Ruhren Scott, Handel Steven N
Department of Ecology, Evolution, and Natural Resources, 1 College Farm Road, Rutgers, The State University of New Jersey, New Brunswick, NJ 08901-1582, USA e-mail:
Oecologia. 1999 May;119(2):227-230. doi: 10.1007/s004420050780.
Many plants secrete nectar from extrafloral nectaries (EFNs), specialized structures that usually attract ants which can act as plant defenders. We examined the nectar-mediated interactions between Chamaecrista nictitans (Caesalpineaceae) and jumping spiders (Araneae, Salticidae) for 2 years in old fields in New Jersey, USA. Previous research suggests that spiders are entirely carnivorous, yet jumping spiders (Eris sp. and Metaphidippus sp.) on C. nictitans collected nectar in addition to feeding on herbivores, ants, bees, and other spiders. In a controlled-environment experiment, when given a choice between C. nictitans with or without active EFNs, foraging spiders spent 86% of their time on plants with nectar. C. nictitans with resident jumping spiders did set significantly more seed than plants with no spiders, indicating a beneficial effect from these predators. However, the presence of jumping spiders did not decrease numbers of Sennius cruentatus (Bruchidae), a specialist seed predator of C. nictitans. Jumping spiders may provide additional, unexpected defense to plants possessing EFNs. Plants with EFNs may therefore have beneficial interactions with other arthropod predators in addition to nectar-collecting ants.
许多植物通过花外蜜腺（EFNs）分泌花蜜，花外蜜腺是一种特殊结构，通常会吸引蚂蚁，而蚂蚁可充当植物的防御者。我们在美国新泽西州的旧耕地里，对含羞草决明（豆科云实亚科）与跳蛛（蜘蛛目，跳蛛科）之间由花蜜介导的相互作用进行了为期两年的研究。先前的研究表明蜘蛛完全是肉食性的，然而，在含羞草决明上的跳蛛（艾蛛属和后蛛属）除了取食草食动物、蚂蚁、蜜蜂和其他蜘蛛外，还采集花蜜。在一个可控环境实验中，当在有或没有活跃花外蜜腺的含羞草决明之间做出选择时，觅食的蜘蛛将86%的时间花在了有花蜜的植株上。有常驻跳蛛的含羞草决明所结的种子明显比没有蜘蛛的植株多，这表明这些捕食者具有有益作用。然而，跳蛛的存在并没有减少豆象（豆象科）的数量，豆象是含羞草决明的一种专性种子捕食者。跳蛛可能会为拥有花外蜜腺的植物提供额外的、意想不到的防御。因此，除了采集花蜜的蚂蚁外，拥有花外蜜腺的植物可能还会与其他节肢动物捕食者产生有益的相互作用。
