Effects of Supplemental Pollen Feeding on Honey Bee (Hymenoptera: Apidae) Colony Strength and Nosema spp. Infection

High Rates of Honey Bee Colony Losses and Regional Variability in Ethiopia Based on the Standardised COLOSS 2023 Survey

The COLOSS research association has been assessing honey bee colony losses, associated risk factors and management, focusing on Western countries but with a progressive international expansion. Here, we report the first survey on the loss rates of colonies in 2022/2023 in Ethiopia using COLOSS monitoring survey tools. A face-to-face interview questionnaire survey was conducted on 64 beekeepers selected from Oromia and Tigray regions. This covered 1713 honey bee colonies distributed in 68 apiaries. The percentages of colonies lost were significantly different between Oromia (24.1%) and Tigray (66.4%) regions. Colony losses were attributed as unsolvable queen problems (8% in Oromia; 10% in Tigray), natural disaster (32%; 82%), and empty hives or dead colonies (60%; 8%). The loss rate was significantly affected by queen replacement (p < 0.0001), use of natural comb (p < 0.0001), feed supplementation (p < 0.0001), region (p < 0.0001), varroa treatment (p < 0.0001), colony splitting (p < 0.01), and merging (p < 0.01). Beekeepers in Oromia managed more colonies and implemented improved practices compared to those in Tigray. However, all beekeepers in Oromia detected at least some bees with signs of deformed wing virus, compared to 76% of beekeepers in Tigray. In conclusion, the colony loss rate was significantly different between Oromia and Tigray regions due to differences in natural disasters, management, environment and health factors.

Neonicotinoid exposure increases Varroa destructor (Mesostigmata: Varroidae) mite parasitism severity in honey bee colonies and is not mitigated by increased colony genetic diversity

Agrochemical exposure is a major contributor to ecological declines worldwide, including the loss of crucial pollinator species. In addition to direct toxicity, field-relevant doses of pesticides can increase species' vulnerabilities to other stressors, including parasites. Experimental field demonstrations of potential interactive effects of pesticides and additional stressors are rare, as are tests of mechanisms via which pollinators tolerate pesticides. Here, we controlled honey bee colony exposure to field-relevant concentrations of 2 neonicotinoid insecticides (clothianidin and thiamethoxam) in pollen and simultaneously manipulated intracolony genetic heterogeneity. We showed that exposure increased rates of Varroa destructor (Anderson and Trueman) parasitism and that while increased genetic heterogeneity overall improved survivability, it did not reduce the negative effect size of neonicotinoid exposure. This study is, to our knowledge, the first experimental field demonstration of how neonicotinoid exposure can increase V. destructor populations in honey bees and also demonstrates that colony genetic diversity cannot mitigate the effects of neonicotinoid pesticides.

The effects of protein supplementation, fumagillin treatment, and colony management on the productivity and long-term survival of honey bee (Apis mellifera) colonies

In this study, we intensively measured the longitudinal productivity and survival of 362 commercially managed honey bee colonies in Canada, over a two-year period. A full factorial experimental design was used, whereby two treatments were repeated across apiaries situated in three distinct geographic regions: Northern Alberta, Southern Alberta and Prince Edward Island, each having unique bee management strategies. In the protein supplemented treatment, colonies were continuously provided a commercial protein supplement containing 25% w/w pollen, in addition to any feed normally provided by beekeepers in that region. In the fumagillin treatment, colonies were treated with the label dose of Fumagilin-B® each year during the fall. Neither treatment provided consistent benefits across all sites and dates. Fumagillin was associated with a large increase in honey production only at the Northern Alberta site, while protein supplementation produced an early season increase in brood production only at the Southern Alberta site. The protein supplement provided no long-lasting benefit at any site and was also associated with an increased risk of death and decreased colony size later in the study. Differences in colony survival and productivity among regions, and among colonies within beekeeping operations, were far larger than the effects of either treatment, suggesting that returns from extra feed supplements and fumagillin were highly contextually dependent. We conclude that use of fumagillin is safe and sometimes beneficial, but that beekeepers should only consider excess protein supplementation when natural forage is limiting.

