Pollen Proteins Research Articles

Social but not solitary bee abundance tracks pollen protein accumulation in forest canopy gaps

Abstract Forest restoration projects that create canopy gaps can promote floral diversity and may provide reservoirs for bee–flower interactions. However, periods of bee activity must match availability of floral nutrition for bees to benefit from these effects. We model variation in canopy gap size, floral density, pollen protein and bee and floral traits to test the hypothesis that patterns of floral visitation in bee–flower interactions are predicted by patch structure, variation in bee life histories and floral phenotypes. Canopy gap size did not predict overlap of foraging bee abundances and floral protein, but bee life‐history traits did. Foraging activity of large ground‐nesting bees matched accumulation of protein density, whereas activity of small cavity‐nesting bees and kleptoparasitic species preceded peak protein density. Floral visual traits predicted visitation rates, with more interactions for taller species with large floral displays. Both native and invasive species have high nutritional value for bees in canopy gaps and can support frequent and rich interactions. Landscapes with both weedy and native floral species may have higher phenological diversity and provide more foraging opportunities for early‐season bees. We conclude that canopy gap creation is likely to have similar impacts on bee–flower interactions regardless of gap size, but activity periods of larger bees are more aligned with pollen protein density than activity of small bees, and floral visual displays are decoupled from pollen protein content.

Fungicides and strawberry pollination-Effects on floral scent, pollen attributes and bumblebee behavior.

Fungicides are used in agriculture to protect crops from various fungal diseases. However, they may modulate the plants metabolism. Moreover, fungicides can accumulate in the environment and may cause toxic effects on non-target organisms such as nectar microbes and pollinators. Nectar microbes contribute to the volatile profile of flowers and can influence pollinators behaviour. Thus, fungicide treatment could potentially affect the pollination. In this study, we investigated the influence of fungicide treatment on floral attributes as well as the behavioural impact on bumblebees. In separate experiments, we used one or both strawberry cultivars (Fragaria × ananassa var. Darselect and Malwina), which were either kept untreated (control) or treated with either Cuprozin® progress or SWITCH® fungicide. We analysed various flower traits including volatiles, pollen weight, pollen protein, and the attraction of bumblebees towards the flowers in the greenhouse. Additionally, we analysed the viability of pollen and pollen live-to-dead ratio, as well as the composition of nectar fungi in the field. A treatment with Cuprozin® progress led to a lower emission of floral volatiles and a slightly lower pollen protein content. This had no impact on the visit latency of bumblebees but on the overall visit frequency of these flowers. The treatment with the fungicide SWITCH® resulted in a higher emission of floral volatiles as well as a delayed first visit by bumblebees. Furthermore, flowers of control plants were visited more often than those treated with the two fungicides. Plant-pollinator interactions are highly complex, with many contributing factors. Fungicides can have an impact on the pollen quality and pollinator attraction, potentially leading to an altered pollen dispersal by pollinators and a change in fruit quality.

Multi-omics research on common allergens during the ripening of pollen and poplar flocs of Populus deltoides.

Populus deltoides is widely cultivated in China and produces a large number of pollen and poplar flocs from March to June per year. Previous studies have found that the pollen of P. deltoides contains allergens. However, studies on the ripening mechanism of pollen/poplar flocs and their common allergens are very limited. Proteomics and metabolomics were used to study the changes of proteins and metabolites in pollen and poplar flocs of P. deltoides at different developmental stages. Allergenonline database was used to identify common allergens in pollen and poplar flocs at different developmental stages. Western blot (WB) was used to detect the biological activity of common allergens between mature pollen and poplar flocs. In total, 1400 differently expressed proteins (DEPs) and 459 different metabolites (DMs) were identified from pollen and poplar flocs at different developmental stages. KEGG enrichment analysis showed that DEPs in pollen and poplar flocs were significantly enriched in ribosome and oxidative phosphorylation signaling pathways. The DMs in pollen are mainly involved in aminoacyl-tRNA biosynthesis and arginine biosynthesis, while the DMs in poplar flocs are mainly involved in glyoxylate and dicarboxylate metabolism. Additionally, 72 common allergens were identified in pollen and poplar flocs at different developmental stages. WB showed that there were distinct binding bands between 70 and 17KD at the two groups of allergens. A multitude of proteins and metabolites are closely related to the ripening of pollen and poplar flocs of Populus deltoides, and they contain common allergens between mature pollen and poplar flocs.

