Predation risk of caterpillar preys in urban agroecosystem is shaped by arthropods and local landscape but not leaf herbivory: a common garden experiment

Abstract

Prey-predator interactions are fundamental to ecosystems, with predators regulating prey populations. Yet, the degree of this interaction varies, depending on the conditions and structure of the ecosystem. We investigated the impact of urbanisation and tree cover, together with leaf herbivory, on the risk of predation of caterpillar prey. We used 1500 artificial caterpillars across ten study sites in southcentral Mindanao, Philippines. We found that the predation rate was similar across leaf herbivory treatments, but the risk differed significantly according to the predator and landscape variables. Arthropods were the most significant predators, and local landscape and plot-level variables affected the overall predation risk of caterpillar prey. Increasing canopy and tree cover increased the risk of predation. This study implies that, irrespective of the specific foraging locations chosen by arthropod prey, predators are likely to prey on the available prey within the environment. Our results align with the ‘Enemies hypothesis’, which suggests that the effectiveness of top-down control by predators increases with heightened tree cover. This further suggests that adjacent small-scale restoration interventions, such as native tree planting to bolster habitat heterogeneity and structure, would benefit top-down control (i.e. natural pest control) within urban agroecosystems.