The microbiome and gene expression of honey bee workers are affected by a diet containing pollen substitutes

Pollen is the primary source of dietary protein for honey bees. It also includes complex polysaccharides in its outer coat, which are largely indigestible by bees but can be metabolized by bacterial species within the gut microbiota. During periods of reduced availability of floral pollen, supplemental protein sources are frequently provided to managed honey bee colonies. The crude proteins in these supplemental feeds are typically byproducts from food manufacturing processes and are rarely derived from pollen. Our experiments on the impact of different diets showed that a simplified pollen-free diet formulated to resemble the macronutrient profile of a monofloral pollen source resulted in larger microbial communities with reduced diversity, reduced evenness, and reduced levels of potentially beneficial hive-associated bacteria. Furthermore, the pollen-free diet sharply reduced the expression of genes central to honey bee development. In subsequent experiments, we showed that these shifts in gene expression may be linked to colonization by the gut microbiome. Lastly, we demonstrated that for bees inoculated with a defined gut microbiota, those raised on an artificial diet were less able to suppress infection from a bacterial pathogen than those that were fed natural pollen. Our findings demonstrate that a pollen-free diet significantly impacts the gut microbiota and gene expression of honey bees, indicating the importance of natural pollen as a primary protein source.

Honey Bees Prefer Pollen Substitutes Rich in Protein Content Located at Short Distance from the Apiary

The availability of floral resources is crucial for honey bee colonies because it allows them to obtain protein from pollen and carbohydrates from nectar; typically, they consume these nutrients in the form of bee bread, which has undergone fermentation. However, the intensification of agriculture, urbanization, changes to the topography, and harsh environmental conditions are currently impacting foraging sites due to habitat loss and scarcity of food resources. Thus, this study aimed to assess honey bee preference for various pollen substitute diet compositions. Bee colonies perform poorly because of specific environmental problems, which ultimately result in pollen scarcity. Pollen substitutes located at various distance from the bee hive were also investigated in addition to determining the preferences of honey bees for various pollen substitute diets. The local honey bee (Apis mellifera jemenitica) colonies and different diets (four main treatments, namely, chickpea flour, maize flour, sorghum flour, wheat flour; each flour was further mixed with cinnamon powder, turmeric powder, flour only, flour mixed with both cinnamon and turmeric powder) were used. Bee pollen was used as a control. The best performing pollen substitutes were further placed at 10, 25, and 50 m distances from the apiary. Maximum bee visits were observed on bee pollen (210 ± 25.96) followed by chickpea flour only (205 ± 19.32). However, there was variability in the bee visits to the different diets (F (16,34) = 17.91; p < 0.01). In addition, a significant difference in diet consumption was observed in control (576 ± 58.85 g) followed by chickpea flour only (463.33 ± 42.84 g), compared to rest of the diets (F (16,34) = 29.75; p < 0.01). Similarly, foraging efforts differed significantly (p < 0.01) at the observed time of 7-8 A.M., 11-12 A.M., and 4-5 P.M. at the distance of 10, 25, and 50 m away from the apiary. Honey bees preferred to visit the food source that was closest to the hive. This study should be very helpful for beekeepers in supplementing their bee colonies when there is a shortage or unavailability of pollens, and it is much better to keep the food source near the apiary. Future research needs to highlight the effect of these diets on bee health and colony development.

The impact of mass-flowering crops on bee pathogen dynamics

Nearly two fifths of the Earth's land area is currently used for agriculture, substantially impacting the environment and ecosystems. Besides the direct impact through land use change, intensive agriculture can also have an indirect impact, for example by changing wildlife epidemiology. We review here the potential effects of mass-flowering crops (MFCs), which are rapidly expanding in global cropping area, on the epidemiology of known pathogens in bee pollinators. We bring together the fifty MFCs with largest global area harvested and give an overview of their pollination dependency as well as their impact on bee pollinators. When in bloom these crops provide an abundance of flowers, which can provide nutrition for bees and increase bee reproduction. After their short bloom peak, however, the fields turn into green deserts. These big changes in floral availability strongly affect the plant-pollinator network, which in turn affects the pathogen transmission network, mediated by shared flowers. We address this dual role of flowers provided by MFCs, serving as nutritional resources as well as pathogen transmission spots, and bring together the current knowledge to assess how MFCs could affect pathogen prevalence in bee pollinator communities.

