variability and flexibility. Molecular docking showed that Phe107 contributed the most energy. RNA interference (RNAi) results showed that OBP17 knockdown significantly enhanced the electrophysiological response of the bees' forelegs to imidacloprid. Our study indicated that OBP17 could precisely touch and sense sublethal doses of neonicotinoid imidacloprid in the natural environment through its high expression in legs, and the upregulation expression of OBP17 exposure to imidacloprid probably implied that it participate in the detoxification processes of A. cerana. Also, our research enriches the theoretical knowledge of the sensing and detoxifying activities of non-target insects' olfactory sensory system to environmental sublethal doses of systemic insecticides.

Variations in Spring Atmospheric Circulation on the Southwestern Tibetan Plateau During Holocene Linked to High‐ and Low‐Latitude Forcing

AbstractRecent climate and environment over the Tibetan Plateau (TP) have undergone significant changes, dominated by variations in the Westerlies and the Indian summer monsoon. However, long‐term shifts in atmospheric circulation during the transitional seasons are still lacking. Here we investigate the modern distribution of Tsuga pollen over the central‐western TP and confirm it as an indicator of variable atmospheric circulation in spring. By combining our Tsuga record from Taro Co with existing records in the Tsuga pollen source area, we suggest that a potential particle transport pathway from the southern slope of the Himalayas to the interior of the plateau appeared in the spring of the late Holocene. Our results show that the springtime atmospheric circulation over the southwestern TP during the early and late Holocene is closely related to the substantial remnants of ice sheets at northern high latitudes and the frequency of El Niño events, respectively.

Melissopalynological analysis and floral spectra of Apis mellifera scutellata Lepeletier bees in different agroecologies of southwest Ethiopia

The availability of bee forage limits honeybee productivity and is very important for beekeepers. Therefore, the current study aimed to identify the major botanical resources of honeybee, A. mellifera scutellata, in Southwest Ethiopia. Between October 2019 and October 2020, 69 group discussions (8–12 beekeepers), field observations, and pollen analysis were used to collect data. A total of 72 honey samples were collected from five districts at different seasons for pollen analysis. Most of the honey samples tested (93.06%) were multifloral, while 6.94% were monofloral. Melissopalynological analysis indicated that Eucalyptus camaldulensis (52.02%) was the predominant pollen type and is considered monofloral honey. Terminalia spp. (25.96%), Guizotia spp. (17.80%), and Bidens spp. (17.61%) were secondary pollen types and classified as multifloral honey. Terminalia spp., Guizotia spp., Vernonia spp., Bidens ssp., Plantago spp., and E. camaldulensis were pollen types recorded in honey samples in all agroecologies. Beekeepers ranked Schefflera abyssinica, Vernonia amygdalina, and Cordia africana as the first source of pollen and nectar for honeybees in highland, midland, and lowland, respectively. Additionally, V. amygdalina, Coffea arabica, Croton macrostachyus, and C. africana were commonly observed bee flora in all agroecologies. Honey bee management, such as bee forage shortages, the occurrence of brood and swarming, varied significantly (P < 0.05) among different agroecologies. In the present study, 53 honeybee plants were identified as pollen and nectar sources for honeybees. Various herbs (41.50%), trees (30.20%), and shrubs (28.30%) played a major role in honey production. Thus, beekeeping should be integrated with vegetation conservation for livelihood improvement and food security. Furthermore, existing bee flora should be cultivated in areas to increase the harvesting of honeybee products and improve the apiculture industry.

Nicho de polen de Melipona crinita Moure y Kerr, 1950 (Hymenoptera: Apidae) en un meliponario de Acre, Brasil: un estudio de caso

