Melissopalynological Analysis Research Articles

Pollen morphology and its taxonomic significance in the genus euphorbia L. (Euphorbiaceae), from northern Pakistan: Insights for honeybees‐plant interactions

AbstractEuphorbia L. includes 2055 species with native range of this genus being cosmopolitan. In the present study, we assessed pollen morphology of 18 species of this genus occurring mostly in northern Pakistan. Pollen morphology of Euphorbia species is poorly investigated for its taxonomic significance. Here, we examined quantitative characters, including polar diameter, equatorial diameter, P/E ratio. Exine thickness, colpi length, and width were also examined. Among the qualitative characters, pollen shape, type, exine sculpturing, and aperture features were determined. The main aim of this study is to determine and investigate the foraging behavior of the honeybees that interact with Euphorbia species. The current finding will be helpful in melissopalynological analysis for developing beekeeping practices and can be used in the authentication of honey. Pollen quantitative traits applied through a multivariate analysis and diverse sampling also improve botanical and geographical characterization of a particular region. In addition, it is concluded that some palynomorphs of Euphorbia species may contain secondary compounds and can promote signs of toxicity in honeybees. However, the beekeepers wrongly correlate the fact that milky latex from Euphorbia taxa has burning and skin irritation effects on other animals, particularly humans, with honeybee deaths, which might be due to other factors. Our observations indicate with the sense that actual forage plants may not poison their pollinators and honeybees might occasionally be dead due to unidentified factors. We have suggested that beekeepers should attempt to identify the root causes for occasional bee deaths in the area.

Eudermic Properties and Chemical-Physical Characterization of Honeys of Different Botanical Origin.

Background: Honey is a natural product that, thanks to its composition, particularly the high sugar content, is highly appreciated as an energy nourishment. In addition to sugars, it contains many other substances (carbohydrates, free amino acids, enzymatic proteins, organic acids, polyphenols) from which the therapeutic properties of honey arise: hydrating and osmotic activity, antimicrobial action, and antioxidant and anti-inflammatory power. Objectives: The present work aims to deepen our knowledge/understanding of the activity of skin protection exerted by honey, as a synergic result of its multiple therapeutic effects. Moreover, this study wants to find possible correlations between biological properties and the chemical-physical traits of honey. Methods: To carry out this research, five varieties of citrus honey, one of acacia honey, one of chestnut honey, and one of multifloral honey were used. The honeys were first characterized by chemical-physical analysis and then were subjected to qualitative melissopalynological analysis. Tests were also carried out to evaluate both their antioxidant power and the effect on collagenase, an enzyme involved in the degradation of collagen present in the extracellular matrix and, therefore, in the processes of skin aging. Finally, honey samples were then used in in vitro experiments to assess their action in stimulating cell viability and proliferation on human keratinocytes. Results: Chemical-physical analysis demonstrated a good water content (about 17%), an important sugar content (with the monosaccharides glucose and fructose being the most represented in all the honey samples), various amino acids (with proline remarkably being the highest in all honeys), and a high concentration of polyphenols and total flavonoids (the maximum in chestnut honey, 762 mg/kg and 514 mg/kg, respectively). Conclusions The results obtained in this work confirm the ethnopharmacological use of honey in wound care, bring new scientific knowledge on the use of honey in dermatology, and highlight two fields of excellence, particularly incitrus and chestnut honey.

HERBAL-INFUSED EGYPTIAN BEE HONEY, A BOON OR A CURSE, ITS IMPACT ON SENSORIAL, PHYSICOCHEMICAL & ANTIBACTERIAL PROPERTIES

Herbal honey mixture remedies are well known for their therapeutic benefits in traditional medicine. This research aspired to assess melissopalynological, sensorial, physicochemical, & antibacterial activity for three types of honey (clover, citrus, and cucurbits) and their mixtures with black seed, date palm pollen, & wheat germ at 1, 2.5, & 5%. The best mixtures were chosen according to overall acceptability. Consumer’s preference was given to raw honey. However, some mixtures were as acceptable as raw honey. Melissopalynological analysis and lower glucose level compared to fructose are evidences that honeys are natural. Infusing herbs with different types of honey caused higher electrical conductivity, free acidity, ash, H2O2, HMF levels, and lower pH. Type of honey and herb may affect the physicochemical characteristics of honey in different ways. Honey whether used alone or in combination with the three herbs, demonstrated the same significant antibacterial effect for Staphylococcus aureus and MRSA. Inhibition zones of honey and its mixtures were lower than the control for Pseudomonas aeruginosa. Most undiluted samples created larger bacterial inhibition zones than their 50% diluted counterparts. Depending on the type of honey, the herb and additive concentration, infusing herbs with honey could alter its chemical, physical, and antibacterial qualities.