Fertilizer and herbicide alter nectar and pollen quality with consequences for pollinator floral choices.

Pollinating insects provide economically and ecologically valuable services, but are threatened by a variety of anthropogenic changes. The availability and quality of floral resources may be affected by anthropogenic land use. For example, flower-visiting insects in agroecosystems rely on weeds on field edges for foraging resources, but these weeds are often exposed to agrochemicals that may compromise the quality of their floral resources. We conducted complementary field and greenhouse experiments to evaluate the: (1) effect of low concentrations of agrochemical exposure on nectar and pollen quality and (2) relationship between floral resource quality and insect visitation. We applied the same agrochemcial treatments (low concentrations of fertilizer, low concentrations of herbicide, a combination of both, and a control of just water) to seven plant species in the field and greenhouse. We collected data on floral visitation by insects in the field experiment for two field seasons and collected pollen and nectar from focal plants in the greenhouse to avoid interfering with insect visitation in the field. We found pollen amino acid concentrations were lower in plants exposed to low concentrations of herbicide, and pollen fatty acid concentrations were lower in plants exposed to low concentrations of fertilizer, while nectar amino acids were higher in plants exposed to low concentrations of either fertilizer or herbicide. Exposure to low fertilizer concentrations also increased the quantity of pollen and nectar produced per flower. The responses of plants exposed to the experimental treatments in the greenhouse helped explain insect visitation in the field study. The insect visitation rate correlated with nectar amino acids, pollen amino acids, and pollen fatty acids. An interaction between pollen protein and floral display suggested pollen amino acid concentrations drove insect preference among plant species when floral display sizes were large. We show that floral resource quality is sensitive to agrochemical exposure and that flower-visiting insects are sensitive to variation in floral resource quality.

Nutritional, biological, and structural properties of bioactive peptides from bellflower, Persian-willow, and bitter-orange pollens.

In this study, the composition of amino acids, nutritional characteristics, degree of hydrolysis (DH), antioxidant properties, and antibacterial activity of proteins and hydrolysates of bellflower (Campanula latifolia), Persian willow (Salix aegyptiaca), and bitter orange (Citrus aurantium L.) were investigated under the influence of different proteases (Alcalase: Al, trypsin: Tr, pancreatin: Pa, and pepsin: Pe). Evaluation of the structural features of the proteins showed amide regions (amide A, B, I-III) and secondary structures. Hydrophobic amino acids (∼38%), antioxidants (∼21%), and essential types (∼46%) form a significant part of the structure of flower pollen. The digestibility and nutritional quality (PER) of the hydrolyzed samples (CP: 1.67; CA: 1.89, and PW: 1.93) were more than the original protein. Among proteins and peptides, the highest degree of hydrolysis (34.6%: Al-PWH), inhibition of free radicals DPPH (84.2%: Al-CPH), ABTS (95.2%: Pa-CPH), OH (86.7%: Tr-CAH), NO (57.8%: Al-CPH), reducing power (1.31: Pa-CPH), total antioxidant activity (1.46: Pa-CPH), and chelation of iron ions (80%: Al-CPH and Al-CAH) and copper (50.3%: Pa-CAH) were affected by protein type, enzyme type, and amino acid composition. Also, the highest inhibition of the growth of Escherichia coli (25 mm) and Bacillus cereus (24 mm) were related to CP and PW hydrolysates, respectively. The results of this research showed that hydrolyzed flower pollens can be used as a rich source of essential amino acids as well as natural antioxidants and antibacterial in food and dietary products. PRACTICAL APPLICATION: Enzymatic hydrolysis of Campanula latifolia, Persian willow, and Citrus aurantium pollen proteins was performed. The hydrolyzed ones had high nutritional quality and digestibility (essential amino acids and PER index). Antioxidant properties and chelation of metal ions of peptides were affected by the type of protein and enzyme. The hydrolysates showed inhibitory activity against the growth of Esherichia coli and Bacillus cereus.

Floral volatiles evoke partially similar responses in both florivores and pollinators and are correlated with non-volatile reward chemicals.

