Strey O F, Teel P D, Longnecker M T, Needham G R
Department of Entomology, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843-2475, USA.
J Med Entomol. 1996 Jan;33(1):63-73. doi: 10.1093/jmedent/33.1.63.
Off-host survival, water balance, and cold tolerance of unfed adult, Cayenne ticks, Amblyomma cajennense (F.), were examined to evaluate species characteristics important to zoogeography and off-host ecology. Survivorship decreased when males and females were subjected to progressively drier constant environmental conditions. Average maximum survival was 641.2 and 682.5 d at 85% RH and 23 degrees C (2.98 mm Hg) for males and females, respectively. Mean survival in both sexes was progressively less variable in drier conditions. Slopes of log-linear models of survival days based on saturation deficit (mm Hg) were significantly different between males and females at 50%, but not at 25 or 0%. Whole-body water loss rates for 4-wk-old adults were measured at 0% RH and 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 males, 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 females, although, the duration encompassing all recuperative cycles was generally longer for females and on average, females gained 8.16% more weight than males upon each rehydration. Estimates of the mean critical 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 species zoogeographic distribution may be constrained by an intolerance to cold.
为评估对动物地理学和离体生态学重要的物种特征，研究了未进食的成年卡宴蜱（钝缘蜱属，美洲钝缘蜱）的离体存活、水分平衡和耐寒性。当雄性和雌性蜱暴露于逐渐干燥的恒定环境条件下时，存活率下降。在85%相对湿度和23摄氏度（2.98毫米汞柱）条件下，雄性和雌性蜱的平均最长存活时间分别为641.2天和682.5天。在较干燥条件下，两性的平均存活时间变异性逐渐减小。基于饱和亏缺（毫米汞柱）的存活天数对数线性模型的斜率在50%时雄性和雌性之间存在显著差异，但在25%或0%时无差异。在0%相对湿度和23摄氏度条件下测量4周龄成年蜱的全身失水率，直至蜱不再活动。雌性蜱的平均全身失水率为0.06128%/小时，比雄性蜱的0.06914%/小时低11.3%。虽然不再活动的蜱看似死亡，但将每种性别的个体从0%相对湿度环境中取出并暴露于96%相对湿度环境24小时后，超过一半的个体恢复了活动状态。其中，雄性蜱的恢复（活动）周期平均比雌性多0.44个，不过，涵盖所有恢复周期的持续时间雌性通常更长，并且平均而言，每次补水后雌性蜱比雄性蜱增重8.16%。雄性和雌性蜱的平均临界平衡活性估计值分别为0.74 av和0.79 av。发现美洲钝缘蜱成虫比分布涵盖更多温带地区的成年美洲钝眼蜱更不耐受-12.5摄氏度。尽管美洲钝缘蜱表现出很少的宿主偏好并且能够在离体状态下长时间存活，但该物种超出其动物地理分布范围建立种群可能会受到耐寒性差的限制。
