Progress 10/01/23 to 09/30/24
Outputs
PROGRESS REPORT Objectives (from AD-416): Meaningful contributions towards enhancing the economic value of the nation⿿s commercially managed honey bee populations can be achieved through identifying, characterizing and breeding more robust bees. The proposed 5-year plan focuses on synergistic projects (Fig.1) that capitalize on genetic and breeding approaches with the following objectives: Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Sub-objective 1B: Evaluate genotype-dependent nutrient efficiency in commercial honey bee stocks. Sub-objective 1C: Evaluate genotype-dependent nutritional stress resistance in commercial honey bee stocks. Sub-objective 1D: Characterize the impact of genetically based variation in vitellogenin -- the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan -- on colony and reproductive (queen and drone) health and productivity. Sub-objective 1E: Identify and characterize genetic and physiological mechanisms of pesticide resistance in honey bees. Objective 2: Characterize genetic, physiological and behavioral aspects of important traits, strains and stocks. Sub-objective 2A: Examine patterns of genetic diversity and loci under selection in United States honey bee breeding populations, with a focus on stocks exhibiting high VSH activity. Sub-objective 2B: Elucidate the interaction between individual and social immune defenses. Sub-objective 2C: Improve understanding of the biology of the VSH trait. Objective 3: Conduct traditional breeding or marker-assisted selection of honey bees. Sub-objective 3A: Ascertain the effect of inbreeding on genetic diversity across the honey bee genome to support breeding and maintaining health of breeding populations. Sub-objective 3B. Assess genetic diversity at the sex locus of commercial breeding populations of honey bee stocks developed by USDA, ARS HBBGPL. Sub-objective 3C: Determine the potential usefulness of a simple hygiene assay as a selection tool to predict VSH-based mite resistance in honey bee colonies. Objective 4: Develop management tools for improving honey bee health. Sub-objective 4A: Identify and characterize genetic differences in honey bee response to introduced dsRNA, and test for correlations with viral infection and resistance. Sub-objective 4B: Improve understanding of the flight activity of Russian honey bees during almond pollination. Sub-objective 4C: Evaluate the efficacy of a microalgae platform to improve honey bee colony performance and health. Sub-objective 4D: Determine the sublethal effects of fungicides on honey bee health. Sub-objective 4E: Assess sustainability of Varroa control methods. Approach (from AD-416): Honey bee health is threatened by parasites, pathogens, poor nutrition and pesticides. Breeding robust bees with improved resistance (or tolerance) to threats could mitigate these problems. The project combines diverse approaches and techniques to seek and exploit genotype-dependent responses of honey bees to biotic-, nutrition- and pesticide-related stressors. The project improves understanding of genetic diversity across U.S. commercial stocks, enabling both marker-assisted selection and conservation of genetic resources. This will enhance the effectiveness of contemporary breeding programs. Varroa destructor (hereafter, Varroa) is the greatest threat to bee health worldwide. The project builds on past successes by improving selection efficiency for resistance to Varroa and for elevated colony performance, promoting adoption by beekeepers. Investigations target relationships between genetic diversity across stocks, immune responses, and treatment effectiveness against Varroa, viruses, and other related biotic threats. This is critical because of recent beekeeper reports of miticide- (amitraz-) resistant Varroa. Given the threat from Varroa, the plan outlines novel (Sub-objectives 2B, 4A) and continuing (Sub- objectives 2C, 3C, 4B) research on breeding and management related to Varroa-resistant honey bees. In addition, we also initiate a suite of new studies addressing the negative impact of stressors whose prevalence has increased across managed honey bees in the past decade. These studies will assess differences in genotype-dependent responses to viruses and other pathogens (Sub-objectives 1A, 2B), poor nutrition (Sub-objectives 1B, 1C, 1D, 4C), and pesticides (Sub-objectives 1E, 4D, 4E). The project seeks to improve nutrient assimilation efficiency through breeding. Similarly, genotype-dependent differences in bee responses to pesticides will be targeted for breeding less susceptible bees and reducing queen failures. Biomarkers identified as useful for signaling emerging health threats will be verified, benefitting beekeepers by allowing for rapid corrective intervention. These approaches will capitalize on novel sequencing technologies to examine many of these issues at a higher level of resolution across the honey bee genome (Sub-objectives 2A, 3A, 3B). In work related to identification and evaluation of traits, strains and stocks for improved bee health (Objective 1), progress has been made with respect to viral infection (1A) and nutritional responses (1C, 1D). Efforts toward selective breeding for honey bees that are resistant to viral infection (1Ai) continued to focus on drone-based selection in collaboration with a commercial beekeeping operation. Analyses determined that drone responses are consistent within a colony and assessed age- based responses, allowing for increased efficiency in breeding progress. Current work aims to confirm the relationship between drone responses and their sisters (worker honey bees) and offspring to fully assess the viability of drone- based selection. Additional work examined the relationship between viral infection and breeding for disease and mite- resistance via hygienic-based traits (i.e. behavior where adult bees remove sick or mite-infested larvae and pupae from the hive) (1Aii). Genomic sequencing of viral loads of samples collected as part of a large effort in five different geographically distinct beekeeping operations provided insight into viral dynamics in mite-resistant versus mite- susceptible honey bee colonies. Virus work as part of subordinate projects indicated that caged bees show a preference for sugar syrup contaminated with deformed wing virus (DWV), which has implications for viral transmission at floral sources. To examine how different genetic stocks respond to a resource dearth, colonies from two different stocks (Russian and Italian honey bees) were fit with pollen traps that reduce the amount of incoming pollen have access to, thus compromising their nutrition. Their temperament, colony resources, and colony population were sampled weekly to see if effects of nutritional deprivation are consistent across the genetic backgrounds of colonies. Gene expression analyses were completed from Year 1 of the study, confirming that previously identified aggression genes are differentially regulated in response to the nutritional stress. Year 2 has shown that there is a genetic component to nutritional deprivation in terms of resulting bee temperament, but that the nutritional component overwhelms the genetic component in regard to nosema spore load. Progress was also made in the characterization of the impact of genetically based variation in vitellogenin (Vg)⿿the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan⿿on colony and reproductive (queen and drone) health and productivity (1D). Measurements of lines produced via bi- directional selection for high and low Vg were taken including overwintering success, spring buildup and productivity. An additional selection program for Vg allelic variants has begun as part of subordinate international collaborative work. Other collaborative work with the University of Minnesota continued exploring the relationship between Vg expression and swarming behavior. In collaboration with the Tucson research unit, research was completed examining honey bee stock comparisons in different climates with implications for climate change. Mite-resistant (Pol-line and Russian) and Italian honey bee stocks were compared in variable-temperature cage experiments (200 bees per cage) with respect to food consumption, thermoregulation, gene expression, and lifespan, in three experiments over two years. The Italian stock bees consumed more syrup and pollen on average than the mite-resistant stocks, but the mite-resistant stocks maintained higher cluster temperatures and had median lifespans 8 days longer. Model results indicated that, to maintain the same colony size as the mite-resistant stocks, Italian stock colonies would need about 13% more sealed brood to offset reduced worker lifespans. These differences among bee stocks likely influence colony-level productivity and health, and showed the importance of experimental replication. Research has continued characterizing genetic, physiological and behavioral aspects of important traits, strains and stocks (Objective 2). Work investigating genetic diversity across the honey bee genome (2A) resulted in the first honey bee pangenome reference tool and its use in the analysis of commercial and research-relevant breeding lines. Research combining laboratory and field assessments of colony and larval susceptibility to disease has indicated that larvae that respond with a stronger physiological immune response are more likely to be from hygienic colonies, suggesting that this immune signal alerts adult bees to remove them (2B). Additional developments include establishment of a ⿿working group with members of the Russian Honey Bee Breeders Association, academia and non-profits to assess how the traits of the Russian honey bees have changed since their release by the Unit, investigation of barriers to wider adoption of the stock by beekeepers, and development of strategies to recruit new breeders to the association. A case study on a stakeholder⿿s commercial beekeeping operation using mite-resistant and susceptible stocks showed a high potential for economic gain for using mite-resistant honey bees. Locational differences between apiaries had a greater impact than bee stock in honey production, queen loss was high in both stocks, and the Varroa-resistant bee stock had less Varroa than the non-resistant one. Collaborative work also began with Louisiana State University to determine how selection for mite resistance has affected behavioral development in Russian and Pol-line stocks. Work to develop traditional breeding and marker-assisted selection (MAS) strategies in honey bees (Objective 3) continues. We conducted research on semen storage and viability, a critical logistic limitation to the application of genomic-based MAS (3A). Direct tests of viability were promising in lab, and efforts continue to examine effective viability in the field. Collaborative studies with Colorado State University included a proof of concept for MAS using metabolic rate since the trait is largely determined by a small set of markers. Results showed that for traits associated with few markers (1-3) integration and use of MAS is possible. Additional collaboration with Breeding Insight continues for more complex traits and panels to reduce the turnaround time for genotyping towards the effective application of MAS in honey bees. Development of management tools to improve bee health (Objective 4) has progressed in several areas. Work continued to test the utility of microalgae diet nutritional supplements for beekeepers to provide to maintain or encourage colony growth during periods of dearth (4C). A study in cooperation with a commercial beekeeping operation found that colonies supplemented with feed containing the microalgae spirulina had improved brood production and thermoregulation prior to almond pollination relative to unfed controls. Based on these findings, manufactures of honey bee nutrition supplements have developed a commercial product available at the end of July. Progress continued on the development of an edible therapeutic based on genetic engineering of blue-green algae that activates the antiviral response of honey bees and has shown to reduce DWV replication and increase survival of honey bees exposed to the virus in the laboratory. A study was initiated on the effects of colony boxes that stimulate propolis deposition (antimicrobial plant resins collected by the bees) on Varroa infestation in honey bee colonies (4E). Preliminary evidence suggests that a propolis-enriched environment does reduce mite infestation loads, as suggested by previously published work, but that it only does so in colonies that are susceptible to mites. Russian honey bees and Pol-line honey bee colonies maintained low mite levels regardless of increased propolis in the nest environment. This work is being continued, but shows support for the value of mite resistant honey bees and using alternative equipment that can easily be integrated into operations to reduce impacts of Varroa. A new collaborative, subordinate project to evaluate the use of these propolis-enriched hive boxes with the Michigan State University and a cooperating commercial beekeeper investigated if propolis improves health of honey bee colonies during and post-blueberry pollination. Research to develop