Department of Animal Biology, Autonomous University of Barcelona, Barcelona, Spain.
Plant Signal Behav. 2011 Apr;6(4):547-50. doi: 10.4161/psb.6.4.14839. Epub 2011 Apr 1.
The indirect effect of ants on plants through their mutualism with honeydew-producing insects has been extensively investigated. Honeydew-producing insects that are tended by ants impose a cost on plant fitness and health by reducing seed production and/or plant growth. This cost is associated with sap intake and virus transmissions but may be overcompesated by tending ants if they deter or prey on hebivorous insects. The balance between cost and benefits depends on the tending ant species. In this study we report other indirect effects on plants of the mutualism between aphids and ants. We have found that two Lasius ant species, one native and the other invasive, may change the composition of volatile organic compounds (VOCs) of the holm oak (Quercus ilex) blend when they tend the aphid Lachnus roboris. The aphid regulation of its feeding and honeydew production according to the ant demands was proposed as a plausible mechanism that triggers changes in VOCs. Additionally, we now report here that aphid feeding, which is located most of the time on acorns cap or petiole, significantly increased the relative content of linolenic acid in acorns from holm oak colonized by the invasive ant. This acid is involved in the response of plants to insect herbivory as a precursor or jasmonic acid. No effect was found on acorn production, germination or seedlings quality. These results suggest that tending-ants may trigger the physiological response of holm oaks involved in plant resistance toward aphid herbivory and this response is ant species dependant.
蚂蚁通过与产蜜露昆虫的互惠关系对植物的间接影响已经得到了广泛的研究。被蚂蚁照顾的产蜜露昆虫通过减少种子产生和/或植物生长，对植物的适应性和健康造成了代价。这种代价与汁液摄入和病毒传播有关，但如果照顾它们的蚂蚁能够阻止或捕食草食性昆虫，这种代价可能会得到补偿。成本和收益之间的平衡取决于照顾蚂蚁的种类。在这项研究中，我们报告了蚜虫和蚂蚁之间的互惠关系对植物的其他间接影响。我们发现，两种拉氏蚁（Lasius），一种是本地种，另一种是入侵种，当它们照顾蚜虫 Lachnus roboris 时，可能会改变 Holm 橡树（Quercus ilex）混合体中挥发性有机化合物（VOCs）的组成。根据蚂蚁的需求调节蚜虫的取食和蜜露生产被认为是触发 VOCs 变化的一种合理机制。此外，我们现在还报告说，蚜虫的取食大部分时间都在橡子的帽或叶柄上，这显著增加了被入侵蚂蚁殖民的 Holm 橡树橡子中亚麻酸的相对含量。这种酸作为茉莉酸的前体或参与了植物对昆虫取食的反应。对橡子的产量、萌发或幼苗质量没有影响。这些结果表明，照顾蚂蚁可能会引发 Holm 橡树参与植物对蚜虫取食的抗性的生理反应，而这种反应取决于蚂蚁的种类。
