Giusto Bruno, Anstett Marie-Charlotte, Dounias Edmond, McKey Doyle B
Centre d'Ecologie Fonctionnelle et Evolutive, UPR CNRS 9056, 1919 route de Mende, 34293, Montpellier cedex 5, France.
Oecologia. 2001 Nov;129(3):367-375. doi: 10.1007/s004420100734. Epub 2001 Nov 1.
Benefits to plants in facultative ant protection mutualisms are highly variable. This allows examination of the sources of this variation and the mechanisms by which ants protect plants. We studied opportunistic interactions between ants and an extrafloral nectary-bearing vine, Dioscorea praehensilis, during 3 different years. Variation in plant protection among years was striking. Several factors affected the effectiveness of the biotic defence. Stems recently emerged from the underground tuber were self-supporting, contacting no other plants and encountering few foraging ants. Stems then became lianescent, and contact with supporting plants greatly increased ant recruitment. Both species and number of ant workers influenced the effect of ants on the major herbivore, the chrysomelid beetle Lilioceris latipennis. Protective actions included limitation of oviposition (reduction in the number of eggs laid on the plant) and predation, leading to increased larval mortality. The probability of successful predation was strongly dependent on larval size. If temporarily low ant-patrolling activity allows larvae to grow beyond a critical size, their mechanical (thick integument) or chemical (plant-derived compounds in a fecal shield) defences become more effective against ants. Secondary metabolites derived from the host plant thus appear to be important for the anti-predator mechanisms of this beetle, being necessary for its survival and reproduction on a host plant that actively recruits ants as a biotic defence against herbivores.
在兼性蚂蚁保护共生关系中，植物所获得的益处差异很大。这使得我们能够研究这种差异的来源以及蚂蚁保护植物的机制。我们在3个不同年份研究了蚂蚁与一种带有花外蜜腺的藤蔓植物——缠绕薯蓣之间的机会主义相互作用。年份之间植物受到的保护差异显著。有几个因素影响了生物防御的有效性。刚从地下块茎长出的茎能够自我支撑，不与其他植物接触，遇到的觅食蚂蚁也很少。随后茎变成藤本状，与支撑植物的接触极大地增加了蚂蚁的招募。蚂蚁的种类和数量都会影响蚂蚁对主要食草动物——叶甲科甲虫宽胫翠叶甲的作用。保护行为包括限制产卵（减少在植物上产的卵的数量）和捕食，从而导致幼虫死亡率增加。成功捕食的概率很大程度上取决于幼虫的大小。如果蚂蚁暂时的低巡逻活动使幼虫生长到临界大小以上，它们的机械防御（厚外皮）或化学防御（粪便盾牌中的植物衍生化合物）对蚂蚁就会变得更有效。因此，宿主植物衍生的次生代谢产物似乎对这种甲虫的反捕食机制很重要，对于其在积极招募蚂蚁作为抵御食草动物的生物防御的宿主植物上生存和繁殖是必要的。