integrated pest management tools for beekeepers to use against the fungal pathogen Ascosphaera apis, which causes chalkbrood, are ongoing in both the field and laboratory. Larger scale laboratory and field experiments include collaborations with University of Florida and University of Minnesota. Work to identify effects of other stressors and tools to combat them include a collaboration with Mississippi State University to quantify the temporal, directional and epidemiological patterns of drift (i.e. bees returning to the wrong colony. Additional collaborations with Southern University have been established to test how honey bees of different genetic stocks are impacted by industrialization along the Mississippi corridor. In collaboration with the Tucson, Arizona research unit, a longitudinal study on queen health in a commercial beekeeping operation was completed. We explored gut microbiota, host gene expression, and pathogen prevalence in honey bee queens overwintering in a warm southern climate. Biologically older queens had larger microbiotas, particularly enriched in Bombella and Bifidobacterium. Both DWV-A and B were highest in the fat body tissue in January, correlating with colony Varroa levels and worker DWV titers. High viral titers in queens were associated with decreased Vg expression, suggesting a potential trade-off between immune function and reproductive capacity. Overall, our findings highlight the intricate interplay between pathogens, metabolic state, and immune response in honey bee queens. ACCOMPLISHMENTS 01 Novel feed additives improve artificial diets for honey bees.. Beekeepers rely on providing honey bee colonies with supplemental diets so that they can be productive, especially going into winter and to fulfill pollination services. ARS researchers at Baton Rouge, Louisiana found that microalgae-based feed additives are an effective and sustainable feed additive for managed honey bees involved in agricultural pollination. A series of laboratory experiments and trials in commercial beekeeping operations have been completed showing that the microalgae-based diets improve colony size and that the nutritional content is similar to that of pollen. The beekeeping industry has begun translating our research into commercial products including a new microalgae-containing bee food product released in July 2024. Further optimization of bee diets will improve feed sustainability and agricultural pollination efficiency by supporting larger, healthier honey bee colonies. 02 Edible treatments to improve honey bee virus resistance.. Honey bees are regularly infected with multiple viruses that reduce colony productivity and can lead to death of the colony. However, no antiviral treatments are currently available to beekeepers. A novel, RNA interference (RNAi)-based treatment has been developed using edible blue-green algae that have been genetically engineered to deliver therapeutic double-stranded RNAs (dsRNAs) to honey bees via feeding. Once consumed, the dsRNAs are released into the bee gut and trigger a sequence-specific RNAi response, targeting viral pathogens. Treatments targeting deformed wing virus⿿a notorious pathogen⿿suppressed viral infection and improved survival in honey bees. This design presents a versatile and sustainable therapeutic that can be directly incorporated into supplemental feeds for managed pollinators to mitigate viruses and support global food security. 03 Genomic advances improve global understanding of honey bee genetics.. Using improved sequencing methods and genome assembly methods the first honey bee (Apis mellifera) commercial and research pangenome has been developed. This tool unifies genetic variation from six key honey bee populations into a common reference allowing for the robust characterization of honey bee genetic diversity and the novel ability to identify and catalogue larger structural variants (e.g. indels, duplications, etc.). This novel tool represents a method by which to increase our understanding of genetic variation and improve breeding tools to allow the beekeeping industry to more rapidly and effectively select for specific traits. ARS researchers at Baton Rouge, Louisiana future work will focus on expanding the robustness of the tool by developing a pangenome that includes worldwide honey bee genetic representation, and will provide a foundation for all genomic work in honey bees.
Impacts
(N/A)
Publications
- Rinkevich Jr, F.D., Danka, R.G., Rinderer, T.E., Margotta, J., Bartlett, L. , Healy, K. 2024. Relative impacts of varroa infestation and pesticide exposure and their effects on honey bee colony health and survival in a high-intensity corn and soybean producing region in northern Iowa. Journal of Insect Science. Vlume 25 Issue 3 Page 18. https://doi.org/10.1093/ jisesa/ieae054.
- French, S.K., Pepinelli, M., Conflitti, I.M., Higo, H., Common, J., Bixby, M., Walsh, E.M., Guarna, M.M., Pernal, S.F., Hoover, S.E. 2024. A systems approach to honey bee health. Current Biology. Volume 34 Page 1893-1903. https://doi.org/10.1016/j.cub.2024.03.039.
- McMenamin, A., Weiss, M., Meikle, W.G., Ricigliano, V.A. 2023. Efficacy of a microalgal feed additive in commercial honey bee colonies used for crop pollination. ACS Agricultural Science and Technology. 3(9):701-834. https:/ /doi.org/10.1021/acsagscitech.3c00082.
- Lang, S., Simone-Finstrom, M., Healy, K. 2023. Effects of honey bee queen exposure to Deformed wing virus-A on queen and juvenile infection and colony strength metrics. Journal of Apicultural Research. https://doi.org/ 10.1080/00218839.2023.2284034.
- Rinkevich Jr, F.D. 2024. Temperature, strip age, exposure surface area affect the outcomes of testing for amitraz resistance in Varroa destructor. Journal of Apicultural Research. https://doi.org/10.1080/00218839.2024. 2314420.
- Shanahan, M., Simone-Finstrom, M., Tokarz, P.G., Rinkevich Jr, F.D., Read, Q.D., Spivak, M. 2024. Thinking inside the box: restoring the propolis envelope facilitates honey bee social immunity. PLOS ONE. https://doi.org/ 10.1371/journal.pone.0291744.
- Ewert, A.M., Simone-Finstrom, M., Read, Q.D., Husseneder, H., Ricigliano, V.A. 2023. Effects of ingested essential oils and propolis extracts on honey bee (Hymenoptera: Apidae) health and gut microbiota. Journal of Insect Science. 23/6. https://doi.org/10.1093/jisesa/iead087.
- Lu, R.X., Bhatia, S., Simone-Finstrom, M., Rueppell, O. 2023. Quantitative trait loci mapping for survival of virus infection and virus levels in honey bees. Infection, Genetics and Evolution. 116. https://doi.org/10. 1016/j.meegid.2023.105534
- Ricigliano, V.A., Mcmenamin, A., Martin, A.M., Adjaye, D.F., Simone- Finstrom, M., Rainey, V.P. 2024. Green biomanufacturing of edible antiviral therapeutics for managed pollinators. NPJ Sustainable Agriculture. 2:Article4. https://doi.org/10.1038/s44264-024-00011-7.
- Gomes Viana, J., Avalos, A., Zhang, Z., Nelson, R., Hudson, M. 2024. Common signatures of selection reveal target loci for breeding across soybean populations. The Plant Genome. e20426. https://doi.org/10.1002/ tpg2.20426.
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Progress 10/01/22 to 09/30/23
Outputs
PROGRESS REPORT Objectives (from AD-416): Meaningful contributions towards enhancing the economic value of the nation⿿s commercially managed honey bee populations can be achieved through identifying, characterizing and breeding more robust bees. The proposed 5-year plan focuses on synergistic projects (Fig.1) that capitalize on genetic and breeding approaches with the following objectives: Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Sub-objective 1B: Evaluate genotype-dependent nutrient efficiency in commercial honey bee stocks. Sub-objective 1C: Evaluate genotype-dependent nutritional stress resistance in commercial honey bee stocks. Sub-objective 1D: Characterize the impact of genetically based variation in vitellogenin -- the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan -- on colony and reproductive (queen and drone) health and productivity. Sub-objective 1E: Identify and characterize genetic and physiological mechanisms of pesticide resistance in honey bees. Objective 2: Characterize genetic, physiological and behavioral aspects of important traits, strains and stocks. Sub-objective 2A: Examine patterns of genetic diversity and loci under selection in United States honey bee breeding populations, with a focus on stocks exhibiting high VSH activity. Sub-objective 2B: Elucidate the interaction between individual and social immune defenses. Sub-objective 2C: Improve understanding of the biology of the VSH trait. Objective 3: Conduct traditional breeding or marker-assisted selection of honey bees. Sub-objective 3A: Ascertain the effect of inbreeding on genetic diversity across the honey bee genome to support breeding and maintaining health of breeding populations. Sub-objective 3B. Assess genetic diversity at the sex locus of commercial breeding populations of honey bee stocks developed by USDA, ARS HBBGPL. Sub-objective 3C: Determine the potential usefulness of a simple hygiene assay as a selection tool to predict VSH-based mite resistance in honey bee colonies. Objective 4: Develop management tools for improving honey bee health. Sub-objective 4A: Identify and characterize genetic differences in honey bee response to introduced dsRNA, and test for correlations with viral infection and resistance. Sub-objective 4B: Improve understanding of the flight activity of Russian honey bees during almond pollination. Sub-objective 4C: Evaluate the efficacy of a microalgae platform to improve honey bee colony performance and health. Sub-objective 4D: Determine the sublethal effects of fungicides on honey bee health. Sub-objective 4E: Assess sustainability of Varroa control methods. Approach (from AD-416): Honey bee health is threatened by parasites, pathogens, poor nutrition and pesticides. Breeding robust bees with improved resistance (or tolerance) to threats could mitigate these problems. The project combines diverse approaches and techniques to seek and exploit genotype-dependent responses of honey bees to biotic-, nutrition- and pesticide-related stressors. The project improves understanding of genetic diversity across U.S. commercial stocks, enabling both marker-assisted selection and conservation of genetic resources. This will enhance the effectiveness of contemporary breeding programs. Varroa destructor (hereafter, Varroa) is the greatest threat to bee health worldwide. The project builds on past successes by improving selection efficiency for resistance to Varroa and for elevated colony performance, promoting adoption by beekeepers. Investigations target relationships between genetic diversity across stocks, immune responses, and treatment effectiveness against Varroa, viruses, and other related biotic threats. This is critical because of recent beekeeper reports of miticide- (amitraz-) resistant Varroa. Given the threat from Varroa, the plan outlines novel (Sub-objectives 2B, 4A) and continuing (Sub- objectives 2C, 3C, 4B) research on breeding and management related to Varroa-resistant honey bees. In addition, we also initiate a suite of new studies addressing the negative impact of stressors whose prevalence has increased across managed honey bees in the past decade. These studies will assess differences in genotype-dependent responses to viruses and other pathogens (Sub-objectives 1A, 2B), poor nutrition (Sub-objectives 1B, 1C, 1D, 4C), and pesticides (Sub-objectives 1E, 4D, 4E). The project seeks to improve nutrient assimilation efficiency through breeding. Similarly, genotype-dependent differences in bee responses to pesticides will be targeted for breeding less susceptible bees and reducing queen failures. Biomarkers identified as useful for signaling emerging health threats will be verified, benefitting beekeepers by allowing for rapid corrective intervention. These approaches will capitalize on novel sequencing technologies to examine many of these issues at a higher level of resolution across the honey bee genome (Sub-objectives 2A, 3A, 3B). As part of identification and evaluation of traits, strains and stocks for improved bee health (Objective 1), efforts have continued to focus on viral infection (1A), nutritional responses (1B, 1C, 1D) and pesticide sensitivity (1E). The selective breeding effort to produce honey bees that are resistant to viral infection (1Ai) has shifted focus by using drone susceptibility to DWV inoculation as the target for selection. This has been done in coordination with a commercial beekeeping partner who has documented virus resistance in their population along with the Pol- line stock developed by the Unit. Investigation into colony-level responses and how breeding for disease and mite-resistance influences viral infection has also expanded through a collaborative study with commercial beekeeping partners. Data analysis is also ongoing to identify if the Hilo bee population, highly selected for Varroa Sensitive Hygienic (VSH) behavior, is distinct from stock that are susceptible to the parasitic Varroa mite across a geographic transect of five different environmental locations and a temporal transect of 3 years (1Aii and subordinate project). Other subordinate projects related to Obj 1A include