Propolis Counteracts Some Threats to Honey Bee Health

Architecture and potential roles of a delta-class glutathione S-transferase in protecting honey bee from agrochemicals

The European honey bee, Apis mellifera, serves as the principle managed pollinator species globally. In recent decades, honey bee populations have been facing serious health threats from combined biotic and abiotic stressors, including diseases, limited nutrition, and agrochemical exposure. Understanding the molecular mechanisms underlying xenobiotic adaptation of A. mellifera is critical, considering its extensive exposure to phytochemicals and agrochemicals present in the environment. In this study, we conducted a comprehensive structural and functional characterization of AmGSTD1, a delta class glutathione S-transferase (GST), to unravel its roles in agrochemical detoxification and antioxidative stress responses. We determined the 3-dimensional (3D) structure of a honey bee GST using protein crystallography for the first time, providing new insights into its molecular structure. Our investigations revealed that AmGSTD1 metabolizes model substrates, including 1-chloro-2,4-dinitrobenzene (CDNB), p-nitrophenyl acetate (PNA), phenylethyl isothiocyanate (PEITC), propyl isothiocyanate (PITC), and the oxidation byproduct 4-hydroxynonenal (HNE). Moreover, we discovered that AmGSTD1 exhibits binding affinity with the fluorophore 8-Anilinonaphthalene-1-sulfonic acid (ANS), which can be inhibited with various herbicides, fungicides, insecticides, and their metabolites. These findings highlight the potential contribution of AmGSTD1 in safeguarding honey bee health against various agrochemicals, while also mitigating oxidative stress resulting from exposure to these substances.

Chemical Characterization and Biological Activities of Jandaíra Stingless Bee Products (Melipona subnitida, Ducke, 1911): A Brief Review

Melipona subnitida (Ducke, 1911), a species of stingless bee, popularly known as Jandaíra, has a wide distribution in the Brazilian Northeast region, being an important pollinator of the Caatinga biome. This bee produces products such as honey, geopropolis, pollen (saburá) and wax that are traditionally used for therapeutic purposes and some studies report the biological properties, as well as its chemical composition. This review aimed to select, analyze and gather data published in the literature focusing on the chemical profile and bioactivities described for M. subnitida products. Data collection was carried out through the Capes Journal Portal platform, using the following databases: Web of Science, Scopus, and PubMed. Original articles published in English and Portuguese were included, with no time limitation. The chemical composition of M. subnitida products has been investigated through chromatographic analysis, demonstrating the presence of a variety of phenolic compounds, such as flavonoids and phenylpropanoids, among other classes of secondary metabolites. These products also have several biological activities, including antioxidant, healing, antinociceptive, anti-inflammatory, antidepressant, antidyslipidemic, antiobesity, antifungal, antibacterial and prebiotic. Among the biological activities reported, the antioxidant activity was the most investigated. These data show that products derived from the stingless bee M. subnitida have promising bioactive compounds. This review provides useful information about the bioactivities and chemical profile of Melipona subnitida bee products, and a direction for future research, which should focus on understanding the mechanisms of action associated with the already elucidated pharmacological activities, as well as the bioactive properties of the main isolate's constituents identified in the chemical composition of these products.

Thinking inside the box: Restoring the propolis envelope facilitates honey bee social immunity

When wild honey bee colonies (Apis mellifera) nest in hollow tree cavities, they coat the rough cavity walls with a continuous layer of propolis, a substance comprised primarily of plant resins. Studies have shown that the resulting "propolis envelope" leads to both individual- and colony-level health benefits. Unfortunately, the smooth wooden boxes most commonly used in beekeeping do little to stimulate propolis collection. As a result, most managed bees live in hives that are propolis-poor. In this study, we assessed different surface texture treatments (rough wood boxes, boxes outfitted with propolis traps, and standard, smooth wood boxes) in terms of their ability to stimulate propolis collection, and we examined the effect of propolis on colony health, pathogen loads, immune gene expression, bacterial gene expression, survivorship, and honey production in both stationary and migratory beekeeping contexts. We found that rough wood boxes are the most effective box type for stimulating propolis deposition. Although the use of rough wood boxes did not improve colony survivorship overall, Melissococcus plutonius detections via gene expression were significantly lower in rough wood boxes, and viral loads for multiple viruses tended to decrease as propolis deposition increased. By the end of year one, honey bee populations in migratory rough box colonies were also significantly larger than those in migratory control colonies. The use of rough wood boxes did correspond with decreased honey production in year one migratory colonies but had no effect during year two. Finally, in both stationary and migratory operations, propolis deposition was correlated with a seasonal decrease and/or stabilization in the expression of multiple immune and bacterial genes, suggesting that propolis-rich environments contribute to hive homeostasis. These findings provide support for the practical implementation of rough box hives as a means to enhance propolis collection and colony health in multiple beekeeping contexts.

Assessment of Efficacy of Algerian Propolis against the Parasitic Mite Varroa destructor and Safety for Honey Bees by Spray Treatment

Varroa destructor is an ectoparasitic mite and is considered one of the most important causes of honey bee population loss. In the last years, substances of botanical origin have emerged as natural alternatives to diminish the mite population levels. Propolis is a natural product and is used by honey bees for multiple tasks, including protection from pathogens and parasites, and varroacidal activity of propolis extracts has been shown. In this study, we investigated the potential of propolis, collected by native Algerian honey bee subspecies (Apis mellifera intermissa and A. m. sahariensis) in different locations in Algeria and extracted by ultrasound, to control mites of V. destructor and tested the safety for the honey bees. The most important results were that the best propolis extracts at 10% killed 100% of the Varroa mites within 3-4 h in a Petri dish assay. In addition, when we sprayed A. m. intermissa bees infested with Varroa mites with a 10% concentration in a mini-hive setup, we scored a high mite mortality of 85-87% with the best propolis extracts, and importantly, there was no mortality in the bees. Our data demonstrated that propolis extracts in Algeria could be used in honey bee colonies by spraying against Varroa mite infestations, which may develop as an easy method for local beekeepers to control Varroa in their hives. Further research should investigate the mechanism of action.

GC-MS based metabolic profile and toxicological evaluation of three Algerian propolis

This study aimed to investigate the chemical composition and toxicity of methanolic extracts of three Algerian propolis collected from Oum el Bouaghi (MEPO), El Harrouch (MEPH) and Collo (MEPC) regions. The chemical profile was characterised by GC-MS. The toxicity of the extracts was tested using brine shrimp model. The GC-MS analysis revealed the presence of ferulic acid (23.8%), pinostrobin chalcone (15.8%) and α-eudesmol (11.3%) as major compounds in MEPO, pinostrobin chalcone (22.2%), 9-octadecenoic acid, methyl ester, (E)- (17.4%), and γ-gurjunenepoxide-(2) (11.7%) were the most abundant components in MEPH, whereas MEPC was dominated by 1-heptatriacotanol (17.8%), pinostrobin chalcone (14.7%), totarol (13.7%) and 9-octadecenoic acid, methyl ester, (E)- (13.0%). The brine shrimp lethality test indicated that the extracts had moderate toxicity in which MEPC exhibited the highest activity with LC50 of 201.61 ± 7.27 µg/mL. All extracts showed no toxicity at 25 µg/mL concentration and below.