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MFC can greatly differ in nutritional quality and availability for bees.

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MFC can alter the pathogen transmission network of bees.

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MFC can abruptly alter the nutritional landscape during bloom and after.

The Effect of Supplementary Feeding with Different Pollens in Autumn on Colony Development under Natural Environment and In Vitro Lifespan of Honey Bees

Honey bees need pollen and nectar sources to survive in nature. Particularly, having young bees in colonies is vital before wintering, and proper feeding is necessary to achieve this. In the present study, the effect of feeding with pollen sources of different protein content on colony performance, wintering ability and in-vitro longevity of colonies that weakened after feeding with pine honey in autumn, or that needed to enter the winter period, was investigated. The experiment was carried out in 48 colonies divided into six groups as follows: control, syrup, mixed pollen, Cistus creticus pollen (Pink rock-rose), Papaver somniferum pollen (Opium poppy), and commercial bee cake groups. In particular, the P. somniferum pollen group was different (p < 0.01) from the other experiment groups with the number of bee frames (3.44), the area with brood (1184.14 cm2) and the wintering ability of 92.19%. The effect of nutritional differences on survival was found to be statistically significant in vitro and this supports the colony results in the natural environment (p < 0.001). The P. somniferum group has the longest longevity with 23 days. Pollen preferences of honey bees were P. somniferum, C. creticus, and mixed pollen, respectively.

Frontiers in effective control of problem parasites in beekeeping

Demand for better control of certain parasites in managed western honey bees (Apis mellifera L.) remains apparent amongst beekeepers in both Europe and North America, and is of widespread public, scientific, and agricultural concern. Academically, interest from numerous fields including veterinary sciences has led to many exemplary reviews of the parasites of honey bees and the treatment options available. However, summaries of current research frontiers in treating both novel and long-known parasites of managed honey bees are lacking. This review complements the currently comprehensive body of literature summarizing the effectiveness of parasite control in managed honey bees by outlining where significant gaps in development, implementation, and uptake lie, including integration into IPM frameworks and separation of cultural, biological, and chemical controls. In particular, I distinguish where challenges in identifying appropriate controls exist in the lab compared to where we encounter hurdles in technology transfer due to regulatory, economic, or cultural contexts. I overview how exciting frontiers in honey bee parasite control research are clearly demonstrated by the abundance of recent publications on novel control approaches, but also caution that temperance must be levied on the applied end of the research engine in believing that what can be achieved in a laboratory research environment can be quickly and effectively marketed for deployment in the field.

Effects of different artificial diets on commercial honey bee colony performance, health biomarkers, and gut microbiota

Background

Honey bee colonies managed for agricultural pollination are highly dependent on human inputs, especially for disease control and supplemental nutrition. Hives are routinely fed artificial “pollen substitute” diets to compensate for insufficient nutritional forage in the environment. The aim of this study was to investigate the effects of different artificial diets in a northern California, US commercial beekeeping operation from August through February. This time period represents an extended forage dearth when supplemental nutrition is used to stimulate late winter colony growth prior to almond pollination in the early spring. A total of 144 honey bee colonies were divided into 8 feeding groups that were replicated at three apiary sites. Feeding groups received commercial diets (Global, Ultra Bee, Bulk Soft, MegaBee, AP23, Healthy Bees), a beekeeper-formulated diet (Homebrew), or a sugar negative control. Diets were analyzed for macronutrient and amino acid content then evaluated with respect to honey bee colony population size, average bee weight, nutrition-related gene expression, gut microbiota abundance, and pathogen levels.