Plants often use floral displays to attract mutualists and prevent antagonist attacks. Chemical displays detectable from a distance include attractive or repellent floral volatile organic compounds (FVOCs). Locally, visitors perceive contact chemicals including nutrients but also deterrent or toxic constituents of pollen and nectar. The FVOC and pollen chemical composition can vary intra- and interspecifically. For certain pollinator and florivore species, responses to these compounds are studied in specific plant systems, yet we lack a synthesis of general patterns comparing these two groups and insights into potential correlations between FVOC and pollen chemodiversity. We reviewed how FVOCs and non-volatile floral chemical displays, i.e. pollen nutrients and toxins, vary in composition and affect the detection by and behaviour of insect visitors. Moreover, we used meta-analyses to evaluate the detection of and responses to FVOCs by pollinators vs. florivores within the same plant genera. We also tested whether the chemodiversity of FVOCs, pollen nutrients and toxins is correlated, hence mutually informative. According to available data, florivores could detect more FVOCs than pollinators. Frequently tested FVOCs were often reported as pollinator-attractive and florivore-repellent. Among FVOCs tested on both visitor groups, there was a higher number of attractive than repellent compounds. FVOC and pollen toxin richness were negatively correlated, indicating trade-offs, whereas a marginal positive correlation between the amount of pollen protein and toxin richness was observed. Plants face critical trade-offs, because floral chemicals mediate similar information to both mutualists and antagonists, particularly through attractive FVOCs, with fewer repellent FVOCs. Furthermore, florivores might detect more FVOCs, whose richness is correlated with the chemical richness of rewards. Chemodiversity of FVOCs is potentially informative of reward traits. To gain a better understanding of the ecological processes shaping floral chemical displays, more research is needed on floral antagonists of diverse plant species and on the role of floral chemodiversity in visitor responses.

Quality of bee pollen submitted to drying, pasteurization, and high-pressure processing – A comparative approach

Bee Pollen is a valuable and useful natural food product that can be used for different purposes, among which medical ones. This matrix is deemed a superfood because of its chemical composition, which is rich in nutrients and possesses significant bioactivities, including antioxidant and microbiological properties. Nevertheless, the storage conditions and processing methods must be optimized to maintain their properties and maximise their application. This work investigates the best bee pollen conservation process and its impact on individual constituents. Monofloral bee pollen was analysed for 30 and 60 days after three different storage processes (drying, pasteurization, and high-pressure pasteurization). The results showed a decrease mainly in fatty acid and amino acid content for the dried samples. The best results were obtained with high-pressure pasteurization, maintaining the proteins, amino acids and lipids characteristics of pollen and the lowest microbial contamination.

Composition and Nutrition of Wild Bees in Solanum melongena L. Agroecosystems in Pune, Maharashtra, India

Eggplant, (Solanum melongena L.), also called aubergine or Guinea squash, in the nightshade family (Solanaceae) is an economically important crop in India. We investigated the significance of Solanum melongena pollen in the diet of wild bees found in agroecosystems by examining pollen on the bees using a pollen load analysis and a nutritive analysis. We selected five agricultural sites that cultivate S. melongena near Pune, Maharashtra, India. At each site, over a two-year period, we sampled the wild bees that visited mature flowers. We sampled pollen from mature flowers and also from the bodies of the bee specimens. The pollen grains from the bees were observed under a light microscope and a scanning electron microscope. They were counted using a Neubauer chamber and the pollen probability index for each bee species was calculated. The nutritive value of S. melongena pollen was estimated by extracting and characterising their proteins using liquid chromatography mass-spectrometry. Protein peptides sequences were extracted from the NCBI protein database to examine their essential amino acids. We collected 324 bees representing 11 species in three families involved in S. melongena pollination. Apis florea and A. cerana were the most abundant bees that visited S. melongena flowers. Pollen load size is highly variable ranging between few thousand to 134146 pollen grains per bee. However, the pollen probability index indicated a high degree of specificity to S. melongena pollen. S. melongena has high pollen protein content and a total of 10 different proteins were identified that are important for plant cell activities as well as the nourishment of pollinators. Further proteomic characterization of the indicated that nearly half the essential amino acids played and nutrient role in the bees. This study highlights that nutrititive composition of S. melongena pollen and highlights its potential to play a significant role in wild bee diets.

Comparative Transcriptome Analysis Reveals a Potential Regulatory Network for Ogura Cytoplasmic Male Sterility in Cabbage (Brassica oleracea L.)