Biochemical Profile and Antioxidant Properties of Propolis from Northern Spain

The antioxidant, anti-inflammatory, and antimicrobial characteristics of propolis, a bioactive compound collected from hives, have prompted its use in the food sector in recent times. This study investigated the physicochemical characteristics, phenolic profile, and antioxidant capacity of 31 propolis extracts collected from Northern Spain. The physicochemical composition (resins, waxes, ashes mineral content, and heavy metals) was within the allowable regulatory limits. The analysis of bioactive compounds enabled the identification of 51 constituents: flavonoids (apigenin, catechin, chrysin, quercetin, and pinocembrin) and phenolic acids (caffeic, ferulic, and coumaric). The mean value of total polyphenols was 42.72 ± 13.19 Pinocembrin-Galangin Equivalents/100 g, whereas a range between 1.64 ± 0.04 and 4.95 ± 0.36 Quercetin Equivalents (QE) g/100 g was found for total flavonoids content. The determination of bioactivities revealed significant antioxidant capacity using DPPH (1114.28 ± 10.39 µM Trolox Equivalents and 3487.61 ± 318.66 µM Vitamin C Equivalents). Resin content in propolis samples was positively and significantly correlated with both polyphenols (rho = 0.365; p = 0.043) and flavonoid composition (rho = 0.615; p = 0.000) as well as the antioxidant capacity TEAC DPPH (rho = 0.415; p = 0.020). A multiple regression analysis modeled the correlation between resin composition, flavonoids, and TEAC DPPH values, yielding a significant regression equation (R2 = 0.618; F (2,28) = 22.629; p < 0.000; d = 2.299). Therefore, evaluating physicochemical parameters and biological activities provides a promising framework for predicting propolis' quality and antioxidant properties, thus suggesting its potential as a functional and bioactive compound for the food industry.

Effects of ingested essential oils and propolis extracts on honey bee (Hymenoptera: Apidae) health and gut microbiota

Managed honey bee (Hymenoptera: Apidae: Apis mellifera Linnaeus) hives require frequent human inputs to maintain colony health and productivity. A variety of plant natural products (PNPs) are delivered via feeding to control diseases and reduce the use of synthetic chemical treatments. However, despite their prevalent use in beekeeping, there is limited information regarding the impact of ingested PNPs on bee health. Here, we tested the effects of different essential oils and propolis extracts on honey bee life span, nutrient assimilation, xenobiotic detoxification, and gut microbiota abundance. Brazilian propolis extract lengthened worker life span, while the other PNPs (Louisiana propolis extract, lemongrass oil, spearmint oil, and thyme oil) exerted variable and dose-dependent effects on life span. Vitellogenin (vg) gene expression was reduced by Brazilian propolis extract at high doses. Expression of CYP6AS1, a detoxification-related gene, was reduced by low doses of thyme oil. The abundances of 8 core gut microbiota taxa were largely unaffected by host consumption of PNPs. Our results suggest that in addition to propolis's structural and immunomodulatory roles in the colony, it may also exert beneficial health effects when ingested. Thyme oil, a commonly used hive treatment, was toxic at field-realistic dosages, and its use as a feed additive should be viewed with caution until its effects on bee health are more thoroughly investigated. We conclude that the tested propolis extracts, lemongrass oil, and spearmint oil are generally safe for bee consumption, with some apparent health-promoting effects.

The effects of UV filters on health and the environment

Sunscreens are an important means of protection against sunburns, dyspigmentation, photoaging, and photocarcinogenesis. Sunscreens come in a variety of formulations that can protect against ultraviolet B (UVB) radiation, both UVB and ultraviolet A (UVA) radiation (broad-spectrum sunscreens), and UVB, UVA, and visible light (tinted broad-spectrum sunscreens). In the USA, there is currently a paucity of FDA-approved broad-spectrum filters on the market. Studies have identified the presence of multiple UV filters in water sources globally. Many laboratory studies have implicated the potential impact of UV filters on coral reef bleaching, the food chain, and human health. However, many of these studies are performed at concentrations that are much higher than those present in the natural environment. With increasing discussion surrounding the role of organic and inorganic UV filters as potential environmental pollutants over the past decade, approval of additional broad-spectrum filters would be an important means of alleviating the use of more controversial filters. The aim of this article is to review the effects of UV filters on health and the environment and explore potential adjunctive agents for photoprotection.

Chemical and Functional Characterization of Propolis Collected from Different Areas of South Italy

This study investigated the chemical and functional characterization of propolis collected in southern Italy, in particular in Basilicata, a region rich in ecological and vegetative biodiversity. Sixteen samples of propolis, collected within a radius of 40 km from each other in the Basilicata region, showed significant differences between the chemical and functional parameters investigated: color index (L*, a*, b*; p < 0.05) and variation in chemical composition and antioxidant activities by ABTS and FRAP assays. In general, Lucanian propolis had a low content of waxes (p < 0.05) and a high content of resin (p < 0.05) and balsams (p < 0.05). The content of the total phenolic compounds and flavonoids was highly variable, as was the biological capacity. In conclusion, Lucanian propolis showed remarkable variability, highlighting significant diversification according to the geographical position and the diversity of the flora surrounding the apiary that the bees use as a source of resin. This study, therefore, contributes to the enhancement of the quality of propolis, laying the foundations for the production and marketing of propolis not only in the food industry but also in the pharmaceutical and cosmetic industries.

Caffeine Consumption Helps Honey Bees Fight a Bacterial Pathogen

Caffeine has long been used as a stimulant by humans. Although this secondary metabolite is produced by some plants as a mechanism of defense against herbivores, beneficial or detrimental effects of such consumption are usually associated with dose. The Western honey bee, Apis mellifera, can also be exposed to caffeine when foraging at Coffea and Citrus plants, and low doses as are found in the nectar of these plants seem to boost memory learning and ameliorate parasite infection in bees. In this study, we investigated the effects of caffeine consumption on the gut microbiota of honey bees and on susceptibility to bacterial infection. We performed in vivo experiments in which honey bees, deprived of or colonized with their native microbiota, were exposed to nectar-relevant concentrations of caffeine for a week, then challenged with the bacterial pathogen Serratia marcescens. We found that caffeine consumption did not impact the gut microbiota or survival rates of honey bees. Moreover, microbiota-colonized bees exposed to caffeine were more resistant to infection and exhibited increased survival rates compared to microbiota-colonized or microbiota-deprived bees only exposed to the pathogen. Our findings point to an additional benefit of caffeine consumption in honey bee health by protecting against bacterial infections. IMPORTANCE The consumption of caffeine is a remarkable feature of the human diet. Common drinks, such as coffee and tea, contain caffeine as a stimulant. Interestingly, honey bees also seem to like caffeine. They are usually attracted to the low concentrations of caffeine found in nectar and pollen of Coffea plants, and consumption improves learning and memory retention, as well as protects against viruses and fungal parasites. In this study, we expanded these findings by demonstrating that caffeine can improve survival rates of honey bees infected with Serratia marcescens, a bacterial pathogen known to cause sepsis in animals. However, this beneficial effect was only observed when bees were colonized with their native gut microbiota, and caffeine seemed not to directly affect the gut microbiota or survival rates of bees. Our findings suggest a potential synergism between caffeine and gut microbial communities in protection against bacterial pathogens.

Effects of Propolis Impregnation on Polylactic Acid (PLA) Scaffolds Loaded with Wollastonite Particles against Staphylococcus aureus, Staphylococcus epidermidis, and Their Coculture for Potential Medical Devices

Several diseases and injuries cause irreversible damage to bone tissues, which may require partial or total regeneration or replacement. Tissue engineering suggests developing substitutes that may contribute to the repair or regeneration process by using three-dimensional lattices (scaffolds) to create functional bone tissues. Herein, scaffolds comprising polylactic acid and wollastonite particles enriched with propolis extracts from the Arauca region of Colombia were developed as gyroid triply periodic minimal surfaces using fused deposition modeling. The propolis extracts exhibited antibacterial activity against Staphylococcus aureus (ATCC 25175) and Staphylococcus epidermidis (ATCC 12228), which cause osteomyelitis. The scaffolds were characterized using scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry, contact angle, swelling, and degradation. Their mechanical properties were assessed using static and dynamic tests. Cell viability/proliferation assay was conducted using hDP-MSC cultures, while their bactericidal properties against monospecies cultures (S. aureus and S. epidermidis) and cocultures were evaluated. The wollastonite particles did not affect the physical, mechanical, or thermal properties of the scaffolds. The contact angle results showed that there were no substantial differences in the hydrophobicity between scaffolds with and without particles. Scaffolds containing wollastonite particles suffered less degradation than those produced using PLA alone. A representative result of the cyclic tests at F_max = 450 N showed that the maximum strain reached after 8000 cycles is well below the yield strain (i.e., <7.5%), thereby indicating that even under these stringent conditions, these scaffolds will be able to work properly. The scaffolds impregnated with propolis showed a lower % of cell viability using hDP-MSCs on the 3rd day, but these values increased on the 7th day. These scaffolds exhibited antibacterial activity against the monospecies cultures of S. aureus and S. epidermidis and their cocultures. The samples without propolis loads did not show inhibition halos, whereas those loaded with EEP exhibited halos of 17.42 ± 0.2 mm against S. aureus and 12.9 ± 0.5 mm against S. epidermidis. These results made the scaffolds possible bone substitutes that exert control over species with a proliferative capacity for the biofilm-formation processes required for typical severe infectious processes.