determinations on how viral infection impacts bee vision and foraging choices, a follow-up to previous research that indicated that viral infection altered diet choice and type of resources that foraging bees collected. The breeding potential for reduced susceptibility to pesticide exposure in honey bees was evaluated. Sensitivity to phenothrin, chlorpyrifos, and clothianidin was evaluated from 11 honey bee genetic lines. There was little variation in insecticide sensitivity (<3-fold) among these stocks, indicating minimal variation to select for insecticide resistant lines. Additional exploratory selection work was conducted through collaborative work with Agriculture and Agri-Food Canada. Data was curated and analyzed from the three year chalkbrood-stock experiment. Honey bee stock variation in chalkbrood infections correlated with hygienic behavior and in some stocks correlated with propolis production. Molecular work to determine the relationships between asymptomatic and symptomatic infections is ongoing. Another project aimed to evaluate the potential of susceptibility to pesticide exposure could be a trait for breeding selection in honey bees. Sensitivity to phenothrin, chlorpyrifos, and clothianidin was evaluated from 11 honey bee genetic lines. There was little variation in insecticide sensitivity (<3-fold) among these stocks indicating minimal variation to select for insecticide resistant lines. Additional exploratory selection work was conducted under collaborative work with Agriculture and Agri-Food Canada. Data was curated and analyzed from the three year chalkbrood-stock experiment. Some stocks are more resistant to chalkbrood than others, this correlated with hygienic behavior and sometimes correlated with propolis production in this study. Molecular work to determine the relationships between asymptomatic and symptomatic infections is ongoing. Progress has continued characterizing genetic, physiological and behavioral aspects of important traits, strains and stocks (Objective 2). In terms of genetic characterization, the Unit has led an inter-Agency collaboration to develop the first pangenome for honey bees while simultaneously applying this tool in the analysis of genetic diversity across research and commercial honey bee breeding lines (Obj 2A). This effort has also directly led to an international collaboration to develop a world-wide honey bee pangenome that incorporates genetic representation from all known honey bee subspecies. Assessment of how social immunity or colony-level behavioral defenses interact with individual bee physiological defenses determined that there was no trade-off of among the defenses measures (grooming, resin collection, hygienic behavior, larval immunity), but that a colony⿿s level of hygienic behavior (tendency to remove dead or infected larvae and pupae) was positively associated with the immune response of larvae (2B). This finding provides further support for the hypothesis that larvae and pupae may be signaling to indicate their health status. Additionally, results indicate that selection for one social immune trait does not reduce a colony⿿s expression of another trait, so selection for multiple traits of resistance should be a high priority. Studies also described volatile chemicals released by Varroa-resistant stocks subject to hygienic uncapping (2C). Complementary research was developed as an international collaboration with researchers in Argentina to examine parallel selection programs for Varroa Sensitive Hygienic (VSH) behavior. Phenotypic data contrasting US and Argentinian populations and a model was developed to more fully capture the entire set of information gained during the phenotyping process. Efforts will eventually lead to an examination of the genetic architecture of the trait in the Argentinian population and assess how broadly distributed the VSH trait may be and the consistency of the underlying genetic architecture mediating it. To examine the influence of nutritional status on colony behavior, Pol- line colonies were fit with pollen traps that reduce the amount of incoming pollen and thus nutrition colonies have access to. Their temperament, colony resources, and colony population were sampled weekly. Colonies that had pollen trapped had higher aggressive scores than colonies which were allowed to keep the pollen they collected. Continued work will focus on additional stocks to see if effects of nutritional deprivation are consistent across the genetic backgrounds of colonies. Specific progress related to Objective 3, with the goal of conducting traditional breeding or marker-assisted selection of honey bees has been made through subordinate projects. Allele-based breeding for predicted functional variants of the multifunctional gene vitellogenin began as a test case for neural network predicted marker assisted selection. Biomarkers for health and resilience have been identified and validation initiated through work with Agriculture and Agri-Food Canada and other Canadian partners. Development of management tools to improve bee health (Objective 4) has progressed in several areas. Research has completed on effects of chlorothalonil on colony performance. Colonies treated with chlorothalonil experience higher rates of colony losses due to higher Varroa infestation. For an examination of how different stocks may be managed differently for pollination services (4B), the foraging rates of Russian, Pol-Line, and unselected stocks were compared in almond orchards in California using hive monitoring technology. Data was collected on honey bee flight activity, colony weight, adult bee populations, and pollen collection loads. Amitraz resistant Varroa were subject to non-amitraz miticide applications to evaluate treatment success in collaboration with Auburn University (4E). This study also included the first evaluation of Varroa non-reproduction in amitraz resistant Varroa. Additionally, as part of a subordinate project, the bee toxicity of a potential new miticide to control Varroa was assessed. Research complementary to the broader goal of Obj. 4E was developed to examine the genetic mechanisms of resistance to control in the Varroa mite. The project aims to provide a US-wide catalogue of genetic variation of Varroa as a critical pest of honey bees while simultaneously conducting genome-wide association studies focusing on resistance to the primary mite control method (Amitraz). Results are expected to outline the key mutation(s) conferring resistance to this control method, opening a potential avenue to address this limitation. A number of subordinate projects related to management tools also progressed. A final patent disclosure was submitted for ⿿Engineered microalgae to improve honey bee pathogen resistance and nutrition. Expanding on this work, an RNAi treatment against Varroa mites using engineered microalgae is currently being tested. Work to improve artificial diets for honey bees has begun by characterizing feeding stimulants in pollen with the aim of recapitulating those effects in artificial diets. This has major implications for the beekeeping industry, where the use of artificial diets has become commonplace due to climate change and agricultural intensification. Current research focused on evaluating the impacts of bacterial extracts on honey bee toxicity in collaboration with Johns Hopkins University. These bacterial extracts may be harmful to bees when it is the only food source they are fed, but bee mortality is reduced with presented with alternative food sources and bees learn to avoid food containing bacterial extracts. Additional studies include the effects of colony boxes that stimulate propolis deposition on Varroa infestation in 3 stocks of honey bees. Lastly, to improve reliability of honey bee queen insemination process, tests have been conducted to on the viability of honey bee semen stored for long periods of time under heat stress. ACCOMPLISHMENTS 01 Genetic mutation and beekeeper management predict mite resistance to miticide. The parasitic Varroa mite significantly impacts honey bee health and is the largest driver of colony mortality. Recently, reports indicate that chemical control of the mites by the most widely used treatment, Amitraz, has been inconsistent. How often and why the mites are developing resistance is key to improve treatment decisions. Mites from more than 1,382 colonies from 146 apiaries across 82 beekeeping operations have been sampled. Each beekeeping operation has its own resident Varroa population with Amitraz resistance levels likely to be driven by amitraz use patterns. Highly resistant Varroa tends to be the result of overuse (intensity and frequency) and overreliance on Amitraz as the sole measure of Varroa control. Evidence also indicates that Amitraz resistant Varroa do not move passively among beekeeping operations, even in close proximity and at high colony density. Through an international effort, a genetic mutation strongly associated with amitraz resistance in Varroa in the U.S. has been confirmed. This research is of importance to the beekeeping industry as the reduced efficacy of amitraz to control Varroa is increasing demand for alternative miticides and Varroa management practices. Results have also informed beekeepers of the need to change management practices by rotating types of miticide treatment to reduce the likelihood of resistance developing in their population. 02 Nutritional deprivation increases honey bee aggression and alters how they process food. Honey bee colonies are routinely provided with nutritional supplements during periods of drought and associated food shortages. In a changing climate, these events may increase in intensity and frequency, or occur at unexpected intervals. Understanding how bees respond to challenging nutritional times critically determines management strategies and breeding tactics. When colonies were deprived of pollen, they became more aggressive, overall, than colonies that had access to pollen resources. Temperament and aggression are sometimes used to select breeding stock in rearing operations, so these findings are important in light of breeding initiatives in our changing world. Additional research identified that honey bee stocks derived from Italian and Russian honey bees respond to nutritional deprivation in distinct ways. Russian honey bee workers appear to conserve individual nutritional stores at the expense of producing nutrient rich brood food components. Conversely, Italian honey bee workers continue production of brood food components at the expense of nutrient stores. This has potential implications for traits that are beneficial in a changing climate and informs beekeepers about when and how to use nutritional supplements based on the type of honey bee. 03 Using advanced technologies to improve honey bee breeding and stock- specific selection. The Russian honey bee stock was the first population where use of a marker-based, genetic stock identification (GSI) assay was applied in breeding. Recent developments in sequencing have increased our ability to understand, evaluate and use genetic tools to advance breeding efforts. An updated stock identification panel using novel genetic variation would provide a more accurate discrimination tool and serve as a pilot for future marker panels. Using recent genomic data and historically preserved DNA, a new marker panel was developed using a microfluidic platform. The resulting assay outperformed the original GSI while simultaneously increasing efficiency and reducing cost. This novel approach is currently being finalized to incorporate in stakeholder breeding decisions. In addition, the method is inherently modular and has pioneered analytical approaches that can be directly implemented in trait-based or other marker-assisted selection panels. 04 New antiviral drug target identified in honey bees and field test completed. Honey bees contend with many parasites and pathogens that greatly impact colony productivity and survival. Viral infections, either transmitted by the parasitic Varroa mite or spread from bee to bee, cause both direct and subtle effects on bee behavior and lifespan. Despite the fact that honey bees are often co-infected with multiple viruses at both the individual bee and colony levels, there are no antivirals available for beekeepers. In collaboration with Louisiana State University, a compound was tested both in the laboratory and under field conditions that activates honey bee potassium ion channels. By regulating these channels, the drug increases a honey bee⿿s ability to fight infection of multiple viruses. Field tests feeding this drug to virus-inoculated colonies confirmed laboratory results and for the first time showed that pharmacological treatment against viruses is possible for honey bee colonies. This research identified a physiological target to focus on in honey bees that can be used to develop a drug treatment that could be approved to improve honey bee resilience to viral infection. As there are no treatments currently available against honey bee viruses, finding ways to reduce the impacts of virus in honey bees is a critical need to reduce potential virus spread to other bee species and increase the sustainability of the beekeeping industry.