Evaluation of the Bioactive Compounds of Apis mellifera Honey Obtained from the Açai (Euterpe oleracea) Floral Nectar.

The biodiversity of Brazil provides an excellent climate and favorable pollination conditions for Apis mellifera L., especially in the Eastern Amazon region, which boasts vast floral wealth, including an abundance of açaí (Euterpe oleracea) flowers and fruits. In the present study, seven types of honey were evaluated: three containing floral nectar from açaí (Açaí honey) collected in the Eastern Amazon region (Açaí honey from Breu Branco (AH1 and AH2) and Açaí honey from Santa Maria (AH3), both from the state of Pará, Brazil) and four honeys from different regions of Brazil (Aroeira honey from Minas Gerais, Cipó-Uva honey from Distrito Federal, Mangue honey from Pará, and Timbó honey from Rio Grande do Sul). The characteristics of these honeys were evaluated by examining their physicochemical properties, melissopalynological aspects, color, antioxidant potential, and their constituent compounds, which were confirmed through GC-MS analysis. Açaí floral nectar honeys presented physicochemical results similar to those of other honeys, aligning with Brazilian legislation norms, but differed in their high values of free acidity, apparent sugars, and lower reducing sugars, which are directly related to their botanical origin. These differences correlate with unique flavor and distinct aroma characteristics. Melissopalynological analysis confirmed the botanical origin of the honeys containing açaí floral nectar, which had a color range from amber to dark amber. The three açaí honeys demonstrated high antioxidant capacity and superior flavonoid and polyphenol content compared to other honeys, particularly the açaí honey from Breu Branco (AH1), which had four times the content to combat free radicals compared to the honey with the highest potential (Aroeira honey). GC-MS analysis confirmed the presence of antioxidant properties as well as potential anti-inflammatory, antibacterial, antimicrobial, and antitumor capabilities in açaí honeys, which have not yet been fully studied.

Nutritional position of managed honey bees during pollination of native plants by the melissopalynology method

Pollination services are crucial for maintaining ecological stability and ensuring food security for humans. Managed honey bees, which are economically valuable and are experiencing population growth due to the increasing demand for their products, play a significant role in pollination. To produce high-quality honey, beekeepers often choose natural high meadows, characterized by high plant species richness, for their apiaries. This practice, in turn, may contribute to the pollination of native plants, as managed honey bees are likely to forage on diverse floral resources within these meadows In this study, we investigated the nutritional position of managed bees in the pollination of native plants in Iran using the melissopalynology method to determine the extent of their contribution to the pollination of native plants. Ninety-four honey samples were collected from beekeepers located in the natural pastures of two biodiversity hotspots in Iran (Zagros and Alborz). Then, plant pollens were extracted from the honey and photographed by scanning electron microscopy. In the next step, plant species were identified, and their abundance was calculated. The results showed that managed bees visited 54 plant genera, seven of which were non-native plants. Additionally, more plant species and the highest abundance of pollen were observed at altitudes ranging from 1000 to 3000 m. Therefore, beekeepers set up their hives in this altitude range to obtain high-quality honey. In general, in this study, the results of melissopalynological analysis, involving the identification of plant genera and pollen counts, revealed that managed honey bees likely contributed less than 3% to the pollination of native plant species in Iran.

Foraging of Honeybees from Different Ecological Areas Determined through Melissopalynological Analysis and DNA Metabarcoding.

