Lower temperature limits for activity of several Ixodid ticks (Acari: Ixodidae): effects of body size and rate of temperature change.

Uncoordinated activity threshold temperature, the temperature below which ticks can no longer seek a host in a coordinated manner, and the activity threshold temperature, when all activity ceases, were examined for three species of ticks found in coastal sections of New York. The mean uncoordinated activity threshold and activity threshold temperatures were determined for nymphal, female and male Ixodes scapularis Say, nymphal, female, and male Amblyomma americanum (L.), and for female and male Dermacentor variabilis (Say). Only the uncoordinated activity threshold and activity threshold temperatures for adult I. scapularis were significantly correlated to the rate of temperature decrease. The mean uncoordinated activity threshold and activity threshold temperatures were significantly correlated to the mean size of each tick species.