Search Results (97)

Honey bees, as vital pollinators and essential contributors to terrestrial ecosystems, play a critical role in maintaining biodiversity and ecological stability. Beyond their role as pollinators, honey bees are increasingly recognized as bioindicators of environmental health, with their microbiomes reflecting habitat quality, agricultural practices, and broader ecological conditions. This study examines the impact of monoculture and polyculture systems on bee-associated microbiomes, focusing on microbial diversity, composition, and functional roles. Microbial communities from floral surfaces, pollen, nectar, foraging bees, hive matrices, and bioaerosols were analyzed across three agricultural plots: a rape monoculture, a pear monoculture, and a polyculture plot. Using 16S rRNA amplicon sequencing, network co-occurrence analysis, and microbial source tracking, the findings reveal that plant species and cultivation methods significantly shape microbial dynamics (Adonis = 0.67 ***). Floral microbiomes exhibit host specificity (Adonis = 0.73 ***), while the honey bee body surface functions as a microbial hub linking environmental, floral, and hive microbial networks (average degree pear: 21.86; rape: 21.96). The polyculture system improves microbial diversity due to the diversity of nectar plants, enhancing ecosystem connectivity and potentially benefiting honey bee health. These results highlight the ecological importance of optimizing agricultural practices to preserve microbial diversity, enhance honey bee health, and maintain ecological stability. Full article

Rowanberries (Sorbus aucuparia) are valued for their high content of bioactive compounds. This study examined the effects of sweeteners (sucrose, xylitol, erythritol, steviol glycosides), fruit pulp preparation (fresh vs. steamed), and storage conditions (4 °C and 30 °C, 3 months) on the composition of rowanberry nectars. Polyphenols were quantified using LC-PDA-QTOF/MS and UPLC-PDA-FL, and carotenoids, organic acids, antioxidant capacity (FRAP), and physicochemical properties were also determined. Steaming increased total polyphenol levels in nectars by 13–52%, with the highest values observed in formulations containing steviol glycosides (up to 1833 mg/100 mL). Changes in carotenoid content during storage varied depending on the sweetener type. In steamed nectars with erythritol stored at 4 °C, carotenoid levels remained close to those measured in the corresponding unsweetened steamed sample. Storage influenced turbidity and viscosity in all variants, with the largest viscosity increases recorded in stevia- and erythritol-sweetened nectars. Overall, the combined effects of fruit preparation, sweetener type, and storage determined the final composition and stability of rowanberry nectars. Full article

Pollinators play a crucial role in global biodiversity, providing essential ecosystem services such as crop pollination. However, their abundance and diversity have been gradually decreasing in recent years. Despite increasing interest in sustainable agriculture, information on vegetable crops that attract insect pollinators remains limited. We hypothesize that variation in floral traits among vegetable crop cultivars, especially nectar volume, nectar sugar concentration, and pollen characteristics, significantly influences visitation patterns and species composition. To test this, we evaluated multiple cultivars of six vegetable crops (cowpea, sweet potato, eggplant, green bean, mustard, and chickpea) over two years, focusing on five key pollinator groups (honey bees, bumble bees, carpenter bees, sweat bees, and wasps). Cowpea and sweet potato consistently attracted the most pollinators, whereas chickpea attracted the fewest. In 2022, nectar volume was highest in sweet potato (16.45 ± 0.37 µL) and lowest in chickpea (1.18 ± 0.75 µL). Similarly, in 2023, sweet potato recorded the highest nectar volume (8.33 ± 2.95 µL), and chickpea the lowest (0.02 ± 0.01 µL). However, chickpea (31.00 ± 1.58 °Bx) and mustard (30.10 ± 1.12 °Bx) recorded the highest nectar sugar concentration in both years, and chickpea and eggplant produced significantly more pollen grains. A significant positive correlation was observed between nectar volume and pollinator abundance. Comprehensively, this two-year study demonstrates the complex relationship between floral traits and pollinator preferences. These findings offer growers practical guidance on selecting vegetable intercrops that attract specific pollinators, thereby enhancing pollination services, supporting biodiversity, and improving the yield of pollinator-dependent crops. Full article