Impacts
(N/A)
Publications
- Dostalkova, S., Kodrik, D., Simone-Finstrom, M., Petrivalsky, M., Danihlik, J. 2022. Fine-scale assessment of Chlorella syrup as a nutritional supplement for honey bee colonies. Frontiers in Ecology and Evolution. 10(1028037):1-12. https://doi.org/10.3389/fevo.2022.1028037.
- Rinkevich Jr, F.D., Moreno-Marti, S., Hernandez-Rodriguez, C.S., Gonzalez- Cabrera, J. 2023. Confirmation of the Y215H mutation in the ÿ2-octopamine receptor in Varroa destructor is associated with contemporary cases of amitraz resistance in United States. Pest Management Science. pp.1-6. https://doi.org/10.1002/ps.7461.
- Dickey, M., Walsh, E.M., Shepherd, T.F., Medina, R.F., Tarone, A., Rangel, J. 2023. Transcriptomic analysis of the honey bee (Apis mellifera) queen brain reveals that gene expression is affected by pesticide exposure during development. PLOS ONE. 18(4):e0284929. https://doi.org/10.1371/ journal.pone.0284929.
- Penn, H., Simone-Finstrom, M., De Guzman, L.I., Tokarz, P.G., Dickens, R.D. 2022. Viral species differentially influence macronutrient preferences based on honey bee genotype. Biology Open. 11(10):bio059039. https://doi. org/10.1242/bio.059039.
- Fellows, C., Simone-Finstrom, M., Anderston, T., Swale, D. 2023. Potassium ion channels as a druggable target to inhibit viral replication in honey bees. Virology. 20(134):1-17. https://doi.org/10.1186/s12985-023-02104-0.
- Ihle, K.E. 2023. Genetic stock affects expression patterns of the multifunctional gene Vitellogenin in honey bee workers. Journal of Apicultural Research. p. 1-3. https://doi.org/10.1080/00218839.2023. 2166231.
- Traniello, I.M., Bukhari, S.A., Dibaeinia, P., Serrano, G., Avalos, A., Ahmed, A.C., Sankey, A., Hernaez, M., Sinha, S., Zhao, S.D., Catchen, J., Robinson, G.E. 2023. Single-cell dissection of a collective behaviour in honeybees. Nature Ecology and Evolution. 2:1-25. https://doi.org/10.3389/ finsc.2022.998310.
- Avalos, A., Bilodeau, A.L. 2022. Russian honey bee genotype identification through enhanced marker panel set. Frontiers in Insect Science. 2:998310. https://doi.org/10.3389/finsc.2022.998310.
- Nichols, B.J., Ricigliano, V.A. 2022. Uses and benefits of algae as a nutritional supplement for honey bees. Frontiers in Sustainable Food Systems. 6:1005058. https://doi.org/10.3389/fsufs.2022.1005058.
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Progress 10/01/21 to 09/30/22
Outputs
PROGRESS REPORT Objectives (from AD-416): Meaningful contributions towards enhancing the economic value of the nation⿿s commercially managed honey bee populations can be achieved through identifying, characterizing and breeding more robust bees. The proposed 5-year plan focuses on synergistic projects (Fig.1) that capitalize on genetic and breeding approaches with the following objectives: Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Sub-objective 1B: Evaluate genotype-dependent nutrient efficiency in commercial honey bee stocks. Sub-objective 1C: Evaluate genotype-dependent nutritional stress resistance in commercial honey bee stocks. Sub-objective 1D: Characterize the impact of genetically based variation in vitellogenin -- the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan -- on colony and reproductive (queen and drone) health and productivity. Sub-objective 1E: Identify and characterize genetic and physiological mechanisms of pesticide resistance in honey bees. Objective 2: Characterize genetic, physiological and behavioral aspects of important traits, strains and stocks. Sub-objective 2A: Examine patterns of genetic diversity and loci under selection in United States honey bee breeding populations, with a focus on stocks exhibiting high VSH activity. Sub-objective 2B: Elucidate the interaction between individual and social immune defenses. Sub-objective 2C: Improve understanding of the biology of the VSH trait. Objective 3: Conduct traditional breeding or marker-assisted selection of honey bees. Sub-objective 3A: Ascertain the effect of inbreeding on genetic diversity across the honey bee genome to support breeding and maintaining health of breeding populations. Sub-objective 3B. Assess genetic diversity at the sex locus of commercial breeding populations of honey bee stocks developed by USDA, ARS HBBGPL. Sub-objective 3C: Determine the potential usefulness of a simple hygiene assay as a selection tool to predict VSH-based mite resistance in honey bee colonies. Objective 4: Develop management tools for improving honey bee health. Sub-objective 4A: Identify and characterize genetic differences in honey bee response to introduced dsRNA, and test for correlations with viral infection and resistance. Sub-objective 4B: Improve understanding of the flight activity of Russian honey bees during almond pollination. Sub-objective 4C: Evaluate the efficacy of a microalgae platform to improve honey bee colony performance and health. Sub-objective 4D: Determine the sublethal effects of fungicides on honey bee health. Sub-objective 4E: Assess sustainability of Varroa control methods. Approach (from AD-416): Honey bee health is threatened by parasites, pathogens, poor nutrition and pesticides. Breeding robust bees with improved resistance (or tolerance) to threats could mitigate these problems. The project combines diverse approaches and techniques to seek and exploit genotype-dependent responses of honey bees to biotic-, nutrition- and pesticide-related stressors. The project improves understanding of genetic diversity across U.S. commercial stocks, enabling both marker-assisted selection and conservation of genetic resources. This will enhance the effectiveness of contemporary breeding programs. Varroa destructor (hereafter, Varroa) is the greatest threat to bee health worldwide. The project builds on past successes by improving selection efficiency for resistance to Varroa and for elevated colony performance, promoting adoption by beekeepers. Investigations target relationships between genetic diversity across stocks, immune responses, and treatment effectiveness against Varroa, viruses, and other related biotic threats. This is critical because of recent beekeeper reports of miticide- (amitraz-) resistant Varroa. Given the threat from Varroa, the plan outlines novel (Sub-objectives 2B, 4A) and continuing (Sub- objectives 2C, 3C, 4B) research on breeding and management related to Varroa-resistant honey bees. In addition, we also initiate a suite of new studies addressing the negative impact of stressors whose prevalence has increased across managed honey bees in the past decade. These studies will assess differences in genotype-dependent responses to viruses and other pathogens (Sub-objectives 1A, 2B), poor nutrition (Sub-objectives 1B, 1C, 1D, 4C), and pesticides (Sub-objectives 1E, 4D, 4E). The project seeks to improve nutrient assimilation efficiency through breeding. Similarly, genotype-dependent differences in bee responses to pesticides will be targeted for breeding less susceptible bees and reducing queen failures. Biomarkers identified as useful for signaling emerging health threats will be verified, benefitting beekeepers by allowing for rapid corrective intervention. These approaches will capitalize on novel sequencing technologies to examine many of these issues at a higher level of resolution across the honey bee genome (Sub-objectives 2A, 3A, 3B). This report documents progress of the third year for project 6050-21000- 016-000D (Using Genetics to Improve the Breeding and Health of Honey Bees) , which began in March 2020. Progress was made in research objectives that fall under National Program 305, Component 2, Bees and Pollination. The goal of this research is to enhance the economic value of the nation⿿s commercially managed honey bee populations through identifying, characterizing, and breeding more robust bees while also informing management practices. For research related to identifying and evaluating traits, strains, and stocks for improved bee health (Obj 1), developments across several projects were made and findings often highlighted the continued need to integrate bee genotype with external factors (environment, social, etc.) to fully evaluate traits. Projects done in collaboration with stakeholders provide key examples, such as a recent analysis of performance of the mite-resistant Pol-line population, developed in Baton Rouge, Louisiana, in commercial beekeeping. The study also identified major determining factors that lead to colony death during migratory beekeeping, such as viral infections. A series of collaborative studies with ARS researchers in Houma, Louisiana, and Beltsville, Maryland, examined how different stocks respond to viral infections in the laboratory. Results from each study highlighted the importance of evaluating the interaction between genetic background (bee stock) and viral strains, as there are variable outcomes when different bee stocks and different types of viruses interact (Obj 1A). This was evident in terms of how viral infections spread throughout bee tissues after infection and how viral infections alter diet and foraging choices. In other viral work, a new collaboration was developed with a stakeholder and conducted bi-directional selection for viral susceptibility based on drone responses to Deformed wing virus (Obj 1A). This breeding effort combined with ongoing work with collaborators from the University of Alberta should lead to identifying genetic markers associated with antiviral resistance. Complementarily, additional projects include development of novel RNAi-based delivery systems to mitigate the effects of honey bee viruses that combine nutritional supplementation with antiviral treatments. Other drug-based antiviral field testing is being conducted with collaborators at Louisiana State University. Projects in Obj 1 also advanced our knowledge of how different genetic stocks responded to periods of nutritional stress. Colonies of three different stocks of bees (Italian, Pol-line, or Russian) were evaluated in two different geographic locations (Louisiana and Arizona) under nutritionally restricted conditions in collaboration with ARS researchers in Tucson, Arizona. Results indicated that geographic location plays a large factor in stock-related performance metrics (Obj 1C). Basic research into nutritional mechanisms has provided a pathway to improve honey bee health and resiliency through a new breeding program for enhanced vitellogenin (Vg) production. Vg is a key storage protein in honey bees that is associated with longevity and overwintering success. Initial bi-directional selection for high and low Vg lines has been completed and continued selection is ongoing to develop these lines further (Obj 1D). In addition, assessment of more than 150 queens from over 10 different stakeholders have been examined with a focus on pesticide sensitivity finding both