Pollen Samples Research Articles

CSI Pollen: Diversity of Honey Bee Collected Pollen Studied by Citizen Scientists.

Simple SummaryHoney bee colonies collect pollen from plants as a source of nutrients. Diverse diets comprising pollen from many different plant species are beneficial for honey bee colony health, because they contain a greater diversity of nutrients than monofloral diets of one plant species only. Here, we present the results of the COLOSS “CSI Pollen” study on the diversity of pollen collected by honey bee colonies. In this study, beekeepers acted as citizen scientists sampling and analyzing pollen collected by their own colonies. As a simple measure of diversity, beekeepers determined the number of different colors found in pollen samples that were collected in a coordinated and standardized way. The support of 750 beekeepers allowed the collection of information about almost 18,000 pollen samples from many European countries. We found that the pollen samples consistently comprised approximately six different colors in total, of which four colors were abundant. ‘Urban’ habitats or ‘artificial surfaces’ were associated with higher pollen color diversity. This investigation highlights seasonal- and land-use-related differences in the pollen supply for honey bees, which affects beekeeping and pollinator health. Determining pollen colors is a simple, useful technique for beekeepers to estimate pollen diversity.A diverse supply of pollen is an important factor for honey bee health, but information about the pollen diversity available to colonies at the landscape scale is largely missing. In this COLOSS study, beekeeper citizen scientists sampled and analyzed the diversity of pollen collected by honey bee colonies. As a simple measure of diversity, beekeepers determined the number of colors found in pollen samples that were collected in a coordinated and standardized way. Altogether, 750 beekeepers from 28 different regions from 24 countries participated in the two-year study and collected and analyzed almost 18,000 pollen samples. Pollen samples contained approximately six different colors in total throughout the sampling period, of which four colors were abundant. We ran generalized linear mixed models to test for possible effects of diverse factors such as collection, i.e., whether a minimum amount of pollen was collected or not, and habitat type on the number of colors found in pollen samples. To identify habitat effects on pollen diversity, beekeepers’ descriptions of the surrounding landscape and CORINE land cover classes were investigated in two different models, which both showed that both the total number and the rare number of colors in pollen samples were positively affected by ‘urban’ habitats or ‘artificial surfaces’, respectively. This citizen science study underlines the importance of the habitat for pollen diversity for bees and suggests higher diversity in urban areas.

Comparing whole-genome shotgun sequencing and DNA metabarcoding approaches for species identification and quantification of pollen species mixtures.

Molecular identification of mixed‐species pollen samples has a range of applications in various fields of research. To date, such molecular identification has primarily been carried out via amplicon sequencing, but whole‐genome shotgun (WGS) sequencing of pollen DNA has potential advantages, including (1) more genetic information per sample and (2) the potential for better quantitative matching. In this study, we tested the performance of WGS sequencing methodology and publicly available reference sequences in identifying species and quantifying their relative abundance in pollen mock communities. Using mock communities previously analyzed with DNA metabarcoding, we sequenced approximately 200Mbp for each sample using Illumina HiSeq and MiSeq. Taxonomic identifications were based on the Kraken k‐mer identification method with reference libraries constructed from full‐genome and short read archive data from the NCBI database. We found WGS to be a reliable method for taxonomic identification of pollen with near 100% identification of species in mixtures but generating higher rates of false positives (reads not identified to the correct taxon at the required taxonomic level) relative to rbcL and ITS2 amplicon sequencing. For quantification of relative species abundance, WGS data provided a stronger correlation between pollen grain proportion and sequence read proportion, but diverged more from a 1:1 relationship, likely due to the higher rate of false positives. Currently, a limitation of WGS‐based pollen identification is the lack of representation of plant diversity in publicly available genome databases. As databases improve and costs drop, we expect that eventually genomics methods will become the methods of choice for species identification and quantification of mixed‐species pollen samples.