Results

Replicated at three apiary sites, two pollen-containing diets (Global and Homebrew) produced the largest colonies and the heaviest bees per colony. Two diets (Bulk Soft and AP23) that did not contain pollen led to significantly larger colonies than a sugar negative control diet. Diet macronutrient content was not correlated with colony size or health biomarkers. The sum of dietary essential amino acid deficiencies relative to leucine content were correlated with average bee weight in November and colony size used for almond pollination in February. Nutrition-related gene expression, gut microbiota, and pathogen levels were influenced by apiary site, which overrode some diet effects. Regarding microbiota, diet had a significant impact on the abundance of Bifidobacterium and Gilliamella and trended towards effects on other prominent bee gut taxa.

Conclusions

Multiple colony and individual bee measures are necessary to test diet efficacy since honey bee nutritional responses are complex to evaluate. Balancing essential amino acid content relative to leucine instead of tryptophan may improve diet protein efficiency ratios. Optimization of bee diets could improve feed sustainability and agricultural pollination efficiency by supporting larger, healthier honey bee colonies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12917-022-03151-5.

Reviewing the Efficacy of Pollen Substitutes as a Management Tool for Improving the Health and Productivity of Western Honey Bee (Apis mellifera) Colonies

Western honey bees (Apis mellifera L.) collect pollen from flowers as their source of protein, fat, vitamins, and minerals. Beekeepers feed pollen substitutes to their honey bee colonies to mitigate a lack of natural pollen resources in the environment. Despite their widespread use, it is unclear if pollen substitutes are beneficial to colony health and productivity. Herein, we review the literature regarding pollen substitute efficacy in four major categories: (1) consumption/palatability of pollen substitutes, (2) colony productivity, (3) pest and disease response, and (4) physiological response. Collectively, the literature shows a mix of positive, neutral, and negative impacts of pollen substitutes on honey bee colony health. Additionally, we recommend areas for improvement in pollen substitute research. We hope this review will lead to more research on pollen substitutes given nutrition is a key factor impacting the health of managed honey bees globally.

Tracing the Fate of Pollen Substitute Patties in Western Honey Bee (Hymenoptera: Apidae) Colonies

Commercial beekeepers need healthy, productive honey bee (Apis mellifera L.) colonies, even when the landscape lacks adequate pollen forage to sustain the colonies. As a result, many commercial beekeepers spend significant money and labor on the use of pollen substitutes in their colonies. However, there is little consensus in the literature about the benefits and drawbacks of pollen substitute use on honey bee colony health. In order to understand this critically, it is important to know first how honey bees distribute pollen substitute patties throughout their colonies. We traced the fate of three commercially available pollen substitute patties (MegaBee, UltraBee, AP23) dyed with a nontoxic food coloring (Brilliant Blue FCF) and undyed as negative controls, a dyed positive control (fondant), and a dyed consumption control (Crayola Model Magic Clay) in 44 honey bee colonies. Using spectrophotometry and visual inspection, we analyzed adult bee guts, larval guts, bee bread stores and colony debris underneath the hive for presence of the dye. Our data suggest that (1) a proportion of adult bees ingest the patty, (2) adult bees likely do not feed patty directly to larvae, (3) adult bees do not store patty like bee bread, and (4) only a very small proportion of patty is lost as debris. Collectively our data suggest that honey bee colonies use pollen substitute patties. However, patties likely do not replace the function of natural pollen entirely in terms of larval provisioning and long-term storage as bee bread.