within and between stock variation. Enzymatic activity evaluation and DNA sequencing efforts are ongoing using bees from the 6 stocks tested (Obj 1E). Efforts toward characterizing genetic, physiological, and behavioral aspects of important traits, strains, and stocks (Obj 2) was made via enhanced and strengthened collaborative efforts. A honey bee pangenome from research lines and commercially relevant populations is being made to catalog genetic diversity in the U.S. (Obj 2A). Baton Rouge is leading this effort as part of a collaborative project with ARS units in Stoneville, Mississippi; Beltsville, Maryland; and Hilo, Hawaii. Component reference genomes are currently being generated as part of the development process. Together with complementary population sequencing, the project will result in the most complete catalogue of genetic variation within U.S. honey bee populations. For one specific stock, the Russian honey bee population, genetic diversity data analysis has been conducted showing healthy breeding populations and will be used to inform breeding decisions for the Russian honey bee stock managed by the Russian Honey Bee Breeders Association. A collaboration with the University of Illinois resulted in a gene network analysis that was used to refine genetic markers associated with traits of interest. While much focus has been on characterizing genetic aspects of traits, recent progress on identifying behavioral aspects related to parasite resistance in stocks, highlighted our need to further evaluate our stocks. One defense that the original host of the damaging, invasive parasitic varroa mite uses to prevent it from killing its colonies is a behavior called social apoptosis. It is a defense where mite-infested pupae rapidly die and thus prevent the mite from becoming a colony-wide threat. Research found that Russian honey bee pupae infested with mites have decreased survival suggesting they may exhibit this trait as one of their mechanisms of mite resistance (Obj 2B). Work related to traditional breeding and marker-assisted selection of honey bees (Obj 3) continued to develop. To quantify the effects of constrained breeding on population health, colonies were setup, monitored, and bred for subsequent generations to study effects on inbreeding depression focused on targeted areas of reduced genome diversity (Obj 3A). One genomic area of interest has been the complimentary sex determiner (csd) locus. Genetic analysis of csd of the mite resistant Russian honey bee population was completed, providing general characterization of the overall health and strength of the breeding population (Obj. 3B). Work with the University of Missouri to identify molecular markers directly correlated with the Varroa Sensitive Hygiene (VSH) trait has continued. The project implements candidate genes (in-house) analysis and ⿿eQTL, an approach that uses gene expression and whole genome sequencing to discover markers with a high degree of certainty. Breeding for productive, Varroa-resistant bees has also continued in a public-private partnership in which bees selected by the Unit for VSH formed much of the founding population in the development of a stock called Hilo Bees. Research in collaboration with the University of Minnesota, conducted in a commercial beekeeping operation, has shown the benefits of propolis in beekeeping management with colonies kept in rough boxes with more propolis having more stable immune responses and larger populations in almonds. Lastly, projects involving development of management tools for improving honey bee health (Obj 4) advanced. Significant developments were made toward evaluating the efficacy of microalgal diets for improving honey bee health (Obj 4C). A large-scale field trial testing a microalgae-based artificial diet was conducted in a commercial beekeeping operation located in California. Colony performance, health biomarkers and thermoregulatory behavior was monitored in hives fed microalgae or a commercial protein supplement and unfed hives were used as a control. Hives fed microalgae produced more brood relative to the protein supplement at one of the apiary sites tested. In general algae-fed hives showed improved performance relative to unfed hives. Overall nutritional supplementation improved brood area thermoregulation. In collaboration with scientists at the University of North Carolina at Greensboro, further research aimed to determine the utility of artificial microalgal based diets for honey bees focusing on fine-scale measures. Results indicated that microalgae have potential as sustainable bee feed additives and health-modulating natural products. Metabolomics-guided diet development could eventually help tailor feed interventions to achieve precision nutrition in honey bees. Additional work with collaborators at University of Olomouc, Czech Republic explored alternative algal species for supplemental diets in honey bees. Experiments have been conducted to determine the sublethal effects of fungicides on colony health (Obj 4D). Both technical grade and formulated chlorothalonil showed synergism, antagonism, or no effect on insecticide sensitivity. This project expanded to include collaboration with Mississippi State University to test effects on the royal jelly fed by nurse bees to developing queen larvae to fully assess any sublethal effects of fungicide exposure on the full queen developmental process. In addition, colony level experiments are assessing the effects of chlorothalonil on queen health and colony performance and colonies are being monitored through spring of FY 23. Work on amitraz resistance in varroa mites (Obj. 4E) is also a major research focus and a major concern for the beekeeping industry as cases of resistance have been noted in the field. Expansion of the amitraz resistance monitoring network in 2021 allowed for tests to be performed on 426 colonies across 34 apiaries managed by 24 beekeepers. A survey on amitraz use patterns and colony management was conducted in collaboration with researchers at Auburn University to identify factors that lead to amitraz resistance in varroa mites. Genomic analyses are being conducted to identify what genes are involved in amitraz resistance in varroa mites. DNA tests to detect resistance in pooled collections of varroa mites are being developed in collaboration with researchers at University of Maryland and University of Valencia in Spain. ACCOMPLISHMENTS 01 Improving artificial diets for honey bees. Honey bee colonies managed for agricultural pollination are highly dependent on human inputs, especially for supplemental nutrition. Hives are routinely fed artificial pollen substitute diets to compensate for insufficient pollen forage in the environment. ARS researchers in Baton Rouge, Louisiana, conducted a large-scale field experiment in collaboration with a commercial beekeeper to test the effects of different artificial diets on commercial honey bee colony performance. The results indicated that diet efficacy was correlated with essential amino acid ratios, which will help to inform industry regarding the development of improved bee feed. Additional work carried out by ARS scientists in Baton Rouge, Louisiana, in collaboration with University of North Carolina Greensboro applied metabolomic analyses to better understand the impact of novel microalgae-based artificial diets developed at the Baton Rouge location. The metabolomics results are useful to understand mechanisms underlying favorable growth performance and health characteristics in bees fed the microalgae diets. Metabolomics-guided diet development can help tailor feed interventions to achieve precision nutrition in honey bees and other livestock animals. 02 Testing and finding new traits of resistance to damaging mite pests in honey bees. Honey bee colonies face a variety of parasites and pathogens that result in significant annual losses by beekeepers and management costs. Breeding efforts for traits of resistance and a greater understanding of how resistant populations prevent damaging infestations, particularly from the damaging varroa mite, are of the utmost importance for the sustainability of the beekeeping industry. Research conducted by ARS researchers in Baton Rouge, Louisiana, in collaboration with Louisiana State University and a commercial beekeeper tested the functionality of mite-resistant Pol-line bees. The Pol-line stock expresses a high level of resistance to the varroa mite based on a trait called Varroa Sensitive Hygiene which results in the inability of mites to reproduce in a colony and transmit fewer viruses, as shown by this study. The Pol-line bees were found to be highly productive in the commercial migratory operation and were more successful through almond pollination than the control bees that the beekeeper would have normally relied on. While Pol-line rely on VSH behavior, other stocks like the Russian honey bees express multiple traits of resistance that are still being understood. Research has recently identified that Russian honey bees exhibit, social apoptosis, where varroa mite infested pupae die more quickly, and thus can prevent mites from successfully reproducing and producing offspring on pupae. These results shed light on how important it is to fully evaluate stocks to enhance resistance traits and also that breeding for multiple traits of resistance can provide robust support against parasites like varroa mites.
Impacts
(N/A)
Publications
- Ricigliano, V.A., Cank, K.B., Todd, D.A., Knowles, S.L., Oberlies, N.H. 2022. Metabolomics-guided comparison of pollen and microalgae-based artificial diets in honey bees. Journal of Agricultural and Food Chemistry. https://doi.org/10.1021/acs.jafc.2c02583.
- Avalos, A., Traniello, I.M., Perez Claudio, E., Giray, T. 2021. Parallel mechanisms of visual memory formation across distinct regions of the honey bee brain. Journal of Experimental Biology. 224(19):jeb242292. https://doi. org/10.1242/jeb.242292.
- Lang, S.A., Simone-Finstrom, M., Healy, K. 2022. Context-dependent viral transgenerational immune priming in honey bees (Hymenoptera: apidae). Journal of Insect Science. 22(1):19. https://doi.org/10.1093/jisesa/ ieac001.
- Simone-Finstrom, M., Strand, M.K., Tarpy, D.R., Rueppell, O. 2022. 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. Journal of Insect Science. 22(1):17. https://doi. org/10.1093/jisesa/ieab096.
- Gomes Viana, J.P., Fang, Y., Avalos, A., Song, Q., Nelson, R., Hudson, M.E. 2022. Impact of multiple selective breeding programs on genetic diversity in soybean germplasm. Theoretical and Applied Genetics. 135(5):1591⿿1602. https://doi.org/10.1007/s00122-022-04056-5.
- Bilodeau, A.L., Beaman, G.D. 2022. Differential expression of three dopamine receptors in varroa-resistant honey bees. Journal of Insect Science. 22(1):1-5. https://doi.org/10.1093/jisesa/ieab109.