Ogura cytoplasmic male sterility (CMS) lines are widely used breeding materials in cruciferous crops and play important roles in heterosis utilization; however, the sterility mechanism remains unclear. To investigate the microspore development process and gene expression changes after the introduction of orf138 and Rfo, cytological observation and transcriptome analysis were performed using a maintainer line, an Ogura CMS line, and a restorer line. Semithin sections of microspores at different developmental stages showed that the degradation of tapetal cells began at the tetrad stage in the Ogura CMS line, while it occurred at the bicellular microspore stage to the tricellular microspore stage in the maintainer and restorer lines. Therefore, early degradation of tapetal cells may be the cause of pollen abortion. Transcriptome analysis results showed that a total of 1287 DEGs had consistent expression trends in the maintainer line and restorer line, but were significantly up- or down-regulated in the Ogura CMS line, indicating that they may be closely related to pollen abortion. Functional annotation showed that the 1287 core DEGs included a large number of genes related to pollen development, oxidative phosphorylation, carbohydrate, lipid, and protein metabolism. In addition, further verification elucidated that down-regulated expression of genes related to energy metabolism led to decreased ATP content and excessive ROS accumulation in the anthers of Ogura CMS. Based on these results, we propose a transcriptome-mediated induction and regulatory network for cabbage Ogura CMS. Our research provides new insights into the mechanism of pollen abortion and fertility restoration in Ogura CMS.

Heat shock cognate 70 protein like-2 protein in camphor pollen is one of the major culprits of asthma.

In recent decades, Cinnamomum camphora have gradually become the main street trees in Shanghai. This study aims to investigate the allergenicity of camphor pollen. A total of 194 serum samples from patients with respiratory allergy were collected and analyzed. Through protein profile identification and bioinformatics analysis, we hypothesized that heat shock cognate protein 2-like protein (HSC70L2) is the major potential allergenic protein in camphor pollen. Recombinant HSC70L2 (rHSC70L2) was expressed and purified, and a mouse model of camphor pollen allergy was established by subcutaneous injection of total camphor pollen protein extract (CPPE) and rHSC70L2. Specific IgE was found in the serum of 5 patients in response to camphor pollen and three positive bands were identified by Western blotting. Enzyme-linked immunosorbent assay (ELISA), Immune dot blot and Western blot experiments confirmed that CPPE and rHSC70L2 can cause allergies in mice. Moreover, rHSC70L2 induces polarization of peripheral blood CD4+ T cells to Th2 cells in patients with respiratory allergies and mice with camphor pollen allergy. Finally, we predicted the T cell epitope of the HSC70L2 protein, and through the mouse spleen T cell stimulation experiment, we found that the 295EGIDFYSTITRARFE309 peptide induced T cells differentiation to Th2 and macrophages differentiation to the alternatively activated (M2) state. Moreover, 295EGIDFYSTITRARFE309 peptide increased the serum IgE levels in mice. The identification of HSC70L2 protein can provide novel diagnostic and therapeutic targets for allergies caused by camphor pollen.

The triticale mature pollen and stigma proteomes – assembling the proteins for a productive encounter

Triticeae crops are major contributors to global food production and ensuring their capacity to reproduce and generate seeds is critical. However, despite their importance our knowledge of the proteins underlying Triticeae reproduction is severely lacking and this is not only true of pollen and stigma development, but also of their pivotal interaction. When the pollen grain and stigma are brought together they have each accumulated the proteins required for their intended meeting and accordingly studying their mature proteomes is bound to reveal proteins involved in their diverse and complex interactions. Using triticale as a Triticeae representative, gel-free shotgun proteomics was used to identify 11,533 and 2977 mature stigma and pollen proteins respectively. These datasets, by far the largest to date, provide unprecedented insights into the proteins participating in Triticeae pollen and stigma development and interactions. The study of the Triticeae stigma has been particularly neglected. To begin filling this knowledge gap, a developmental iTRAQ analysis was performed revealing 647 proteins displaying differential abundance as the stigma matures in preparation for pollination. An in-depth comparison to an equivalent Brassicaceae analysis divulged both conservation and diversification in the makeup and function of proteins involved in the pollen and stigma encounter. SignificanceSuccessful pollination brings together the mature pollen and stigma thus initiating an intricate series of molecular processes vital to crop reproduction. In the Triticeae crops (e.g. wheat, barley, rye, triticale) there persists a vast deficit in our knowledge of the proteins involved which needs to be addressed if we are to face the many upcoming challenges to crop production such as those associated with climate change. At maturity, both the pollen and stigma have acquired the protein complement necessary for their forthcoming encounter and investigating their proteomes will inevitably provide unprecedented insights into the proteins enabling their interactions. By combining the analysis of the most comprehensive Triticeae pollen and stigma global proteome datasets to date with developmental iTRAQ investigations, proteins implicated in the different phases of pollen-stigma interaction enabling pollen adhesion, recognition, hydration, germination and tube growth, as well as those underlying stigma development were revealed. Extensive comparisons between equivalent Triticeae and Brassiceae datasets highlighted both the conservation of biological processes in line with the shared goal of activating the pollen grain and promoting pollen tube invasion of the pistil to effect fertilization, as well as the significant distinctions in their proteomes consistent with the considerable differences in their biochemistry, physiology and morphology.