West Coast vegetation shifts as a response to climate change over the past 130,000 years: geographic patterns and process from pollen data

ABSTRACT We compiled pollen sequences from lake and offshore cores at least 6,000 years old (6 ka) for the Mediterranean and Marine ecoregions of the US West Coast. Principal Component Analysis highlighted vegetation differences in core-tops, the Holocene Thermal Maximum (6 ka) and Last Glacial Maximum (LGM, 19 ka). Core-top and HTM ordination produced clusters that reflected geographic clusters in the Sierra Nevada, and the Pacific Northwest coast. Little change in these clusters between 6-0 ka suggested that vegetation communities in coastal and alpine settings persisted, despite warmer global temperatures. PCA outliers reflect distinct pollen assemblages that often were isolated sites or bordered the Great Basin. During the LGM, greater shrub and herb presence in the Marine ecoregion interior indicated enhanced aridity, while conifer presence in coastal and Southern California indicated moist conditions. Qualitatively, tree taxa from the Last Interglacial (~130–120 ka) showed how vegetation shifted over 6–10 kyr from alder, to oak, then redwood, a successional pattern that began again at the Late Glacial (~15 ka). In future West Coast pollen studies, sampling and chronologic control at centennial resolution will enable further study of more time periods and rates of vegetation change in response to climate.

Beehive products as bioindicators of antimicrobial resistance contamination in the environment

The use of antimicrobials in agricultural, veterinary and medical practice exerts selective pressure on environmental microbiota, promoting the emergence and spread of antimicrobial resistance (AMR), a global concern for the One Health Initiative Task Force (OHITF). Honeybees have been studied as bioindicators of AMR in the environment, but little is known about beehive products like honey and pollen. The aim of this study was to assess the prevalence of AMR genes (ARGs) in beehive products and investigated their origins. Specifically, possible associations between ARGs, microbiota and other characteristics of different honey and pollen samples, including country of origin, flower type, type of commercial distribution and environmental factors, such as land use, weather and composition of the environment surrounding the beehives were investigated. We found that beehive products harboured ARGs conferring resistance to β-lactams, macrolides, (fluoro)quinolones and polymyxins. Most samples possessed resistance to multiple antimicrobial classes, with honey and pollen showing similar ARG profiles. Even if Lactobacillus and Acinetobacter genera were common in the microbial communities of both honey and pollen, Bacillus, Clostridium, and Bombella defined honey microbiota, while Pseudomonas and Vibrio were enriched in pollen. ErmB and blaTEM-1 co-occurred with Lactobacillus and Fructobacillus, while positive associations between β-lactams and macrolides and anthropogenic environments (i.e. industrial and commercial areas and non-irrigated arable lands) were found. Altogether, our findings suggest that ARGs in honey and pollen might originate from the honeybee foraging environment, and that the beehive products can be used as bioindicators of the AMR environmental contamination.

The content and health risk assessment of selected elements in bee pollen and propolis from Turkey

This study aimed to determine the concentrations of potentially toxic elements (PTEs), including Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Se, Sn, V, and Zn, in pollen and propolis samples collected from migratory beekeeping areas in Turkey. A health risk assessment was performed to identify the potential risk of these PTEs to consumers in terms of public health. Concentrations of the elements were analyzed by inductively coupled plasma optical emission spectroscopy. The most abundant element in the bee pollen and propolis samples was Fe, with average concentrations of 47.3 and 390 mg kg−1, respectively, followed by Al, Zn, Mn and Sn. Concentrations of all elements except Cu, Mn and Sn were higher in propolis than in pollen. The concentrations of Fe, Al, and Zn in the propolis samples were over eight, seven, and two times higher than in the bee pollen samples, respectively. Se, Cd, and Hg in pollen and Se and Cd in propolis were below the detection limits. Pb, Co, and Cr were detected below 0.62, 0.06, and 0.91 mg kg−1, in pollen samples, respectively. Co and Hg were detected below 0.68, and 0.18 mg kg−1, in propolis samples, respectively. Detection of the PTEs contamination level and assessment of the health risks in pollen and propolis is necessary to ascertain quality and safety before consumption. In this study, we concluded that bee pollen and propolis may be good indicators for the screening of environmental pollution with PTEs and standards regulating acceptable concentrations of these pollutants in bee products should be established. In addition, it has been determined that consumption at the specified rates does not pose a risk. This study suggests the determination of admissible concentrations of PTEs in bee pollen and propolis.