- Ricigliano, V.A., Williams, S.T., Oliver, R. 2022. Effects of different artificial diets on commercial honey bee colony performance, health biomarkers, and gut microbiota. BMC Veterinary Research. 18(52):1-14. https://doi.org/10.1186/s12917-022-03151-5.
- Bilodeau, A.L. 2022. Genetic diversity and structure in a closed breeding system of Russian honey bees. Journal of Economic Entomology. 115(2):682- 687. https://doi.org/10.1093/jee/toab266.
- Penn, H., Simone-Finstrom, M., De Guzman, L.I., Tokarz, P.G., Dickens, R.D. 2022. Colony-level viral load influences collective foraging in honey bees. Frontiers in Insect Science. 2:894482. https://doi.org/10.3389/finsc. 2022.894482.
- Penn, H., Simone-Finstrom, M., Lang, S.A., Chen, Y., Healy, K. 2021. Host genotype and tissue type determine DWV infection intensity. Frontiers in Insect Science. Article 756690:1-12. https://doi.org/10.3389/finsc.2021. 756690.
- Penn, H.J., Simone-Finstrom, M.D., Chen, Y., Healy, K.B. 2022. Honey bee genetic stock determines DWV symptom severity but not viral load or dissemination following pupal exposure. Frontiers in Genetics. 13:909392. https://doi.org/10.3389/fgene.2022.909392.
- O'Shea-Wheller, T.A., Rinkevich Jr, F.D., Danka, R.G., Simone-Finstrom, M., Tokarz, P.G., Healy, K.B. 2022. A derived honey bee stock confers resistance to Varroa destructor and associated viral transmission. Scientific Reports. 12(1). Article 4852. https://doi.org/10.1038/s41598- 022-08643-w.
- Ihle, K.E., De Guzman, L.I., Danka, R.G. 2022. Social apoptosis in Varroa mite resistant western honey bees (Apis mellifera). Journal of Insect Science. 22(1):13. https://doi.org/10.1093/jisesa/ieab087.
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Progress 10/01/20 to 09/30/21
Outputs
PROGRESS REPORT Objectives (from AD-416): Meaningful contributions towards enhancing the economic value of the nation⿿s commercially managed honey bee populations can be achieved through identifying, characterizing and breeding more robust bees. The proposed 5-year plan focuses on synergistic projects (Fig.1) that capitalize on genetic and breeding approaches with the following objectives: Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Sub-objective 1B: Evaluate genotype-dependent nutrient efficiency in commercial honey bee stocks. Sub-objective 1C: Evaluate genotype-dependent nutritional stress resistance in commercial honey bee stocks. Sub-objective 1D: Characterize the impact of genetically based variation in vitellogenin -- the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan -- on colony and reproductive (queen and drone) health and productivity. Sub-objective 1E: Identify and characterize genetic and physiological mechanisms of pesticide resistance in honey bees. Objective 2: Characterize genetic, physiological and behavioral aspects of important traits, strains and stocks. Sub-objective 2A: Examine patterns of genetic diversity and loci under selection in United States honey bee breeding populations, with a focus on stocks exhibiting high VSH activity. Sub-objective 2B: Elucidate the interaction between individual and social immune defenses. Sub-objective 2C: Improve understanding of the biology of the VSH trait. Objective 3: Conduct traditional breeding or marker-assisted selection of honey bees. Sub-objective 3A: Ascertain the effect of inbreeding on genetic diversity across the honey bee genome to support breeding and maintaining health of breeding populations. Sub-objective 3B. Assess genetic diversity at the sex locus of commercial breeding populations of honey bee stocks developed by USDA, ARS HBBGPL. Sub-objective 3C: Determine the potential usefulness of a simple hygiene assay as a selection tool to predict VSH-based mite resistance in honey bee colonies. Objective 4: Develop management tools for improving honey bee health. Sub-objective 4A: Identify and characterize genetic differences in honey bee response to introduced dsRNA, and test for correlations with viral infection and resistance. Sub-objective 4B: Improve understanding of the flight activity of Russian honey bees during almond pollination. Sub-objective 4C: Evaluate the efficacy of a microalgae platform to improve honey bee colony performance and health. Sub-objective 4D: Determine the sublethal effects of fungicides on honey bee health. Sub-objective 4E: Assess sustainability of Varroa control methods. Approach (from AD-416): Honey bee health is threatened by parasites, pathogens, poor nutrition and pesticides. Breeding robust bees with improved resistance (or tolerance) to threats could mitigate these problems. The project combines diverse approaches and techniques to seek and exploit genotype-dependent responses of honey bees to biotic-, nutrition- and pesticide-related stressors. The project improves understanding of genetic diversity across U.S. commercial stocks, enabling both marker-assisted selection and conservation of genetic resources. This will enhance the effectiveness of contemporary breeding programs. Varroa destructor (hereafter, Varroa) is the greatest threat to bee health worldwide. The project builds on past successes by improving selection efficiency for resistance to Varroa and for elevated colony performance, promoting adoption by beekeepers. Investigations target relationships between genetic diversity across stocks, immune responses, and treatment effectiveness against Varroa, viruses, and other related biotic threats. This is critical because of recent beekeeper reports of miticide- (amitraz-) resistant Varroa. Given the threat from Varroa, the plan outlines novel (Sub-objectives 2B, 4A) and continuing (Sub- objectives 2C, 3C, 4B) research on breeding and management related to Varroa-resistant honey bees. In addition, we also initiate a suite of new studies addressing the negative impact of stressors whose prevalence has increased across managed honey bees in the past decade. These studies will assess differences in genotype-dependent responses to viruses and other pathogens (Sub-objectives 1A, 2B), poor nutrition (Sub-objectives 1B, 1C, 1D, 4C), and pesticides (Sub-objectives 1E, 4D, 4E). The project seeks to improve nutrient assimilation efficiency through breeding. Similarly, genotype-dependent differences in bee responses to pesticides will be targeted for breeding less susceptible bees and reducing queen failures. Biomarkers identified as useful for signaling emerging health threats will be verified, benefitting beekeepers by allowing for rapid corrective intervention. These approaches will capitalize on novel sequencing technologies to examine many of these issues at a higher level of resolution across the honey bee genome (Sub-objectives 2A, 3A, 3B). This report documents progress of the second year for project 6050-21000- 016-00D (Using Genetics to Improve the Breeding and Health of Honey Bees), which began in March 2020. Progress was made by ARS scientists at Baton Rouge, Louisiana in research objectives that fall under National Program 305, Component 2, Bees and Pollination. The goal of this research is to enhance the economic value of the nation⿿s commercially managed honey bee populations through identifying, characterizing and breeding more robust bees while concurrently informing management practices. ARS scientists at Baton Rouge, Louisiana research regarding identification and evaluation of traits, strains and stocks for improved honey bee health (Obj. 1) progressed with specific developments in experiments related to viral infection, nutrigenomics and susceptibility to pesticides. Progress was made by ARS scientists at Baton Rouge, Louisiana in understanding resistance and tolerance traits associated with viral infection and how honey bees stocks and genotypes differentially respond to Deformed wing virus, Israeli acute paralysis virus and Chronic bee paralysis virus across levels of biological organization (cellular, individual and colony levels) (Obj. 1A). This work involves several projects including collaborative efforts with Louisiana State University, University of Minnesota, University of Alberta, and University of Olomouc (Czech Republic). Progress has also been made by ARS scientists at Baton Rouge, Louisiana toward the development of a novel RNAi delivery system to mitigate honey bee pathogens (in-house) and on initial field trials of chemical-based viral treatments (collaboration with Louisiana State University). In assessments of nutritionally regulated traits for potential future breeding efforts, different honey bee genotypes were assessed by ARS scientists at Baton Rouge, Louisiana for efficiency of food conversion (Obj 1B), proteomic responses to rich and poor nutrient conditions (Obj 1C), and production of the key storage protein vitellogenin (Obj 1D). Results suggest that genotype-dependent nutritional responses are present, with promising implications for honey bee breeding efforts and tailored approaches to diet and health. To aid in understanding the genetic variation in pesticide detoxification capabilities (Obj. 1E), an extensive literature review by ARS scientists at Baton Rouge, Louisiana produced a large database on honey bee pesticide toxicity. ARS scientists at Baton Rouge, Louisiana collaborating with University of Minnesota and Louisiana State University improved understanding of the influences that environmental factors, the nest environment (e.g. amount of propolis deposition) or broader apiary conditions, impart on pesticide exposure and sensitivity. Developments were made by ARS scientists at Baton Rouge, Louisiana in the characterization of genetic, physiological and behavioral aspects of important traits, strains and stocks (Obj. 2). Samples have been sequenced by ARS scientists at Baton Rouge, Louisiana for follow-up work to our earlier large-scale genomic sequencing effort examining genetic diversity across seven commercial honey bees stocks in order to expand those initial results and conduct more detailed analysis on specific genomic regions (Obj 2A). Additional analyses by ARS scientists at Baton Rouge, Louisiana include a collaboration with ARS researchers in Stoneville, Mississippi involving the construction of a honey bee pangenome from research lines and commercially relevant populations and subsequent validation with current and historical samples. ARS scientists at Baton Rouge, Louisiana collaborative work with researchers at the University of Puerto Rico Rio Piedras and Florida International University involves genome assembly of African honey bees (Apis mellifera scutellata), and Puerto Rican honey bees as a representative hybrid population with the aim of characterizing genetic diversity in ancestral and derived populations. A focus on information specifically to mitigate Varroa mites and support various resistance traits in honey bees continued with ARS scientists at Baton Rouge, Louisiana research aimed at identifying upregulated genes in mite-infested pupae targeted for removal by bees performing Varroa sensitive hygienic (VSH) behavior (Obj 2B). ARS scientists at Baton Rouge, Louisiana efforts to support traditional breeding or marker-assisted selection of honey bees progressed (Obj. 3). Genetic diversity at the