Living with Tropilaelaps mercedesae: its history and impact on Chinese beekeeping

Tropilaelaps mercedesae is an ectoparasitic mite of the honey bee Apis dorsata. In the 1950s, T. mercedesae jumped the species barrier from its original host A. dorsata and started causing problems in Apis mellifera colonies in China. Thus, this mite has been part of Chinese beekeeping for over 60 years. Initial reports of collapsing colonies were from three provinces, all outside the range of A. dorsata , indicating the important role of migratory beekeeping in spreading this pest. Then long-distance movement of beehives spread T. mercedesae throughout China. Several miticides used in China against the Varroa destructor mite were ineffective against T. mercedesae because the mites spend little time outside sealed brood cells. Hence, sublimed sulfur and formic acid are used to treat T. mercedesae since the latter compound can penetrate brood cell cappings. Also, brood breaks are commonly used by Chinese beekeepers. Four major gaps in our knowledge of T. mercedesae are discussed: how the mite survives long broodless periods; mite reproduction in its native and new hosts; treatment thresholds; and resistance mechanisms against the mite in A. dorsata and A. cerana .