acterization of the architecture of hygienic behavior of honeybees to enable breeding for improved honeybee health

High honeybee colony losses in the last decade have raised the scientific efforts to determine and mitigate the causes of declining honeybee health. Although honeybees are exposed to a variety of stressors, infestation by the ectoparasitic mite (Varroa destructor) and the viruses it vectors are considered to be the most significant biological problem of A. mellifera worldwide. Management of viral diseases is problematic and mainly focuses on control of Varroa. Current Varroa control suffers from the evolution mite resistance, negative effects on bees and bee products, and other inefficiencies and impracticalities. This situation necessitates the development of an integrated strategy for Varroa pest management. Breeding honeybee stocks that are resistant to mites is an essential part of any sustainable long-term control of Varroa. We have focused our study on the behavioral trait of worker hygienic behavior that has been described as a social colony defense mechanism against Varroa and some other brood diseases. The main original objectives of our proposal were: 1) Characterize the phenotypic architecture of the hygienic behavior and its cost (age and intensity of uncapping, removal, recapping, higher sensitivity of workers, stronger signaling by the brood, as well as the age of first foraging, longevity, and individual immunity of workers, and colony level of Varroa and viruses); 2) Determine patterns of inheritance of the key aspects of hygienic behavior by phenotyping of multiple crosses over several generations and reciprocal crosses; 3) Identify a robust core marker set for hygienic behavior by comparative transcriptomic analyses and QTL mapping of the hygienic trait; 4) Verify the core marker set in study of the general honeybee population to associate marker genotypes with hygienic performance; 5) Test the colony-level outcomes of introgressing hygienic-selection lines under field conditions into locally adapted populations. During the course of the project, we conducted a number of field experiments in our research apiaries and with beekeepers at different sites in Israel.