complementary sex-determiner (csd) locus was assessed by ARS scientists at Baton Rouge, Louisiana in Pol-line and Hilo bees and was determined to be comparable to other selected stocks. ARS scientists at Baton Rouge, Louisiana in collaboration with University of Missouri, a global standardized nomenclature system for honey bee csd alleles was developed and made publicly available in the Hymenopteramine database. (Obj. 3B). Allelic data for csd are currently being used by ARS scientists at Baton Rouge, Louisiana to inform breeding decisions for Pol- line and Hilo stocks. Modernization of the established stock identification assay for Russian honey bees progressed, identifying approximately 200 potentially informative markers to be applied using microfluidics technology. This platform has the strong potential to be used for additional marker-assisted selection assays and csd sequencing going forward. An assay using the chemical ecology that regulates expression of hygienic behavior was tested (Obj 3C), and results indicated that the assay, developed by collaborators from the University of North Carolina at Greensboro, may require further refinement before it can be effectively used as a selection tool for VSH. Work is also ongoing by ARS scientists at Baton Rouge, Louisiana to identify molecular markers related to expression of the trait of VSH, including approaches using candidate genes (in-house), whole-genome sequencing and marker discovery using both gene expression and sequence information via ⿿eQTL (with the University of Missouri). Breeding for productive, Varroa-resistant bees continues in a public-private partnership in which bees selected by the Unit for Varroa sensitive hygiene form much of the founding population for a new stock, called Hilo Bees. ARS scientists at Baton Rouge, Louisiana research in collaboration with the University of Minnesota and a commercial beekeeper cooperator has continued to clarify the role of propolis in honey bee immunity and its potential benefits in beekeeping management, and to breed bees with improved health, founded on social immunity. Progress was also made by ARS scientists at Baton Rouge, Louisiana in projects related to the development of management tools for improving honey bee health (Obj. 4). As an initial assessment of potential genotypic differences in responsiveness to RNAi-based treatments, the robustness of RNAi pathway response was evaluated by ARS scientists at Baton Rouge, Louisiana for Russian, Pol-line and Saskatraz honey bee stocks (Obj 4A). Evaluation of a new nutritional supplement, ARS scientists at Baton Rouge, Louisiana in collaboration with a commercial beekeeping operation, was conducted to evaluate the use of microalgae as an alternative nutrition source for bees (Obj 4C). Results indicate that this preliminary formulation is comparable to current commercial products, at least with respect to colony survival rates. Additional collaborative efforts with North Carolina State University and beekeeper stakeholders characterized the overall effectiveness of and the metabolic responses to natural and artificial diets used by commercial beekeepers as well as novel microalgae-based diets developed in-house. From a toxicological perspective, preliminary experiments have begun with regard to chlorothalonil toxicity (Obj. 4D). Both technical grade and formulated product yielded very little mortality and no effects on longevity in tests performed in the lab. Experiments are underway by ARS scientists at Baton Rouge, Louisiana to study if chlorothalonil synergizes insecticide toxicity or acts as an inhibitor of detoxification, and how the lab results translate to colony-level exposures. Work on amitraz resistance in Varroa mites (Obj. 4E) has seen significant strides. A second year of resistance testing was able to be completed by utilizing a network of collaborators, and samples are being prepared for genomic analyses. Collaboration with a USDA-ARS scientist (Beltsville, Maryland) has shown that changes in the physical or chemical properties of amitraz do not explain control failures, which are most likely due to amitraz resistance in Varroa mites. This work has led to additional collaborations on this subject with The Ohio State University, Michigan State University and Bee Informed Partnership to greatly expand the scope of the resistance monitoring program. In subordinate projects, research was conducted by ARS scientists at Baton Rouge, Louisiana on the influence of propolis deposition on insecticide sensitivity and detoxification activity in honey bees, and to determine the presence of pesticides in propolis collected from colonies across different landscapes. Two longitudinal field trials of two years each are yielding information about the biotic and abiotic health threats to honey bees in commercial beekeeping operations. These trials were conducted by ARS scientists at Baton Rouge, Louisiana in collaboration with Louisiana State University. Progress was also made in collaboration with North Carolina State University and University of Pennsylvania to clarify the genetic determinants of queen quality. Record of Any Impact of Maximized Teleworking Requirement: The maximized telework posture impacted ARS scientists at Baton Rouge, Louisiana ability to initiate new research projects and the scope of many projects. Maximized telework posture has, however, allowed for increased time devoted to curating largescale datasets, a task that is often put aside during field research season. This period has also provided an opportunity to foster and develop collaborative projects within and outside the agency for future work. ACCOMPLISHMENTS 01 Commercial breeding improves resistance to parasites in honey bees. ARS scientists at Baton Rouge, Louisiana suggests the parasitic varroa mite is responsible for nearly 50% of annual honey bee colony losses. Widespread breeding for resistance to this mite is a complex process, which has deterred adoption by stakeholders. ARS scientists at Baton Rouge, Louisiana worked collaboratively with beekeepers in Hilo, Hawaii to develop a strategic breeding program designed to encourage use of mite-resistant honey bee lines developed in coordination with ARS to the beekeeping industry. The collaboration resulted in an independent breeding operation in Hilo, Hawaii and mass production of queens from that population. This effort shows that breeding for mite resistance can be implemented at a commercial scale. The roadmap established by this collaboration provides a precedent for other interested beekeeping stakeholders to develop their own breeding operations. Ultimately, breeding for desirable traits, particularly parasite resistance, will improve honey bee health and have a direct impact on global food security. 02 Honey bee genetics influence bee⿿s response to nutrition. ARS scientists at Baton Rouge, Louisiana believes malnutrition is a major factor underlying honey bee colony declines with poor nutrition continually listed as a top cause of annual colony death. Currently beekeepers provide supplements to improve bee health, but how these diets may differentially help certain bee stocks based on genetic differences is unknown. ARS scientists at Baton Rouge, Louisiana tested the influence of honey bee genetic variation on physiological responses to natural and artificial bee diets. Additional research with ARS scientists at Houma, Louisiana examined how different stocks infected with virus differentially forage for pollen and nectar. Results of each study indicated that stock-dependent nutritional responses are present in honey bees, which has promising implications for new breeding efforts and tailored approaches to diet and health in a changing global climate.
Impacts
(N/A)
Publications
- Saelao, P., Simone-Finstrom, M., Avalos, A., Bilodeau, A.L., Danka, R.G., De Guzman, L.I., Rinkevich Jr, F.D., Tokarz, P.G. 2020. Genome-wide patterns of differentiation within and across U.S. commercial honey bee stocks. BMC Genomics. 21:1-12. https://doi.org/10.1186/s12864-020-07111-x.
- Black, T.E., Fofah, O., Dinges, C., Ortiz-Alvarado, C.A., Avalos, A., Ortiz-Alvarado, Y., Abramson, C.I. 2021. Effects of Aversive Conditioning on Expression of Physiological Stress in Honey Bees (Apis mellifera). Neurobiology of Learning and Memory. 178:107363. https://doi.org/10.1016/j. nlm.2020.107363.
- Gerdts, J., Roberts, J., Simone-Finstrom, M., Ogbourne, S., Tuccie, J. 2021. Genetic variation of Ascosphaera apis and colony attributes do not explain chalkbrood disease outbreaks in Australian honey bees. Journal of Invertebrate Pathology. 180:107540. https://doi.org/10.1016/j.jip.2021. 107540.
- Ricigliano, V.A., Dong, C., Richardson, L.T., Donnarummar, F., Williams, S. T., Solouki, T., Murrary, K.K. 2020. Honey bee proteome responses to plant and cyanobacteria (blue-green algae) diets. ACS Food Science and Technology. 1:1-10. https://doi.org/10.1021/acsfoodscitech.0c00001.
- Spivak, M., Simone-Finstrom, M. 2019. Propolis. Int: Starr C. (eds) International Union for the Study of Scial Insects Congress. 1-3. https:// doi.org/10.1007/978-3-319-90306-4_134-1.
- Ricigliano, V.A., Sica, V.P., Knowels, S.L., Diette, N., Howarth, D.G., Oberlies, N.K. 2020. Bioactive diterpenoid metabolism and cytotoxic activities of genetically transformed Euphorbia lathyris roots. Phytochemistry. 179:1-9. https://doi.org/10.1016/j.phytochem.2020.112504.
- Bilodeau, A.L., Avalos, A., Danka, R.G. 2020. Genetic diversity of the complementary sex-determiner (csd) gene in two closed breeding stocks of Varroa-resistant honey bees.. Apidologie. 51(6):1125-1132. https://doi.org/ 10.1007/s13592-020-00790-1.
- Giordano, R., Donthu, R.K., Zimin, A.V., Julca Chavez, I.C., Gabalon, T., van Munster, M., Hon, L., Hall, R., Badger, J.H., Nguyen, M., Flores, A., Potter, B., Giray, T., Sato-Adames, F.N., Weber, E., Marcelino, J. A.P., Fields, C.J., Voegtlin, D.J., Hill, C.B., Hartman, G.L., Akraiko, Ta., Aschwanden, A., Avalos, A., Band, M., Bonning, B., Bretaudeau, A., Chiesa, O., Chirumamilla, A., Coates, B.S., Cocuzza, G., Cullen, E., Desborough, P. , Diers, B., DiFonzo, C., Heimpel, G.E., Herman, T., Huanga, Y., Knodel, J. , Ko, C., Labrie, G., Lagos-Kutz, D., Lee, J., Lee, S., Legeai, F., Mandriolo, M.,, Manicadi, G.C., Mazzoni, E., Melchiori, G., Micijevic, A., Miller, N., Nasuddin, A., Nault, B.A., O⿿Neal, M.E, Panini, M., Pessino, M. , Prischmann-Voldseth, D., Robertson, H.M., Liu, S., Song, H., Tilmon, K., Tooker, J., Wu, K., Zhan, S. 2020. Soybean aphid biotype 1 genome: Insights into the invasive biology and adaptive evolution of a major agricultural pest. Insect Biochemistry and Molecular Biology. 120:103334. https://doi.org/10.1016/j.ibmb.2020.103334.
- Hoffman, Gloria D., Corby-Harris, Vanessa L., Chen, Yanping, Graham, Henry, Chambers, Mona L., Watkins De Jong, Emily E., Ziolkowski, Nicholas F., Kang, Yun, Gage, Stepanhie L., Deeter, Megan E., Simone-Finstrom, Michael, De Guzman, Lilia, I. 2020. Can supplementary pollen feeding reduce varroa mite and virus levels and improve honey bee colony survival?. Experimental and Applied Acarology. 82:455-473. https://doi.org/10.1007/s10493-020- 00562-7.
