Dominant honeybee colony infestation by Varroa destructor (Acari: Varroidae) K haplotype in Japan

Varroa destructor Anderson and Trueman (Acari: Varroidae) are ectoparasitic mites found in the western honeybee Apis mellifera Linnaeus (Hymenoptera: Apidae). Varroa destructor is classified into two haplotypes, i.e., Korea (K) and Japan (J), based on mtDNA sequences. Among these, V. destructor K haplotype is possibly a more severe threat to A. mellifera colonies. Previous studies collected both V. destructor haplotypes from honeybee colonies in Japan. However, no detailed surveillance of infestation of Japanese apiaries by V. destructor or identification of their genetic structure has been conducted to date. We surveyed V. destructor at 15 different Japanese apiaries of A. mellifera. Varroa destructor was collected from 14 Japanese apiaries, and all mites were classified as V. destructor K haplotype. Varroa destructor infestation of the Japanese honeybee A. cerana japonica Radoszkawsi (Hymenoptera: Apidae) was also analyzed. Varroa destructor K haplotype was predominant in A. cerana colonies. Despite the different host species, all collected V. destructor K haplotype samples were classified into a single haplogroup, i.e., K1-1/K1-2. These results indicate that A. mellifera and A. cerana were infested by the same V. destructor haplogroup. This is the first report detailing a survey on V. destructor prevalence and haplogroups among Japanese apiaries.