Chemodiversity of propolis samples collected in various areas of Benin and Congo: Chromatographic profiling and chemical characterization guided by 13 C NMR dereplication

INTRODUCTION

Propolis is a resinous natural substance collected by honeybees from buds and exudates of various trees and plants; it is widely accepted that the composition of propolis depends on the phytogeographic characteristics of the site of collection.

OBJECTIVES

The aim of this study was to determine the phytochemical composition of ethanolic extracts from eight propolis batches collected in different regions of Benin (north, center, and south) and Congo, Africa.

MATERIAL AND METHODS

Characterization of propolis samples was performed by using different hyphenated chromatographic methods combined with carbon-13 nuclear magnetic resonance (¹³ C NMR) dereplication with MixONat software. Their antioxidant or anti-advanced glycation end-product (anti-AGE) activity was then evaluated by using diphenylpicrylhydrazyl and bovine serum albumin assays, respectively.

RESULTS

Chromatographic analyses combined with ¹³ C NMR dereplication showed that two samples from the center of Benin exhibited, in addition to a huge amount of pentacyclic triterpenes, methoxylated stilbenoids or phenanthrenoids, responsible for the antioxidant activity of the extract for the first one. Among them, combretastatins might be cytotoxic. For the second one, the prenylated flavanones known in Macaranga-type propolis were responsible for its significant anti-AGE activity. The sample from Congo was composed of many triterpene derivatives belonging to Mangifera indica species.

CONCLUSION

Therefore, propolis from the center of Benin seems to be of particular interest, due to its antioxidant and anti-AGE properties. Nevertheless, as standardization of propolis is difficult in tropical zones due to its great chemodiversity, a systematic phytochemical analysis is required before promoting the use of propolis in food and health products in Africa.

Determination of productivity, yield and bioactivity of propolis extract produced by Tetragonula spp. Cultivated in Modular tetragonula hives

This study investigated the effects of microclimate conditions on the activity of Tetragonula laeviceps, Tetragonula biroi, and Tetragonula drescheri cultivated in Modular Tetragonula Hives for producing crude propolis. The hives were equipped with sensors that recorded microclimate data within the hive as well as the total activity of bees entering and leaving the hives. This study also investigated the effects of cultivating T. laeviceps, T. drescheri, and T. biroi with P. merkusii resin towards the productivity of crude propolis and the effects of different extraction methods on the yield, total phenolic content, total flavonoid content, and antibacterial activity of propolis extract produced by the Tetragonula spp. Based on the statistical analysis, there is a significant positive correlation between temperature and light intensity towards the activity Tetragonula spp. entering and leaving the beehives. The productivity of crude propolis lies in the range of 1.22-5.88 g/colony/week whereas the yield of propolis extract varies from 15.12 to 24.17%. The total phenolic and flavonoid content of the propolis extract lies in the range of 123.81-343.93 mg GAE/g and 5.48-35.77 mg QE/g, respectively. The highest propolis yield (32.45 ± 0.90%) was obtained from the crude propolis produced by T. drescheri followed by Soxhlet extraction method. Propolis extract with the highest phenolic content (343.93 ± 44.32 mg GAE/g) and flavonoid content (35.77 ± 9.94 mg QE/g) was obtained from the propolis produced by T. laeviceps followed by maceration method. All the propolis extracts inhibited the growth of Staphylococcus aureus with the inhibition diameter varies from 6.58 ± 0.04 mm to 9.70 ± 0.7 mm which be considered as moderate antimicrobial activity.

Antimicrobial, Antibiofilm and Toxicological Assessment of Propolis

Antimicrobial resistance is a serious problem for the control of infections and infectious diseases. Propolis is a substance produced by honeybees with antimicrobial and antibiofilm properties. To consider propolis as an alternative to the use of antimicrobials for infection control, we assessed its antimicrobial and antibiofilm activities. To assess propolis for topical medical use, toxicological studies were also performed. A Portuguese 70% propolis ethanolic extract was chemically evaluated and studied for antimicrobial activity on staphylococcal field isolates (n = 137) and antibiofilm action (n = 45). Cell toxicological assessment was performed using keratinocytes and fibroblasts. Pinobanksin, chrysin, acacetin, apigenin, pinocembrin, and kaempferol-dimethyl-ether were detected. All 137 isolates were susceptible to 6.68 mg/mL or lower propolis concentration (80% isolates were susceptible to <1 mg/mL). The mean percentage of biofilm inhibition was 71%, and biofilm disruption was 88.5%. Propolis (<1 mg/mL) was well-tolerated by fibroblasts and moderately tolerated by keratinocytes. The combined antimicrobial and antibiofilm effect of propolis, together with its low toxicity to connective tissue and epithelial cells, suggests a good applicability for topical antibacterial treatment. Therefore, propolis seems to be a good alternative to antimicrobials for the treatment of infections with Staphylococcus spp. that deserves to be evaluated in vivo.

A review of stingless bees' bioactivity in different parts of the world

Stingless bees, also known as meliponines, live in beehives. However, reports on the distribution of stingless bees are scattered, resulting in a lack of precision. Honey and propolis are the main components that can be harvested from their beehive, with a great commercial value of up to 610 million USD. Despite the enormous potential profits, discrepancies in their bioactivities have been observed worldwide, leading to a lack of confidence. Therefore, this review provided oversight on the potential of stingless bee products and highlighted the differences between stingless bees in Asia, Australia, Africa, and America. The bioactivity of stingless bee products is diverse and exhibits great potential as an antimicrobial agent or in various diseases such as diabetes, cardiovascular disease, cancers, and oral problems.

Brazilian Brown Propolis: an Overview About Its Chemical Composition, Botanical Sources, Quality Control, and Pharmacological Properties

Brazil is one of the largest propolis producers in the world. Propolis is produced by bees from plant exudates and tissues, leading to many variations in the types of propolis. Generally, Brazilian propolis types are green, brown, and red. Despite not being the main research focus as the green and red propolis, brown propolis is the second most produced propolis type in Brazil and has tremendous economic and medicinal importance. Propolis has drawn attention with the rise in the search for healthier lifestyles, functional foods, biocosmetics, and natural products as therapeutic sources. This review covers the main chemical constituents identified in different types of Brazilian brown propolis, and their botanical sources, chemistry, and biological activities. The economic aspect of brown propolis is also presented. There are many gaps to be filled for brown propolis regarding the development of analytical methods, and quality control to allow its standardization, limiting its applicability in the food and pharmaceutical industries. Future perspectives regarding brown propolis research were discussed, especially biological activities, to support the medicinal uses of different types of brown propolis.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43450-023-00374-x.

Determination of Botanical Origin and Mineral Content of Propolis Samples from Balveren (Şırnak) Beekeepers Accommodation Areas

Researches on bee products have become popular in recent years. In fact, the content and component of bee products varies depending on many ecological and floristic factors and its nutritional and therapeutic properties are directly related to its content. Balveren (Şırnak province) beekeepers place their hives in locations with different geographical structure, floristic and topographic characteristics. This variability not only affects the quality of honey but also changes the properties of propolis. Studies on propolis, known as bee glue, have gained importance in recent years. As with other bee products, the propolis content also depends on the floristic characteristics of the region. In this study, propolis samples were collected from the regions where Balveren beekeepers stayed and their botanical origins, wax ratios, phenolic content, and mineral substance contents were analyzed. In the microscopic analysis, pollen grains belonging to 14 different families used by bees were determined. It was determined that the total phenolic and mineral contents of propolis vary completely depending on the location. With this study, the propolis properties of the hives in the region were tried to be revealed and it was aimed that this study would help the region's propolis to be used for technological and therapeutic purposes.

