THE DILEMMA OF PRESERVING THE PARASITE biodiversity of rare, endangered, or extinct hosts has been highlighted recently. Host extinction also results in coextinction in nature of all associated hostspecific parasites. Further, visible ectoparasites often are removed purposely from rare or endangered animals with an aim towards increasing host fitness and survival. Because the number of parasitic species may be about four times that of free-living species on earth such practices could have dire consequences for parasite biodiversity, which represents a significant proportion of total biodiversity. Negative human perception of parasites, in addition to the typically small size of the latter, has hindered the conservation of rare parasites and actually has decreased the abundance of certain species.   

Few, if any, parasites rank lower on the human acceptance scale than ticks. The common practice of intentional parasite removal, either directly or by the administration of parasiticides, often seems justified if the survival of a host species is at stake. This impinges on the frequently posed question, "Of what use are ticks?"  Given their bloodfeeding habit and the numerous pathogens they transmit, most people would instinctively answer "none." However, ticks (and other parasites) are an integral component of healthy ecosystems and have important roles in nature, some of which may still be incompletely understood.  

Our intention in this paper has been to provoke interest in the plight of rare ticks and other parasites and to propose that conservation measures be considered. If we are concerned with the conservation of all biodiversity, perhaps the practice of parasite removal from rare hosts should be reevaluated. Although fewer parasite species would come as a welcome relief to most animals, including humans, such a loss also would result in significantly less biodiversity.  

Host-Parasite Coextinction and the Plight of Tick Conservation
LANCE A. DURDEN AND JAMES E. KEIRANS

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