Honey bee stressor networks are complex and dependent on crop and region.

Honey bees play a major role in crop pollination but have experienced declining health throughout most of the globe. Despite decades of research on key honey bee stressors (e.g., parasitic Varroa destructor mites and viruses), researchers cannot fully explain or predict colony mortality, potentially because it is caused by exposure to multiple interacting stressors in the field. Understanding which honey bee stressors co-occur and have the potential to interact is therefore of profound importance. Here, we used the emerging field of systems theory to characterize the stressor networks found in honey bee colonies after they were placed in fields containing economically valuable crops across Canada. Honey bee stressor networks were often highly complex, with hundreds of potential interactions between stressors. Their placement in crops for the pollination season generally exposed colonies to more complex stressor networks, with an average of 23 stressors and 307 interactions. We discovered that the most influential stressors in a network-those that substantively impacted network architecture-are not currently addressed by beekeepers. Finally, the stressor networks showed substantial divergence among crop systems from different regions, which is consistent with the knowledge that some crops (e.g., highbush blueberry) are traditionally riskier to honey bees than others. Our approach sheds light on the stressor networks that honey bees encounter in the field and underscores the importance of considering interactions among stressors. Clearly, addressing and managing these issues will require solutions that are tailored to specific crops and regions and their associated stressor networks.

Warmer autumns and winters could reduce honey bee overwintering survival with potential risks for pollination services.

Honey bees and other pollinators are critical for food production and nutritional security but face multiple survival challenges. The effect of climate change on honey bee colony losses is only recently being explored. While correlations between higher winter temperatures and greater colony losses have been noted, the impacts of warmer autumn and winter temperatures on colony population dynamics and age structure as an underlying cause of reduced colony survival have not been examined. Focusing on the Pacific Northwest US, our objectives were to (a) quantify the effect of warmer autumns and winters on honey bee foraging activity, the age structure of the overwintering cluster, and spring colony losses, and (b) evaluate indoor cold storage as a management strategy to mitigate the negative impacts of climate change. We perform simulations using the VARROAPOP population dynamics model driven by future climate projections to address these objectives. Results indicate that expanding geographic areas will have warmer autumns and winters extending honey bee flight times. Our simulations support the hypothesis that late-season flight alters the overwintering colony age structure, skews the population towards older bees, and leads to greater risks of colony failure in the spring. Management intervention by moving colonies to cold storage facilities for overwintering has the potential to reduce honey bee colony losses. However, critical gaps remain in how to optimize winter management strategies to improve the survival of overwintering colonies in different locations and conditions. It is imperative that we bridge the gaps to sustain honey bees and the beekeeping industry and ensure food and nutritional security.

Developing a method to rear Varroa destructor in vitro.

Varroa destructor is a significant mite pest of western honey bees (Apis mellifera). Developing a method to rear and maintain populations of V. destructor in vitro would provide year-round access to the mites, allowing scientists to study their biology, behavior, and control more rapidly. In this study, we determined the impact of various rearing parameters on V. destructor survival and reproduction in vitro. This was done by collecting V. destructor from colonies, placing them in gelatin capsules containing honey bee larvae, and manipulating the following conditions experimentally: rearing temperature, colony source of honey bee larva, behavioral/developmental stages of V. destructor and honey bee larva, and mite:bee larva ratio. Varroa destructor survival was significantly impacted by temperature, colony source of larvae and mite behavioral stage. In addition, V. destructor reproduction was significantly impacted by mite: larva ratio, larval developmental stage, colony source of larva, and temperature. The following conditions optimized mite survival and reproduction in vitro: using a 4:1 mite:larva ratio, beginning the study with late stage uncapped larvae, using mites collected from adult bees, maintaining the rearing temperature at 34.5° C, and screening larval colony source. Ultimately, this research can be used to improve V. destructor in vitro rearing programs.

Automated precision beekeeping for accessing bee brood development and behaviour using deep CNN.