Host-microbiome metabolism of a plant toxin in bees

While foraging for nectar and pollen, bees are exposed to a myriad of xenobiotics, including plant metabolites, which may exert a wide range of effects on their health. Although the bee genome encodes enzymes that help in the metabolism of xenobiotics, it has lower detoxification gene diversity than the genomes of other insects. Therefore, bees may rely on other components that shape their physiology, such as the microbiota, to degrade potentially toxic molecules. In this study, we show that amygdalin, a cyanogenic glycoside found in honey bee-pollinated almond trees, can be metabolized by both bees and members of the gut microbiota. In microbiota-deprived bees, amygdalin is degraded into prunasin, leading to prunasin accumulation in the midgut and hindgut. In microbiota-colonized bees, on the other hand, amygdalin is degraded even further, and prunasin does not accumulate in the gut, suggesting that the microbiota contribute to the full degradation of amygdalin into hydrogen cyanide. In vitro experiments demonstrated that amygdalin degradation by bee gut bacteria is strain-specific and not characteristic of a particular genus or species. We found strains of Bifidobacterium, Bombilactobacillus, and Gilliamella that can degrade amygdalin. The degradation mechanism appears to vary since only some strains produce prunasin as an intermediate. Finally, we investigated the basis of degradation in Bifidobacterium wkB204, a strain that fully degrades amygdalin. We found overexpression and secretion of several carbohydrate-degrading enzymes, including one in glycoside hydrolase family 3 (GH3). We expressed this GH3 in Escherichia coli and detected prunasin as a byproduct when cell lysates were cultured with amygdalin, supporting its contribution to amygdalin degradation. These findings demonstrate that both host and microbiota can act together to metabolize dietary plant metabolites.

Chemical Composition and Biological Activity of Argentinian Propolis of Four Species of Stingless Bees

The chemical composition of propolis of four species of stingless bees (SLBs) from Argentina was determined, and its antibacterial and anticancer activity was evaluated on selected types of microbes and cancer cell lines. Volatile secretions of all propolis samples are formed by 174 C₂-C₁₅ organic compounds, mainly mono- and sesquiterpenes and their derivatives. The chromatograms of ether extracts showed 287 peaks, of which 210 were identified. The most representative groups in the extracts of various propolis samples were diterpenoids (mainly resin acids), triterpenoids and phenolic compounds: long-chain alkenyl phenols, resorcinols and salicylates. The composition of both volatile and extractive compounds turned out to be species-specific; however, in both cases, the pairwise similarity of the propolis of Scaptotrigona postica and Tetragonisca fiebrigi versus that of Tetragona clavipes and Melipona quadrifasciata quadrifasciata was observed, which indicated the similarity of the preferences of the respective species when choosing plant sources of resin. The composition of the studied extracts completely lacked flavonoids and phenolcarboxylic acids, which are usually associated with the biological activity and medicinal properties of propolis. However, tests on selected microbial species and cancer cell lines showed such activity. All propolis samples tested against Paenibacillus larvae, two species of Bacillus and E. coli showed biofilm inhibition unrelated to the inhibition of bacterial growth, leading to a decrease in their pathogenicity. Testing the anticancer activity of ether extracts using five types of cell cultures showed that all four types of propolis studied inhibit the growth of cancer cells in a dose- and time-dependent manner. Propolis harvested by T. clavipes demonstrated the highest cytotoxicity on all tested cell lines.

Natural Substances, Probiotics, and Synthetic Agents in the Treatment and Prevention of Honeybee Nosemosis

Honeybees are important pollinators, but they are continuously exposed to a variety of fungal and bacterial diseases. One of the various diseases affecting honeybees is nosemosis caused by microsporidia from the Nosema genus. Honeybees are mainly infected through consumption of infected food or faeces containing Nosema spp. spores. Nosemosis causes damage to the middle intestine epithelium, which leads to food absorption disorders and honeybee malnutrition. Fumagillin, i.e., the antibiotic used to treat nosemosis, was withdrawn in 2016 from EU countries. Therefore, researchers have been looking for compounds of both natural and synthetic origin to fight nosemosis. Such compounds should not have a negative impact on bees but is expected to inhibit the disease. Natural compounds tested against nosemosis include, e.g., essential oils (EOs), plant extracts, propolis, and bacterial metabolites, while synthetic substances tested as anti-nosemosis agents are represented by porphyrins, vitamins, antibiotics, phenolic, ascorbic acids, and others. This publication presents an 18-year overview of various studies of a number of natural and synthetic compounds used in the treatment and prevention of nosemosis cited in PubMed, GoogleScholar, and CrossRef.

Characterization and Evaluation of Colombian Propolis on the Intestinal Integrity of Broilers

Nutritional additives such as propolis seek to improve intestinal health as an alternative to the global ban on in-feed antibiotics used as growth promoters (AGP). The objective of this study was to evaluate the effect of propolis supplementation in diet of broilers. Four hundred and fifty straight-run Ross 308 AP broilers were fed with a basal diet (BD) throughout the whole experimental period. Birds were randomly distributed into 5 groups at d 14: negative control without antibiotics nor propolis (AGP-), positive control 500 ppm of Zinc Bacitracin as growth promoter (AGP+), and 3 groups supplemented with 150, 300, and 450 ppm of propolis. Every group included 6 replicates of 15 birds each. Propolis concentration was increased from d 22 to 42, in experimental groups to 300, 600, and 900 ppm of propolis, and 10% of raw soybean was included as a challenge in all groups during the same period. Analysis of productive parameters, intestinal morphometry, and relative quantification of genes associated with epithelial integrity by qPCR were performed at 21 and 42 d. The groups with the greatest weights were those that consumed diets including 150 (21 d) and 900 ppm (42 d) of propolis compared with all treatments. The lowest score of ISI was found at 300 (21 d) and 600 ppm (42 d). A lower degree of injury in digestive system was seen with the inclusion of 300 ppm (21 d) and 900 ppm (42 d). Up-regulation of zonula occludens-1 (ZO-1) was observed in jejunum of broilers supplemented with 150 and 300 ppm at 21 d. Up-regulation of ZO-1 and TGF-β was also evidenced in ileum at all propolis inclusion levels at 42-day-old compared to AGP+ and AGP-. The beneficial effects were evidenced at inclusion levels of 150 ppm in the starter and 900 ppm in the finisher. According to the results, the Colombian propolis inclusion can improve productive performance, physiological parameters, and gene expression associated with intestinal integrity.

The Suitability of Propolis as a Bioactive Component of Biomaterials

Propolis is a resinous product collected by bees from plant exudates to protect and maintain hive homeostasis. Propolis has been used therapeutically for centuries as folk medicine. Modern research investigating the diversity of the chemical composition and plant sources, biological activity, extraction processes, analytical methods, and therapeutic properties in clinical settings have been carried out extensively since the 1980s. Due to its antimicrobial, anti-inflammatory, and immuno-modulator properties, propolis appears to be a suitable bioactive component to be incorporated into biomaterials. This review article attempts to analyze the potential application of propolis as a biomaterial component from the available experimental evidence. The efficacy and compabitility of propolis depend upon factors, such as types of extracts and types of biomaterials. Generally, propolis appears to be compatible with hydroxyapatite/calcium phosphate-based biomaterials. Propolis enhances the antimicrobial properties of the resulting composite materials while improving the physicochemical properties. Furthermore, propolis is also compatible with wound/skin dressing biomaterials. Propolis improves the wound healing properties of the biomaterials with no negative effects on the physicochemical properties of the composite biomaterials. However, the effect of propolis on the glass-based biomaterials cannot be generalized. Depending on the concentration, types of extract, and geographical sources of the propolis, the effect on the glass biomaterials can either be an improvement or detrimental in terms of mechanical properties such as compressive strength and shear bond strength. In conclusion, two of the more consistent impacts of propolis across these different types of biomaterials are the enhancement of the antimicrobial and the immune-modulator/anti-inflammatory properties resulting from the combination of propolis and the biomaterials.