Changes in the Histological Structure of Adrenal Glands and Corticosterone Level after Whey Protein or Bee Pollen Supplementation in Running and Non-Running Rats

Due to the many health-promoting properties of bee pollen and whey protein, both products are widely used as dietary supplements. According to these reports on their health-promoting properties, the aim of our study is to assess whether these products can influence the structure and function of the adrenal glands in rats. Thirty male Wistar rats were divided into six equal groups. Among them, there were three groups which included non-running rats and three groups which included running rats. Both of these running (n = 3) and non-running (n = 3) groups included non-supplemented (control groups), bee-pollen-supplemented groups, and whey-protein-supplemented groups. After 8 weeks, the rats were decapitated, their adrenal glands were collected, and paraffin slides were prepared. Then, staining according to the standard H&E and Masson's trichrome protocols was performed. Fecal and urine samples were collected prior to the end of the study to measure corticosterone levels. In the group of non-running rats, the consumption of bee pollen was noted to be significantly higher when compared to the group of running rats (p < 0.05). The thickness of the particular adrenal cortex layers was similar among all of the groups (p > 0.05). The statistically significant changes in the microscopic structure of the adrenal glands, especially regarding cell nuclei diameter and structure, as well as the architecture of sinusoids, were observed between the groups. Moreover, urine corticosterone concentrations were found to vary between all of the analyzed groups (p < 0.05). These results indicate that both bee pollen and whey protein have limited stress-reducing potential.

Towards DNA-Based Methods Analysis for Honey: An Update

Honey is a natural product widely consumed all over the world due to its relationship with healthy benefits. Additionally, environmental and ethical issues have a higher weight in the consumer's choice to buy honey as a natural product. Following the high demand of this product, several approaches have been suggested and developed aiming at the assessment of honey's quality and authenticity. Target approaches, such as pollen analysis, phenolic compounds, sugars, volatile compounds, organic acids, proteins, amino acids, minerals, and trace elements, showed an efficacy, particularly concerning the honey origin. However, a special highlight is given to DNA markers, due to their useful applicability in environmental and biodiversity studies, besides the geographical, botanical, and entomological origins. Different DNA target genes were already explored for addressing diverse sources of honey DNA, with DNA metabarcoding attaining a relevant importance. This review aims to describe the latest advances on DNA-based methods applied in honey related studies, identifying the research needs for the development of new and additional required methodologies, and to select the most adequate tools for future research projects.

Physicochemical, antioxidant, antimicrobial, and in vitro cytotoxic activities of corn pollen protein hydrolysates obtained by different peptidases.