Melipona crinita is widely used in meliponiculture for the production of honey, in several places in the Amazon. Thus, the aim of this study was: (i) determine the seasonal characteristics of the pollen collected by M. crinita, regarding the botanical origin; (ii) the growth habit of plants visited by workers and (iii) the contribution of wild and agricultural species in providing pollen for this bee. Our hypotheses were: (i) M. crinita is a generalist species in the use of its pollen sources; (ii) M. crinita adjusts pollen foraging according to flowering variation and (iii) M. crinita visits mainly wild trees and shrubs to collect pollen. The research was carried out from April 2018 to March 2019 in a meliponary located in the rural area of Rio Branco, Acre, Brazil using a colony of M. crinita. The collected samples revealed 46 pollen types, distributed in 25 families and 41 genera of plants. Fabaceae (Mimosoideae) presented a higher frequency of occurrence, FO = 41.67%. The pollen types with the highest frequency of occurrence were: Solanum, FO = 19.72%; Alchornea, FO = 16.13% and Senna, FO = 11.93%, with the least seasonal being: Solanum and Aparisthmium cordatum. From the total plants visited by M. crinita, 71.74% were wild; 28.26% agricultural; 36.96% trees; 34.78% shrubs; 15.22% herbs; 6.52% lianas and 6.52% sub-bushes. Wild trees and shrubs represented 64.80% of all pollen collected by M. crinita. Thus, the conservation of these plants is essential for the successful management of M. crinita in meliponaries

Sensitization characteristics in allergic rhinitis and transport pathway for Artemisia pollen in northern Beijing, China

The genus Artemisia, an important allergen related to Allergic Rhinitis (AR), is widespread in temperate regions. However, the sensitization rate of Artemisia pollen varies significantly, and the source of Artemisia pollen is not clear. Based on continuous daily airborne pollen monitoring in the summer and autumn of 2019 and 2020 in northern Beijing, the daily number of AR patient visits during the same period, and the detection of allergen serum-specific immunoglobulin E (sIgE) in some AR patients, this study discusses the sensitization rate of Artemisia pollen and its transmission pathway and possible source area. The results show that (1) Artemisia pollen is the most important airborne pollen in summer and autumn in northern Beijing, and the pollen concentration is significantly related to the daily number of AR patient visits; (2) the rate of AR patients testing positive for Artemisia pollen allergens is 32.35 %, which is the first risk allergen and is consistent with the high sensitization rate of Artemisia pollen in northern China; and (3) in addition to local sources, central and southern Inner Mongolia, southern Mongolia and northwestern China are potential source areas of Artemisia pollen within the study area. This study provides first-hand data for accurately understanding the allergenic characteristics and sources of Artemisia pollen in northern Beijing and provides a scientific basis for the prevention of AR induced by Artemisia pollen in patients in China.

The hidden diet – examination of crop content reveals distinct patterns of pollen host use by Central European bees of the genus Hylaeus (Hymenoptera, Colletidae)

Masked or yellow-faced bees of the genus Hylaeus (Colletidae) differ in their mode of pollen transportation from most other bees in that they ingest the pollen directly on the flowers and carry it back to the nest inside the crop located in the anterior half of the metasoma. Due to this hidden mode of pollen transportation, the examination of pollen collected by Hylaeus females requires the dissection of the metasoma. Although this method has never been applied in Europe, the great majority of the Central European Hylaeus species were supposed to be pollen generalists based on observations of flower visits. The microscopical analysis of pollen removed from 30 crops each of 36 Central European Hylaeus species revealed that the proportion of species exhibiting an exclusive or strong preference for pollen from a single plant taxon is much higher than hitherto assumed and that the current assumption of the genus Hylaeus to largely consist of pollen generalists is wrong. Nineteen of the 36 species examined are strictly or largely dependent on a single plant taxon for collecting pollen, such as Apiaceae (n = 11 species), Rosaceae (n = 3), Reseda (Resedaceae) (n = 2), Allium (Amaryllidaceae) (n = 1), Asteraceae (n = 1) and Melilotus (Fabaceae) (n = 1). The 36 Hylaeus species examined collected pollen from the flowers of 31 plant families, of which the Apiaceae and Rosaceae (particularly Potentilla and Rubus) were by far the most important contributing almost 60% to the pollen host spectrum of the entire genus. The comparison between pollen host spectrum and flower visiting records showed that the pollen generalists use the flowers of the Asteraceae as nectar rather than pollen sources, corroborating earlier findings that the digestion of Asteraceae pollen requires physiological adaptations to cope with its unfavourable or protective properties. In summary, the patterns of pollen host use by bees of the genus Hylaeus do not substantially differ from those of other Palaearctic bee taxa despite the masked bees’ unusual habit to ingest the pollen directly on the flowers and to transport it inside their body back to the nest.