Harvest Season Significantly Influences the Fatty Acid Composition of Bee Pollen

Simple Summary

Harvesting pollen loads collected from a specific botanical origin is a complicated process that takes time and effort. Therefore, we aimed to determine the optimal season for harvesting pollen loads rich in essential fatty acids (EFAs) and unsaturated fatty acids (UFAs) from the Al-Ahsa Oasis in eastern Saudi Arabia. Pollen loads were collected throughout one year, and the tested samples were selected during the top collecting period in each season. Lipids and fatty acid composition were determined. The highest values of lipids concentration, linolenic acid (C_18:3), stearic acid (C_18:0), linoleic acid (C_18:2), arachidic acid (C_20:0) concentrations, and EFAs were obtained from bee pollen harvested during autumn. The maximum values (%) of oleic acid (C_18:1), palmitic acid (C_16:0), UFAs, and the UFA/saturated fatty acid (SFA) ratio were found in bee pollen harvested during summer. Bee pollen harvested during spring ranked second in its oleic, palmitic, linolenic, stearic, arachidic, behenic, and lignoceric acid concentrations and for EFAs, UFAs, and the UFA/SFA ratio. It was concluded that the FA composition of bee pollen varied among the harvest seasons. We recommend harvesting pollen loads during spring and summer to feed honeybee colonies during periods of scarcity and for use as a healthy, nutritious food for humans.

Abstract

Seasonal variations in the fatty acid (FA) compositions of pollen loads collected from the Al-Ahsa Oasis in eastern Saudi Arabia throughout one year were determined to identify the optimal season for harvesting bee pollen rich in essential fatty acids (EFAs) and unsaturated fatty acids (UFAs). The highest values (%) of lipids, linolenic acid (C_18:3), stearic acid (C_18:0), linoleic acid (C_18:2), arachidic acid (C_20:0), the sum of the C18:0, C18:1, C18:2, and C18:3 concentrations, and EFAs were obtained from bee pollen harvested during autumn. The maximum values (%) of oleic acid (C_18:1), palmitic acid (C_16:0), UFAs, and the UFA/saturated fatty acid (SFA) ratio were found in bee pollen harvested during summer. The highest concentrations (%) of behenic acid (C_22:0), lignoceric acid (C_24:0), and SFAs were found in bee pollen harvested during winter. Bee pollen harvested during spring ranked second in its oleic, palmitic, linolenic, stearic, arachidic, behenic, and lignoceric acid concentrations and for EFAs, UFAs, and the UFA/SFA ratio. The lowest SFA concentration was found in bee pollen harvested during summer. Oleic, palmitic, and linolenic acids were the most predominant FAs found in bee pollen. It was concluded that the FA composition of bee pollen varied among the harvest seasons due to the influence of the dominant botanical origins. We recommend harvesting pollen loads during spring and summer to feed honeybee colonies during periods of scarcity and for use as a healthy, nutritious food for humans.

Pollen protein and lipid content influence resilience to insecticides in honey bees (Apis mellifera)

In honey bees (Apis mellifera), there is growing evidence that the impacts of multiple stressors can be mitigated by quality nutrition. Pollen, which is the primary source of protein and lipids in bees diets, is particularly critical for generating more resilient phenotypes. Here, we evaluate the relationship between pollen protein-to-lipid ratios (P:Ls) and honey bee insecticide resilience. We hypothesized that pollen diets richer in lipids would lead to increased survival in bees exposed to insecticides, as pollen-derived lipids have previously been shown to improve bee resilience to pathogens and parasites. Furthermore, lipid metabolic processes are altered in bees exposed to insecticides.We fed age-matched bees pollen diets of different P:Ls by altering a base pollen by either adding protein (casein powder) or lipids (canola oil) and simulating chronic insecticide exposure by feeding bees an organophosphate (Chlorpyrifos). We also tested pollen diets of naturally different P:Ls to determine if results are consistent. Linear regression analysis revealed that mean survival time for altered diets was best explained by protein concentration (p =0.04 , adjusted R2 =0.92), and that mean survival time for natural diets was best explained by P:L ratio (p =0.008 , adjusted R2 =0.93). Our results indicate that higher ratios of dietary protein to lipid has a negative effect on bee physiology when combined with insecticide exposure, while lower ratios have a positive effect. These results suggest that protein and lipid intake differentially influence insecticide response in bees, laying the groundwork for future studies of metabolic processes and development of improved diets.

