Occurrence of two genotypes of Varroa jacobsoni Oud. in North America

Both the Russian and Japanese genotypes of Varroa jacobsoni were present in the United Stares and Canada. Only the Russian genotype was found in Mexic o. Our results suggest that North America, and especially the United States has had more than one introduction of Varroa jacobsoni. Differences in vir ulence among strains of V. jacobsoni may be the basis for reports of region al variation in honey bee resistance to Varroa. Thus, further studies on th e interaction between Varroa and honey bee genotypes are needed to fully re solve the issue. (C) Inra/DIB/AGIB/Elsevier, Paris.