Nectar composition varies across plant species and environments, influencing pollinator interactions and honey quality. Reliable methods for nectar discrimination, however, remain limited. Here, we demonstrate the use of Fourier-transform infrared (FTIR) spectroscopy combined with chemometric analysis to differentiate nectar samples of Echium vulgare (E. vulgare) and Hedera helix (H. helix) collected in urban locations. Among eight tested preprocessing strategies, simple approaches such as Savitzky–Golay smoothing or even raw spectra provided the best clustering results. The most discriminative spectral regions were consistently the carbohydrate fingerprint (1200–950 cm⁻¹) and the C–H stretching zone (2935–2885 cm⁻¹). Mean spectra and PCA confirmed that variability between locations arises mainly from carbohydrate-associated bands, while solvent type, biological matrix, and environmental exposure also affect spectral fingerprints. These results highlight FTIR spectroscopy as a rapid, non-destructive, and robust method for nectar discrimination, with potential applications in food authentication, ecological research, and pollinator–plant studies. Full article

Tea oil tree (Camellia oleifera), a woody oil crop native to Southern China, relies on insect pollination for fruit and seed production. However, its nectar is toxic to honey bees (Apis spp.) due to their inability to digest the oligosaccharide present in the nectar. This toxicity raises concerns about the trade-off between the benefits of pollination and the risks posed by exposures to toxic nectar. We aimed to investigate whether tea oil tree yield is enhanced by honey bee pollination, while also examining the impact of nectar toxicity and exploring potential mitigation methods. We evaluated the fruit set, seed yield, and oil quality of the crop with or without eastern honey bee (A. cerana) pollination during 2019–2022. We also characterized nectar oligosaccharide compositions collected from both flowers and bee hives. We administered α-galactosidase (an enzyme to promote oligosaccharide digestion) onto bee larvae fed with crop nectar. We found that A. cerana could significantly enhance fruit set and seed yield. The administration of α-galactosidase could enhance larval survivorship challenged by nectar toxicity. The effectiveness of honey bee pollination can vary between years, with warmer temperatures significantly enhancing honey bee pollination benefits. The results suggest that a decision to use honey bees for pollinating tea oil trees should involve consideration of the impact of local weather conditions, as low temperatures may compromise pollination benefits while increasing risks posed by toxic nectar. The administration of digestive enzymes to honey bees shows potential for mitigating natural toxins in tea oil tree nectar. Full article

Fragaria vesca L. is a common plant species in Slovenia. It flowers from May to July. Our study was conducted throughout the 2024 season in two locations at which we sampled nectar in F. vesca flowers. To take the nectar samples, we used microcapillaries. We studied Fragaria vesca nectar production and its composition (sugars, amino acids, and phenolic compounds) throughout the day. We had some problems with sampling nectar in the afternoon, which affected our research, since there were times during which we could not obtain any samples. F. vesca on average secreted 0.02 μL nectar per one flower sample. Our data show that nectar production is highest in the morning, nectar is hexose-dominant, and the time of day affects the sugar concentration, which reaches a maximum at noon. The most common amino acid in F. vesca nectar is proline, and the amino acid concentration is highest in the morning. Quercetin and rutin are common phenolic compounds in the nectar of F. vesca, and the concentration of phenolic acids is highest at noon, as bees are the most active in the spring when mornings are colder. Full article