The applications of protein hydrolysates as food preservatives and nutraceutical ingredients have attracted much attention because of their beneficial effects. The interest in these ingredients has shifted toward their biological activities with benefits to human health. Bioactive peptides are known as antioxidant agents that could promote health-promoting effects and prolong food shelf-life beyond their basic nutritional value. Thus, the aim of this study was to investigate antioxidant, antimicrobial, and in vitro cytotoxic properties of corn pollen protein (CPP) hydrolysates obtained by different enzymes. Proteolytic activity in terms of degree of hydrolysis (DH) and SDS-PAGE analysis was measured in pancreatin (H-Pan), pepsin (H-Pep), and trypsin (H-Tri) hydrolysates. Amino acid composition, antioxidant and antimicrobial activities, and cytotoxicity of hydrolysates were evaluated. DH and SDS-PAGE revealed higher proteolytic activity of pepsin compared to other enzymes. Amino acid analysis showed that the functional amino acids such as antioxidant types were most predominant in H-Pep compared to two other samples. Antioxidant activity of hydrolysates was found to be affected by the type of enzyme and the concentration of hydrolysates. There was a significant difference (p < 0.05) between antioxidant activity of different hydrolysates. The highest antioxidant activity in terms of Trolox equivalent antioxidant capacity (0.23-2.75 mM), DPPH (33.3%-64.8%), and hydroxyl (33.7%-63.2%) radical scavenging activities, chelation of iron (33.2%-62.5%) and copper (30.2%-50.5%) metals, and total antioxidant activity (0.65-0.85) was obtained for H-Pep followed by H-Pan and H-Tri samples. Antibacterial tests showed that pepsin-hydrolyzed protein was not significantly (P > 0.05) effective against E.coli at any concentrations, however, it showed significant (P < 0.05) concentration-dependent effect against S.aureus (with inhibition zones of 15-25 mm). Cytotoxicity results revealed that CPP, as a nonhydrolyzed protein, did not generally show antiproliferative activity, however, a significant (P < 0.05) ability of H-Pep hydrolysate in decreasing HT-29 colon cancer cell line viability was seen in a concentration-dependent manner (the lowest cell viability of 32% at 5mg/mL). Overall, investigating the application of protein-based hydrolysates is one of the possible strategies that govern their applied intentions as preservatives and nutraceuticals in the food and pharmaceutical industries.

Assessment of Cry1Ac and Cry2Ab proteins in pollen of various transgenic cotton cultivars and effect on Apis mellifera L. colonies’ development

Assessment of Cry1Ac and Cry2Ab proteins in pollen of various transgenic cotton cultivars and effect on Apis mellifera L. colonies’ development

Effects of ultrasound assisted cell wall disruption on physicochemical properties of camellia bee pollen protein isolates.

Camellia bee pollen protein isolates were extracted by cell wall disruption using ultrasonication, freeze-thawing, enzymatic hydrolysis, and their combinations. The effects of these methods on microstructure of cell wall, protein release, protein yield, physiochemical properties and structure of proteins were investigated. As compared with physical treatments (ultrasonication, freeze-thawing and their combination), the enzymatic hydrolysis significantly improved the yield of proteins, because it not only promoted the release of proteins from the inside of pollen, but also released proteins in pollen wall. The proteins extracted by enzymatic hydrolysis method also exhibited better solubility, emulsifying and gelation properties due to the partial hydrolysis of proteins by protease. In addition, when ultrasound was combined with freeze-thawing or enzymatic hydrolysis, it could further improve the yield of proteins and the functional properties of proteins, which was mainly related to the changes of protein structure induced by cavitation effect of ultrasound.

Impact of different pollen protein diets on the physiology of Apis mellifera L. (Hymenoptera: Apidae) workers from essential plant sources

BackgroundThe primary food sources for honey bees in colonies are processed nectar and fermented pollen. However, there are relatively few blooming plants that provide full sustenance to the bees, and their impacts on the physiology of honey bees in Pakistan have not yet been assessed. Diet with meager nutritional contents can affect various physiological parameters like hypopharyngeal glands (HPGs) sizes, rectal weight contents (RWCs), food intake and longevity of worker bees which indirectly affects overall colony development and make it vulnerable to diseases and pests. MethodsThis study was designed to investigate the impact of protein diets in the form of different pollen on some physiological parameters of honey bee (Apis mellifera L.) from major plant sources serving as melliferous resources in the agro-climatic conditions of Dera Ismail Khan, Khyber Pakhtunkhwa, Pakistan. ResultsResults indicated Brassica napus L. as the most effective pollen diet which took the highest time for 50 % of individuals’ mortality. B. napus L. also gave the highest increase of HPG size (278.47 µm) followed by Trifolium alaxandrinum L. Acacia modesta L., and Zea mays L., in comparison to sugar syrup (control) with 261.73, 237.49, 124.38 and 107.65 µm, respectively. Pollen intake followed a similar pattern, with B. napus having the highest levels (3.03 mg/bee/day), and bee bread (3.37 mg/bee/day), with an overall mean of 25.279. The overall mean for RWC demonstrates how easily the pollen diet may be digested. It was negatively correlated with the volume of rectal contents. When compared to pollen diets, honeybee workers given bee bread had the lowest overall mean (3.95 mg) for rectal contents, suggesting the greatest degree of digestibility. ConclusionDiets from B. napus were taken and digested more quickly than those from A. modesta, Z. mays, and T. alaxandrinum.

Impacts of soil nutrition on floral traits, pollinator attraction, and fitness in cucumbers (Cucumis sativus L.)