The environment significantly impacts the lives of bees and their feeding. This study aimed to investigate bee foraging using melissopalynological analysis and DNA metabarcoding in intensive farming, reserved, and urbanized areas. The highest alpha diversity was observed in the reserved and intensive farming areas. The urbanized area had less diversity. In the intensive farming area, Sinapis, Helianthus, and Fagopyrum predominated; in the reserved area, Melilotus, Helianthus, and Brassica predominated. In the urbanized area, garden plants, namely radish (Raphanus sativus) and cucumber (Cucumis hystrix), and agricultural plants, namely soybean (Glycine max) and melon (Cucumis melo), were often found. The most significant agreement was between the rbcL and the melissopalynological analysis. The ITS2 revealed equal matches with both rbcL and melissopalynology, but this marker missed or underestimated some genera. Trifolium pretense and Brassica nigra were identified simultaneously by the melissopalinology method and two genetic markers in DNA metabarcoding. The species Convolvulus arvensis, Melilotus officinalis, Echium vulgare, Brassica rapa, Helianthus divaricatus, and Onobrychis viciifolia were found in all ecological areas. Imperfect databases impose some limits in the identification of some taxa using metabarcoding. The further research and expansion of plant databases is needed. Studying the food preferences of bees in different environmental conditions and landscapes is necessary to develop measures to preserve their populations.

Comparing the acetolysed and hydrated methods for the pollen analysis of honey

Melissopalynology is an integral part of honey analysis and indicates the honey's botanical and geographical origin. Two preparation methods for light microscopy are commonly and interchangeably used in laboratories: acetolysis and hydration of honey samples. In this study, an extended comparison of the two methods was performed. Eight honey samples from eight locations in central Europe were analysed according to both standard procedures. We identified the pollen grains with 1000× magnification to the lowest possible taxonomic rank and counted out the relative abundances of each pollen type in the sample. In addition, potential other biases that might affect the results were investigated by analysing one honey sample multiple times with each method, consecutively. Across all honey samples, more pollen types were identified with the hydrated method (136) compared to the acetolysed method (95). For the hydrated method, less washing steps were necessary and a higher amount of pollen grains remained. No taxa-specific loss could be observed, apart from Myosotis sp., which was present in significantly lesser amounts in acetolysed compared to hydrated samples. This study shows a detailed analysis of the advantages and disadvantages of the two methods, which are also highlighted in a side-by-side comparison box. Both methods are equally suitable to perform melissopalynological analysis of the most common pollen types and pollen type combinations in honey. However, to identify the largest variety of pollen types in honey samples, the hydrated method is more efficient.

Melissopalynological Analysis of Honey from French Guiana.

Beekeeping directly depends on the floral biodiversity available to honey bees. In tropical regions, where nectar and pollen resources are numerous, the botanical origin of some honey is still under discussion. A precise knowledge of plants foraged by honey bees is useful to understand and certify the botanical origin of honey. In this study, attention was paid to honey samples from the French Guiana Atlantic coast where beekeepers generally place their hives in four types of biotopes: seaside vegetation, mangrove, savannah, and secondary forest. Pollen analysis of 87 honey samples enabled the identification of major plants visited by Africanized honey bees during the dry season (approximately from July to January). Through melissopalynologic analysis, 51 pollen types were identified and classified according to their relative presence. Frequently observed pollens (with relative presence > 50%) in French Guiana kinds of honey were those from Mimosa pudica, Cocos sp., Rhyncospora sp., Avicennia germinans, Paspalum sp., Spermacoce verticillata, Tapirira guianensis, Cecropia sp., Myrtaceae sp., Mauritia flexuosa sp., Solanum sp., and Protium sp. In many honeys, only M. pudica was over-represented (relative frequency > 90%). Color and electrical conductivity in French Guiana honeys exhibit significant variations, with color ranging from 27 mm to 110 mm Pfund, and electrical conductivity ranging from 0.35 to 1.22 mS/cm.

Melissopalynological analysis and microbiological safety of fresh and market honey (Apis mellifera L. and Meliponulabeccarii L.) from Western Oromia, Ethiopia