Identification, characterization and evaluation of honeybee floras in Kafa, Sheka and Benchi Maji Zones of Southern Nations Nationalities and Peoples Region (SNNPR), Ethiopia

The study was aimed with identifying and characterizing honeybee floras and their flowering seasons in south western parts of the country. Relevant data were collected through conducting questionnaire survey, focus group discussions, field observations and lab analysis of pollen and honey samples. In addition, seasonal performance of colonies in terms of brood area, adult population, pollen and nectar stores were evaluated. The obtained data were analyzed using SPSS-ver.20 and MsExcels. Accordingly, a total of 200floral species categorized under 77families identified. Of which, 26(13%) grouped under 16 families characterized as major bee floras. Seasons, January to February, July to August were considered as Dearth periods; March, September to October were brooding seasons, April, November to December were major nectar flow seasons. March to April and November to December were major honey flow seasons being the first for high land and mid land areas and the later for lowland areas whose major botanical origin was Schefflera abyssinica and Guizetia scabra respectively. However, in some areas with better forest covers, Manilkara butij become a major honey source plant. Whereas, January, June to July, March (in low lands) were considered as minor/mini harvesting seasons whose major botanical origin was Vernonia species, Croton macrostachyus and Combritum species respectively. It was noted that there was a significant correlation among brood area, adult population, pollen store and nectar stores at p<0.01.

Pollen analysis of cavity‐nesting bees (Hymenoptera: Anthophila) and their food webs in a city

1. Urban areas can host speciose bee communities due partially to the species‐rich combination of both native and alien plant species found in these landscapes. However, in intensively‐constructed zones, it could be expected to record a low plant diversity used by bees because of the high proportion of paved surfaces in these areas.2. We investigated the influence of urbanisation on the cavity‐nesting bee‐plant community and interaction network structures in a medium‐sized city. The floral diversity used by nesting females in cell provisioning was retrieved from the pollen content obtained from trap‐nests collected in 11 sites located in an urban landscape gradient.3. Eighty pollen types belonging to 20 families were identified in the 155 pollen samples analysed. At least seven alien plant species were identified in samples from all sampling points. The landscape analysis revealed a positive influence of the proportion of green areas on the pollen type richness, although the null model was also selected as best model. Likewise, all network metrics but connectance were not influenced by any of the landscape variables.4. Our findings demonstrated that notwithstanding the sampling sites the floral diversity used by bees and the alien pollen type richness were similar. Likewise, the bee‐plant networks were modular, asymmetric, and highly specialised. The positive adaptation that cavity‐nesting bee species present in urban environments and the presence of bee species that can explore a diverse flora may indicate that the local variation in the landscape had little influence on their interactions with plants.

The Airflow Field Characteristics of the Unmanned Agricultural Aerial System on Oilseed Rape (Brassica napus) Canopy for Supplementary Pollination

Pollination success is essential for hybrid oilseed rape (OSR, Brassica napus) seed production, but traditional pollination methods are not efficient. The unmanned agricultural aerial system (UAAS) has developed rapidly and has been widely used in China. When flying, the wind field generated by the rotors overcomes the UAAS gravity, and it blows and disturbs the crops below, which helps the pollen spread. In order to investigate the distribution law of the three-dimensional (direction x, y, z) airflow field, experiments involving three levels of flight speed (FS) at 4.0, 5.0, and 6.0 m/s, and three levels of flight height (FH) at 1.5, 2.0, and 2.5 m were conducted in the OSR field by using an electric four-rotor UAAS P20. The effects of FS and FH on airflow velocities (vx, vy, vz) were analyzed. High-speed dynamic camera (HSDC) technology was used to capture the swings of OSR plants under airflow field disturbance. OSR pollen samples were collected during the experiments. The results showed that the airflow field in the direction x was mainly concentrated on the center of the flight path (S3), and the maximum wind velocity of direction x was 8.01 m/s (T1, S3). The direction x airflow field width was distributed almost symmetrically, but the center position shifted easily, due to crosswind. The airflow field in the direction y was distributed on both sides of the center flight path, and the velocity was generally larger, with the maximum at 7.91 m/s (T1, S2). The airflow field in the direction z was distributed irregularly, and the velocity was small. The FH had highly significant impacts on vx (p < 0.01), and the interaction of FS and FH had significant impacts on vx (0.01 < p < 0.05), while the FS had no significant impact on vx (p = 0.70804 > 0.05). The FS, FH, and interaction of FS and FH all had highly significant impacts on vy (p < 0.01). The swings of the OSR plant captured by the HSDC proved that the UAAS airflow field could effectively blow the OSR plant. The swing amplitude changes showed a positive correlation with airflow velocities (vx) in general. Although the observed OSR plant swung forward and backward repeatedly, there was a law of first forward, and then backward, and forward again at the beginning of each swing. The pollen collected on the sampler verified that the UAAS airflow field could help with pollen spread. The research results provide technical support for UAAS application on supplementary pollination for hybrid OSR seed production.