Annual plants allocate soil nutrients to floral display and pollinator rewards to ensure pollination success in a single season. Nitrogen and phosphorus are critical soil nutrients whose levels are altered by intensive land use that may affect plants’ fitness via pollinator attractiveness through floral display and rewards. In a controlled greenhouse study, we studied in cucumbers (Cucumis sativus) how changes in soil nitrogen and phosphorus influence floral traits, including nectar and pollen reward composition. We evaluated how these traits affect bumble bee (Bombus impatiens, an important cucumber pollinator) visitation and ultimately fruit yield. While increasing nitrogen and phosphorus increased growth and floral display, excess nitrogen created an asymptotic or negative effect, which was mitigated by increasing phosphorus. Male floral traits exhibited higher plasticity in responses to changes in soil nutrients than female flowers. At 4:1 nitrogen:phosphorus ratios, male flowers presented increased nectar volume and pollen number resulting in increased bumble bee visitation. Interestingly, other pollinator rewards remained consistent across all soil treatments: male and female nectar sugar composition, female nectar volume, and pollen protein and lipid concentrations. Therefore, although cucumber pollination success was buffered in conditions of nutrient stress, highly skewed nitrogen:phosphorus soil ratios reduced plant fitness via reduced numbers of flowers and reward quantity, pollinator attraction, and ultimately yield.

Detection and pH-Thermal Characterization of Proteinases Exclusive of Honeybee Worker-Fate Larvae (Apis mellifera L.)

The occurrence of the honeybee caste polyphenism arises when a change in diet is transduced into cellular metabolic responses, resulting in a developmental shift mediated by gene expression. The aim of this investigation was to detect and describe the expression profile of water-soluble proteases during the ontogenesis of honeybee worker-fate larvae. The extraction of insect homogenates was followed by the electrophoretic separation of the protein extract in polyacrylamide gels under semi-denaturing condition, precast with gelatin, pollen, or royal jelly protein extracts. The worker-fate honeybee larva showed a proteolytic pattern that varied with aging, and a protease with the highest activity at 72 h after hatching was named PS4. PS4 has a molecular weight of 45 kDa, it remained active until cell sealing, and its enzymatic properties suggest a serine-proteinase nature. To define the process that originates a queen-fate larvae, royal jelly and pollen were analysed, but PS4 was not detected in either of them. The effect of food on the PS4 was investigated by mixing crude extracts of queen and worker-fate larvae with pollen and royal jelly, respectively. Only royal jelly inhibited PS4 in worker-fate larvae. Taken together, our data suggest that PS4 could be involved in caste differentiation.

Melissopalynology: The Louveaux method on honey samples in the marche region and their allergenic potential

The research arises from the interest in investigating the pollen contained in the various honey samples analyzed to identify its geographical and botanical origin and to evaluate its allergenic potential. With the Louveaux method, the pollen content shall be observed under a microscope using the same procedure as the aerobiological analysis described in national and European standards. From the microscopic observation of the pollen grains, it is possible to identify the plants that produced them, thus going back to a particular type of vegetation that distinguishes the production area. The percentage values for pollen of nectariferous plants identified have been calculated to establish frequency classes and dominant species. Starting from an exploratory analysis, the results obtained with melissopalynology provide assessments that, combined with sensory and physical analysis, represent a useful control tool to address the growing trend of food fraud as an element of consumer choice. By comparing the percentages of the pollen taxa contained in the honey analyzed with those reported in the characterization cards, it was possible to verify the conformity to the declared botanical origin. The samples were analyzed in duplicate to reduce operator uncertainty and to ensure the identification of the largest number of species/families present and the recognition of botanical families. The results provided a clear picture of a first assessment of the conformity of the reference values; in general, most of the samples examined, both those taken on the market and those of local producers, are in line with the data obtained. Bibliographical research on cross allergies related to the presence of pollen in honey has established that allergic forms to honey are still a rare condition and the incidence does not exceed 0.001%. Studying the few reported cases worldwide, it is difficult to say that pollen proteins are the only and directly responsible for the allergic manifestations that follow the ingestion of honey; however, if we wanted to attribute the responsibility, we could refer in particular to Compositae pollens, such as mugwort, ragweed, and dandelion. This work, while identifying many possible triggers for allergic reactions, has detected a very low number of cases of ingestion of honey; therefore, the study can be a starting point to investigate the allergenic potential.