Sunflower (Helianthus annuus L.) is a cross-pollinated species that relies on pollinators, attracted by itsnectar composition. Nectar consists primarily of sugars (up to 70%), with sucrose, glucose, and fructose being dominant, while minor components such as mannose, arabinose, xylose, and sugar alcohols (e.g., mannitol and inositol) occur in lower concentrations and vary with biotic and abiotic factors. This study developed a robust high-performance liquid chromatography method with refractive index detection (HPLC-RID) for the simultaneous quantification of eight sugars (D-ribose, xylose, arabinose, fructose, mannose, glucose, sucrose, and maltose) and two sugar alcohols (mannitol, meso-inositol) in wild sunflower nectar. A Box–Behnken design (BBD), coupled with response surface methodology (RSM), was used to systematically optimize column temperature (20–23 °C), acetonitrile concentration (80–85%), and flow rate (0.7–1 mL/min), while achieving baseline separation of critical sugar pairs, including the previously co-eluting glucose/mannitol and glucose/mannose. Satisfactory resolution (Rs > 1 for all analytes) was achieved under optimized separation conditions comprising a column temperature of 20 °C, 82.5% acetonitrile, and a flow rate of 0.766 mL/min. The RSM efficiently evaluated factor interactions to maximize chromatographic performance, resulting in an optimized protocol that provides a cost-effective and environmentally friendly alternative to conventional sugar analysis methods. Method validation confirmed satisfactory linearity across relevant concentration ranges (50–500 mg/L for most sugars; 50–5500 mg/L for fructose and glucose), with correlation coefficients (R) between 0.985 and 0.999. The limits of detection (LOD) and quantification (LOQ) for the analyzed sugars and sugar alcohols ranged from 4.04 to 19.46 mg/L and from 13.46 to 194.61 mg/L, respectively. Glucose exhibited the highest sensitivity showing LOD of 4.04 and LOQ of 13.46 mg/L, whereas mannose was identified as the least sensitive analyte, with LOD of 19.46 mg/L and LOQ of 194.61 mg/L. The described method represents a reliable tool for sugar and sugar alcohol analysis in sunflower nectar and can be extended to other plant and food matrices with suitable sample preparation. Full article

Honeybee populations are increasingly threatened by various environmental stressors, including pesticides, pathogens, and climate change. Emerging research highlights the vital role of pollen polyphenols in supporting honeybee health through a network of antioxidants, immune responses, and detoxification mechanisms. This review synthesizes current findings on the chemical diversity, bioactivity, and functional relevance of polyphenolic compounds in honeybee nutrition. Pollen polyphenols, which include flavonoids and phenolic acids, possess remarkably high antioxidant potential, up to 235 times greater than that of nectar. They also significantly increase the expression of antioxidant enzymes, immune system genes, and detoxification pathways such as cytochrome P450s and glutathione-S-transferases. These compounds also demonstrate antimicrobial effects against key pathogens and mitigate the toxic effects of pesticides. The content and composition of polyphenols vary seasonally and geographically, impacting the resilience of honeybee colonies. Field and laboratory studies confirm that polyphenol-rich diets improve survival, gland development, and stress resistance. Advanced analytical techniques, including metabolomics, have expanded our understanding of polyphenol profiles and their effects on honeybee physiology. However, knowledge gaps remain in pharmacokinetics and structure–function relationships. Integrating this evidence into conservation strategies and good beekeeping practices, such as habitat diversification and targeted feed supplementation, is crucial for maintaining honeybee health and ecosystem services in a rapidly changing environment. Full article

Honey is a natural product produced by bees from the nectar of plants and has been widely used as a sweetener for centuries. In addition to its traditional use, it is also employed for other purposes due to its biological and nutraceutical properties. Although honey production is mostly associated with bees of the genus Apis, species from other genera, such as Melipona, also produce it, albeit on a smaller scale. The honey produced by these two genera shows significant differences in its composition. Moreover, distinct geographical localizations, which, consequently, have different flora, guide the chemical compositions of these samples. Regarding the Amazon region, the amount of knowledge about the honey samples from Melipona species is still scarce. In this context, the present study aimed to characterize the volatile compositions of honey from Melipona interrupta and Melipona seminigra, as well as from the floral sources available, in addition to evaluating their nutritional aspects, antioxidant activity, and antibacterial activity. The analysis of chemical composition was performed using gas chromatography coupled to mass spectrometry (GC-MS). Antioxidant activity was determined by DPPH and ABTS assays, while antimicrobial activity was tested against Escherichia coli, Staphylococcus aureus, Klebsiella pneumoniae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus epidermidis, Enterococcus faecalis, Salmonella enterica, Serratia marcescens, Bacillus subtilis, Candida albicans, Candida tropicalis, and Candida parapsilosis. The results allowed the identification of volatiles present in the honey and floral sources. The samples displayed moderate antioxidant activity and slightly antibacterial activity (MIC) of 75 μg/mL against two bacterial strains tested, demonstrating potential antimicrobial activity. Full article

