Of. Strey et al., SURVIVAL AND WATER-BALANCE CHARACTERISTICS OF UNFED ADULT AMBLYOMMA CAJENNENSE (ACARI, IXODIDAE), Journal of medical entomology, 33(1), 1996, pp. 63-73
Off-host survival, water balance, and cold tolerance of unfed adult, C
ayenne ticks, Amblyomma cajennense (F.), were examined to evaluate spe
cies characteristics important to zoogeography and off-host ecology. S
urvivorship decreased when males and females were subjected to progres
sively drier constant environmental conditions. Average maximum surviv
al was 641.2 and 682.5 d at 85% RH and 23 degrees C (2.98 mm Hg) for m
ales and females, respectively. Mean survival in both sexes was progre
ssively less variable in drier conditions. Slopes of log-linear models
of survival days based on saturation deficit (mm Hg) were significant
ly different between males and females at 50%, but not at 25 or 0%. Wh
ole-body water loss rates for 4-wk-old adults were measured at 0% RH a
nd 23 degrees C until ticks became nonambulatory. The mean whole-body
water loss rate of females, 0.06128% h(-1), was 11.3% less than for ma
les, 0.06914% h(-1). Although nonambulatory ticks appeared dead, >1/2
of the individuals from each sex regained ambulatory status after they
were removed from 0% RH and exposed to 96% RH for 24 h. Among these,
male ticks averaged 0.44 more recuperative (ambulatory) cycles than fe
males, although, the duration encompassing all recuperative cycles was
generally lone;er for females and on average, females gained 8.16% mo
re weight than males upon each rehydration. Estimates of the mean crit
ical equilibrium activity for males and females were 0.74 av and 0.79
av, respectively. A. cajennense adults were found to be less tolerant
to -12.5 degrees C than adult lone star ticks, Amblyomma americanum (L
.), whose distribution encompasses more temperate regions. Although A.
cajennense exhibit little host preference and are capable of extended
off-host survival, the establishment of populations beyond this speci
es zoogeographic distribution may be constrained by an intolerance to
cold.