Lindsay L R, Barker I K, Surgeoner G A, McEwen S A, Gillespie T J, Addison E M
Department of Environmental Biology, Ontario Agricultural College, University of Guelph, Canada.
J Med Entomol. 1998 May;35(3):189-99. doi: 10.1093/jmedent/35.3.189.
From November 1989 to April 1993, blood-fed females and unfed adults and nymphs of lxodes scapularis Say were maintained in housings within 4 different habitats on Long Point, Ontario, Canada, to evaluate the effects of habitat on tick development. More fed females survived the winter within the maple forest (75.6%) than the cottonwood dune (36.1%), whereas 52.8-62.0% survived the winter within the 2 remaining habitats. The proportions of females that laid eggs within the maple forest (90.3%), oak savannah (83.9%), and white pine habitats (78.4%) were similar and greater than in the cottonwood dune (53.8%). In each habitat and all years, females began laying eggs during late April or early May. The time of egg deposition was consistent whether females fed in November and overwintered, or fed during April of the subsequent year. Significantly more eggs hatched within the maple forest (96.4%) and white pine (79.3%) than in the oak savannah (3.8%) or cottonwood dune habitats (0.0%). Hatch occurred in mid- to late July each year. The proportion of unfed I. scapularis adults that survived the winter was not significantly different among the 4 habitats. Unfed adults held in the oak savannah and cottonwood dune habitats died by early June, whereas ticks survived until late June or early July within the maple forest and white pine habitats. Unfed nymphs survived an average of 3.4 mo (range, 0.5-5.5) longer than unfed adults. Fed larvae placed in the field from 22 April to 3 July 1992 molted or died that year. In contrast, 66.7 and 100% of fed larvae placed in the field between 15 and 28 July, and after 28 July, respectively, overwintered before molting. More larvae successfully molted before overwintering (46.9%) than did those that overwintered (17.9%). The proportion of larvae that successfully molted was greatest within the maple forest and least within the cottonwood dune. Fed nymphs placed in the field from 22 April to 4 June molted or died in 1992, whereas 53.6 and 99.2% of fed nymphs placed in the field between 17 June and 28 July, and later than 28 July, respectively, overwintered before molting. Over all habitats, the proportion of nymphs that molted successfully was similar for those that overwintered (43.5%) and those that did not (36.0%). The proportion of nymphs that molted successfully was greatest in the maple forest (60.6%) and least within the cottonwood dune (13.3%). Differences in seasonal extremes of vapor pressure deficits among habitat types were likely responsible for habitat-specific differences in survival of I. scapularis. Based on observations on captive I. scapularis, the life cycle of this tick on Long Point is completed in 3 or 4 yr.
1989年11月至1993年4月，将饱血雌蜱、未进食的成虫和若虫置于加拿大安大略省长角4种不同栖息地的饲养环境中，以评估栖息地对蜱发育的影响。在枫树林中越冬的饱血雌蜱比例（75.6%）高于三角叶杨沙丘（36.1%），而在其余2种栖息地中越冬的比例为52.8% - 62.0%。在枫树林（90.3%）、橡木稀树草原（83.9%）和白松栖息地（78.4%）产卵的雌蜱比例相似且高于三角叶杨沙丘（53.8%）。在每个栖息地以及所有年份，雌蜱均于4月下旬或5月初开始产卵。无论雌蜱是在11月进食并越冬，还是在次年4月进食，产卵时间均一致。在枫树林（96.4%）和白松栖息地（79.3%）孵化出的卵显著多于橡木稀树草原（3.8%）或三角叶杨沙丘栖息地（0.0%）。每年7月中旬至下旬孵化。在4种栖息地中，未进食的肩突硬蜱成虫越冬比例无显著差异。置于橡木稀树草原和三角叶杨沙丘栖息地的未进食成虫在6月初前死亡，而置于枫树林和白松栖息地的蜱可存活至6月下旬或7月初。未进食的若虫平均存活时间比未进食的成虫长3.4个月（范围为0.5 - 5.5个月）。1992年4月22日至7月3日置于野外的饱血幼虫于当年蜕皮或死亡。相比之下，分别于7月15日至28日以及7月28日之后置于野外的饱血幼虫，66.7%和100%在蜕皮前越冬。成功在越冬前蜕皮的幼虫比例（46.9%）高于越冬的幼虫比例（17.9%）。在枫树林中成功蜕皮的幼虫比例最高，在三角叶杨沙丘中最低。1992年4月22日至6月4日置于野外的饱血若虫于当年蜕皮或死亡，而分别于6月17日至7月28日以及7月28日之后置于野外的饱血若虫，53.6%和99.2%在蜕皮前越冬。在所有栖息地中，成功蜕皮的越冬若虫比例（43.5%）与未越冬若虫比例（36.0%）相似。在枫树林中成功蜕皮的若虫比例最高（60.6%），在三角叶杨沙丘中最低（13.3%）。栖息地类型之间蒸汽压亏缺季节极端值的差异可能是肩突硬蜱生存存在栖息地特异性差异的原因。基于对圈养肩突硬蜱的观察，这种蜱在长角的生命周期为3至4年。