Network-based geoforensics: Connecting pollen and plants to place

Despite the potential for pollen to provide key geographic information, law enforcement agencies have historically underutilized forensic palynology. Pollen samples are rarely collected at crime scenes or on objects of interest, and experts needed to manually identify pollen and its morphological characteristics are often in short supply. Fortunately, the advent of DNA barcoding and metabarcoding is poised to change this, enabling law enforcement agencies to easily and quickly identify individual plant species from mixed pollen samples. However, determining the location of pollen deposition based on identified plant species remains challenging, requiring comprehensive plant geodatabases and complex analytical approaches. This type of analysis is also complicated because pollen samples from forensic objects are not comprehensive. Furthermore, while detecting common plant pollen in a sample is likely, common plants provide less explanatory power due to their ubiquity. Thus, we propose a network-based approach to construct a categorization of ‘forensically-useful’ plants – those species that characterize geographically distinct plant mixes quickly for forensic applications and thus provide significant explanatory power to a geolocation model. The developed tool can better inform more detailed forensic search models, significantly reducing their overall computational burden and enabling high-fidelity forensic computational tools to operate faster, at a higher resolution, and over a more extensive study area.

IN VITRO ASSESSMENT OF THE ANTIVIRAL ACTIVITY OF GREEK BEE BREAD AND BEE COLLECTED POLLEN AGAINST ENTEROVIRUS D68

Bee bread is derived from bee collected pollen which is processed by the bee, fermented and stored in the hive. Few studies have assessed the antimicrobial activity of bee bread against major bacterial pathogens and fungi. However, to the best of our knowledge, neither bee collected pollen nor bee bread, have so far been investigated for their antiviral properties. In the present study, 18 Greek bee bread and 2 pollen samples from different botanical sources and geographical locations were assessed regarding their in vitro antiviral activity against Enterovirus D68. A cell culture assay combined with a comparative Real-Time PCR assay was performed using different sample concentrations to assess the antiviral activity. MTT assay was implemented in order to calculate the sample toxicity levels on cell culture. Our data suggest that Greek bee bread and bee collected pollen exhibit potent antiviral activity against EV-D68 with IC50 values ranging from 0.048 to 5.45 mg/ml. Greek bee bread and bee collected pollen are promising sources of antiviral compounds and should be further studied against diverse viruses in order to explore their full antiviral potential.

Analysis of pollen across the surface sediments of Lake Imbradas, Lithuania

AbstractIn conventional pollen analysis, usually one sediment core per basin is analyzed to reconstruct past environmental conditions. This approach does not consider spatial heterogeneity of pollen assemblages, and assumes that one analyzed location is representative of the whole basin. To improve the spatial resolution of fossil pollen studies, further knowledge of the factors influencing variations in pollen assemblages throughout a basin is needed. We examined the spatial heterogeneity of pollen assemblages from 45 lacustrine surface samples from a lake with relatively simple hydrology and compared this dense network of surface pollen samples with the Lithuanian State Forest Service arboreal vegetation database. Calculations of pollen productivity at different locations across the lake revealed variations in the behavior of a pollen-vegetation relationship model in different parts of the basin. Our findings suggest that the model underestimated pollen contributions from the lakeshore vegetation. We demonstrate that detailed investigations of surface pollen as a step prior to fossil pollen investigations can provide useful insights, including understanding the influence of sedimentation rate on modelling results and spatial variations in pollen composition, thus providing guidance for site selection for fossil pollen studies.