Honey is a natural product that is made by bees from the nectar of flowering plants. There is a flora preference by bees. Like other foods ready to eat,honey can be prone to microbial contamination. Honey plant sources can be analyzed from the composition of pollen grains in honey samples. The objective of this study was to assess microbial safety and floral origin of the honey samples. For this study, honey samples were purchased from local market, and collected from hives (fresh honey) in Western Oromia. Floral analysis was determined using harmonized method of melissopalynology. Microbiological safety was assessed through the pour plate procedures from the first serial dilution on a total of 45 honey sample sizes.The melissopalynological analysis demonstrated that A. melliferahoney purchased from the market(AMMH) was considered a multi-floral type while A. mellifera fresh honey (AMFH) cropped directly from the hive and M.beccarii honey purchased from the market (MBMH) was dominated pollen from Coffee arabica (68 % of its pollen grain counted) and Guizotiascabra (50.53 % of its pollen grain counted) plant, respectively. The Aerobic mesophilic bacteria, Staphylococci, Yeast, Mould, and Aerobic spore-forming bacteria were found below the standard countable level (<30 cfu/plate) from A. mellifera and M.beccarii honey bought from the market, while A. mellifera honey collected directly from the hive became free of any microbial contamination. C.arabica and G.scabra are major honey plants and their honey can be harvested in February and October, respectively. Furthermore, Vernoniaamygdalina, Eucalyptus spp, Combretummolle, Trifoliumruppelianum, and Syzgiumguineense were honey plants analyzed from multifloral market honey even though, their pollen dominance varies. M. beccarii visits herbaceous flora whilst A. mellifera visits all floral types. The level of contamination of the honey samples from the study area was very low showing its safety.

Simple and Rapid Characterization of Sarawak Stingless Bee Honey Using Melissopalynological and ATR-FTIR Analysis

AbstractStingless bee honey (SBH) is gaining popularity for its unique flavour and potential nutritional and health benefits. Due to its low yield, SBH is usually more expensive than common honey. Moreover, SBH is also commonly sold as raw honey with higher moisture content, which could jeopardize its shelf life, quality, and safety if not stored properly. Therefore, a rapid method is required to characterize stingless bee honey for authentication and quality assurance. This study aimed to categorize SBH samples from Sarawak using two simple and rapid methods, namely the pollen or melissopalynological analysis and attenuated-total-reflectance Fourier-transform-infrared (ATR-FTIR). The melissopalynological analysis showed that all honey samples analyzed are multifloral honey. Principal Component Analysis (PCA) on the ATR-FTIR spectra clearly illustrated a clear separation between normal honey and SBH; and between raw SBH and processed SBH. Overall, this study provides important insights into the characterization of SBH from Sarawak using two simple and rapid methods. Further research could expand on these findings and contribute to the development of the SBH industry in Malaysia.

Phytochemical profiling of red raspberry (Rubus idaeus L.) honey and investigation of compounds related to its pollen occurrence.

Red raspberry (Rubus idaeus L.) is an important nectar source for honey production in some specific habitats as well as an important crop, so the definition of the features of this kind of honey is noteworthy. However, due to its rarity on the market, red raspberry honey is poorly characterized. The aim of this work was the phytochemical characterization of honey containing red raspberry from different geographical origins, through melissopalynological analyses concurrently with untargeted metabolomics achieved with different chromatographic techniques coupled to mass spectrometry: solid-phase micro-extraction/gas chromatography/mass spectrometry (SPME-GC-MS) and high-performance liquid chromatography/Orbitrap mass spectrometry (HPLC-Orbitrap). Only 4 out of the 12 samples involved in the study contained raspberry pollen as dominant pollen, although these honeys did not group in the hierarchical cluster analysis nor in the classical multidimensional scaling analyses used for data evaluation. The first result was the detection of mislabelling in two samples, which contained raspberry pollen only as minor or important minor pollen. Of the 188 compounds identified by HPLC-Orbitrap and of the 260 identified by SPME-GC-MS, 87 and 31 compounds were present in all samples, respectively. The structurally related compounds nicotinaldehyde and nicotinamide, nicotinic acid and nicotinyl alcohol were present in 100% of the samples and correlated with R. idaeus pollen count (r > 0.60, Pearson's correlation analysis). This study reveals important aspects about the characterization of red raspberry honey and could give new insights on bee diet and preferences, since niacin compounds resulted interestingly to be related to the presence of red raspberry pollen. © 2024 Society of Chemical Industry.