Bees play a significant role in the health of terrestrial ecosystems. The decline of bee populations due to colony collapse disorder around the world constitutes a severe ecological danger. Maintaining high yield of honey and understanding of bee behaviour necessitate constant attention to the hives. Research initiatives have been taken to establish monitoring programs to study the behaviour of bees in accessing their habitat. Monitoring the sanitation and development of bee brood allows for preventative measures to be taken against mite infections and an overall improvement in the brood's health. This study proposed a precision beekeeping method that aims to reduce bee colony mortality and improve conventional apiculture through the use of technological tools to gather, analyse, and understand bee colony characteristics. This research presents the application of advanced digital image processing with computer vision techniques for the visual identification and analysis of bee brood at various developing stages. The beehive images are first preprocessed to enhance the important features of object. Further, object is segmented and classified using computer vision techniques. The research is carried out with the images containing variety of immature brood stages. The suggested method and existing methods are tested and compared to evaluate efficiency of proposed methodology.

Understanding how environmental degradation, microclimate, and management shape honey production across different spatial scales.

Although the abundance, survival, and pollination performance of honeybees are sensitive to changes in habitat and climate conditions, the processes by which these effects are transmitted to honey production and interact with beekeeping management are not completely understood. Climate change, habitat degradation, and beekeeping management affect honey yields, and may also interact among themselves resulting in indirect effects across spatial scales. We conducted a 2-year, multi-scale study on Chiloe Island (northern Patagonia), where we evaluated the most relevant environmental and management drivers of honey produced by stationary beekeepers. We found that the effects of microclimate, habitat, and management variables changed with the spatial scale. Among the environmental variables, minimum temperature, and cover of the invasive shrub, gorse (Ulex europaeus) had the strongest detrimental impacts on honey production at spatial scales finer than 4 km. Specialized beekeepers who adopted conventional beekeeping and had more mother colonies were more productive. Mean and minimum temperatures interacted with the percentage of mother colonies, urban cover, and beekeeping income. The gorse cover increased by the combination of high temperatures and the expansion of urban lands, while landscape attributes, such as Eucalyptus plantation cover, influenced beekeeping management. Results suggest that higher temperatures change the available forage or cause thermal stress to honeybees, while invasive shrubs are indicators of degraded habitats. Climate change and habitat degradation are two interrelated environmental phenomena whose effects on beekeeping can be mitigated through adaptive management and habitat restoration.

The oriental hornet (Vespa orientalis) as a potential vector of honey bee's pathogens and a threat for public health in North-East Italy.

BACKGROUND: Oriental hornets are large predatory hymenoptera that occur in the southern part of Asia and the southeastern Mediterranean. Among many pests of bee colonies, Vespa orientalis was recorded to be one of the most destructive. OBJECTIVES: The aim of this study was to: (1) monitor the presence of pathogens carried by V. orientalis that could potentially threaten honey bees and public health; (2) describe the hornet's predatory behavior on honey bee colonies and (3) collect the medical history of a V. orientalis sting suffered by a 36-year-old woman. METHODS: Observations of V. orientalis predatory behavior and the catches of hornets for parasitological and microbiological examination, using molecular and bacteriological analyses, were carried out in three experimental apiaries, both in spring in order to capture the foundress queens and during the summer to capture the workers. Furthermore, the medical history and photographic documentation of a V. orientalis sting suffered by a 36-year-old woman have been collected. RESULTS: The results obtained highlight that V. orientalis is capable of causing serious damage to beekeeping by killing bees, putting under stress the honey bee colonies and by potentially spreading honey bee pathogens among apiaries. These hornets may also become a public health concern, since they are capable of inflicting multiple, painful stings on humans. CONCLUSIONS: Only the development of an Integrated Management Control Program will be able to contain the negative effects of anomalous population growth and the potentially negative impact on honey bees and public health of V. orientalis.

No evidence to support the use of glycerol-oxalic acid mixtures delivered via paper towel for controlling Varroa destructor (Mesostigmata: Varroidae) mites in the Southeast United States.

