Interactions among spatial scales in the coexistence of predatory coccinellids and their implications for biological control
ecosystem services, conservation biological control, stable isotopes, network of interactions, assemblage rules
Changes in land use and land cover caused by human activities, especially agriculture, have led to the simplification and fragmentation of landscapes. Nevertheless, agricultural landscapes interact with natural systems through the dispersal of species between habitats and depend on biodiversity to sustain important ecosystem services, such as biological control. Aphidophagous coccinellids, important aphid predators in agroecosystems, benefit from the plant diversity of habitat at different spatial scales (site and landscape). Yet the interaction between these scales may affect the formation of their communities and the provision of their biological control service. The coexistence of coccinellid species may depend on species colonization and dispersal among habitats and intraguild interactions. The way species partition habitat and resource use may reduce niche overlap and allow more species to coexist locally, improving the biological control of aphids. Thus, this thesis aims to evaluate the mechanisms acting at different scales that affect aphidophagous coccinellid communities and their prey in agroecosystems. To this end, the thesis will be divided into three chapters. Chapter I will investigate the role of habitat heterogeneity and land use change over time on coccinellid populations and biological control. In chapter II, the effect of local plant diversification on coexistence and partitioning in resource use by coccinellid species will be evaluated, as well as the assemblage rules of aphid and coccinellid communities. In the third chapter, the interactions among species and spatial partitioning in the use of resources locally will be analyzed, evaluating the use of microhabitats and the structure of the network of plantherbivore-predator interactions.