Geographical origin authentication of honey produced in the region of Rtanj Mountain (Serbia)

This paper represents the melissopalynological analysis, physicochemical characteristics (moisture, pH, electrical conductivity, free acidity, glucose, fructose, hydroxymethylfurfural (HMF), and colour parameters), polyphenol profile, and sensory properties of Rtanj honey samples (76) harvested during 2019–2021 from different locations in the Rtanj Mountain region (eastern Serbia) with the aim to 1) characterise this meadow honey and 2) obtain markers for its differentiating within the geographical origin protection. The melissopalynological analysis of Rtanj honey revealed many types of pollen, of which the most important belong to the Rosaceae family, especially the Sorbus group. A relatively low value of the colour parameter L* (22.7 ± 0.19–59.8 ± 1.75), the positive a* value of 1.55 ± 0.07–22.3 ± 1.36, and a high content of K (996 ± 376 mg/kg) can be used as markers for its geographical origin authentication, which was confirmed using principal component analysis (PCA). The phenolic profile was evaluated based on the quantification of epicatechin (0.077 ± 0.005 mg/kg), p-coumaric acid (0.316 ± 0.004 mg/kg), ferulic acid (0.524 ± 0.002 mg/kg), naringenin (3.386 ± 0.011 mg/kg), luteolin (0.022 ± 0.006 mg/kg), kaempferol (0.628 ± 0.010 mg/kg), and apigenin (0.120 ± 0.002 mg/kg) using high performance liquid chromatography. The colour of Rtanj honey samples varied from extra white to light amber.

Antioxidant and anti-glycation activity of eight Moroccan honeys from different botanical origins

Eight monofloral honey samples from different botanical and geographical origins in the central and eastern parts of Morocco were examined for their phenolic composition, capacity to scavenge free radicals, and ability to inhibit advanced glycation end–products. According to the melissopalynological analysis, the examined honey samples were considered to be natural honeys, and were classified as monofloral with very frequent pollen grains characteristic of each types of the selected Moroccan honey samples: Zantaz (Bupleurum sp.), fennel, thistle, eucalyptus, spurge, thyme, jujube, and carob. Our results showed that the average moisture content varied from 16.3 ± 0.1% to 19.9 ± 0.1%, and the mean color intensity ranged from 30.94 ± 7.42 to 166.9 ± 6.43 mm Pfund. The highest total phenolic content recorded was 163.83 ± 1.84 mg of gallic acid equivalent per kg, while the highest flavonoid content was 84.44 ± 1.20 mg of catechin equivalent per kg. Zantaz honey exhibited potent antioxidant capacity, as demonstrated by ABTS, DPPH, β-carotene bleaching, FRAP, and ORAC assays. The most significant results were obtained for the ORAC test, with the highest ORAC value of 4.65 mM Trolox equivalent per gram was recorded for Zantaz honey extract. HPLC–DAD analysis revealed different polyphenolic profiles, which can be attributed to differences in floral origin. Furthermore, our study revealed that the extracts of thistle honey, fennel honey, and Zantaz honey were the most effective glycation inhibitors, with the highest inhibition percentage of 96% obtained for the thistle honey extract.

Comparing antipseudomonal effects of honey samples with different geographical and botanical origin

Pseudomonas aeruginosa, resistant to all broad-spectrum antibiotics, is on the World Health Organization's list of first-priority critical pathogens. Using reserve antibiotics, such as colistin, highlights the imperative for safer, more effective alternatives to combat these superbugs.Medical-grade honey, known for its antibacterial properties and efficacy in wound healing, emerges as a promising candidate.This study analyzed eleven honey samples, diverse in geographical, botanical, and entomological origins, for their antipseudomonal activity using the agar well-diffusion method. Zones of inhibition growth were measured in mm. The function switch was used to approximate the zones of inhibition values for antibacterial activity expressed as minimal inhibitory concentrations MIC99, MIC90, and MIC80, the lowest concentration, killing 99 %, 90 %, and 80 % of organisms, respectively. The authenticity and quality of honey samples complied with the European Commission, Codex Alimentarius, and Serbia Rulebook standards for honey. Melissopalynological analysis ensured the botanical authenticity of tested honey samples. A unique aspect of this research is that it included a honey sample from Serbia's Zlatar mountain region, harvested from Apis mellifera carnica bee colonies. The study's findings reveal that wild-type and multidrug-resistant Pseudomonas clinical isolates were susceptible to the tested honey samples. Honeydew honey from Zlatar showed the highest antibacterial activity on both tested bacteria. Honeydew and buckwheat honey from Zlatar yielded larger inhibition zones than manuka honey. Artificial honey showed no antibacterial effect.In conclusion, this research suggests the potential of honey, particularly from Zlatar, as an alternative therapy for treating infected wounds, warranting further investigation into its antimicrobial efficacy.

