Breeding for hygienic behavior in honey bees (Apis mellifera): a strong paternal effect

The haplodiploid sex determination of honey bees and the multiple mating of queens pose challenges in determining the genetic contribution of drones (male honey bees). This is especially important for breeding programs as, for example, when attempting to reinforce traits governing social immunity against pests and diseases. Here, we focused on breeding aiming at enhancing hygienic behavior, a trait that is known to reduce parasite load in honey bee colonies. To evaluate the contribution of drones versus queens to this trait, we conducted a two-step bidirectional selection program. First, we selected colonies with consistent phenotypes for low- or high-hygienic behavior (generation P). From those, we generated two types of daughter colonies (F1). One type originated from queens that had been artificially inseminated with selected drones that originated from queens of either low- or high-hygienic phenotype. The other type of colonies was set from naturally mated queens. We then compared the hygienic performance of the progeny colonies. In the next step, we used the F1 colonies (from either artificially inseminated or naturally mated queens) to produce naturally mated queens, which subsequently generated F2 colonies. These were then examined for the level of hygienic behavior. The results demonstrate the significant contribution of both parents to the phenotype of offspring. In particular, drones had a consistent and significant influence on the hygienic performance of the progeny throughout generations. These findings emphasize the great potential to propagate the hygienic trait in local populations by selecting lines for drones that carry the high-hygienic trait.