A significant amount of researcher and practitioner effort has focused on developing new chemical controls for the parasitic Varroa destructor mite in beekeeping. One outcome of that has been the development and testing of "glycerol-oxalic acid" mixtures to place in colonies for extended periods of time, an off-label use of the otherwise legal miticide oxalic acid. The majority of circulated work on this approach was led by practitioners and published in nonacademic journals, highlighting a lack of effective partnership between practitioners and scientists and a possible failure of the extension mandate in beekeeping in the United States. Here, we summarize the practitioner-led studies we could locate and partner with a commercial beekeeper in the Southeast of the United States to test the "shop towel-oxalic acid-glycerol" delivery system developed by those practitioners. Our study, using 129 commercial colonies between honey flows in 2017 split into 4 treatment groups, showed no effectiveness in reducing Varroa parasitism in colonies exposed to oxalic acid-glycerol shop towels. We highlight the discrepancy between our results and those circulated by practitioners, at least for the Southeast, and the failure of extension to support practitioners engaged in research.

Probiotics and in-hive fermentation as a source of beneficial microbes to support the gut microbial health of honey bees.

Managed populations of honey bees (Apis mellifera Linnaeus; Hymenoptera: Apidae) are regularly exposed to infectious diseases. Good hive management including the occasional application of antibiotics can help mitigate infectious outbreaks, but new beekeeping tools and techniques that bolster immunity and help control disease transmission are welcome. In this review, we focus on the applications of beneficial microbes for disease management as well as to support hive health and sustainability within the apicultural industry. We draw attention to the latest advances in probiotic approaches as well as the integration of fermented foods (such as water kefir) with disease-fighting properties that might ultimately be delivered to hives as an alternative or partial antidote to antibiotics. There is substantial evidence from in vitro laboratory studies that suggest beneficial microbes could be an effective method for improving disease resistance in honey bees. However, colony level evidence is lacking and there is urgent need for further validation via controlled field trials experimentally designed to test defined microbial compositions against specific diseases of interest.

Inducing a summer brood break increases the efficacy of oxalic acid vaporization for Varroa destructor (Mesostigmata: Varroidae) control in Apis mellifera (Hymenoptera: Apidae) colonies.

The ectoparasitic mite, Varroa destructor (Anderson and Trueman), is the leading cause of western honey bee colony, Apis mellifera (L.), mortality in the United States. Due to mounting evidence of resistance to certain approved miticides, beekeepers are struggling to keep their colonies alive. To date, there are varied but limited approved options for V. destructor control. Vaporized oxalic acid (OA) has proven to be an effective treatment against the dispersal phase of V. destructor but has its limitations since the vapor cannot penetrate the protective wax cap of honey bee pupal cells where V. destructor reproduces. In the Southeastern United States, honey bee colonies often maintain brood throughout the year, limiting the usefulness of OA. Prior studies have shown that even repeated applications of OA while brood is present are ineffective at decreasing mite populations. In the summer of 2021, we studied whether incorporating a forced brood break while vaporizing with OA would be an effective treatment against V. destructor. Ninety experimental colonies were divided into 2 blocks, one with a brood break and the other with no brood break. Within the blocks, each colony was randomly assigned 1 of 3 treatments: no OA, 2 g OA, or 3 g OA. The combination of vaporizing with OA and a forced brood break increased mite mortality by 5× and reduced mite populations significantly. These results give beekeepers in mild climates an additional integrated pest management method for controlling V. destructor during the summer season.

Re-using food resources from failed honey bee (Apis mellifera L.) colonies and their impact on colony queen rearing capacity.

For over a decade, beekeepers have experienced high losses of honey bee (Apis mellifera L.) colonies due to a variety of stressors including pesticide exposure. Some of these chemical stressors may residually remain in the colony comb and food resources (pollen and nectar) of failed colonies and be later re-used by beekeepers when splitting and building back new colonies. The practice of re-using comb from previously perished colonies (termed "deadout") is common in beekeeping practice, but its role in affecting colony health is not well understood. Here, we evaluate the impact of reused, pesticide-contaminated "deadout" combs on colony function during the process of replacing a queen bee. Queenless microcolonies were established to monitor queen rearing capacity in two treatment groups: (1) colonies given frames containing food resources from deadout colonies in control "clean" apiaries and, (2) colonies given frames containing "contaminated" resources from deadout colonies originating from apiaries experiencing chronic pesticide exposure from widespread systemic pesticide pollution (including neonicotinoid insecticides: clothianidin and thiamethoxam). Results indicate that colonies given pesticide-contaminated resources produced fewer queen cells per colony and had a lower proportion of colonies successfully raising a functional, diploid egg-laying queen. This research highlights the deleterious effects of re-using deadout combs from colonies previously lost due to pesticide contamination.

