Honey bee populations, especially managed honey bees, have been adversely affected by Colony Collapse Disorder (CCD), Varroa destructor mite infestations and viral pathogens. A variety of viral pathogens have been identified as potential factors contributing to CCD, and viral pathogens are vectored by Varroa mites. Honey bee viruses, including deformed wing virus (DWV), cause individual honey bee mortality and contribute to colony death after Varroa infestation and/or viral infection. Some honey bee viruses, including DWV, have been identified in other species, and inter-species transmission of viruses both to and from honey bees may be contributing to the population level declines of many pollinator species. Identification and selection of lines of honey bees that tolerate or resist viral infections would allow production of queens and colonies that exhibit improved survival in the presence of viral infections and Varroa mite infestations. The first objective will be to screen many different lines of honey bees in search of lines that exhibit reduced mortality after viral infection. If virus resistant lines are identified, then those bees will be characterized by genotyping or genomic resequencing to define genomic features that are associated with viral resistance. If specific molecular markers are found to associate with viral resistance or tolerance, then subsequent work will be directed toward development of a molecular test that enables rapid and affordable identification of bees that possess genotypes which confer viral resistance or tolerance. OBJECTIVES: This project will compare many genetically distinct honey bee lines for their relative survival and mortality after innoculation with honey bee virus. Those colonies that exhibit the lowest levels of mortality will be compared to those colonies that exhibit the highest levels of mortality. Genomic sequences that characterize virus resistant or tolerant honey bees will be identified by genotyping and/or resequencing the most resistant and the most vulnerable bees, and contrasting the genotypes that distinguish resistant and vulnerable lines. Genomic features, such as single nucleotide polymorphisms, which may be markers of resistance to or tolerance of viral infection will be defined by genome wide association testing and comparison of the genome sequence differences that characterize resistant and vulnerable honey bees. The preliminary results will be corrected for population structure, and the final results will eliminate any markers that appear to be confounding features of stratification in the tested populations. Molecular markers that distinguish virus resistant from virus susceptible lines will be used to develop a test that may be used to screen honey bees quickly and accurately for their ability to resist or tolerate viral infection