Pollinator nutrition and its role in merging the dual objectives of pollinator health and optimal crop production

Bee and non-bee insect pollinators play an integral role in the quantity and quality of production for many food crops, yet there is growing evidence that nutritional challenges to pollinators in agricultural landscapes are an important factor in the reduction of pollinator populations worldwide. Schemes to enhance crop pollinator health have historically focused on floral resource plantings aimed at increasing pollinator abundance and diversity by providing more foraging opportunities for bees. These efforts have demonstrated that improvements in bee diversity and abundance are achievable; however, goals of increasing crop pollination outcomes via these interventions are not consistently met. To support pollinator health and crop pollination outcomes in tandem, habitat enhancements must be tailored to meet the life-history needs of specific crop pollinators, including non-bees. This will require greater understanding of the nutritional demands of these taxa together with the supply of floral and non-floral food resources and how these interact in cropping environments. Understanding the mechanisms underlying crop pollination and pollinator health in unison across a range of taxa is clearly a win–win for industry and conservation, yet achievement of these goals will require new knowledge and novel, targeted methods.

This article is part of the theme issue ‘Natural processes influencing pollinator health: from chemistry to landscapes’.

Fungal Community Investigation from Propolis Natural Products: Diversity and Antibacterial Activities Evaluation

Discovering new species and interesting bioactive metabolites from customary sources is becoming progressively laborious. Propolis constitutes the largest diversified reserve of microbial constituents in the beehive. However, fungal communities associated with these environments remain insufficiently established. We present the first detailed investigation of the cultivable fungal community associated with Tunisian propolis, and we evaluate its antibacterial properties against pathogenic bacteria. A total of 80 fungal strains were isolated from propolis samples derived from seven different Tunisian locations. The majority of the isolated fungi were classified as Ascomycota (97.5%), and only 2.5% belonged to Basidiomycota. Our collection was clustered into 15 genera, among which Coniochaeta (36.25%), Aspergillus (15%), Penicillium (13.75%), Cladosporium (10%), Fusarium (7.5%), Didymella (5%), and Alternaria (3.75%) were the most common. Evaluation of the antibacterial activity revealed that 25.6% of the total community showed a broad range of antibacterial activity. Particularly, the Penicillium griseofulvum CC8 strain has manifested the strongest inhibitory effects against all the tested bacteria.

Functional Properties and Antimicrobial Activity from Lactic Acid Bacteria as Resources to Improve the Health and Welfare of Honey Bees

Simple Summary

Honey bees play a pivotal role in the sustainability of ecosystems and biodiversity. Many factors including parasites, pathogens, pesticide residues, forage losses, and poor nutrition have been proposed to explain honey bee colony losses. Lactic acid bacteria (LAB) are normal inhabitants of the gastrointestinal tract of honey bees and their role has been consistently reported in the literature. In recent years, there have been numerous scientific evidence that the intestinal microbiota plays an essential role in honey bee health. Management strategies, based on supplementation of the gut microbiota with probiotics, may be important to increase stress tolerance and disease resistance. In this review, recent scientific advances on the use of LABs as microbial supplements in the diet of honey bees are summarized and discussed.

Abstract

Honey bees (Apis mellifera) are agriculturally important pollinators. Over the past decades, significant losses of wild and domestic bees have been reported in many parts of the world. Several biotic and abiotic factors, such as change in land use over time, intensive land management, use of pesticides, climate change, beekeeper’s management practices, lack of forage (nectar and pollen), and infection by parasites and pathogens, negatively affect the honey bee’s well-being and survival. The gut microbiota is important for honey bee growth and development, immune function, protection against pathogen invasion; moreover, a well-balanced microbiota is fundamental to support honey bee health and vigor. In fact, the structure of the bee’s intestinal bacterial community can become an indicator of the honey bee’s health status. Lactic acid bacteria are normal inhabitants of the gastrointestinal tract of many insects, and their presence in the honey bee intestinal tract has been consistently reported in the literature. In the first section of this review, recent scientific advances in the use of LABs as probiotic supplements in the diet of honey bees are summarized and discussed. The second section discusses some of the mechanisms by which LABs carry out their antimicrobial activity against pathogens. Afterward, individual paragraphs are dedicated to Chalkbrood, American foulbrood, European foulbrood, Nosemosis, and Varroosis as well as to the potentiality of LABs for their biological control.

Land Use Influences the Composition and Antimicrobial Effects of Propolis

Simple Summary

Honey bees collect a multitude of substances from plants, including nectar, pollen, and a lesser-known resin called propolis. Honey bees line their colonies with propolis to fill in cracks and potentially aid in their defense against pathogens such as fungi, bacteria, and viruses. Different plants contain different types of chemicals that are collected by bees to form propolis, and so one would expect the plants that bees visit to influence the quality of the propolis contained within honey bee colonies. This project explored the chemical composition and antibacterial effects of propolis collected from apiaries that were surrounded by different types of land use patterns in Iowa. Propolis samples collected from colonies that were surrounded by the highest levels of agriculture had the lowest abundance of chemical compounds and also the lowest antimicrobial activity detected for two of the bacteria species studied. These results add to a growing body of work that suggests that high intensity agricultural land use negatively impacts multiple aspects of honey bee colony health.

Abstract

Honey bee propolis is a complex, resinous mixture created by bees using plant sources such as leaves, flowers, and bud exudates. This study characterized how cropland surrounding apiaries affects the chemical composition and antimicrobial effects of propolis. The chemical composition and compound abundance of the propolis samples were analyzed using Gas Chromatography-Mass Spectrometry (GC-MS) and the antimicrobial effects were analyzed using the 50% minimum inhibitory concentration (MIC₅₀) assay against four relevant bee pathogens, Serratia marcescens, Paenibacillus larvae, Lysinibacillus sphaericus, and Klebsiella pneumoniae. Propolis composition varied significantly with apiary, and cropland coverage predicted mean sum abundance of compounds. The apiary with the highest cropland coverage exhibited significantly higher MIC₅₀ values for S. marcescens and K. pneumoniae compared to other apiaries. These results demonstrate that agricultural land use surrounding honey bee apiaries decreases the chemical quality and antimicrobial effects of propolis, which may have implications for the impacts of land use on hive immunity to potential pathogens.

Honeybees use propolis as a natural pesticide against their major ectoparasite

Honeybees use propolis collected from plants for coating the inner walls of their nest. This substance is also used as a natural antibiotic against microbial pathogens, similarly to many other animals exploiting natural products for self-medication. We carried out chemical analyses and laboratory bioassays to test if honeybees use propolis for social medication against their major ectoparasite: Varroa destructor. We found that propolis is applied to brood cells where it can affect the reproducing parasites, with a positive effect on honeybees and a potential impact on Varroa population. We conclude that propolis can be regarded as a natural pesticide used by the honeybee to limit a dangerous parasite. These findings significantly enlarge our understanding of behavioural immunity in animals and may have important implications for the management of the most important threat to honeybees worldwide.

Mitigating Nosema ceranae infection in western honey bee (Apis mellifera) workers using propolis collected from honey bee and stingless bee (Tetrigona apicalis) hives

Beekeepers need sustainable control options to treat Nosema ceranae infection in colonies of western honey bees (Apis mellifera L.) they manage. Propolis is a natural product derived from plant resins and contains chemical compounds with potential antimicrobial activity against N. ceranae. Here, we determined the efficacy of propolis from A. mellifera (USA) and Tetrigona apicalis (stingless bees, Thailand) colonies as treatments for N. ceranae infection in honey bee workers. Newly emerged bees were individually fed 2 μL of 50% (w/v) sucrose solution containing 1 × 10⁵N. ceranae spores. Following this, the infected bees were treated with 50% propolis extracted from A. mellifera or T. apicalis hives and fed in 50% sucrose solution (v/v). All bees were maintained at 34 ± 2 °C and 55 ± 5% RH. Dead bees were counted daily for 30 d to calculate survival. We also determined infection rate (# infected bees/100 bees), infectivity (number of spores per bee) and protein content in the hypopharyngeal glands and hemolymph on 7, 14, and 21 d post infection as measures of bee health. Propolis from both bee species significantly reduced bee mortality, infection rate and infectivity compared with those of untreated bees and led to significantly greater protein contents in hypopharyngeal glands and hemolymph in treated bees than in untreated ones (p < 0.0001). In conclusion, propolis from A. mellifera and T. apicalis colonies shows promise as a control against N. ceranae infection in honey bees.

