Apple J, Feener D
Department of Biology, University of Utah, 84112, Salt Lake City, UT, USA.
Oecologia. 2001 May;127(3):409-416. doi: 10.1007/s004420000605. Epub 2001 May 1.
Extrafloral nectary (EFN) plants are widespread and can be quite species-rich in some communities. Thus, ants that utilize extrafloral nectar may have the opportunity to discriminate among a wide variety of nectar sources, resulting in variation in the ant attention EFN plants receive. In this study, we compare ant visitation rates of three Passiflora species that coexist in an early successional neotropical forest. These three vine species (Passiflora auriculata, P. biflora, and P. oerstedii) differ in their extrafloral nectary structure and placement, and thus may attract different numbers or species of ants. Through censuses of ants tending extrafloral nectaries, we found that P. auriculata received significantly higher numbers of ant visitors than P. oerstedii, but did not differ significantly from P. biflora in its attractiveness to ants. We also found that termite worker baits (simulating herbivores) placed on P. auriculata and P. biflora were discovered by ants significantly more quickly than baits placed on P. oerstedii. In both ant visitation censuses and in termite bait trials, we found no significant associations between Passiflora species and the species of ant visitors. We also performed experimental manipulations of several characteristics of P. auriculata, which resulted in changes in levels of ant visitation. When petiolar nectaries of P. auriculata were experimentally blocked, visitation by the common ant Ectatomma ruidum declined, even though nectaries on the leaf surfaces were still functional. Connections with other vegetation also had an effect on ant visitation. Though experimental creation of connections between growing P. auriculata shoots and other vegetation did not enhance ant visitation, eliminating connections resulted in a significant decline in the number of ant visitors. The results of this study suggest factors that may contribute to variation in ant visitation of extrafloral nectary plants. In addition, this study demonstrates that extrafloral nectary plants co-occurring in a habitat and available to the same ants may differ in patterns of visitation by ants and perhaps in the quality of protection from herbivores that they receive.
花外蜜腺（EFN）植物分布广泛，在一些群落中物种丰富度颇高。因此，利用花外花蜜的蚂蚁可能有机会在多种花蜜来源之间进行区分，从而导致花外蜜腺植物获得的蚂蚁关注度出现差异。在本研究中，我们比较了在新热带地区早期演替森林中共存的三种西番莲属植物的蚂蚁访花率。这三种藤本植物（耳叶西番莲、二花西番莲和奥氏西番莲）的花外蜜腺结构和位置各不相同，因此可能吸引不同数量或种类的蚂蚁。通过对照料花外蜜腺的蚂蚁进行普查，我们发现耳叶西番莲吸引的蚂蚁访客数量显著高于奥氏西番莲，但在吸引蚂蚁方面与二花西番莲没有显著差异。我们还发现，放置在耳叶西番莲和二花西番莲上的白蚁工蚁诱饵（模拟食草动物）比放置在奥氏西番莲上的诱饵被蚂蚁发现的速度要快得多。在蚂蚁访花普查和白蚁诱饵试验中，我们都没有发现西番莲属植物与蚂蚁访客种类之间存在显著关联。我们还对耳叶西番莲的几个特征进行了实验操作，结果导致蚂蚁访花水平发生变化。当对耳叶西番莲的叶柄蜜腺进行实验性阻断时，常见蚂蚁红胸猛蚁的访花率下降，尽管叶片表面的蜜腺仍然起作用。与其他植被的连接也对蚂蚁访花有影响。虽然在生长的耳叶西番莲嫩枝与其他植被之间进行实验性连接并没有增加蚂蚁访花，但消除连接会导致蚂蚁访客数量显著下降。本研究结果表明了可能导致花外蜜腺植物蚂蚁访花差异的因素。此外，本研究表明，在同一栖息地且可供相同蚂蚁利用的花外蜜腺植物，在蚂蚁访花模式上可能存在差异，也许在它们获得的免受食草动物侵害的保护质量上也存在差异。
