The overall goal of this research is to develop and use genetic resistance or tolerance of honey bees to biotic agents, and to devise management strategies to improve the quality of queen honey bees. This will enhance the economic value of the nation’s honey bees for pollination, honey production, overwintering and hazard resistance. Over the next five years we will focus on interrelated projects with the following objectives: Objective 1: Identify and evaluate traits, strains, and stocks for improved honey bee health, e.g., improved immunity, tolerance, or resistance to Varroa and tracheal mites, the fungi Nosema and chalkbrood, and viruses. Sub-objective 1A: Evaluate the potential for viral resistance. Sub-objective 1B: Establish and characterize genetically and functionally distinct lines that differentially respond to Nosema. Sub-objective 1C: Evaluate the potential of worker brood to suppress reproduction by Varroa. Sub-objective 1D: Determine the effect of Varroa infestations on honey bee behavior. Sub-objective 1E: Evaluate immune and stress related responses in selected honey bee stocks. Objective 2: Characterize genetic and physiological aspects of important traits, strains, and stocks and their interaction with biotic and abiotic stressors. Sub-objective 2A: Characterize the chemical ecology of VSH to aid the development of a practical selection method. Sub-objective 2B: Understand the genetic basis of Ascosphaera apis (chalkbrood) resistance observed in RHB larvae. Sub-objective 2C: Genomic sequencing of multiple stocks of honey bees. Sub-objective 2D: Differential responses to Nosema in honey bees. Objective 3: Conduct traditional and marker-assisted breeding and develop management tools for improved bees. Sub-objective 3A: Develop and use improved methods to evaluate Varroa-resistant phenotypes. Sub-objective 3B: Determine management methods using ionizing radiation to increase honey bee colony fitness. Sub-objective 3C: Evaluate autogrooming as a common resistance mechanism towards tracheal and Varroa mites. Sub-objective 3D: Use traditional and marker-assisted selection programs to improve honey bees with VSH-based resistance. Funding will be used in support of Objective 3: Conduct traditional and marker-assisted breeding and develop management tools for improved bees. [NP305, Component 2, Problem Statements 2A and 2B] Objective 4: Improve knowledge of the biology, physiology, genomics, and behavior of pests (i.e. mites and the small hive beetle) that may be useful for improving their management. Sub-objective 4A: Elucidate the Nosema infection process. Sub-objective 4B: Understand effects of resistance level on Nosema infection across honey bee life stages. Sub-objective 4C: Identify new methods to limit SHB population growth in honey bee colonies.
The health and availability of honey bees (Apis mellifera) have been diminished by multiple biological problems, most notably the parasitic mite Varroa (V.) destructor. Other important threats include fungi (Nosema spp. and chalkbrood), viruses, small hive beetles and tracheal mites. Some of these interact and result in mortality described as colony collapse disorder (CCD). The major goal of this project is to mitigate these threats by finding and selecting for genetically based traits of honey bees that confer resistance to the biological problems. Scientists also will improve management techniques and describe pest biology related to control. Most research targets V. destructor. Efforts that build on our prior work with Varroa-resistant honey bees include using knowledge about Russian Honey Bees to find new traits that enhance resistance, and to improve selection methods. Honey bees with Varroa sensitive hygiene are undergoing traditional and molecular-marker-assisted selection. Marker-assisted selection would be a valuable tool to overcome the difficulty of phenotyping this trait, and increase the capacity to select and breed Varroa-resistant bees. Novel traits for Varroa resistance also are being sought. New selection of honey bees will target Nosema ceranae and Deformed Wing Virus because these pathogens are thought to contribute significantly to colony losses. Research with Nosema, viruses, tracheal mites and chalkbrood will culminate in development of molecular markers for resistance factors. Management research will expand promising preliminary findings about queen and drone health associated with the irradiation of comb in mating colonies The products of this research -- knowledge and technology -- will strengthen integrated pest management strategies for controlling honey bee pests and diseases. This in turn should lead to better profitability for beekeeping and crop pollination.
ARS scientists are in the active field research season of the third year of the project. Work continues on searching for stable resistance to Nosema, impacts of Varroa on activities and physiology of workers and drones, benefits of irradiating combs to suppress microbial agents, testing and enhancing Varroa-resistant bees, developing genomic and transcriptomic databases for small hive beetles and developing a genomic sequence database for several types of commercial bees. New research has begun on selection for resistance to deformed wing virus, and on determining the comparative roles of physiological immunity (of individual bees) and behavioral resistance (of the colony) in disease resistance. It has been difficult to establish genetic lines of bees with differential responses to Nosema; this has led to contingency work in some subobjectives (1B, 2D, 4B). Molecular markers related to Nosema resistance and to Varroa sensitive hygiene have not been validated as being useful outside of the original mapping populations. Vacancies and changes in scientific personnel have particularly delayed progress in work on identifying parameters that support Varroa resistance, on chemical ecology and molecular characterization of Varroa sensitive hygiene, and on generalized grooming behavior against parasitic mites. Two years of field work have been completed in a study of pesticide exposure and health of colonies in an area of intensive agriculture in the Upper Midwest. Analyses of pesticide residues in colonies are ongoing.
