Data from: Ant–scale mutualism increases scale infestation, decreases folivory, and disrupts biological control in restored tropical forests

Ant–hemipteran mutualisms can have positive and negative effects on host plants depending on the level of hemipteran infestation and plant protection conferred by ants against folivory. Differential effects of such mutualisms on plant survival are well documented in undisturbed and ant‐invaded systems, but few have explored how anthropogenic disturbance affects interactions between hemipterans and native ant species and what the consequences may be for recovering ecosystems. Within a fragmented landscape in Costa Rica, restored tropical forests harbor a mutualism between the native ant Wasmannia auropunctata and the scale insect Alecanochiton marquesi on the abundant, early‐successional tree Conostegia xalapensis. I added A. marquesiscales to C. xalapensis seedlings and either allowed or excluded W. auropunctata to investigate if this mutualism leads to increased scale infestation, decreased scale mortality, and decreased folivory. I also examined whether these effects are mediated by the percentage of remnant forest cover in the landscape. I found that seedlings with ants excluded had fewer scale insects and higher herbivory than plants with ants present. I also found evidence that scale mortality due to fungal attack and parasitism was higher on ant‐excluded versus ant‐allowed seedlings but only at sites with high surrounding landscape forest cover. Together, these results suggest that mutualisms between scale insects and native ants can promote scale infestation, reduce folivory on native plant species, and potentially disrupt biological control of scale insects in recovering tropical forests. Further, my experiment underscores the importance of remnant tropical forests as sources of biological control in anthropogenically disturbed landscapes.

蚂蚁-半翅目昆虫互利共生（Ant–hemipteran mutualisms）对宿主植物的影响兼具正负两面，具体取决于半翅目昆虫的侵染水平以及蚂蚁为宿主植物提供的针对食叶害虫的防护作用。这类互利共生对植物存活的差异化影响在未受干扰和蚂蚁入侵的生态系统中已有充分记载，但鲜有研究探讨人为干扰如何影响半翅目昆虫与本地蚂蚁间的相互作用，以及这一过程对恢复中生态系统的潜在后果。在哥斯达黎加的破碎化景观中，恢复中的热带森林内存在本地蚂蚁Wasmannia auropunctata与介壳虫Alecanochiton marquesi之间的互利共生关系，二者的宿主为广布的早期演替树种Conostegia xalapensis。本研究将Alecanochiton marquesi介壳虫接种至Conostegia xalapensis幼苗上，并设置允许蚂蚁定居与排除蚂蚁的两组处理，以探究该互利共生是否会提升介壳虫侵染水平、降低介壳虫死亡率以及减轻食叶虫害。同时，本研究还考察了这些效应是否受景观中残余森林覆盖率的调控。研究结果显示，排除蚂蚁的幼苗介壳虫数量更少，但食叶虫害程度高于有蚂蚁存在的幼苗。此外，研究发现排除蚂蚁的幼苗上，由真菌侵染和寄生作用导致的介壳虫死亡率更高，但这一现象仅出现在周边森林覆盖率较高的样地。综合来看，这些结果表明介壳虫与本地蚂蚁间的互利共生可提升介壳虫侵染水平、减轻本地植物的食叶虫害，但也可能在恢复中的热带森林中干扰介壳虫的生物防治。进一步而言，本实验强调了在人为干扰的景观中，残余热带森林作为生物防治资源库的重要性。