Urban environments pose challenges for pollinators due to habitat loss and limited floral resources. However, green infrastructure, particularly street and ornamental trees, can play a critical role in supporting urban pollinator communities. In this study, we evaluated nectar volume, sugar content, and amino acid composition across eight urban tree species commonly planted in South Korea. Using standardized productivity metrics at the flower, tree, and hectare scales, we compared their nutritional contributions. Our results revealed substantial interspecific differences in nectar quantity and composition. Tilia amurensis, Heptacodium miconioides, Aesculus turbinata, and Wisteria floribunda exhibited high nectar yields or amino acid productivity, whereas species such as Cornus kousa, though lower in nutritional yield, may offer complementary value due to their distinct flowering periods or other phenological traits. These findings underscore the importance of selecting tree species not only for aesthetic value but also for ecological function, providing an evidence-based approach to pollinator-friendly urban biodiversity planning and landscape management. Full article

Butterflies have nectar-feeding preferences based on various floral characteristics, including flower shape, size, color, fragrance, and nectar composition, which in turn affect their survival, reproduction, and roles in pollination. The National Botanical Garden (NBG) in Lalitpur, Nepal, holds a variety of flowering plants and butterfly populations, providing a suitable study site to test the hypotheses on floral preferences of butterflies. This study assessed the floral preferences of the butterfly community in the NBG based on flower color, the origin of flowering plants (native and alien), and the type of plants (herbs and shrubs). It also tested the association between butterfly proboscis lengths and corolla tube lengths of flowers. Data were collected from 10 blocks (each 5 × 5 m²) through direct observation during the spring and autumn seasons, from March to October 2022. A total of 24 species of butterflies were recorded during the study period, with the chocolate pansy (Junonia iphita) being the most abundant. The relative abundance of pink flowers was higher in the NBG, but the butterflies’ visitation frequency was significantly higher on yellow flowers (p < 0.05) than on other colors. The visitation frequencies of butterflies significantly varied with the flowers’ origin and types. Butterflies visited flowers of alien origin more frequently than native ones (p < 0.05) and those of herbs over shrubs (p < 0.05). Flowers from alien plants, such as Calluna vulgaris and Viola tricolor, were among the most frequently visited. The proboscis length of butterflies showed a significantly strong positive correlation with the corolla tube length of flowers (τ = 0.74, p < 0.001). These results can inform conservation practices and garden management strategies aimed at supporting butterfly diversity through the intentional selection of floral resources. Full article

Climate change significantly influences plants’ physiology, flowering phenology, and nectar production, affecting pollinator interactions and apicultural sustainability. This study examines the physiological responses of Pseudolysimachion rotundum (Nakai) Holub var. subintegrum (Nakai) T.Yamaz. (Plantaginaceae) under projected climate change scenarios, focusing on flowering traits, nectar secretion, and honey production potential. Elevated CO₂ levels enhanced its net photosynthesis and water-use efficiency, supporting sustained carbohydrate assimilation and promoting aboveground biomass accumulation. However, the increased nitrogen demand for vegetative growth and inflorescence production may have led to reduced allocation of nitrogen to the nectar, contributing to a decline in its amino acid concentrations. The flowering period advanced with rising temperatures, with peak bloom occurring up to four days earlier under the SSP5 conditions. While the nectar secretion per flower remained stable, an increase in floral abundance led to a 3.8-fold rise in the estimated honey production per hectare. The analysis of the nectar’s composition revealed that sucrose hydrolysis intensified under higher temperatures, shifting the nectar toward a hexose-rich profile. Although nectar quality slightly declined due to reductions in sucrose and nitrogen-rich amino acids, phenylalanine—the most preferred amino acid by honeybees—remained dominant across all scenarios. These findings confirm the strong climate resilience of P. rotundum var. subintegrum, highlighting its potential as a sustainable nectar source in future apicultural landscapes. Given the crucial role of nitrogen in both plant growth and nectar composition, future research should explore soil nitrogen dynamics and plant nitrogen metabolism to ensure long-term sustainability in plant–pollinator interactions and apicultural practices. Full article