Beekeeping in Europe facing climate change: A mixed methods study on perceived impacts and the need to adapt according to stakeholders and beekeepers.

The beekeeping sector is suffering from the detrimental effects of climate change, both directly and indirectly. Despite numerous studies conducted on this subject, large-scale research incorporating stakeholders' and beekeepers' perspectives has remained elusive. This study aims to bridge this gap by assessing the extent to which stakeholders involved in the European beekeeping sector and European beekeepers perceive and experience the impacts of climate change on their operations, and whether they had to adapt their practices accordingly. To this end, a mixed-methods study including in-depth stakeholder interviews (n = 41) and a pan-European beekeeper survey (n = 844) was completed within the frame of the EU-funded H2020-project B-GOOD. The development of the beekeeper survey was informed by insights from literature and the stakeholder interviews. The results highlighted significant regional disparities in the perceived impacts of climate change, with beekeepers in Southern European regions expressing more negative outlooks, while Northern European beekeepers reported more favourable experiences. Furthermore, survey analysis revealed beekeepers who were classified as 'heavily impacted' by climate change. These beekeepers reported lower average honey yields, higher colony winter loss rates and a stronger perceived contribution of honey bees to pollination and biodiversity, underscoring climate change's detrimental impacts on the beekeeping sector. Multinomial logistic regression revealed determinants of the likelihood of beekeepers being classified as 'heavily impacted' by climate change. This analysis indicates that Southern European beekeepers experienced a 10-fold likelihood of being classified as heavily impacted by climate change compared to Northern European beekeepers. Other significant factors distinguishing 'winners' and 'losers' were self-reported level of professionalism as a beekeeper (ranging from pure hobbyist to fully professional, Odds Ratio (OR) = 1.31), number of years active in beekeeping (OR = 1.02), availability of floral resources throughout the bee season (OR = 0.78), beehives located in a forested environment (OR = 1.34), and the presence of local policy measures addressing climate change-related challenges (OR = 0.76).

A longitudinal experiment demonstrates that honey bee colonies managed organically are as healthy and productive as those managed conventionally.

Honey bee colony management is critical to mitigating the negative effects of biotic and abiotic stressors. However, there is significant variation in the practices implemented by beekeepers, which results in varying management systems. This longitudinal study incorporated a systems approach to experimentally test the role of three representative beekeeping management systems (conventional, organic, and chemical-free) on the health and productivity of stationary honey-producing colonies over 3 years. We found that the survival rates for colonies in the conventional and organic management systems were equivalent, but around 2.8 times greater than the survival under chemical-free management. Honey production was also similar, with 102% and 119% more honey produced in conventional and organic management systems, respectively, than in the chemical-free management system. We also report significant differences in biomarkers of health including pathogen levels (DWV, IAPV, Vairimorpha apis, Vairimorpha ceranae) and gene expression (def-1, hym, nkd, vg). Our results experimentally demonstrate that beekeeping management practices are key drivers of survival and productivity of managed honey bee colonies. More importantly, we found that the organic management system-which uses organic-approved chemicals for mite control-supports healthy and productive colonies, and can be incorporated as a sustainable approach for stationary honey-producing beekeeping operations.

A survey of UK beekeeper's Varroa treatment habits.

The global spread of the parasitic mite Varroa destructor instigated a substantial decline in both managed and feral honeybee (Apis mellifera) colonies mainly across the Northern hemisphere. In response, many beekeepers began to treat their colonies with chemical acaricides to control mite populations in managed colonies. However, some countries or beekeepers allowed their bees to develop mite-resistance by adopting a "treatment-free" approach, rather than using selective breeding programs. Yet, the distribution and proportion of beekeepers either treating or not within the United Kingdom (UK) is unknown, as it is in most Northern hemisphere countries. Therefore, the aim of this study was to conduct a beekeeper survey to determine the current treatment strategies within the UK. We gathered 2,872 beekeeper responses from an estimated 30,000 UK beekeepers belonging to 242 bee-associations in the winter of 2020/21. The survey indicated that the majority (72-79%) of UK beekeepers are still treating their bees for Varroa, typically twice-yearly using chemical-based methods. Six percent or 1,800 UK beekeepers were treatment-free for six years or more. This is reflected by our finding that 78 associations out of 242 consist of responders who entirely treated, while only four associations had more than 75% of their members that were non-treating. Overall treatment status was not affected by association currently. Using the baseline data from this survey it will be possible in the future to observer if a shift towards treatment-free beekeeping occurs or not.

