Yes, the Bavarian State Institute for Viticulture and Horticulture, Bee Research Center, Veitshöchheim, Germany—see Dr. Berg’s article
“Hyperthermia—The Principle Works,” Deutsches Bienenjournal 01/2017. In this regard, the Belgian Bee Institute CARI attributes an efficacy of over 95% to the Varroa Controller
(Actu API 2012/3)