Bee Products: A Representation of Biodiversity, Sustainability, and Health

Biodiversity strengthens the productivity of any ecosystem (agricultural land, forest, lake, etc.). The loss of biodiversity contributes to food and energy insecurity; increases vulnerability to natural disasters, such as floods or tropical storms; and decreases the quality of both life and health. Wild and managed bees play a key role in maintaining the biodiversity and in the recovery and restoration of degraded habitats. The novelty character of this perspective is to give an updated representation of bee products’ biodiversity, sustainability, and health relationship. The role of bees as bioindicators, their importance in the conservation of biodiversity, their ecosystem services, and the variety of the bee products are described herein. An overview of the main components of bee products, their biological potentials, and health is highlighted and detailed as follows: (i) nutritional value of bee products, (ii) bioactive profile of bee products and the related beneficial properties; (iii) focus on honey and health through a literature quantitative analysis, and (iv) bee products explored through databases. Moreover, as an example of the interconnection between health, biodiversity, and sustainability, a case study, namely the “Cellulose Park”, realized in Rome (Italy), is presented here. This case study highlights how bee activities can be used to assess and track changes in the quality of agricultural ecosystems—hive products could be valid indicators of the quality and health of the surrounding environment, as well as the changes induced by the biotic and abiotic factors that impact the sustainability of agricultural production and biodiversity conservation in peri-urban areas.

Resin Use by Stingless Bees: A Review

Stingless bees (Meliponini) are highly social bees that are native to tropical and sub-tropical ecosystems. Resin use is vital to many aspects of stingless bee colony function. Stingless bees use resin to build essential nest structures, repel predators, and kill would-be invaders. Furthermore, resin-derived compounds have been found to enrich the cuticular chemical profiles of many stingless bee species, and resin may play an important role in shaping the microbial communities associated with stingless bees and their nests. Despite its importance for colony function, previous reviews of resin use by stingless bees are lacking. This topic grows increasingly urgent as changes in beekeeping and land use practices occur, potentially diminishing stingless bees' ability to incorporate resin into the nest environment. In this article, we review existing literature on resin use by stingless bees and discuss potential areas of future research.

The effects of crude propolis, its volatiles and ethanolic extracts on the ecto-parasitic mite, Varroa destructor and health of the African savannah honey bee, Apis mellifera scutellata

Propolis is a hive product composed of biologically active plant resins, and has been shown to enhance individual honey bee (Apis mellifera L.) health. Propolis has also been demonstrated to mitigate, in part, the negative effects caused by the ecto-parasitic mite Varroa destructor and its associated viruses on the health of managed European honey bee colonies. However, its effect on the health status of African honey bees remains largely unknown. Here, we found that the African savannah honey bees, A. m. scutellata in Kenya, deposited approximately two and half-fold more propolis in their colonies during periods of increased than reduced worker brood rearing. This finding suggested that A. m. scutellata may use high quantities of propolis prophylactically to protect their young brood; yet, we observed no significant correlation between the quantity of propolis and the amount of worker brood or mite-infestation level on adult workers. Furthermore, whereas propolis volatiles or propolis placed in direct contact with the mites had no effect on mite survival under laboratory conditions, the ethanolic extract of propolis significantly reduced mite survival when compared with untreated control. These results suggest the presence of mite deterrent compounds in the ethanolic extract of the African honey bee propolis.

Immunity and physiological changes in adult honey bees (Apis mellifera) infected with Nosema ceranae: The natural colony environment

Nosema ceranae is a microsporidium that infects Apis mellifera, causing diverse physiological and behavioral alterations. Given the existence of individual and social mechanisms to reduce infection and fungal spread in the colony, bees may respond differently to infection depending on their rearing conditions. In this study, we investigated the effect of N. ceranae in honey bee foragers naturally infected with different fungal loads in a tropical region. In addition, we explored the effects of N. ceranae artificially infected young bees placed in a healthy colony under field conditions. Honey bees naturally infected with higher loads of N. ceranae showed downregulation of genes from Toll and IMD immune pathways and antimicrobial peptide (AMP) genes, but hemolymph total protein amount and Vitellogenin (Vg) titers were not affected. Artificially infected bees spread N. ceranae to the controls in the colony, but fungal loads were generally lower than those observed in cages, probably because of social immunity. Although no significant changes in mRNA levels of AMP-encoding were observed, N. ceranae artificially infected bees showed downregulation of miR-989 (an immune-related microRNA), lower vitellogenin gene expression, and decreased hemolymph Vg titers. Our results demonstrate for the first time that natural infection by N. ceranae suppresses the immune system of honey bee foragers in the field. This parasite is detrimental to the immune system of young and old bees, and disease spread, mitigation and containment will depend on the colony environment.

Microbiota, pathogens, and parasites as mediators of tritrophic interactions between insect herbivores, plants, and pollinators

Insect-associated microbes, including pathogens, parasites, and symbionts, influence the interactions of herbivorous insects and pollinators with their host plants. Moreover, herbivory-induced changes in plant resource allocation and defensive chemistry can influence pollinator behavior. This suggests that the outcomes of interactions between herbivores, their microbes and host plants could have implications for pollinators. As epizootic diseases occur at high population densities, pathogen and parasite-mediated effects on plants could have landscape-level impacts on foraging pollinators. The goal of this minireview is to highlight the potential for an herbivore's multitrophic interactions to trigger plant-mediated effects on the immunity and health of pollinators. We highlight the importance of plant quality and gut microbiomes in bee health, and how caterpillars as model herbivores interact with pathogens, parasites, and symbionts to affect plant quality, which forms the centerpiece of multitrophic interactions between herbivores and pollinators. We also discuss the impacts of other herbivore-associated factors, such as agricultural inputs aimed at decreasing herbivorous pests, on pollinator microbiomes.

Winter honeybee (Apis mellifera) populations show greater potential to induce immune responses than summer populations after immune stimuli

In the temperate climates of central Europe and North America, two distinct honeybee (Apis mellifera) populations are found in colonies: short-living summer bees emerge in spring and survive until summer, whereas long-living winter bees emerge in late August and overwinter. Besides the difference in their life spans, each of these populations fulfils a different role in the colonies and individual bees have distinct physiological and immunological adaptations depending on their roles. For instance, winter worker bees have higher vitellogenin levels and larger reserves of nutrients in the fat body than summer bees. The differences between the immune systems of both populations are well described at the constitutive level; however, our knowledge of its inducibility is still very limited. In this study, we focus on the response of 10-day-old honeybee workers to immune challenges triggered in vivo by injecting heat-killed bacteria, with particular focus on honeybees that emerge and live under hive conditions. Responses to bacterial injections differed between summer and winter bees. Winter bees exhibited a more intense response, including higher expression of antimicrobial genes and antimicrobial activity, as well as a significant decrease in vitellogenin gene expression and its concentration in the hemolymph. The intense immune response observed in winter honeybees may contribute to our understanding of the relationships between colony fitness and infection with pathogens, as well as its association with successful overwintering.

Honey as a Functional Food for Apis mellifera

Although nectar is consumed, primarily as a supplemental food, by a broad range of insects spanning at least five orders, it is processed and stored by only a small number of species, most of which are bees and wasps in the superfamily Apoidea. Within this group, Apis mellifera has evolved remarkable adaptations facilitating nectar processing and storage; in doing so, this species utilizes the end product, honey, for diverse functions with few if any equivalents in other phytophagous insects. Honey and its phytochemical constituents, some of which likely derive from propolis, have functional significance in protecting honey bees against microbial pathogens, toxins, and cold stress, as well as in regulating development and adult longevity. The distinctive properties of A. mellifera honey appear to have arisen in multiple ways, including genome modification; partnerships with microbial symbionts; and evolution of specialized behaviors, including foraging for substances other than nectar. That honey making by A. mellifera involves incorporation of exogenous material other than nectar, as well as endogenous products such as antimicrobial peptides and royal jelly, suggests that regarding honey as little more than a source of carbohydrates for bees is a concept in need of revision.