Comparative Study of Machine Learning Models for Bee Colony Acoustic Pattern Classification on Low Computational Resources.

In precision beekeeping, the automatic recognition of colony states to assess the health status of bee colonies with dedicated hardware is an important challenge for researchers, and the use of machine learning (ML) models to predict acoustic patterns has increased attention. In this work, five classification ML algorithms were compared to find a model with the best performance and the lowest computational cost for identifying colony states by analyzing acoustic patterns. Several metrics were computed to evaluate the performance of the models, and the code execution time was measured (in the training and testing process) as a CPU usage measure. Furthermore, a simple and efficient methodology for dataset prepossessing is presented; this allows the possibility to train and test the models in very short times on limited resources hardware, such as the Raspberry Pi computer, moreover, achieving a high classification performance (above 95%) in all the ML models. The aim is to reduce power consumption and improves the battery life on a monitor system for automatic recognition of bee colony states.

Short communication: Varroa destructor re-invasion dynamics during autumn and winter in Apis mellifera colonies from a temperate climate.

Infestation with Varroa destructor compromises the survival of Apis mellifera colonies, especially during the winter season. In order to prevent colony losses due to the presence of Varroa mites, determination of the infestation level and the application of autumn treatment is highly recommended. However, autumn reinvasion by inter-apiary and intra-apiary horizontal transmission might threaten the control strategies. Drivers like the infestation level of untreated colonies, the presence of bee brood during late autumn and the colonies disposition within the apiary might explain at least partially the re-invasion rates of treated colonies during autumn and winter. A total of six apiaries with five colonies were distributed within a 30 km radius. Colonies were arranged within each apiary following a circular or a lineal disposition. Twenty-four of the thirty colonies were treated during late summer against V. destructor and one colony per apiary remained untreated. The phoretic Varroa infestation and the adult bee population, brood area and nutritional reserves in the colonies was estimated before and after treatment and then for the next four months (late autumn and winter season). In this study, a model for the V. destructor re-invasion dynamics during autumn and winter in honey bee colonies from a temperate climate was fitted. According to these results, the re-invasion probability is higher for lineal disposition of the colonies that also present a higher amount of brood availability during late autumn and winter. Beekeeping practical implications are discussed in the context of an Integrated Pest management approach.

Apicultura na Amazônia brasileira: revisão sistemática de literatura, 2000 - 2022 / Beekeeping in the brazilian Amazon: systematic literature review, 2000 - 2022 / Apicultura en la Amazonia brasileña: revisión sistemática de la literatura, 2000 - 2022

As abelhas africanas (Apis mellifera scutellata) foram introduzidas no Brasil na década de 1950 e, por acidente, cruzaram com outras subespécies de abelhas melíferas europeias. Isso proporcionou o surgimento de híbridos conhecidos atualmente como abelhas africanizadas, que possuem características de rusticidade e maior capacidade de enxamear. A Amazônia mostra potencial para o desenvolvimento da apicultura devido suas características e diversidade floral. Neste sentido, este estudo busca reunir produções científicas sobre apicultura na Amazônia brasileira nos últimos 22 anos, por meio da metodologia de revisão sistemática de literatura, o objetivo é mostrar como tal tema tem sido abordado nas pesquisas. Neste cenário as publicações têm se mostrado crescentes, o que demonstra a tentativa de alinhamento com a Iniciativa Internacional para a Conservação e Uso Sustentável dos polinizadores. Entretanto, os resultados apontam muitas lacunas na produção apícola como, por exemplo, a área de pesquisas higiênico- sanitárias sobre combate de parasitas nas colmeias. No âmbito socioeconômico, as deficiências são ainda mais evidentes pela falta de pesquisas sobre políticas de financiamento da atividade, análises da cadeia de valor entre outros temas. Diante da importância econômica, social e ambiental das abelhas é de suma importância o aprofundamento dos estudos acadêmicos sobre apicultura na Amazônia.(AU)