Effects of vegetation structure and environmental characteristics on pollinator diversity in urban green spaces

With accelerating urbanization, insect pollinators in urban ecosystems face challenges such as reduced pollen sources, habitat fragmentation, and damage to the nesting environment. Urban green spaces (UGS) are essential for the stability of pollinator communities. However, little is known about the relationship between vertical layer heterogeneity and horizontal layer complexity of vegetation structure in UGS and pollinator communities. The present study aimed to assess how vegetation structure and environmental characteristics shape the insect pollinator community in UGS. To this end, this study was conducted with seven typical vegetation types which were selected according to the biotope mapping classification system (BMCS) in the ring parks around Hefei City, in Anhui province, China. A total of 11,401 pollinators belonging to 6 orders and 34 families were identified during the eight-month survey. Among the seven habitats under the BMCS, mainly successional short-cut shrub and partly open green space, trees two- or multi-layered broad-leaved mixed forest and partly closed green space, and mainly successional tall grass and partly open green space were identified as high-quality insect pollinator habitats. According to the results of the generalized linear regression, the explanatory power of the four best-fitting generalised linear models is relatively high (over 77%). In four optimal models, the effect of vegetation structure on pollinator community was greater than that of environmental characteristics. The redundancy discriminant analysis showed that the flowering abundance of nectar plants, herb richness, and shrub coverage rate were the three most important factors influencing insect pollinator communities, with a cumulative explanatory power of up to 78.8%. Pollinator abundance was positively influenced by spontaneous herbs and low-intensity management. However, high-intensity management, low diversity of plants, low nectar plant richness, ignoring seasonal nectar plant configuration, and dense tree distribution could limit pollinator reproduction and population growth. These results reflect the status of insect pollinator community in UGS in Hefei city and present a possible direction for improving urban green habitats and plant configurations.

Foraging distances, habitat preferences and seasonal colony performance of honeybees in Central European forest landscapes

Abstract Unmanaged forest is considered as native habitat of the Western honeybee Apis mellifera and is assumed to provide important pollen and nectar sources. However, resource supply might be spatially and temporally restricted in managed forests and landscape‐scale studies in European forest regions are currently lacking. Capitalizing on a unique communication behaviour, the waggle dance, we investigated honeybee foraging in a deciduous forest region in southern Germany. We analysed 2022 waggle dances performed by bees of 12 colonies placed in the centre of landscapes with varying degree of forest cover (50%–99% at a 2‐km radius) from March to August 2019, thereby identifying foraging distances and habitat preferences over almost an entire foraging season. By connecting dance information with colony weight recordings, we assessed the role of landscape composition and the contribution of different habitat types to colony weight gain. Foraging distances generally increased with the amount of forest in the surrounding landscape pointing to inferior food resources in the forest. Yet, this effect strongly depended on the season and was more pronounced for pollen than for nectar foraging. Even though colonies in forest‐dominated landscapes had to fly further, colony weight was not significantly affected by forest cover. Compared to expectations based on the proportions of different habitats, colonies foraged more frequently in grassland and cropland than in deciduous and coniferous forests, with late summer being an especially difficult period for pollen foraging in forests. During a phase of colony weight gain in early summer, the use of forests for nectar/honeydew foraging was close to the expectation, highlighting forests as an important complementary source of carbohydrates during short periods of the year. Policy implication. The ecological and economic value of managed forest as habitat for honeybees could be significantly increased by the continuous provision of floral resources, especially for pollen foraging. Therefore, we recommend diversifying forest stands with insect‐pollinated trees, permitting secondary successions in forest gaps, and at larger scales, creating forest landscapes with high habitat diversity. This will not only help native, wild‐living honeybees and beekeepers' colonies residing in forest areas but will also foster social bees in general.