RESEARCH OF THE HONEY BACTERICIDAL ACTION AGAINST SALMONELLA ENTERICA

Salmonellosis is a registered gastrointestinal disorder in the EU caused by the consumption of foods contaminated with Salmonella enterica. Symptoms include gastroenteritis, abdominal cramps, bloody diarrhea, fever, myalgia, headache, nausea, and vomiting. The current direction of research is the search for ways and means of preventing salmonellosis, including the consumption of health products. Natural honey has broad bactericidal properties. The aim of the research was to establish the bactericidal effect of monofloral type of honey against Salmonella enterica. The materials were 26 samples of monofloral varieties of honey: rapeseed, acacia, linden, sunflower; and bacterial strains from the international collection of typical cultures of the Salmonella enterica serovar. Typhimurium CCM 3807. The botanical origin of the honey samples was established using melissopalynological analysis. The antibacterial effect was studied by testing the minimum bactericidal concentration of honey using the microdilution method, using the incubation of microplates with a nutrient medium and the application of a bacterial suspension. The botanical origin of the examined honey samples was established: 11 Helianthus, 10 Robinia, 3 Brassica, 2 Tilia. Of them, 12 samples of honey showed a bactericidal effect: 6 Helianthus, 3 Robinia, 1 Brassica, 2 Tilia. Only 1 sample of sunflower honey (No. 8) caused the death of bacteria at a low concentration of 0.118 g/ml. It didn't have a high level of monoflorality – 68% (Helianthus 68%, Medicago 18%, Trifolium 14%). Other samples of honey when diluted in low concentrations didn't show a bactericidal effect. At a concentration of 0.375 g/ml, 4 studied samples showed a bactericidal effect, including 2 sunflower (No. 5, 13), linden (No. 18) and rapeseed (No. 14). At a concentration of 0.750 g/ml, 7 tested samples showed a bactericidal effect, including 3 sunflower types (No. 20, 24, 25), 3 acacia (No. 4, 9, 15) and 1 linden types (No. 19).

ВОЗМОЖНОСТЬ ИСПОЛЬЗОВАНИЯ ТРИХЛОРУКСУСНОЙ КИСЛОТЫ ДЛЯ АЦЕТОЛИЗА ПЫЛЬЦЕВЫХ ЗЕРЕН ПРИ МЕЛИССОПАЛИНОЛОГИЧЕСКОМ АНАЛИЗЕ

The possibility of using trichloroacetic acid instead of the classical mixture of acetic anhydride with sulfuric acid for acetolysis of pollen grains in the melissopalynological analysis of honey is demonstrated. This substance in comparison with other derivatives of acetic acid allows holding the sample in a boiling water bath that improves the result of acetolysis of pollen grains. The possibility of using various solvents for transferring acetolyzed pollen grains to glass slides for further microscopy was also investigated. The optimal reagents and parameters for this analysis were studied and identified during the experiments.

Identification of Floral Resources Used by the Stingless Bee Melipona beecheii for Honey Production in Different Regions of the State of Campeche, Mexico

The stingless bee Melipona beecheii is experiencing colony decline due to floral resource scarcity caused by deforestation. A study was conducted to identify the floral resources used by M. beecheii using honey samples collected in four regions of the state of Campeche, Mexico. A melissopalynological analysis of sixteen collected honey samples identified 69 plant species from 24 families, and established that Fabaceae was the main plant family visited. Based on botanical origin, seven samples were classified as monofloral and nine as multifloral. The predominant species were Bursera simaruba, Lonchocarpus longistylus, Piscidia piscipula, Senna pallida and Senna racemosa. Shannon diversity index values (2.06–2.55) indicated moderate diversity in floral resources and Simpson diversity index values (0.82–0.89) indicated a moderate dominance of plant species in the studied regions. The results suggest M. beecheii is polylectic with some degree of specialization. The plant species identified as predominant in the studied honey samples are candidates for use in strategies intended to conserve the food resources used by M. beecheii on the Yucatan Peninsula.