Integrated approach for the analysis of neonicotinoids in fruits and food matrices

We searched for five neonicotenoids (namely acetamiprid, clothianidin, imidacloprid, thiacloprid and thiamethoxam) in 67 samples of fruits, leaves, pollen and honey via HPLC-MS by employing QueChERs for extraction and purification. Clothianidin was never detected, while imidacloprid was identified in apple (9.2 µg/kg) and pollen (18–28 µg/Kg), thiacloprid in peaches (21–35 µg/kg) and acetamiprid was identified in the hazel leaves (1266 µg/kg), honey (13–26 µg /Kg) and pollen (11–24 µg/kg). Since the levels found of acetamiprid in hazel, honey and pollen were concerning, we accomplished a study to identify and characterize the possible transformation products via a laboratory simulation. The methodology exploited the analysis by HPLC-HRMS and its application in all matrices. We identify twelve transformation products, whose formation involved dimerization, hydroxylation, oxidation, demethylation and cleavage of the molecule. Three of them were also detected in hazel leaves.

Nutritive Value of 11 Bee Pollen Samples from Major Floral Sources in Taiwan.

Bee pollen is a nutrient-rich food that meets the nutritional requirements of honey bees and supports human health. This study aimed to provide nutritive composition data for 11 popular bee pollen samples (Brassica napus (Bn), Bidens pilosa var. radiata (Bp), Camellia sinensis (Cs), Fraxinus griffithii (Fg), Prunus mume (Pm), Rhus chinensis var. roxburghii (Rc), Bombax ceiba (Bc), Hylocereus costaricensis (Hc), Liquidambar formosana (Lf), Nelumbo nucifera (Nn), and Zea mays (Zm)) in Taiwan for the global bee pollen database. Macronutrients, such as carbohydrates, proteins, and lipids, were analyzed, which revealed that Bp had the highest carbohydrate content of 78.8 g/100 g dry mass, Bc had the highest protein content of 32.2 g/100 g dry mass, and Hc had the highest lipid content of 8.8 g/100 g dry mass. Only the bee pollen Hc completely met the minimum requirements of essential amino acids for bees and humans, and the other bee pollen samples contained at least 1–3 different limiting essential amino acids, i.e., methionine, tryptophan, histidine, valine, and isoleucine. Regarding the fatty acid profile of bee pollen samples, palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1), linoleic acid (C18:2), and linolenic acid (C18:3) were predominant fatty acids that accounted for 66.0–97.4% of total fatty acids. These data serve as an indicator of the nutritional quality and value of the 11 bee pollen samples.

Maine's Bumble Bees (Hymenoptera: Apidae)-Part 2: Comparisons of a Common (Bombus ternarius) and a Rare (Bombus terricola) Species.

As part of a quantitative survey of Maine's bumble bee fauna (Butler et al. 2021), we compared and contrasted genetic diversity, parasite and pathogen burdens, and pesticide exposure of the relatively common Bombus ternarius Say, 1937 and the spatially rare Bombus terricola Kirby, 1837. We recorded 11 Bombus species at 40 survey sites across three Maine ecoregions, and B. ternarius was the most common species, while B. terricola was spatially rare. Nonmetric multidimensional scaling indicated that B. terricola was associated with higher elevation sites in Maine, while B. ternarius was more broadly distributed in the state. Pollinator networks constructed for each bee indicated B. ternarius foraged on more plant species than B. terricola, but that there was considerable overlap (73%) in plant species visited. Genetic diversity was greater in the spatially restricted B. terricola, whereas the widely distributed B. ternarius was characterized by greater genetic differentiation among regions. Bombus terricola had higher molecular marker levels of the microsporidian fungi Nosema spp. and the trypanosome Crithidia spp., and both species had high levels of Trypanosoma spp. exposure. No Western Honey Bee (Apis mellifera, Linnaeus, 1758) viruses were detected in either species. Pesticides were not detected in pollen samples collected from workers of either species, and B. ternarius worker tissue samples exhibited only trace levels of diflubenzuron.

Proportion of commodity crop pollens and pesticide contamination in honey bee diets in two different landscapes