Status and Trend of the Main Allergenic Pollen Grains and Alternaria Spores in the City of Rome (2003–2019)

Today a large part of the European population is exposed to levels of air pollution exceeding the standards recommended by the World Health Organization. Moreover, air pollution and the seasonal emission of allergenic pollen are progressively affecting human health and can cause severe allergic reactions, particularly when air pollution combines with pollen allergen peaks. Unlike atmospheric pollutants of anthropogenic origin, pollen sources have a pulsating trend that leads to high values in the flowering period and values close to, or equal to, zero in the rest of the year. This aspect makes essential the definition of data coverage standards for the main allergenic taxa. For air quality assessment detailed classification criteria for monitoring stations are defined by international standards, not the same from the European Standards for the Sampling and analysis of airborne pollen grains and fungal spores. This paper describes the status and the air concentration trends of the main allergenic pollen and the Alternaria spore measured in Rome from 2003 to 2019 by the Aerobiological Monitoring Center of Tor Vergata (Rome) and calculated by the Seasonal Kendall test with the open-source OpenAir R package. The analysis was carried out on the daily concentrations of the most widespread allergenic taxa in Italy: Asteraceae, Betulaceae, Corylaceae, Cupressaceae/Taxaceae, Poaceae, Oleaceae, Urticaceae and the Alternaria spores.

Marvellous moths! pollen deposition rate of bramble (Rubus futicosus L. agg.) is greater at night than day.

Widespread concerns about declines of wild pollinating insects has attracted considerable research interest, largely directed towards identifying key nectar sources and assessing the contribution of pollinators towards ecosystem services. However, previous work has almost exclusively focussed on bees and other diurnal invertebrate taxa. This study aimed to assess the relative contribution of diurnal and nocturnal insects to the pollination of bramble (Rubus fruticosus agg.), a common and widespread species aggregate across Europe, which has been identified as a key source of pollen and nectar for diurnal pollinators. Bramble flower visitation rates by diurnal and nocturnal insects were quantified by analysing over 380,000 interval photographs taken over a 3-day period across 10 sites. A pollinator exclusion experiment was also undertaken to assess the importance of diurnal and nocturnal insects for pollination by analysing pollen deposition on 480 bramble stigmas of nocturnally exposed, diurnally exposed and unvisited control flowers across all sites. Flower visitation was significantly higher during the day, comprising 83% of all visits made by a range of taxa. Nocturnal visitation was almost exclusively by moths. Crucially, pollen deposition rates of bramble were significantly higher during the night compared with the day. No relationship was detected between pollen counts and flower visitation rates, suggesting that moths are more efficient pollinators of bramble compared with diurnal insects. Overall, this work provides further evidence of the value of bramble as a resource for pollinators and demonstrates that moths likely play an important role in bramble pollination.

Physicochemical and immunological characterization of Amb a 12, a novel ragweed (Ambrosia artemisiifolia) pollen allergen

BackgroundRagweed is an invasive plant in Europe, causing hay fever and asthma in allergic patients. Climate change is predicted to increase expansion and allergenicity. Elevated NO2 induced upregulation of a new allergen in ragweed pollen, an enolase, Amb a 12. Objectiveof this study was producing ragweed enolase as a recombinant protein and characterizing its physicochemical and immunological features. MethodsAmb a 12 was designed for E. coli and insect cell expression. Physicochemical features were determined by mass spectrometry, circular dichroism measurements and enzymatic activity assay. Immunological characteristics were determined in ELISA, in a mediator release assay and by investigation of association with clinical symptoms. Common allergen sources were screened for similar proteins. ResultsRagweed enolase was produced as a 48 kDa protein forming oligomers in both expression systems, showing differences in secondary structure content and enzymatic activity depending on expression system. IgE frequency and allergenicity were low regardless of expression system. Enolase-specific serum bound to similar sized molecules in mugwort, timothy grass and birch pollen, as well as food allergen sources, while highest IgE inhibition was achieved with peach pulp extract. ConclusionsAmb a 12 had high sequence similarity and comparable IgE frequency to enolase allergens from different sources. 50 kDa proteins were found in other pollen and food allergen sources, suggesting that enolases might be pan-allergens in pollen and plant foods.

Plant Species as Potential Forage for Honey Bees in the Al-Baha Mountain Region in Southwestern Saudi Arabia.

