Winter-exposedAmblyomma americanumandDermacentor variabilisadults (Acari: Ixodidae) do not exhibit behavioral diapause

Behavioral diapause was evaluated for overwintering Amblyomma americanum (L.) and Dermacentor variabilis (Say) laboratory strains. Ticks were placed in outdoor arenas on 30 Oct. 1996. On 9 Jan. 1997 specimens were removed for infestation on New Zealand white rabbits exposed to outside conditions or in a temperature and photoperiod controlled vivarium. Upon repletion, females were placed in tick rearing chambers indoors or returned to natural conditions. Both tick species readily attached when placed outside or in controlled conditions. Significantly more D. variabilis (63%) were attached than A. americanum (47%) three days post infestation. All females of both species failed to oviposit and perished when returned to natural winter conditions, while all successfully laid viable eggs under standard laboratory conditions. Based on the criteria of ability to attach, feed and oviposit, behavioral diapause was not in evidence during January for lone star and American dog tick females.