Validating a multi-locus metabarcoding approach for characterizing mixed-pollen samples

BackgroundThe mutualistic interaction between entomophilous plants and pollinators is fundamental to the structure of most terrestrial ecosystems. The sensitive nature of this relationship has been disrupted by anthropogenic modifications to natural landscapes, warranting development of new methods for exploring this trophic interaction. Characterizing the composition of pollen collected by pollinators, e.g. Apis mellifera, is a common means of exploring this relationship, but traditional methods of microscopic pollen assessment are laborious and limited in their scope. The development of pollen metabarcoding as a method of rapidly characterizing the abundance and diversity of pollen within mixed samples presents a new frontier for this type of work, but metabarcoding may have limitations, and validation is warranted before any suite of primers can be confidently used in a research program. We set out to evaluate the utility of an integrative approach, using a set of established primers (ITS2 and rbcL) versus melissopalynological analysis for characterizing 27 mixed-pollen samples from agricultural sites across Canada.ResultsBoth individual markers performed well relative to melissopalynology at the family level with decreases in the strength of correlation and linear model fits at the genus level. Integrating data from both markers together via a multi-locus approach provided the best rank-based correlation between metagenetic and melissopalynological data at both the genus (ρ = 0.659; p < 0.001) and family level (ρ = 0.830; p < 0.001). Species accumulation curves indicated that, after controlling for sampling effort, melissopalynological characterization provides similar or higher species richness estimates than either marker. The higher number of plant species discovered via the metabarcoding approach simply reflects the vastly greater sampling effort in comparison to melissopalynology.ConclusionsPollen metabarcoding performed well at characterizing the composition of mixed pollen samples relative to a traditional melissopalynological approach. Limitations to the quantitative application of this method can be addressed by adopting a multi-locus approach that integrates information from multiple markers.

Melissopalynological analysis of Apis honey from northern districts of West Bengal

The assessment of botanical origin of honey in northern districts of West Bengal, viz. Coochbehar, Jalpaiguri and Alipurduar districts through melissopalynological analysis is the focus of this study. Ten different honey samples were analysed, from which 78 different pollen taxa representing 34 different plant families have been detected. Asteraceae, Brassicaceae and Fabaceae were the most frequently encountered families. Asteraceae had highest number of representative pollen types (14 types) followed by Fabaceae (11 types). Seven honey samples were recorded as unifloral honey and three were multifloral honey. Litchi chinensis was found as a predominant pollen in two samples, whereas Brassica sp., Canna indica, Leucas aspera, Mimosa pudica and Rosa sp. were the other predominant pollen taxa. In multifloral honey samples Brassica sp. was found to have a higher frequency. Honey samples collected from regions with close proximity during the same season showed a higher similarity index. All the honey samples were poor in honey dew elements (HDEs) having HDE/P ratio (P = total number of pollen grains) of 0.000 to 0.056. The absolute pollen count (APC) varied from 7500 to 696 000 pollen/10 g honey. High variation in pollen spectra with less preference to a particular bee forage in summer honey samples may indicate the onset of dearth period.

Diversity in bee pollen from three phytogeographical regions in Turkey

Bee pollen is a mixture of bee secretions, plant pollen and nectar and has a valuable nutritional composition for both bees and humans. The aim of this study was to investigate plant diversity in pollen collected by honey bees from three phytogeographic regions (Mediterranean, Euro-Siberian and Irano-Turanian). Melissopalynological analysis of bee pollen pellets collected from Mediterranean (15), Irano-Turanian (6), and Euro-Siberian (7) in Turkey were analysed. The Shannon–Weaver diversity (H′), richness, and Pielou’s evenness index (J′) were used to compare between bee pollen pellets. In all three phytogeographic regions, herbaceous species are more than tree and shrub species. A total of 80 pollen types belonging to 38 families were identified in these regions. Cistus sp., Trifolium sp., Papaver sp. and Verbascum sp. in Mediterranean; Filipendula sp. and Salix sp. in Irano-Turanian; and Sambucus sp., Helianthemum sp., Onobrychis sp., and Rubus sp. in Euro-Siberian were all determined to be predominant taxa. When pollen was evaluated based on its morphological characteristics, bees preferred medium (41), isopolar (74), prolate (38), 3-colporate (49), reticulate (23), and psilate (22) pollen than other characteristics. The H′ values in polyfloral pollen were higher than bifloral and monofloral pollens. The J’ of polyfloral, bifloral, and monofloral was 0.73 to 0.85, 0.68 to 0.84, and 0.32–0.97, respectively. The results obtained in this study, are important for the establishment of beekeeping in the right areas in terms of plant diversity.