Wise David H
Department of Biological Sciences, University of Maryland Baltimore County, 21228, Catonsville, Maryland, USA.
Oecologia. 1979 Aug;41(3):289-300. doi: 10.1007/BF00377433.
A field experiment was performed to determine if food is a limited resource for adult females of two species of orb-weaving spiders, Mecynogea lemniscata and Metepeira labyrinthea. Spiders built webs after being added to open experimental units located in a mixed deciduous-pine forest in Maryland, USA. Each unit was a frame supporting dead branches of the type used by both species for anchoring webs. Spiders on half the units were exposed to natural prey densities only, while each spider on the other units was given laboratory-reared flies in order to increase prey availability above natural levels. Supplemental feeding continued for 2.5 months. At the end of the experiment all egg sacs were removed from the units.Providing additional prey did not increase the survival rate on the units (net effect of mortality, emigration and immigration). However, both species responded to additional prey by significantly increasing the number of eggs produced per female, indicating that food was a limited resource for these species. Median egg production per female increased from 34 to 62 for Mecynogea lemniscata and from 65 to 145 for Metepeira labyrinthea. Egg weight was not affected.Feeding rates and nearest neighbor distances were determined for spiders in non-experimental populations, which permitted evaluation of the experiment's naturalness. The effects of food supply upon the reproductive rates of the two species are discussed in relation to their numerical response and population dynamics.
进行了一项野外实验，以确定食物是否是两种圆蛛（Mecynogea lemniscata和Metepeira labyrinthea）成年雌蛛的有限资源。蜘蛛被放入位于美国马里兰州一片落叶松混合林中的开放式实验单元后开始织网。每个单元是一个框架，支撑着两种蜘蛛用于固定蛛网的那种枯枝。一半单元中的蜘蛛仅暴露于自然猎物密度下，而另一半单元中的每只蜘蛛都被给予实验室饲养的苍蝇，以便将猎物供应量提高到自然水平之上。补充喂食持续了2.5个月。实验结束时，从各个单元中取出了所有卵囊。提供额外的猎物并没有提高各单元中的存活率（死亡率、迁出率和迁入率的净效应）。然而，两种蜘蛛都通过显著增加每只雌蛛产生的卵数来对额外的猎物做出反应，这表明食物是这些蜘蛛的有限资源。Mecynogea lemniscata每只雌蛛的平均产卵数从34增加到62，Metepeira labyrinthea从65增加到145。卵的重量没有受到影响。测定了非实验种群中蜘蛛的进食率和最近邻距离，从而可以评估实验的自然程度。结合两种蜘蛛的数量反应和种群动态，讨论了食物供应对其繁殖率的影响。