Honey bees are the most important managed pollinators in commercial agriculture. Large irrigated mixed agricultural landscapes in the mid-south United States can be vital to maintaining commercial honey bee operations during times of prolonged nectar dearth, even if those crops are not dependent on bee pollinators. Severe declines in bee populations have generated concerns about the relationship of pesticide-treated seeds and crops and the health of honey bees. To investigate the role of pollen from seed-treated crops as a component of honey bee diet and pesticide contamination in pollen diet of honey bees from agricultural and urban landscapes, we monitored honey bee colonies in both agricultural and urban areas. Pollen collection began in mid-March, before seed-treated crops were planted, and continued through the end of August, after crops had ceased blooming. Pollen samples from returning bees were identified to determine the botanical origin of the bees’ pollen diet, and were also analyzed for pesticide contamination. Honey bees in the agricultural landscape visited crop sources only during the seasonal period of natural nectar dearth, when other wildflower sources were limited, and they encountered acutely toxic pesticide residues (above LD50) during this period. These bees also encountered toxic levels of herbicide on multiple occasions throughout the season, in pollen from non-crop plants. Bees in the urban area were also exposed to toxic levels of insecticides on several occasions. Urban bees were exposed to herbicides throughout the season, but not at concentrations approaching acute toxicity. Simultaneous exposure to multiple pesticides occurred at both sites on multiple occasions. The results underscore the need to conserve areas of habitat and forage for both wild and managed pollinators within both agricultural and urban landscapes.

Characterization of Bee Pollen: Physico-Chemical Properties, Headspace Composition and FTIR Spectral Profiles.

Chemical characterization of bee pollen is of great importance for its quality estimation. Multifloral and unifloral bee pollen samples collected from continental, mountain and Adriatic regions of Croatia were analyzed by means of physico-chemical, chromatographic (GC-MS), and spectroscopic (FTIR-ATR) analytical tools, aiming to conduct a comprehensive characterization of bee pollen. The most distinctive unifloral bee pollen with regard to nutritional value was Aesculus hippocastanum (27.26% of proteins), Quercus spp. (52.58% of total sugars), Taraxacum officinale (19.04% of total lipids), and Prunus avium (3.81% of ash). No statistically significant differences between multifloral and unifloral bee pollen from different regions were found for most of the physico-chemical measurement data, with an exception of melezitose (p = 0.04). Remarkable differences were found among the bee pollen HS VOCs. The major ones were lower aliphatic compounds, monoterpenes (mainly linalool derivatives, especially in Prunus mahaleb and P. avium bee pollen), and benzene derivatives (mainly benzaldehyde in T. officinale and Salix spp.). Aldehydes C9 to C17 were present in almost all samples. FTIR-ATR analysis revealed unique spectral profiles of analyzed bee pollen exhibiting its overall chemical composition arising from molecular vibrations related to major macromolecules—proteins, lipids, and carbohydrates (sugars).

Using a sentinel colony of Apis mellifera (Hymenoptera: Apidae) to assess pesticides and food sources.

Honey bee populations are declining as occurs with other pollinators. One suggested cause of this decline is the impact of pesticides. To improve bees’ health, pesticides and food sources may be monitored using sentinel hives, given that bees forage in a 2.5 km radius around the hive. We extracted 20 (twenty) bees, as well as samples of wax, honey and pollen from a sentinel hive. Six pesticides were detected in the samples, except for the honey. All detected pesticides in the sentinel hive are pro- hibited in Argentina. Eight different plant families and genera were detected in the honey and pollen samples. Our work suggests that monitoring pesticides with sentinel beehives will be useful to improve agricultural practices in the region.

Identities, concentrations, and sources of pesticide exposure in pollen collected by managed bees during blueberry pollination

Bees are critical for crop pollination, but there is limited information on levels and sources of pesticide exposure in commercial agriculture. We collected pollen from foraging honey bees and bumble bees returning to colonies placed in blooming blueberry fields with different management approaches (conventional, organic, unmanaged) and located across different landscape settings to determine how these factors affect pesticide exposure. We also identified the pollen and analyzed whether pesticide exposure was correlated with corbicular load composition. Across 188 samples collected in 2 years, we detected 80 of the 259 pesticide active ingredients (AIs) screened for using a modified QuEChERS method. Detections included 28 fungicides, 26 insecticides, and 21 herbicides. All samples contained pesticides (mean = 22 AIs per pollen sample), with pollen collected from bees on conventional fields having significantly higher average concentrations (2019 mean = 882.0 ppb) than those on unmanaged fields (2019 mean = 279.6 ppb). Pollen collected by honey bees had more AIs than pollen collected by bumble bees (mean = 35 vs. 19 AIs detected at each farm, respectively), whereas samples from bumble bees had higher average concentrations, likely reflecting differences in foraging behavior. Blueberry pollen was more common in pollen samples collected by bumble bees (25.9% per sample) than honey bees (1.8%), though pesticide concentrations were only correlated with blueberry pollen for honey bees. Pollen collected at farms with more blueberry in the surrounding landscape had higher pesticide concentrations, mostly AIs applied for control of blueberry pathogens and pests during bloom. However, for honey bees, the majority of AIs detected at each farm are not registered for use on blueberry at any time (55.2% of AIs detected), including several highly toxic insecticides. These AIs therefore came from outside the fields and farms they are expected to pollinate. For bumble bees, the majority of AIs detected in their pollen are registered for use on blueberry during bloom (56.9% of AIs detected), though far fewer AIs were sprayed at the focal farm (16.7%). Our results highlight the need for integrated farm and landscape-scale stewardship of pesticides to reduce exposure to pollinators during crop pollination.