The contribution of bee forages in the form of nectar, pollen, and propolis to beekeeping development depends on plant species diversity. The data concerning the increase in honey production in southwestern Saudi Arabia, which was unexpected with the deterioration of the vegetation cover, becomes a concrete background for this study, which planned to list the bee plant species contributing as sources of nectar, pollen, and propolis. The sampling method followed a purposive random sampling approach, and 20 × 20 m plots were considered with a total of 450 sample plots. Bee forage plants were identified based on flower morphology and honey bees' actions during floral visits at active foraging hours. A checklist of bee forages containing 268 plants species belonging to 62 families was documented. The number of pollen source plants (122) was more than nectar (92) and propolis (10) source plants. Regarding seasonal distribution, spring and winter were relatively good seasons for honey bees in terms of pollen, nectar, and propolis availability. Generally, this study is an essential step towards understanding, conserving, and rehabilitating plant species providing nectar, forage, and propolis to honey bees in Al-Baha Region of Saudi Arabia.

Geography shapes the microbial community in Heliconius butterflies.

Heliconius butterflies are an ideal organism for studying ecology, behavior, adaptation, and speciation. These butterflies can be found in various locations and habitats in Central and South America, where they encounter and interact with different sources of pollen, nectar, and host plants. However, there is limited knowledge on how geographic and habitat variations affect the microbiota of these insects, and whether microbial associates play a role in their ability to exploit different habitats. To date, research on the microbial communities associated with Heliconius has mainly focused on host phylogenetic signal in microbiomes or microbiome characterization in specific communities of butterflies. In this study, we characterized the microbiomes of several species and populations of Heliconius from distant locations that represent contrasting environments. We found that the microbiota of different Heliconius species is taxonomically similar but vary in abundance. Notably, this variation is associated with a major geographic barrier-the Central Cordillera of Colombia. Additionally, we confirmed that this microbiota is not associated with pollen-feeding. Therefore, it seems likely that geography shapes the abundance of microbiota that the butterfly carries, but not the taxonomic diversity of the microbial community. Based on the current evidence, the bacterial microbiota associated with Heliconius does not appear to play a beneficial role for these butterflies.

Identification and characterization of honeybee flora calendar in Southwest Jimma Zone, Ethiopia

Abstract. Mossie T, Worku H. 2023. Identification and characterization of honeybee flora calendar in Southwest Jimma Zone, Ethiopia. Asian J For 7: 54-66. The study was conducted to identify, characterize and document major bee forages, develop an appropriate flora calendar, their phenology, and pollen potential in the various agro-ecological conditions of the Jimma Zone, Ethiopia. A total of 90 beekeepers were purposefully selected from three districts and interviewed to get primary data. The density and abundance of flowering plants were determined using quadrat sampling techniques. In addition, pollen specimens were collected using pollen traps at seven-day intervals and were also traced back to plant species level under a light microscope. The study has revealed the presence of 141 pollen and/or nectar-source honeybee plant species belonging to sixty-two families in the study area. Herbs were the most dominant bee flora growth forms, accounting for 62 (44%) of a total of 141 honeybee plant species, followed by trees at 48 (34%) and shrubs at 31 (22%), respectively. The herbaceous plant had a greater density value of plant species per plot than did trees and shrubs. One hundred fifteen (81.6%) were both sources of pollen and nectar, whereas fifteen (10.6%) were pollen sources and the remaining eleven (7.8%) were nectar-source plant species. The Shannon diversity index and evenness were found to be 2.8 and 0.6, respectively. This indicated that the study area has a rich bee floral plant species and is suitable for beekeeping. Two main flowering periods of honeybee plants were followed by two honey flow seasons. Therefore, beekeepers should follow the floral calendar of honeybee plants to exploit the potential of the area for honey production.

Characterization of Turkish Astragalus honeys according to their phenolic profiles and biological activities with a chemometric approach