The Herbal Supplements NOZEMAT HERB® and NOZEMAT HERB PLUS®: An Alternative Therapy for N. ceranae Infection and Its Effects on Honey Bee Strength and Production Traits

Honey bees (Apis mellifera L.) are the most effective pollinators for different crops and wild flowering plants, thus maintaining numerous ecosystems in the world. However, honey bee colonies often suffer from stress or even death due to various pests and diseases. Among the latter, nosemosis is considered to be one of the most common diseases, causing serious damage to beekeeping every year. Here, we present, for the first time, the effects from the application of the herbal supplements NOZEMAT HERB^® (NH) and NOZEMAT HERB PLUS^® (NHP) for treating N. ceranae infection and positively influencing the general development of honey bee colonies. To achieve this, in autumn 2019, 45 colonies were selected based on the presence of N. ceranae infections. The treatment was carried out for 11 months (August 2019–June 2020). All colonies were sampled pre- and post-treatment for the presence of N. ceranae by means of light microscopy and PCR analysis. The honey bee colonies’ performance and health were evaluated pre- and post-treatment. The obtained results have shown that both supplements have exhibited statistically significant biological activity against N. ceranae in infected apiaries. Considerable enhancement in the strength of honey bee colonies and the amount of sealed workers was observed just one month after the application of NH and NHP. Although the mechanisms of action of NH and NHP against N. ceranae infection are yet to be completely elucidated, our results suggest a new holistic approach as an alternative therapy to control nosemosis and to improve honey bee colonies’ performance and health.

Prioritizing changes in management practices associated with reduced winter honey bee colony losses for US beekeepers

Beekeepers attempt to manage their honey bee colonies in ways that optimize colony health. Disentangling the impact of management from other variables affecting colony health is complicated by the diversity of practices used and difficulties handling typically complex and incomplete observational datasets. We propose a method to 1) compress multi-factored management data into a single index, to holistically investigate the real world impact of management on colony mortality, and 2) simplify said index to identify the core practices for which a change in behavior is associated with the greatest improvement in survivorship. Experts scored the practices of US beekeepers (n = 18,971) documented using four years of retrospective surveys (2012-2015). Management Index scores significantly correlated with loss rates, with beekeepers most in line with recommendations suffering lower losses. The highest ranked practices varied by operation type, as recommendations accounted for the current prevalence of practices. These results validate experts' opinion using empirical data, and can help prioritize extension messages. Improving management will not prevent all losses; however, we show that few behavioral changes (in particular related to comb management, sources of new colonies and Varroa management) can lead to a non-negligible reduction in risk.

Impact of Protoporphyrin Lysine Derivatives on the Ability of Nosema ceranae Spores to Infect Honeybees

Simple Summary

Honeybees, which are important for the development and maintenance of natural ecosystems, are infected by microsporidia, Nosema apis and N. ceranae. These parasites induce a disease named nosemosis contributing to the impairment of digestion and nutrient absorption, ultimately leading to total colony collapse. The need for research into the control of N. ceranae has become increasingly important. Promising compounds for the treatment of nosemosis are porphyrins. In the present study, we examined the effects of three different porphyrins on the infectivity of N. ceranae microsporidia. A significantly lower level of infection was observed in the bees infected with the porphyrin-treated spores than in the control bees (infected with untreated spores). We showed that protoporphyrin lysine derivatives in particular prevented the development of Nosema spores and simultaneously extended bee life spans (up to 50%). The results also indicate that these porphyrins may contribute to the reduction in digestive nutrient absorption disorders in bees. The present findings can be used to develop a new class of drugs for combating nosemosis. These compounds may serve as preventive or disinfection agents through direct inactivation of Nosema both in the midgut and outside the host body, i.e., in the hive.