Validation of QuEChERS Method for Estimation of Imidacloprid and its Metabolites in Cotton Flower, Pollen, Nectariferous Tissue, and Honey.

Exposure of Apis mellifera to neonicotinoid insecticides is one of the factors attributed to the recent decline in A. mellifera populations resulting in economic and ecological losses due to loss of pollination services. Honeybees can get exposed to neonicotinoids like imidacloprid directly in the field at the time of application as well as during consumption of pollen and nectar from treated plants. In addition, some metabolites of imidacloprid are more toxic than the parent compound. So, the fate of imidacloprid and its metabolites in commodities to which honeybees get exposed needs to be overhauled. To validate QuEChERS method for estimation of imidacloprid and its metabolites in cotton flower, pollen, nectariferous tissue, and honey using HPLC. The QuEChERS method was validated in terms of selectivity, linearity, LOD, LOQ, matrix match, accuracy, and precision. The estimation of residues was done by HPLC. Recoveries of imidacloprid and its metabolites for cotton flowers, nectariferous tissue, pollen and honey samples were in the range of 80.42-99. 83%. LOQ for imidacloprid and its metabolites was 0.01 µg/g. Acceptable precision (RSD < 20%) was obtained. The method allows simple and fast extraction of imidacloprid and its metabolites from cotton flower, pollen, nectariferous tissue, and honey. An accurate, simple, and sensitive analytical method was validated for imidacloprid and its metabolites. The method was validated according to the SANTE/12682/2019 guidelines.

Human landscape modification and expansion of tropical woodland in southern Arabia during the mid‐Holocene from rock hyrax middens

AbstractAimDryland ecosystems, such as those in southern Arabia, are particularly vulnerable to climate and land‐use change. Aridification and human subsistence changes at the end of the Holocene Humid Period at 6–4 ka have been used as an iconic example for evaluating such impacts to resilience of arid systems. Although records of ancient environments can provide critical insight into the biotic and abiotic mechanisms that alter ecosystems, traditional archives, such as lake deposits, are not common in southern Arabia after 6 ka; thus, we must use alternative archives.LocationYemen.TaxonPlants; Rock Hyrax (Procavia capensis).MethodsWe use fossil pollen and stable isotopes (δ15N; δ13C) of rock hyrax (P. capensis) middens from Wadi Sana, Yemen, to look at changes in ecosystem structure and function across this key transition from 6 ka to the present. A total of 17 middens were radiocarbon‐dated and stable isotopes were measured. Of these, pollen was extracted from hyraceum of 14 middens and identified using a light microscope. Fossil pollen assemblages were then compared to existing modern pollen samples from throughout Arabia.ResultsDuring the mid‐Holocene from at least 6 to 4.7 ka, the pollen flora reflects a landscape with abundant tropical trees. These included foundational woody taxa, such as Terminalia and Boswellia sacra (frankincense), which had a strong positive influence on local hydrology and the economy, respectively. Increased charcoal abundances also suggest that wildfire occurred periodically.Main conclusionsConnections with archaeological evidence suggest a strong link between human management and the presence of Terminalia woodland during the mid‐Holocene. These may have promoted increased groundwater storage and ponding as regional rainfall was decreasing. The mid‐Holocene expansion of Boswellia sacra (frankincense) may have helped support resin trade that became a critical export from the region. Fires were more common than today, suggesting semi‐arid but continuous vegetation cover across what is now bare ground. Finally, after 1 ka, increased sedge abundances at the expense of grasses and trees suggest the development of desert conditions.