ERADICATION OF A TROPICAL RAT MITE (ORNITHONYSSUS BACOTI) INFESTATION FROM A CAPTIVE COLONY OF ENDANGERED AMARGOSA VOLES (MICROTUS CALIFORNICUS SCIRPENSIS)

Abstract:  Staff at a university laboratory responsible for management of a captive insurance colony of endangered Amargosa voles (Microtus californicus scirpensis) discovered an outbreak of tropical rat mites (Ornithonyssus bacoti) infesting 106 voles. This bloodsucking mesostigmatid mite typically occurs in laboratory settings and can cause weight loss, wounds, or other negative impacts on health. The source of the infestation was likely feral rodents, and the route was suspected to be straw bedding. Twenty-nine of the 106 (27.4%) infested voles developed ulcerated dorsal skin lesions that resolved when treated with topical selamectin. A triad approach was implemented to eradicate the mites, consisting of environmental management, individual animal treatment, and training. Voles were moved individually into a clean room containing only autoclaved materials (including straw), cages were treated with permethrin-impregnated cotton, treatment order was instituted to avoid transferring mites, and voles comin...