To bee or not to bee? The bee extract propolis as a bioactive compound in the burden of lifestyle diseases

Propolis is a polyphenolic plant resin collected by bees to protect hives against pathogens and temperature drop. It exhibits antibacterial, antioxidant, and antiinflammatory properties. Propolis has been reported to possess antidiabetic properties and display beneficial effects against cardiovascular disease, gut dysbiosis, and chronic kidney disease. It has an excellent clinical safety profile, with no known toxic effects described so far. In this review, we discuss the salutogenic effects of propolis, with particular reference to modulating notable features of chronic kidney disease, notably those involving cardiovascular risks.

Colony-Level Effects of Amygdalin on Honeybees and Their Microbes

Amygdalin, a cyanogenic glycoside, is found in the nectar and pollen of almond trees, as well as in a variety of other crops, such as cherries, nectarines, apples and others. It is inevitable that western honeybees (Apis mellifera) consistently consume amygdalin during almond pollination season because almond crops are almost exclusively pollinated by honeybees. This study tests the effects of a field-relevant concentration of amygdalin on honeybee microbes and the activities of key honeybee genes. We executed a two-month field trial providing sucrose solutions with or without amygdalin ad libitum to free-flying honeybee colonies. We collected adult worker bees at four time points and used RNA sequencing technology and our HoloBee database to assess global changes in microbes and honeybee transcripts. Our hypothesis was that amygdalin will negatively affect bee microbes and possibly immune gene regulation. Using a log2 fold-change cutoff at two and intraday comparisons, we show no large change of bacterial counts, fungal counts or key bee immune gene transcripts, due to amygdalin treatment in relation to the control. However, relatively large titer decreases in the amygdalin treatment relative to the control were found for several viruses. Chronic bee paralysis virus levels had a sharp decrease (-14.4) with titers then remaining less than the control, Black queen cell virus titers were lower at three time points (<-2) and Deformed wing virus titers were lower at two time points (<-6) in amygdalin-fed compared to sucrose-fed colonies. Titers of Lotmaria passim were lower in the treatment group at three of the four dates (<-4). In contrast, Sacbrood virus had two dates with relative increases in its titers (>2). Overall, viral titers appeared to fluctuate more so than bacteria, as observed by highly inconstant patterns between treatment and control and throughout the season. Our results suggest that amygdalin consumption may reduce several honeybee viruses without affecting other microbes or colony-level expression of immune genes.

The Strong Anti-Kinetoplastid Properties of Bee Propolis: Composition and Identification of the Active Agents and Their Biochemical Targets

The kinetoplastids are protozoa characterized by the presence of a distinctive organelle, called the kinetoplast, which contains a large amount of DNA (kinetoplast DNA (kDNA)) inside their single mitochondrion. Kinetoplastids of medical and veterinary importance include Trypanosoma spp. (the causative agents of human and animal African Trypanosomiasis and of Chagas disease) and Leishmania spp. (the causative agents of the various forms of leishmaniasis). These neglected diseases affect millions of people across the globe, but drug treatment is hampered by the challenges of toxicity and drug resistance, among others. Propolis (a natural product made by bees) and compounds isolated from it are now being investigated as novel treatments of kinetoplastid infections. The anti-kinetoplastid efficacy of propolis is probably a consequence of its reported activity against kinetoplastid parasites of bees. This article presents a review of the reported anti-kinetoplastid potential of propolis, highlighting its anti-kinetoplastid activity in vitro and in vivo regardless of geographical origin. The mode of action of propolis depends on the organism it is acting on and includes growth inhibition, immunomodulation, macrophage activation, perturbation of the cell membrane architecture, phospholipid disturbances, and mitochondrial targets. This gives ample scope for further investigations toward the rational development of sustainable anti-kinetoplastid drugs.

Modulating Laying Hens Productivity and Immune Performance in Response to Oxidative Stress Induced by E. coli Challenge Using Dietary Propolis Supplementation

Propolis (PR) is a resin product of bee colonies that has rich bioactive antioxidant and bactericidal compounds. Endotoxin, a byproduct of bacterial growth, is reported to cause progressive induction of endogenous oxidative stress and has negative impacts on individual health and wellbeing. Hereby, we investigated the ability of PR to alleviate the oxidative stress and immunosuppression imposed by avian pathogenic Escherichia coli using laying hen as a based model. In this study, PR was dietary supplemented to hens for 4 weeks at a concentration of 0.1%. At the beginning of the 4th week of the experiment, hens from control and PR treatment were injected with E. coli (O157:H7; 107 colonies/hen) or saline. The results showed significant (p < 0.05) negative impact of E. coli challenge on antioxidant status, immune response and productive performance. PR supplementation reduced (p < 0.05) inflammation markers levels (tumor necrosis factor α (TNFα) and interleukin 1β (IL-1β)) and plasma corticosterone concentration. The antioxidant status was ameliorated with dietary PR supplementation to challenged hens, showing significant (p < 0.05) reduction in malondialdehyde (MDA) levels and increasing total antioxidant capacity (TAC) concentrations. Cell mediated, as well as, humeral immune response improved significantly (p < 0.05) with dietary PR verified by the enhancement of T- and B-lymphocyte proliferation and the positive respond to phytohemagglutinin (PHA). Leucocyte cells viability increased significantly and the apoptotic factor forkhead box O3 (Foxo3) was reduced with PR supplementation. The current study revealed that dietary PR supplementation can effectively be used as an organic feed additive to overcome the endogenous oxidative stress induced by endotoxins challenge.

Propolis as a novel antibacterial agent

Propolis (bee glue) is a bee glue, sticky resinous material released from various plant sources such as bud exudates, flowers, and leaves modified by bee secretions and wax propolis is composed of resins, waxes, polyphenols, polysaccharides, volatile materials, and secondary metabolites that are responsible for various bioactivity such as antibacterial, anti-angiogenic, antiulcer, anti-inflammatory, antioxidant, and anti-viral activities. The physico-chemical characteristics and the natural properties of various kinds of propolis have been studied for the past decade. Novel active anti-microbial compounds have been identified in propolis. Those compounds positively modulated the antimicrobial resistance of multidrug resistant bacteria. Published research has indicated that propolis and its derivatives has many natural antimicrobial compounds with a broad spectrum against different types of bacteria and that it enhanced the efficacy of conventional antibiotics. Besides, the combination of propolis with other compounds such as honey has been studied whereby, such combinations have a synergistic effect against bacterial strains such as Escherichia coli and Staphylococcus aureus. The activity of propolis is very much dependent on seasonal and regional factors, and Middle Eastern propolis have shown best antibacterial efficacy. Propolis and its main flavonoids ingredients should not be overlooked and should be evaluated in clinical trials to better elucidate their potential application in various fields of medicine. Clinical antibacterial potential and its use in new drugs of biotechnological products should be conducted. This review aims at highlighting some of the recent scientific findings associated with the antibacterial properties of propolis and its components.

Does propolis affect the quality of life and complications in subjects with irritable bowel syndrome (diagnosed with Rome IV criteria)? A study protocol of the randomized, double-blinded, placebo-controlled clinical trial

BACKGROUND

Irritable bowel syndrome (IBS) is one of the most frequent and recurrent gastrointestinal diseases. However, up to now, no pharmacological agent has been approved to treat IBS. Emerging evidence showed that inflammation has a vital role in enhancing nervous system sensitivity and perception of abdominal pain in subjects with IBS. Propolis is an herbal substance with a broad spectrum of antioxidants, anti-inflammatory, and prebiotic properties, which might exert beneficial effects to reduce the severity of IBS. The current clinical trial aims to evaluate the efficacy of propolis supplementation on IBS.

