APICULTURE AND SOCIAL INSECTS Inheritance of Resistance to Acarapis woodi (Acari: Tarsonemidae) in Crosses Between Selected Resistant Russian and Selected Susceptible U.S. Honey Bees (Hymenoptera: Apidae)

The pattern of inheritance of tracheal mite resistance in selected Russian bees was determined in bioassays and in samples from Þeld colonies. Resistant colonies of Russian origin and colonies selected for high susceptibility in the United States were used to generate divergent parental populations. Seven groups of F1 colonies were produced by crossing queens and drones from these selected resistant Russian and selected susceptible populations. In a series of bioassays with young workers exposed in infested colonies, average mite abundance (female mites per worker) in F1 colonies was intermediate (1.04 0.13 [mean SE]) and signiÞcantly different from that of both resistant Russian (0.74 0.13) and selected susceptible (1.57 0.13) colonies. Colonies representing the three populations were established in two apiaries in July 2005. Colonies surviving with original queens after 10 mo had mite prevalences supporting the Þndings of the bioassay. All three resistant colonies had undetectable mite levels, whereas prevalences in four F1 colonies ranged from 0 to 53%, and in 10 susceptible colonies ranged from 0 to 90%. Tracheal mite resistance in Russian bees is likely polygenic, but there may be a number of genes with major dominance interacting with minor genes. Use of selected Russian queens mated with Russian drones or with drones from unknown sources is beneÞcial for beekeeping in areas with persistent problems with tracheal mite infestation.