Soil fertility is understood to act in many indirect ways, in addition to directly providing nutrients to plants. Given that higher order indirect interactions frequently are key to understanding community structure, it would be natural to expect that indirect mutualisms should be as important as other interactions in generating such structure. Although mutualisms are ubiquitous in nature, exploring the myriad ways in which they interconnect with other elements of a system is less common. That soil fertility has an indirect effect on community structure is well known, suggests that soil fertility may be important in determining the effect of mutualisms on the structure of the ecological communities in which they are embedded. Here we report on a laboratory study that specifically examines the direct connection between the behavior of a mutualist and nutritional properties of the soil. We tested the effects of soil fertilization (high, medium and low levels) on the Azteca seriseasur–Coccus viridis mutualism on coffee plants in Mexico. We found that ants foraged significantly more on plants that were infected with C. viridis over control plants. Moreover, ants preferred to tend C. viridis on high fertilized over medium and low fertilized plants. This study highlights the importance of the links between soil nutrient properties and their effects on a key ant-hemipteran mutualism, illustrating the cascading effects on other interactions involving this keystone ant species.

除了直接为植物提供营养外，土壤肥力还可以通过许多间接方式发挥作用。鉴于较高级别的间接互动通常是理解社区结构的关键，因此自然会期望间接互惠与其他互动在生成这种结构时同样重要。尽管互惠主义本质上无处不在，但探索它们与系统的其他元素互连的无数方式并不常见。土壤肥力对群落结构具有间接影响是众所周知的，这表明土壤肥力对于确定共生对嵌入它们的生态群落结构的影响可能是重要的。在这里，我们报告了一项实验室研究，该研究专门研究了互惠行为与土壤营养特性之间的直接联系。我们测试了土壤施肥（高，中和低水平）对土壤肥力的影响。墨西哥咖啡植物上的Azteca seriseasur–Coccus viridis共生。我们发现，与对照植物相比，蚂蚁在感染了C. viridis的植物上觅食得多。而且，蚂蚁优选在中，低受精植物上高受精时趋向于梭状芽胞杆菌。这项研究强调了土壤养分特性及其对关键蚂蚁-半翅目共生关系的影响之间联系的重要性，说明了对涉及这种关键蚂蚁物种的其他相互作用的连锁影响。