Abstract

The effect of two protoporphyrin IX derivatives conjugated with single (PP[Lys(TFA)-OH)]₂) or double (PP[Lys(TFA)-Lys(TFA)-OH]₂) lysine moieties on the infectious capacity of Nosema ceranae spores was examined, and their efficacies were compared with those of a cationic porphyrin (H₂TTMePP). Honeybees were inoculated with spores preincubated with porphyrins or with untreated spores (control). A significantly lower level of infection was observed in the bees infected with the porphyrin-treated spores than in the infected control. Porphyrins 1 and 2 reduced the infectious capability of microsporidia more efficiently than porphyrin 3, with bee mortality declining to almost 50%. Confocal analysis of the midguts of infected bees revealed distinct differences in the number of spores between the control group and the group infected with PP[Lys(TFA)-Lys(TFA)-OH]₂-treated spores. Notably, bees with a reduced level of infection consumed less sucrose syrup than the control bees, indicating a reduction in digestive disorders and an improvement in food absorption.

Missing Microbes in Bees: How Systematic Depletion of Key Symbionts Erodes Immunity

Pesticide exposure, infectious disease, and nutritional stress contribute to honey bee mortality and a high rate of colony loss. This realization has fueled a decades-long investigation into the single and combined effects of each stressor and their overall bearing on insect physiology. However, one element largely missing from this research effort has been the evaluation of underlying microbial communities in resisting environmental stressors and their influence on host immunity and disease tolerance. In humans, multigenerational bombardment by antibiotics is linked with many contemporary diseases. Here, we draw a parallel conclusion for the case in honey bees and suggest that chronic exposure to antimicrobial xenobiotics can systematically deplete honey bees of their microbes and hamper cross-generational preservation of host-adapted symbionts that are crucial to health.

Macro- and trace elements content in honeybee pollen loads in relation to the harvest season

The content of macro-and trace elements in honeybee pollen loads collected from the Al-Ahsa oasis, Saudi Arabia during spring, summer, autumn, and winter in 2018/2019 were determined. After critical screening and observation, we found that the major pollen floral resources were rapeseed, sunflower, summer squash, and date palm. The highest values of sodium (Na), potassium (K), calcium (Ca), magnesium (Mg), phosphorus (P) and manganese (Mn) were found in pollen loads trapped during spring and winter. The highest levels of copper (Cu) and iron (Fe) were found from pollen loads harvested during autumn, while the highest content of zinc (Zn) was found in pollen loads collected during the summer. Higher concentrations of the essential elements (Na, K, Ca, Mg and P) for human nutrition found in pollen loads collected during the spring and winter seasons, make them valuable food supplements. Finally, the elements contained in pollen loads can be related to the season of pollen load collection.

Nutritional status of honey bee (Apis mellifera L.) workers across an agricultural land-use gradient

Land use, habitat, and forage quality have emerged as critical factors influencing the health, productivity, and survival of honey bee colonies. However, characterization of the mechanistic relationship between differential land-use conditions and ultimate outcomes for honey bee colonies has been elusive. We assessed the physiological health of individual worker honey bees in colonies stationed across a gradient of agricultural land use to ask whether indicators of nutritional physiology including glycogen, total sugar, lipids, and protein were associated with land-use conditions over the growing season and colony population size the subsequent spring during almond pollination. Across the observed land-use gradient, we found that September lipid levels related to growing-season land use, with honey bees from apiaries surrounded by more favorable land covers such as grassland, pasture, conservation land, and fallow fields having greater lipid reserves. Further, we observed a significant relationship between total protein during September and population size of colonies during almond pollination the following February. We demonstrate and discuss the utility of quantifying nutritional biomarkers to infer land-use quality and predict colony population size.

Scientific Advances in Controlling Nosema ceranae (Microsporidia) Infections in Honey Bees (Apis mellifera)

Honey bees (Apis mellifera) are agriculturally important pollinators that have been recently at risk to severe colony losses. A variety of parasites and pathogens have been linked to colony decline, including the microsporidian parasite Nosema ceranae. While fumagillin has been used to control nosemosis in managed honey bee colonies for decades, research shows that this antibiotic poses a toxic threat and that its efficacy against N. ceranae is uncertain. There is certainly a demand for a new veterinary medication to treat honey bee colonies infected with N. ceranae. In this review, recent scientific advances in controlling N. ceranae infections in honey bees are summarized.