Tropilaelaps mercedesae: rapid geographic expansion in a novel honey bee host.

An ectoparasitic mite of the giant honey bees throughout southern and eastern Asia, Tropilaelaps mercedesae has jumped to the western honey bee Apis mellifera and expanded its range, most recently to Eastern Europe. This has rattled an already precarious A. mellifera beekeeping industry, which is grappling with another invasive ectoparasitic mite called Varroa destructor. Here, we review the known biology and pathology of T. mercedesae in its original and novel hosts, discuss current monitoring and treatment options, and identify gaps in knowledge and preparedness. We also compare the natural histories of T. mercedesae and V. destructor to facilitate future directions for research and outreach that promote a timely response to this mite's growing sphere of influence.