African bees (Apis mellifera scutellata) were introduced in Brazil in the 1950s and, by accident, crossed with other subspecies of European honey bees. This led to the emergence of hybrids today known as Africanized bees, which have characteristics of rusticity and greater swarming capacity. The Amazonia shows potential for the development beekeeping due to its characteristics and floral diversity. Thus, this study brings together scientific productions on beekeeping in the Brazilian Amazonia in the last 22 years, using the methodology of systematic literature review, the objective is to illustrate how this theme has been addressed in research. In this context, publications have been growing, which demonstrates the attempt to align with the International Initiative for the Conservation and Sustainable Use of pollinators. However, the results point to many gaps in bee production, such as the area of hygienic-sanitary research in combating parasites in hives. In the scope of socioeconomics, the deficiencies are even more evident by the lack of research on policies for financing the activity, analysis of the value chain, among other topics. Given the economic, social and environmental importance of bees, it is extremely important to deepen academic studies on beekeeping in Amazonia.(AU)

Las abejas africanas (Apis mellifera scutellata) se introdujeron en Brasil en la década de 1950 y, por accidente, se cruzaron con otras subespecies de abejas europeas. Esto propició el surgimiento de híbridos hoy conocidos como abejas africanizadas, que tienen características de rusticidad y mayor capacidad de enjambrar. La Amazonía muestra potencial para el desarrollo apícola por sus características y diversidad floral. Así, este estudio reúne las producciones científicas sobre la apicultura en la Amazonía brasileña en los últimos 22 años, utilizando la metodología de revisión sistemática de la literatura, el objetivo es ilustrar cómo este tema ha sido abordado en la investigación. En este contexto, las publicaciones han ido en aumento, lo que demuestra el intento de alinearse con la Iniciativa Internacional para la Conservación y Uso Sostenible de polinizadores. Sin embargo, los resultados apuntan a muchas lagunas en la producción apícola, como el área de investigación higiénico-sanitaria en el combate a los parásitos en las colmenas. En el ámbito de la socioeconomía, las deficiencias son aún más evidentes por la falta de investigación sobre políticas de financiamiento de la actividad, análisis de la cadena de valor, entre otros temas. Dada la importancia económica, social y ambiental de las abejas, es de suma importancia profundizar los estudios académicos sobre la apicultura en la Amazonía.(AU)

Water provisioning increases caged worker bee lifespan and caged worker bees are living half as long as observed 50 years ago.

The high loss rates of honey bee colonies drive research for solutions aimed to mitigate these losses. While honey bee colonies are superorganisms, experiments that measure the response to stressors often use caged individuals to allow for inference in a controlled setting. In an initial experiment, we showed that caged honey bees provisioned with various types of water (deionized, 1%NaCl in deionized, or tap) have greater median lifespans than those that did not. While researching the history of water provisioning in cage studies, we observed that the median lifespan of caged honey bees has been declining in the US since the 1970's, from an average of 34.3 days to 17.7 days. In response to this, we again turned to historical record and found a relationship between this trend and a decline in the average amount of honey produced per colony per year in the US over the last 5 decades. To understand the relationship between individual bee lifespan and colony success we used an established honey bee population model (BEEHAVE) to simulate the predicted effects of decreased worker lifespans. Declines in downstream measures of colony population, overall honey production, and colony lifespan resulted from reduced worker bee lifespans. Modeled colony lifespans allowed us to estimate colony loss rates in a beekeeping operation where lost colonies are replaced annually. Resulting loss rates were reflective of what beekeepers' experience today, which suggests the average lifespan of individual bees plays an important role in colony success.

Motivations underpinning honeybee management practices: A Q methodology study with UK beekeepers.