- Milone, J.P., Rinkevich Jr, F.D., McAfee, A., Foster, L.J., Tarpy, D. 2020. Differences in larval pesticide tolerance and esterase activity across honey bee (Apis mellifera) stocks. Ecotoxicology and Environmental Safety. 206:111213. https://doi.org/10.1016/j.ecoenv.2020.111213.
- Smith, R., Kraemer, F., Bader, C., Smith, M., Weber, A., Simone-Finstrom, M., Wilson-Rich, N., Oxman, N. 2021. A rapid fabrication methodology for payload modules, piloted for the observation of queen honeybee (Apis mellifera) in microgravity. Gravitational and Space Research. 9:104-114. https://doi.org/10.2478/gsr-2021-0008.
- Ricigliano, V.A., Ihle, K.E., Williams, S.T. 2021. Nutrigenetic comparison of two Varroa-resistant honey bee stocks fed pollen and spirulina microalgae. Apidologie. 1-14. https://doi.org/10.1007/s13592-021-00877-3.
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Progress 10/01/19 to 09/30/20
Outputs
Progress Report Objectives (from AD-416): Meaningful contributions towards enhancing the economic value of the nation�s commercially managed honey bee populations can be achieved through identifying, characterizing and breeding more robust bees. The proposed 5-year plan focuses on synergistic projects (Fig.1) that capitalize on genetic and breeding approaches with the following objectives: Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Sub-objective 1B: Evaluate genotype-dependent nutrient efficiency in commercial honey bee stocks. Sub-objective 1C: Evaluate genotype-dependent nutritional stress resistance in commercial honey bee stocks. Sub-objective 1D: Characterize the impact of genetically based variation in vitellogenin -- the primary honey bee storage protein with roles in immune function, oxidative stress resistance and lifespan -- on colony and reproductive (queen and drone) health and productivity. Sub-objective 1E: Identify and characterize genetic and physiological mechanisms of pesticide resistance in honey bees. Objective 2: Characterize genetic, physiological and behavioral aspects of important traits, strains and stocks. Sub-objective 2A: Examine patterns of genetic diversity and loci under selection in United States honey bee breeding populations, with a focus on stocks exhibiting high VSH activity. Sub-objective 2B: Elucidate the interaction between individual and social immune defenses. Sub-objective 2C: Improve understanding of the biology of the VSH trait. Objective 3: Conduct traditional breeding or marker-assisted selection of honey bees. Sub-objective 3A: Ascertain the effect of inbreeding on genetic diversity across the honey bee genome to support breeding and maintaining health of breeding populations. Sub-objective 3B. Assess genetic diversity at the sex locus of commercial breeding populations of honey bee stocks developed by USDA, ARS HBBGPL. Sub-objective 3C: Determine the potential usefulness of a simple hygiene assay as a selection tool to predict VSH-based mite resistance in honey bee colonies. Objective 4: Develop management tools for improving honey bee health. Sub-objective 4A: Identify and characterize genetic differences in honey bee response to introduced dsRNA, and test for correlations with viral infection and resistance. Sub-objective 4B: Improve understanding of the flight activity of Russian honey bees during almond pollination. Sub-objective 4C: Evaluate the efficacy of a microalgae platform to improve honey bee colony performance and health. Sub-objective 4D: Determine the sublethal effects of fungicides on honey bee health. Sub-objective 4E: Assess sustainability of Varroa control methods. Approach (from AD-416): Objective 1: Identify and evaluate traits, strains and stocks for improved honey bee health. [NP305, Component 2, Problem Statements 2B and 2C] Sub-objective 1A: Understand the mechanisms of viral transmission and resistance or tolerance to reduce impacts of infection through selective breeding. Hypothesis 1A.i: Honey bee resistance to viruses varies with virus type and inoculation route in addition to genotype and life stage of the bees. (Led by M. Simone-Finstrom with K. Ihle) This is the first report for the project 6050-21000-016-00D (Using Genetics to Improve the Breeding and Health of Honey Bees), which began in March 2020. Progress was made in research objectives that fall under National Program 305, Component 2, Bees and Pollination. The goal of this research is to enhance the economic value of the nation�s commercially managed honey bee populations through identifying, characterizing and breeding more robust bees while concurrently informing management practices. Research by ARS scientists from Baton Rouge, Louisiana, progressed related to identification and evaluation of traits, strains and stocks for improved honey bee health (Obj. 1). Progress was made by ARS scientists from Baton Rouge, Louisiana, in understanding resistance and tolerance traits associated with viral infection and how different honey bees stocks and genotypes differentially respond to Deformed wing virus, Israeli acute paralysis virus and chronic bee paralysis virus (Obj. 1A). This work involves several projects including collaborative efforts with ARS scientists from Baton Rouge, Louisiana, Louisiana State University, University of North Carolina at Greensboro, and University of Olomouc (Czech Republic). Additional work has begun to develop a novel RNAi delivery system to mitigate honey bee pathogens (in-house) and on potential chemical-based viral treatments (collaboration with Louisiana State University). In an assessment of a possible new trait for future breeding efforts, three honey bee stocks were examined to assess influence of honey bee genotype on the efficiency of food conversion (Obj. 1B). Results indicated that some stocks have more variable responses as compared to others, which is an important consideration for a future selection program. With regard to understanding the genetic variation in pesticide detoxification capabilities (Obj. 1E), investigations by ARS scientists from Baton Rouge, Louisiana, began into substrates that can be used as reliable surrogates of insecticide detoxification by esterases, and the relationship of esterase activity inhibition on insecticide toxicity. Progress was made by ARS scientists from Baton Rouge, Louisiana, in the characterization of genetic, physiological and behavioral aspects of important traits, strains and stocks (Obj. 2). Samples have been collected for follow-up work to ARS scientists from Baton Rouge, Louisiana, earlier large-scale genomic sequencing effort examining genetic diversity across seven commercial honey bees stocks in order to expand those initial results and conduct more detailed analysis on specific genomic regions (Obj 2A). Efforts to specifically mitigate Varroa mites and support various resistance traits in honey bees continue to be a focus. An evaluation of �social apoptosis�, or brood fragility, as a mechanism for Varroa resistance in selected stocks of honey bees was completed (Obj. 2B) and suggested that this could be a potential factor particularly in the Russian stock. Analysis by ARS scientists from Baton Rouge, Louisiana, is ongoing on the response of honey bees to developing drones parasitized by Varroa mites (Obj. 2C), but results suggest that there has been no selection for increased hygienic response to infested drone brood in the Russian stock. Efforts to support traditional breeding or marker-assisted selection of honey bees progressed (Obj. 3). Genetic diversity at the complementary sex-determiner (csd) locus was assessed in Pol-line and Hilo bees (Obj. 3B). Allelic data are currently being used to inform breeding decisions for both stocks. An assay using the chemical ecology that regulates expression of hygienic behavior is being tested (Obj 3C). Collaborators from the University of North Carolina at Greensboro developed this tool to evaluate the response of bees in field colonies to chemical stimuli related to Varroa sensitive hygiene. Work by ARS scientists from Baton Rouge, Louisiana, is also ongoing to identify molecular markers related to expression of the trait of Varroa sensitive hygiene, including approaches using candidate genes (in-house), whole-genome sequencing and marker discovery using both gene expression and sequence information via �eQTL� (in collaboration with the University of Missouri). Breeding for productive, Varroa resistant bees continues in a public-private partnership in which bees selected by the Unit for Varroa sensitive hygiene form much of the founding population for a new stock, called Hilo Bees. Research in collaboration with the University of Minnesota and commercial beekeeper cooperators has continued to clarify the role of propolis in honey bee immunity and its potential benefits in beekeeping management, and to breed bees with improved health founded on social immunity. Progress was also made in projects related to the development management tools for improving honey bee health (Obj. 4). In an effort to develop a new nutritional supplement, work was conducted by ARS scientists from Baton Rouge, Louisiana, to evaluate the use of microalgae as an alternative nutrition source for bees (Obj 4C). Results indicated that in controlled, caged settings this microalgal diet performs just as well as a pollen-based diet based on several metrics. Preliminary field trials have also been conducted in collaboration with cooperating beekeeping operations. Baseline data were established for a nationwide assessment of the resistance of Varroa mites to amitraz in commercial beekeeping operations (Obj. 4E). Results documented by ARS scientists from Baton Rouge, Louisiana, showed that some Varroa mite populations do demonstrate resistance to amitraz that is associated with treatment failures, however resistant populations appear to be related to specific operations and amitraz use patterns and not necessarily geographic area. In subordinate projects, research was conducted by ARS scientists from Baton Rouge, Louisiana, on the influence of propolis deposition on insecticide sensitivity and detoxification activity in honey bees, and to determine the presence of pesticides in propolis collected from colonies across different landscapes. Two longitudinal field trials of two years each are yielding information about the biotic and abiotic health threats to honey bees in commercial beekeeping operations. These trials were conducted in collaboration with ARS scientists from Baton Rouge, Louisiana, and Louisiana State University. Progress was made in collaboration with North Carolina State University and University of Pennsylvania to clarify the genetic determinants of queen quality.
Impacts
(N/A)
Publications
- Ricigliano, V.A., Anderson, K.E. 2020. Probing the honey bee diet- microbiota-host axis using pollen restriction and organic acid feeding. Insects. 11(5):1-14.
- Rinkevich Jr, F.D. 2020. Detection of amitraz resistance and reduced Apivar� efficacy in the Varroa mite, Varroa destructor, in commercial beekeeping operations. PLoS One. 1-12.
- Ricigliano, V.A. Microalgae as a promising and sustainable nutrition source for managed honey bees. Archives of Insect Biochemistry and Physiology. 1-8.
- Ricigliano, V.A., Simone-Finstrom, M. 2020. Nutritional and prebiotic efficacy of the microalga Arthrospira platensis (spirulina) in honey bees. Apidologie. 51(2)1-13.
- Mondet, F., Beaurepaire, A., Mcfee, A., Locke, B., Alaux, C., Blanchard, S. , Danka, R.G., Le Conte, Y. 2020. Honey bee survival mechanisms against the parasite Varroa destructor: A systematic review of phenotypic and genomic research efforts. International Journal of Parasitology. 50:433- 447.
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