Mutualisms are known to play a variety of roles in structuring communities and ecosystems. While obligate mutualisms can irreplaceably shape community composition, facultative mutualisms can also play a variety of roles such as in aiding recovery from stressful conditions, accelerating ecosystem processes and modulating the balance between multiple ecosystem processes. Ant-Hemipteran mutualisms are largely facultative, food-reward/protection-driven mutualisms in which ants “tend” many species of insects across unrelated groups of the order Hemiptera including aphids, scale insects, treehoppers and leaf-footed bugs. Honeydew, the excreted product of sap consumption by Hemipterans, is the food-reward to ants in exchange for reduced predation pressure arising from close proximity with ants. The widely context-variant mechanisms and outcomes involved have been well-elucidated in smaller-scale studies of a few species at a time. However, much less is known about the overall diversity of these mutualisms at a single site, and how this diversity impacts their functioning. This is expected to matter in many natural settings, as most species involved are generalists, each interacting with a diverse suite of partners.

I will investigate the patterns and processes structuring ant-Hemipteran mutualisms at a landscape scale across three land use types - grasslands, forests and heavily-logged forests, within Sonai-Rupai Wildlife Sanctuary in Assam. In my first Chapter, I will examine participation in mutualisms by comparing patterns of ant-Hemipteran-host plant networks across the three habitats. I will also consider what can be inferred about the processes shaping participation from the structure of interaction networks alone. In Chapter 2, I will compare three different methods of sampling ant-Hemipteran interactions for purposes of the previous chapter across the land use gradient. This will provide a greater appreciation of the challenges that may be involved in sampling these patchily-distributed interactions in widely differing environments. I will begin Chapter 3 by characterizing mutualisms based on a set of easily observable ecological properties, comment on their relevance and then ask how species traits influence these properties. In my final Chapter, I will perform cafeteria experiments using baits to understand how nutritional balances and competitive dominance and discovery hierarchies influence the use of Hemipteran tending as resources by ants across the land-use types.