Brief Bio: Mari H. Ogihara, PhD, is a researcher of the institute of Livestock and Grassland Science, NARO in Japan. Her areas of research interest are physiology of Varroa mites and honeybees, interaction between Varroa mites and honeybees. In addition, she is working on nationwide surveillances of Varroa damage in the Japanese apiaries to understand actual situation of Japanese apiaries. Dr. Ogihara majored in physiology of Acari and received bachelor’s degree, master’s degree, and PhD in agriculture from Tsukuba University, in 2004, 2006, and 2009, respectively. She worked at Tsukuba University as a JSPS research fellow (tick physiology) and worked at Tokyo University as a post-doc and a JSPS research fellow (insect physiology).

Varroa destructor, Apis mellifera, Apiculture, Acari physiology

Surveillance and genetic characterization of Varroa mites in Japan

Varroa destructor is an important pest of Western honeybee Apis mellifera in Japan. Damage of honeybee by V. destructor infestation is well-recognized in Japanese beekeepers, but intensive surveillance of the mite has not been conducted in Japan. Our group conducted surveillance of V. destructor from 2018 in Japanese apiaries. We focused on three perspectives: Varroa infestation rates in A. mellifera colonies, genetic backgrounds, and possibilities of acaricide resistance of V. destructor in Japan. V. destructor was detected from over 90% of investigated apiaries in Japan. The analysis of genetic background showed that spreading a single haplotype of V. destructor, called Korea haplotype, among A. mellifera colonies in Japan. Though earlier studies detected another haplotype, called Japanese haplotype, from A. mellifera, no mites of Japanese haplotypes were detected in recent surveillance of A. mellifera colonies. In addition, Japanese haplotypes of V. destructor were rarely detected from Japanese honeybee, A. cerana, indicating Korea haplotypes of V. destructor become a dominant haplotype in Japan. The surveillance also showed that the possibility to develop acaricide resistance in V. destructor among Japanese apiaries. Fluvalinate is one of the permitted acaricides for V. destructor control in Japan. We found some of Varroa mites in the Japanese apiaries has a specific amino acid substitution in a fluvalinate-targeted sodium channel, which substitution has been known to confer fluvalinate resistance. These results reveal actual situation of Varroa infestation in Japanese apiaries and indicate the need of more effective Varroa control for Japanese apiaries.