1. Hygienic removal of Varroa-infested brood increases the fall of Varroa mites to the bottom of a colony. Some measures of mite fall are potential indicators of mite resistance of a colony. This research shows the influence that hygiene has on the rate of falling mites, in addition to documenting comparatively strong hygienic removal of mite-infested brood by Russian honey bees.
2. Genetic markers associated with chalkbrood resistance were not validated outside of an original mapping population of bees. Four genetic markers (SNPs) that were developed in a single mapping population of Russian honey bees were not associated with larval resistance to chalkbrood disease in a different population of Russian bees or in VSH or Carniolan bees. This finding indicates the potential difficulty in finding markers suitable for marker-assisted selection of honey bees.
3. Selection of VSH derived Pol-line honey bees. A population of bees with VSH-derived resistance to Varroa mites was selected in commercial beekeeping operations during 2008-2014. Pol-line bees show good potential for further development to have both consistent mite resistance and desirable beekeeping characteristics.
All beekeepers are small farmers. Hence, all of the units research and technology transfer is for this special target population.
De Guzman, L.I., Rinderer, T.E., Frake, A.M., Kirrane, M. 2016. Brood removal influences fall of Varroa destructor (Mesostigmata: Varroidae) in honey bee (Hymenoptera: Apidae) colonies. Journal of Apicultural Research. 54(3):216-225. https://doi.org/10.1080/00218839.2015.1117294.
Chapman, N., Harpur, B., Lim, J., Rinderer, T.E., Alsopp, M., Zayed, A., Oldroyd, B. 2015. A SNP test to identify Africanized honeybees via proportion of 'African' ancestry. Molecular Ecology Resources 15(6):1346-1355
Aronstein, K.A., Colby, D.M., Holloway, B.A. 2015. Validation of genetic markers associated with chalkbrood resistance. Trends in Entomology. 11:47-53.
Aronstein, K.A., Colby, D.M., Boykin, D.L. 2016. Honey bee stock genotypes do not affect the level of physiological responses to chalkbrood fungus, Ascosphaera apis. Journal of BIOMICS 8(1):1-19.
Chantawannakul, P., De Guzman, L.I., Li, J., Williams, G.R. 2015. Pests, pathogens, and parasites of honey bees in Asia. Apidologie 47(3):301-324
Danka, R.G., Harris, J.W., Dodds, G.E. 2015. Selection of VSH-derived Pol-line honey bees and evaluation of their Varroa-resistance characteristics. Apidologie 47(3):483-490.
Villa, J.D., Danka, R.G., Harris, J.W. 2016. Selecting honey bees for worker brood that reduces the reproduction of Varroa destructor. Apidologie ISSN: 0044-8435 (Print), 1297-9678 (On-line).
Aronstein, K.A., Colby, D.M. 2016. A multiplex PCR assay for determination of mating type in isolates of the honey bee fungal pathogen, Ascosphaera apis. Journal of Apicultural Research. doi: 10.1080.
Li-Byarlay1, H., Huang, M., Simone-Finstrom, M., Strand, M.K., Tarpy, D.R., Rueppell, O. 2016. Honey bee (Apis mellifera) drones survive oxidative stress due to increased tolerance instead of avoidance or repair of oxidative damage. Experimental Gerontology 83:15-21.
Haddad, N.J., Batainh, A.M., Saini, D., Migdadi, O.S., Aiyaz, M., Manchiganti, R., Krishnamurthy, V., Al-Shagour, B., Brake, M., Bourgeois, A.L., De Guzman, L.I., Rinderer, T.E., Alhamuri, Z. 2016. Evaluation of Apis mellifera syriaca Levant Region honeybee conservation using Comparative Genome Hybridization. Entomologia Experimentalis et Applicata. doi: 10.107/s10709-016-9897-y
Buawangpong, N., De Guzman, L.I., Khongphinitbunjong, K., Frake, A.M., Burgett, M., Chantawannakul, P. 2015. Prevalence and reproduction of Tropilaelaps mercedesae and Varroa destructor in concurrently infested Apis mellifera colonies. Apidologie 46(6):779-786