Trichodectes canis, an invasive ectoparasite of Alaskan wolves: detection methods, current distribution, and ecological correlates of spread

Abstract

Trichodectes canis, (Ischnocera: Trichodectidae), was first documented on Alaska gray wolves (Canis lupis) in 1981. Two hypotheses may explain why T. canis was not observed in Alaska until the 1980s. Symptomatic wolves could be predisposed to pediculosis, whereas mild infestations outside the observed infestation region are undetected by visual inspection. A second possible explanation is that T. canis is an invasive ectoparasite, and Alaska wolves outside the infestation region do not harbor lice. We examined wolf hides from December 2003 to February 2009, to investigate potential sampling locations, determine T. canis current distribution within Alaska, and investigate potential ecological correlates of spread. We determined that the caudal region of the wolf possessed the highest mean proportion of T. canis and we detected all cases of mild pediculosis. Lice were documented on wolves in a contiguous distribution from Southcentral Alaska to immediately north of the Alaska Range, (estimated area 174,000 km²). Occult infestations were not detected outside of the current infestation zone. That pattern of occurrence suggests that T. canis is a novel parasite within Alaska. Ecological correlates positively associated with T. canis presence include wolf densities greater than eight wolves/1000 km² and mean annual January temperatures warmer than -19°C.