Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, MG, 36570-900, Brazil.
Programa de Pós-Graduação Em Ecologia, Conservação E Manejo da Fauna Silvestre, Instituto de Ciências Biológicas, Universidade Federal de Minas Gerais, Belo Horizonte, MG, 31270-901, Brazil.
Naturwissenschaften. 2023 Jun 30;110(4):31. doi: 10.1007/s00114-023-01858-5.
Plant strategies against herbivores are classically divided into chemical, physical, biotic defences. However, little is known about the relative importance of each type of plant defence, especially in the same species. Using the myrmecophyte Triplaris americana (both with and without ants), and the congeneric non-myrmecophyte T. gardneriana, we tested whether ant defence is more effective than other defences of naturally ant-free myrmecophytes and the non-myrmecophyte congeneric species, all spatially co-occurring. In addition, we investigated how plant traits vary among plant groups, and how these traits modulate herbivory. We sampled data on leaf area loss and plant traits from these tree groups in the Brazilian Pantanal floodplain, and found that herbivory is sixfold lower in plants with ants than in ant-free plants, supporting a major role of biotic defences against herbivory. Whereas ant-free plants had more physical defences (sclerophylly and trichomes), they had little effect on herbivory-only sclerophylly modulated herbivory, but with opposite effects depending on ants' presence and species identity. Despite little variation in the chemicals among plant groups, tannin concentrations and δC signatures negatively affected herbivory in T. americana plants with ants and in T. gardneriana, respectively. We showed that ant defence in myrmecophytic systems is the most effective against herbivory, as the studied plants could not fully compensate the lack of this biotic defence. We highlight the importance of positive insect-plant interactions in limiting herbivory, and therefore potentially plant fitness.
植物抵御草食动物的策略通常分为化学、物理和生物防御。然而，人们对每种植物防御类型的相对重要性知之甚少，尤其是在同一物种中。本研究利用共生植物 Triplaris americana（有蚂蚁和无蚂蚁）和同属非共生植物 T. gardneriana，测试了蚂蚁防御是否比自然无蚂蚁共生植物和同属非共生植物的其他防御更有效，这些植物在空间上共存。此外，我们还研究了植物性状在植物群体之间如何变化，以及这些性状如何调节食草作用。我们从巴西潘塔纳尔湿地平原的这些树种中采样了叶片损失和植物性状的数据，发现有蚂蚁的植物的食草率比无蚂蚁的植物低六倍，这支持了生物防御在抵御食草作用方面的主要作用。虽然无蚂蚁的植物具有更多的物理防御（厚叶和刚毛），但它们对食草作用的影响很小，只有厚叶会调节食草作用，但取决于蚂蚁的存在和物种身份，其影响相反。尽管植物群体之间的化学物质变化不大，但单宁浓度和 δC 特征分别对有蚂蚁的 T. americana 植物和 T. gardneriana 的食草作用产生负面影响。我们表明，在共生系统中，蚂蚁防御是抵御食草作用最有效的防御方式，因为研究中的植物无法完全弥补这种生物防御的缺乏。我们强调了积极的昆虫-植物相互作用在限制食草作用从而潜在地限制植物适应性方面的重要性。
