Seibt U, Wickler W
Max-Planck-Institut für Verhaltensphysiologie, D-8131, Seewiesen, Federal Republic of Germany.
Oecologia. 1990 Mar;82(3):317-321. doi: 10.1007/BF00317477.
This study investigates the suggested protective function of the compact silken nest of two species of social Stegodyphus spiders (S. dumicola and S. mimosarum), as a possible ultimate factor for their sociogenesis. Being inhabitants of African dry thornbush country, these spiders are endangered by overheating and desiccation. In the laboratory, both species were found to avoid temperatures >40° C. In the field, temperature in the nest between 7:00 and 21:00 h tends to be higher than air-temperature outside, and between 13:00 and 15:00 h even tends to exceed 40° C. The nest thus is of no value in temperature regulation. Nor is it effective in protecting the spiders from desiccation: Both species have a body water content of 65.2±3.8% and are extremely desiccation resistant; they survived 9 days at 37°C in an exciccator with PO, with a daily average % liveweight reduction of 4.94(±1.1). In the field, relative humidity inside the nest between 11:00 and 19:00 h tends to be lower than that of the air outside. Inspection of burnt areas showed that the nest does not protect the spiders from bushfire. The nest does protect from wind, hail, and direct sun-radiation; but available natural retreats, or a simple silken shield, or the funnel-shaped silk tube inhabited by solitary Stegodyphus, have the same effect.
本研究调查了两种群居性的刺囊蛛（Dumicola刺囊蛛和Mimosarum刺囊蛛）紧密的丝质巢穴所具有的假定保护功能，将其作为群居起源的一个可能的终极因素。作为非洲干旱荆棘丛地区的居民，这些蜘蛛面临着过热和脱水的危险。在实验室中，发现这两个物种都会避开高于40°C的温度。在野外，巢穴在7:00至21:00之间的温度往往高于外界气温，在13:00至15:00之间甚至往往超过40°C。因此，巢穴在温度调节方面没有作用。它在保护蜘蛛免受脱水方面也无效：这两个物种的身体含水量均为65.2±3.8%，并且具有极强的抗脱水能力；它们在装有P₂O₅的干燥器中于37°C下存活了9天，每天平均体重减轻4.94（±1.1）%。在野外，巢穴在11:00至19:00之间的相对湿度往往低于外界空气的相对湿度。对火灾区域的检查表明，巢穴不能保护蜘蛛免受丛林火灾的影响。巢穴确实能防风、防冰雹和防直射阳光；但现有的天然藏身之处、简单的丝质盾牌或独居刺囊蛛居住的漏斗形丝管也有同样的效果。