Beekeepers are central to pollinator health. For policymakers and beekeeping organisations to develop widely accepted strategies to sustain honeybee populations alongside wild pollinators, a structured understanding of beekeeper motivations is essential. UK beekeepers are increasing in number, with diverse management styles despite calls for coordinated practice to manage honeybee health. Our Q methodology study in Cornwall, UK, indicated five beekeeping perspectives; conventional hobbyists, natural beekeepers, black bee farmers, new-conventional hobbyists and pragmatic bee farmers. Motivations can be shared across perspectives but trade-offs (notably between economic, social responsibility and ideological motivations) result in differing practices, some of which counter 'official' UK advice and may have implications for pollinator health and competition. Honeybee conservation emerged as a key motivator behind non-conventional practices, but wild pollinator conservation was not prioritised by most beekeepers in practice. Q methodology has the potential to facilitate non-hierarchical collaboration and conceptualisation of sustainable beekeeping, moving towards co-production of knowledge to influence policy.

Impact of Honey Bee Migratory Management on Pathogen Loads and Immune Gene Expression is Affected by Complex Interactions With Environment, Worker Life History, and Season.

The effects of honey bee management, such as intensive migratory beekeeping, are part of the ongoing debate concerning causes of colony health problems. Even though comparisons of disease and pathogen loads among differently managed colonies indicate some effects, the direct impact of migratory practices on honey bee pathogens is poorly understood. To test long- and short-term impacts of managed migration on pathogen loads and immunity, experimental honey bee colonies were maintained with or without migratory movement. Individuals that experienced migration as juveniles (e.g., larval and pupal development), as adults, or both were compared to control colonies that remained stationary and therefore did not experience migratory relocation. Samples at different ages and life-history stages (hive bees or foragers), taken at the beginning and end of the active season, were analyzed for pathogen loads and physiological markers of health. Bees exposed to migratory management during adulthood had increased levels of the AKI virus complex (Acute bee paralysis, Kashmir bee, and Israeli acute bee paralysis viruses) and decreased levels of antiviral gene expression (dicer-like). However, those in stationary management as adults had elevated gut parasites (i.e. trypanosomes). Effects of environment during juvenile development were more complex and interacted with life-history stage and season. Age at collection, life-history stage, and season all influenced numerous factors from viral load to immune gene expression. Although the factors that we examined are not independent, the results illuminate potential factors in both migratory and nonmigratory beekeeping that are likely to contribute to colony stress, and also indicate potential mitigation measures.

Compliance with recommended Varroa destructor treatment regimens improves the survival of honey bee colonies over winter.

The ectoparasitic mite Varroa destructor affects honey bee colony health and survival negatively, thus compelling beekeepers to treat their colonies every year. A broadly used mite control regimen is based on two organic molecules: formic and oxalic acids. To ensure optimal efficiency, several applications of these acids at pre-defined time points are recommended. These recommendations are mainly based on experiments conducted under controlled conditions. Studies evaluating the effectiveness under natural field conditions are lacking. We enrolled 30 beekeepers in a longitudinal study in three cantons in Switzerland and monitored the management and health of their colonies for two years. We assessed compliance with mite control recommendations and measured V. destructor infestation rates, indexes of colony productivity (brood size and honey harvest), and colony mortality in 300 colonies. We observed a 10-fold increased risk of colony death when beekeepers deviated slightly from the recommended treatment regimen compared to compliant beekeepers (odds ratio: 11.9, 95% CI: 2.6-55.2, p = 0.002). The risk of colony death increased 25-fold in apiaries with substantial deviations from the recommendations (odds ratio: 50.4, 95% CI: 9.7-262.5, p < 0.0001). The deviations led to increased levels of V. destructor infestation ahead of wintering, which was likely responsible for colony mortality. After communicating the apparent link between low compliance and poor colony survival at the end of the first year to the beekeepers, we observed better compliance and colony survival in the second year. Our results highlight the positive impact of compliance with the recommended V. destructor treatment regimen on the health of honeybee colonies and the need to better communicate the consequences of deviating from the recommendations to improve compliance. Compliance also occasionally decreased, which hints at concept implementation constraints that could be identified and possibly addressed in detail with the help of social sciences to further promote honey bee health.