Life cycles of seven ixodid tick species (Acari: Ixodidae) under standardized laboratory conditions.

Studies of transmission, maintenance, infectivity, virulence, and pathogenicity of tick-borne agents require the use of large numbers of live laboratory-raised ticks. Colonies of Ixodes scapularis Say, Ixodes pacificus Cooley & Kohls, Amblyomma americanum (L.), Dermacentor occidentalis Marx, Dermacentor variabilis (Say), Hemaphysalis leporispalustris (Packard), and Rhipicephalus sanguineus (Latrielle) have been maintained in our laboratory at the Centers for Disease Control and Prevention for five to 18 continuous generations. New Zealand White rabbits (Oryctolagus cuniculus) are used as hosts for all tick species and developmental stages. Between feedings, ticks are stored in environmental incubators at 22-24 degrees C and 90% RH with a day/night photoperiod of 16:8 (L:D) h. The duration of feeding, molting, preoviposition, and periods of postmolting development were recorded. Here, we describe the life cycles of these common North American tick species under standardized laboratory conditions. At 22-24 degrees C, the minimal time needed for each species to complete one life cycle was as follows: I. scapularis, 204-219 d; I. pacificus, 214-229 d; R. sanguineus, 162-177 d; H. leporispalustris, 209-224 d; D. variabilis, 176-191 d; D. occidentalis, 180-195 d; and A. americanum, 192-211 d.