Predator types, urbanization, and tree cover drive top-down control of herbivorous and carnivorous preys in an urban agroecosystem

Abstract

ABSTRACT Prey-predator interactions hold significant importance, widely acknowledged as crucial processes within ecosystems. Yet, there is a scarcity of empirical data that effectively illustrates the influence of urbanization on such interactions. We performed a common garden experiment utilizing 1250 clay models to assess the predation risks faced by herbivorous and carnivorous prey in an urban agroecosystem in the southern Philippines. Our findings revealed significant differences in attack risks between the trophic levels, with herbivorous caterpillars (n = 246; 53.25%) experiencing higher predation rates compared to carnivorous lizards (n = 216; 46.75%). Interestingly, while the trophic level of the prey did not directly predict predation risk, the presence of predators showed significant effects. Arthropods emerged as the dominant predators of herbivorous prey compared to other predators, whereas mammalian predators predominantly attacked carnivorous prey. The landscape variable also had a strong influence on the risk of predation. We found that increasing tree cover was significantly related to increased predation risk, while built-up showed the opposite. Our research findings support the ‘increasing disturbance hypothesis’, suggesting that rising urbanization rates reduce predator diversity, resulting in a decrease and loss of predation pressure.