The genus of Astragalus provides a significant source of pollen and nectar for honeybees. In this study, 37 Astragalus honey samples in 8 different regions from Turkey were investigated for the phenolic compositions and antioxidant, antimicrobial, anti-quorum sensing, anti-inflammatory and enzyme inhibitory (urease, tyrosinase, butyrylcholinesterase (BChE), and acetylcholinesterase (AChE)) activities with chemometric approaches. Seventeen phenolic compounds and organic acids were detected using HPLC-DAD and levulinic, gallic, p-hydroxy benzoic, vanilic and p-coumaric acids were found to be common compounds in all studied Astragalus honey samples. The ET coded Astragalus honey sample from Erzurum showed the best antioxidant activity in DPPH• (IC50: 12.54 ± 0.25 mg/mL), ABTS•+ (IC50: 4.20 ± 0.12 mg/mL) and β-carotene linoleic acid (IC50: 3.85 ± 0.11 mg/mL) assays. Astragalus honey samples studied displayed moderate antimicrobial activity against Candida species, gram-negative and gram-positive bacteria while they showed high quorum sensing inhibition effects. The NB coded Astragalus honey sample from Niğde exhibited the highest anti-inflammatory activity against COX-1 (76.11 ± 0.80%) and COX-2 (55.98 ± 0.93%) enzymes. The studied Astragalus honey samples showed mild enzyme inhibitory activities against AChE, BChE, urease and tyrosinase. The chemometric characterization based on the botanical origin of Astragalus honey samples was determined using principal component analysis (PCA) and hierarchical cluster analysis (HCA).

Improving fruit set and yield of tissue cultured date palm cv. Berhi by using a combined pollination technique

Tissue-cultured (TC) date palms produce no fruit or low yield due to abnormal fruit setting. To improve the yield of TC ‘Berhi’ palms, trees were pollinated using five pollen sources (Gantar, Ghannami, Mazafati, Zahedi, and Jarvis). The experiment was carried out in three replications for two successive years in a randomized complete blocks design. The fruit set, the fruit and seed physical traits at the Khalal stage, bunch weight at the Tamar and Khalal stages, ripeness of Tamar bunch, and the fruit quality at both Khalal and Tamar stages were measured and monitored. Year factor significantly affected the fruit set and the fruit and seed characteristics. Pollen sources affected fruit set and some seed characteristics significantly. Zahedi+Jarvis pollen treatment that induced 50% normal fruit set and the highest ratio of pulp to seed was found superior. It was also a top treatment in Khalal’s bunch weight (3.11 Kg). Zahedi+Gantar treatment was realized superior in Tamar’s bunch weight (6.00 Kg). Ghannami, Jarvis+Ghannami, and Zahedi+Jarvis treatments produced Khalal’s fruits with higher quality indices but Zahedi+Jarvis treatment was superior in fruit quality at the Tamar stage. Overall, the combined application of Zahedi and Jarvis pollens yielded the most desired outcomes.

Attributing long-term changes in airborne birch and grass pollen concentrations to climate change and vegetation dynamics

Changes in climate and land-use may elicit an increased emission of allergenic pollen amounts in the air, causing a rise in respiratory allergies and affecting public health more than previously thought. Here we have used a well-established pollen transport model SILAM (System for Integrated modeLling of Atmospheric coMposition) for attributing the long-term changes in airborne pollen concentrations of birches and grasses to climate change and vegetation dynamics. The pollen transport model is applied for Belgium and is driven by ECMWF ERA5 meteorological data (European Centre for Medium-Range Weather Forecasts, fifth generation of ECMWF atmospheric reanalysis of the global climate). The dynamic vegetation components of the model are based on multi-decadal datasets for 1982–2019 on spatially distributed birch and grass pollen emission sources. For each model gridcell we have computed the change rate of the seasonal birch and grass pollen cycles based on daily pollen concentrations, and of the daily meteorological model input. Finally, the gridcell based association between trends in pollen and climate change are derived. Our findings show that during the period 1982–2019 a strong increase in birch pollen concentrations is associated with increasing radiation, decreasing precipitation and decreasing horizontal wind speed near the surface. A strong decrease of grass pollen concentrations over time is driven by a decreasing trend in grass pollen sources, and it is also associated with decreasing precipitation. The magnitude of the associations between meteorology and airborne birch pollen concentrations are almost twice the association between meteorology and grass pollen, and the spatial variations are substantial even on the scales of small countries. The specific contribution of birch tree and pollen production dynamics to the concentrations of birch pollen in the air over time is highly associated with wind speed and precipitation. Introducing the inter-seasonal variation in birch pollen production during the period 1982–2019 intensifies the climate induced increase of airborne birch pollen concentrations with ∼6%. In contrast, the grass pollen production dynamics resulted into ∼10 times less grass pollen over the studied period compared to climate change effects.