Honey is a multifaceted substance whose composition is intricately affected by various biotic and abiotic elements generated in the bee colony’s surroundings, including botanical and geographical origins, climatic conditions, soil characteristics, and beekeeping techniques. Monofloral honeys are identified by pollen analysis and are derived from the nectar of a predominant plant species, exhibiting rich sensory and nutritional profiles, making them food matrices with unique characteristics and excellent qualities. To explore the monofloral honey potential harvested in different regions of Portugal, a comprehensive study was conducted including the determination of phenolic composition and the assessment of biological activities. In addition to this evaluation, the inter simple sequence repeat (ISSR) was used to help differentiate honeys by botanical origin. The phenolic content and the antioxidant capacity were evaluated by spectrophotometric methods, observing, in general, differences between monofloral honeys. The honey from Citrus sinensis (Silves) exhibited the lowest phenolic content, including total phenols, ortho-diphenols, and flavonoids, whereas honeydew (Vinhais) showed the highest values. Regarding the antioxidant capacity, honey from Lavandula stoechas (Almodôvar) presented the lowest values, while honeydew (Vinhais) displayed the highest values for both DPPH and FRAP assays. In relation to the ABTS assay, the honey from Metrosideros excelsa (Aveiro) exhibited the lowest values, whereas the honey from Eucalyptus spp. (Arouca) showed the highest. The ISSR marker analysis allows the distribution of the samples based on the honey’s botanical origin, suggesting its potential role in honey authentication. Full article

Understanding the complexity of flower scent—a crucial attractant for pollinators and a key factor in ensuring plant reproduction—is an essential ecological task for highly endangered orchids. To address this issue, we studied the flower volatiles profile of Neottia ovata, a nectar-rewarding orchid known for its generalist pollination strategy. We then compared the chemical composition of N. ovata floral scent with scent data of other orchid species to place our findings in the context of general volatile attractants emitted by nectar-rewarding or food-deceptive species. Our results contribute to understanding the complexity of the N. ovata floral scent profile and provide valuable methodological insights. The scented bouquet of N. ovata comprises 100 compounds with a relatively consistent composition across the analyzed samples. It is rich in terpenes, including linalool and trans-/cis-sabinene hydrate, compounds commonly associated with generalized rewarding or food-deceptive pollination systems. Other terpenes identified include α- and β-pinene, limonene, and β-phellandrene, whose presence underscores the generalized nature of the floral scent. Interestingly, in the studied N. ovata populations, the dominance among terpenes is shifting markedly towards γ-terpinene, α-terpinene, and terpinene-4-ol, commonly found in essential oils and the floral scents of some supergeneralist-pollination plants. Aromatic compounds were less represented in the N. ovata scent profile and those of other orchids studied, though benzyl alcohol and benzaldehyde were noticeably more abundant. Aliphatic compounds composed the least prevalent fraction, showing a marked decreasing trend among nectar-rewarding species with generalized or specialized pollination systems. It is worth emphasizing that the applied methodology revealed an extensive group of low-frequency compounds in the N. ovata floral scent. This finding raises new ecological questions about the intraspecific diversity of floral scent profiles and sheds new light on the factors determining effective reproduction in this species of orchid. Full article

Camellia oleifera is an important woody oil plant in southern China, and developing its industry can enhance forest resource uses and increase edible oil supply. This study investigated the floral characteristics of different C. oleifera varieties, analysed the species and diversity of flower-visiting insects in different habitats, identified the main pollinators and their flower-visiting behaviours, and explored the relationship between pollinating insects and their floral characteristics. The floral lifespan of individual C. oleifera flowers was 5–8 d across cultivars, which is essentially the same. However, floral traits and nectar sugar composition exhibited distinct differences. There were 22 species of insect pollinators from 14 genera and 8 families, including Hymenoptera and Diptera, in 3 habitats. High-potential pollinators varied by habitat, with Apis cerana and Phytomia zonata being the most frequent. A comparison showed that A. cerana was the best pollinator, whereas P. zonata had a larger population, was not affected by oil tea nectar poisoning, and could still pollinate. Therefore, the contribution of P. zonata cannot be overlooked. Redundancy analysis revealed the response relationship between the floral traits of C. oleifera and three insect population characteristics. Stamen length was the main floral trait affecting insect populations. Full article