METHODS

This single-center, randomized, double-blind, placebo-controlled clinical trial will be performed to evaluate the effect of propolis supplementation in adult patients with IBS diagnosed with Rome IV criteria. Fifty-two eligible patients will randomly be allocated to receive a propolis tablet (450 mg, containing 100 mg polyphenol compounds) or identical placebo, twice daily for 6 weeks. The primary outcome of the trial is an improvement in IBS severity from baseline to the sixth week of intervention. The secondary outcomes include the change in weight, waist circumference, and IBS quality of life. We will use the paired sample t test or Mann-Whitney U test for the within-group comparison and independent sample t test or Wilcoxon rank-sum and chi-square test or Fisher's exact test for the between-group comparison. Besides, a multivariable-adjusted mean effect will be computed using the ANCOVA test.

DISCUSSION

We hypothesize that propolis supplementation would be useful for treating IBS through its antioxidants, anti-inflammatory, and prebiotic properties. This trial will show the results of propolis supplementation, whether positive or negative, on IBS. If the current trial confirms our hypothesis, propolis supplementation can be a new choice in adjunctive therapy of IBS.

TRIAL REGISTRATION

Iranian Registry of Clinical Trials IRCT20190708044154N1. Registered on 26 December 2019. Updated on 13 February 2020. https://en.irct.ir/trial/40983 SPONSOR: Tabriz University of Medical Sciences, Tabriz, Iran.

North American Propolis Extracts From Upstate New York Decrease Nosema ceranae (Microsporidia) Spore Levels in Honey Bees (Apis mellifera)

Nosema ceranae infections in honey bees (Apis mellifera) pose a severe threat to colony health. Beekeepers have used dicyclohexylammonium fumagillin to control Nosema apis, although it may be ineffective against N. ceranae. We investigated the ability of various propolis extracts collected from Upstate New York (United States) to decrease in vivo N. ceranae infection levels when fed ad libitum to N. ceranae-infected honey bees. Propolis extracts, most notably a dichloromethane extract, significantly lowered spore levels in a dose-dependent fashion 4 days post inoculation. When testing the in vitro anti-Nosema activity of propolis extracts, we report for the first time that spore viability was unaffected after a 24 h exposure to propolis extracts. These results present evidence that propolis extracts may effectively lower Microsporidia infections in honey bees, and that direct exposure of environmental spores to propolis alone does not kill N. ceranae.

Significance of Apoidea as Main Pollinators. Ecological and Economic Impact and Implications for Human Nutrition

Wild and managed bees provide pollination services to crops and wild plants, as well as a variety of other services beneficial to humans. Honey bees are the most economically valuable pollinator worldwide. It has been calculated that 9.5% of the total economic value of agricultural production comes from insect pollination, thus amounting to just under USD 200 billion globally. More than 100 important crops depend on pollination by honey bees. The latter pollinate not only a wide number of commercial crops but also many wild plants, some of which are threatened by extinction and constitute a valuable genetic resource. Moreover, as pollinators, honey bees play a significant role in every aspect of the ecosystem by facilitating the growth of trees, flowers, and other plants that serve as food and shelter for many large and small creatures. In this paper, we describe how the reduction in honey bee populations affects various economic sectors, as well as human health.

Applying GC-MS analysis to identify chemical composition of Iranian propolis prepared with different solvent and evaluation of its biological activity

Background:

Propolis as a natural product has shown beneficial effects on human health. This study was aimed to investigate the chemical compositions and biological activity of three different extracts of propolis from two distinct geographic areas in Iran.

Methods:

The chemical composition of Iranian propolis extracts that were collected in the Spring of 2016 from two provinces in northern Iran: Ardabil and Polur in Mazandaran Province were measured through gas chromatography-mass spectrometry (GC-MS) methods. In addition, antimicrobial activity and cytotoxicity effect on HN5 and LNCaP cell lines were evaluated. The data were analyzed using one-way ANOVA and p<0.05 was considered as significant.

Results:

The GC-MS analysis identified the presence of compounds that belonged to the different groups such as aromatics acids and their related esters, flavonoid and flavonoid derivatives and terpenes. Flavanone was the most dominant compound of flavonoids. The maximum growth inhibition was observed against S. aureus of ethanolic extract of propolis (p<0.05). Moreover, cytotoxicity showed that ethanolic and dichloromethane extracts had more inhibitory effects on cell lines than the water extract.

Conclusion:

The results determined that extracts had the highest percentage of flavonoids. Therefore, it is expected that the synergistic effect of the main components of propolis is related to the increase of biological activity of propolis.

Propolis hosts a diversemicrobial community

Despite the deep knowledge of the honey bee (Apis mellifera) gut microbiome, information on the microbial communities of other hive components is still scarce. Propolis originates from a natural resinous mixture that honeybees collect from different plants sources and modify; it is used mainly to ensure the hygiene of the hive. By virtue of its antimicrobial properties, propolis has been considered relatively aseptic, yet its ability to harbor microorganisms has not been previously investigated. In this study we report the first description of the diversity of the microbial community of propolis by both targeted-metagenomics analysis and cultivation. We demonstrated that propolis hosts a variety of microbial strains belonging to taxa already described in other hive components. Some of them are cultivable in standard laboratory conditions, and show metabolic characteristics compatible with their persistence in different physiological states inside propolis. Isolated bacteria produce antimicrobials against Gram-negative and Gram-positive bacteria, and entomopathogenic fungi, with different spectra of inhibition. Metagenomics analysis shows the presence of bacteria and fungi with great potential to outcompete potentially harmful microorganisms. These findings suggest that the characterized microbiota could contribute to the overall antimicrobial properties of propolis and to its ecological role as "disinfectant" within the hive.

Temperate Agroforestry Systems and Insect Pollinators: A Review

Agroforestry can provide ecosystem services and benefits such as soil erosion control, microclimate modification for yield enhancement, economic diversification, livestock production and well-being, and water quality protection. Through increased structural and functional diversity in agricultural landscapes, agroforestry practices can also affect ecosystem services provided by insect pollinators. A literature review was conducted to synthesize information on how temperate agroforestry systems influence insect pollinators and their pollination services with particular focus on the role of trees and shrubs. Our review indicates that agroforestry practices can provide three overarching benefits for pollinators: (1) providing habitat including foraging resources and nesting or egg-laying sites, (2) enhancing site and landscape connectivity, and (3) mitigating pesticide exposure. In some cases, agroforestry practices may contribute to unintended consequences such as becoming a sink for pollinators, where they may have increased exposure to pesticide residue that can accumulate in agroforestry practices. Although there is some scientific evidence suggesting that agroforestry practices can enhance crop pollination and yield, more research needs to be conducted on a variety of crops to verify this ecosystem service. Through a more comprehensive understanding of the effects of agroforestry practices on pollinators and their key services, we can better design agroforestry systems to provide these benefits in addition to other desired ecosystem services.

Antimicrobial potentials of medicinal plant's extract and their derived silver nanoparticles: A focus on honey bee pathogen

Infectious (or Communicable) diseases are not only the past but also the present problem in developing as well as developed countries. It is caused by various pathogenic microbes like fungi, bacteria, parasites and virus etc. The medicinal plants and nano-silver have been used against the pathogenic microbes. Herbal medicines are generally used for healthcare because they have low price and wealthy source of antimicrobial properties. Like medicinal plants, silver nanoparticles also have emergent applications in biomedical fields due to their immanent therapeutic performance. Here, we also explore the various plant parts such as bark, stem, leaf, fruit and seed against Gram negative and Gram-positive bacteria, using different solvents for extraction i.e. methanol, ethyl acetate, chloroform, acetone, n. hexane, butanol, petroleum ether and benzene. Since ancient to date most of the countries have been used herbal medicines, but in Asia, some medicinal plants are commonly used in rural and backward areas as a treatment for infectious diseases. In this review, we provide simple information about medicinal plants and Silver nanoparticles with their potentialities such as antiviral, bactericidal and fungicidal. Additionally, the present review to highlights the versatile applications of medicinal plants against honey bee pathogen such as fungi (Ascosphaera apis), mites (Varroa spp. and Tropilaelaps sp.), bacteria (Melissococcus plutonius Paenibacillus larvae), and microsporidia (Nosema apis and Nosema ceranae). In conclusion, promising nonchemical (plant extracts) are innocuous to adult bees. So, we strongly believed that this effort was made to evaluate the status of medicinal plants researches globally.