Coexistence of insect species in a phloem feeding guild: Deterministic and stochastic processes

1. Niche theory, neutral theory, and more recently the unifying theory of biodiversity offer alternative views of the structure (or not) of ecological communities. The relative importance of these theories has not been so thoroughly used to explain community assembly processes in phytophagous insects. 2. We studied the mechanisms of community assembly in pine trees phloem feeders, exploring the relative contributions of deterministic and stochastic processes. 3. Temporal and spatial partitioning of wood borers and bark beetles belonging to the pine phloem feeding gild, was assessed through flight traps and pine bolts extracted from felled live Pinus pinaster trees presenting evidence of decline/wilting. 4. We found that deterministic factors explained most cases of coexistence between species, with partitioning in space and time reducing asymmetric competition for resources and intraguild predation, mediated by differences in size. However, in the case of very closely related species with minimum differences in size—in this case three species of Arhopalus—they occupied the same niche in space and time, suggesting that stochastic processes are more likely to maintain co-occurrence. 5. The present work indicates that both niche and stochastic processes contribute to the assembly of the phloem feeding community. This could be one more example of accordance with the unifying theory of biodiversity.