Tanaka Koichi
Laboratory of Applied Entomology and Nematology, Faculty of Agriculture, Nagoya University, Chikusa, 464, Nagoya, Japan.
Oecologia. 1992 Jul;90(4):597-602. doi: 10.1007/BF01875456.
Stage-specific mortality rates and mortality factors for the web-building spiderAgelena limbata, which is suggested to be food-limited, were studied, and the relationship between body size of spiders and survivorship for instar 3 to adults was examined. The mortality rate of the egg sac stage including eggs, deutova (prenymphal stage), and overwintering instar 1 nymphs was low. The low mortality of this stage was partly due to maternal care that reduced the mortality caused by predation and/or abiotic factors. From emergence of instar 1 nymphs from egg sacs to reproduction, the stagespecific mortality rates were almost constant, 32-47%, and the time-specific mortality rates were also constant. These results suggest a Deevey (1947) type II survivorship curve inA. limbata, in contrast to other reports on the wandering or burrowing spiders which suggested type III curves. Important mortality factors for nymphs and adults were parasitism by an ichneumonid wasp and predation by spiders. There were great variations in body size (carapace width) ofA. limbata in the field. Smaller individuals survived at a lower rate to the next stage than larger individuals. This tendency was clearer for the population living under poorer prey availability.A. limbata was unlikely to starve to death in the field because every stage ofA. limbata could survive starvation for a long time in the laboratory, 22-65 days on average. I suggest that the size-dependent survivorship of this spider is associated with vulnerability of smaller individuals to parasitism and predation.
对筑网蜘蛛边缘艾蛛（Agelena limbata）的特定阶段死亡率和死亡因素进行了研究，该蜘蛛被认为受食物限制，并研究了蜘蛛体型与三龄若虫到成虫存活率之间的关系。卵囊阶段（包括卵、二龄若虫前期和越冬一龄若虫）的死亡率较低。该阶段的低死亡率部分归因于母性照料，这种照料降低了捕食和/或非生物因素导致的死亡率。从一龄若虫从卵囊中孵化到繁殖阶段，特定阶段死亡率几乎恒定，为32% - 47%，特定时间死亡率也恒定。这些结果表明边缘艾蛛呈现迪维（1947）II型存活曲线，这与其他关于游走型或穴居型蜘蛛的报道（表明为III型曲线）形成对比。若虫和成虫的重要死亡因素是姬蜂寄生和蜘蛛捕食。野外边缘艾蛛的体型（头胸甲宽度）存在很大差异。较小个体到下一阶段的存活率低于较大个体。对于猎物可获得性较差环境中的种群，这种趋势更为明显。边缘艾蛛在野外不太可能饿死，因为在实验室中，边缘艾蛛的每个阶段都能在饥饿状态下存活很长时间，平均为22 - 65天。我认为这种蜘蛛的体型依赖性存活与较小个体易受寄生和捕食有关。
