Where Art Thou? Urbanization Decreases Attacks on Sentinel Prey by Arthropods, but Not Birds, in a Tropical City

Abstract

Land use and cover in urban and rural landscapes change biotic communities, impacting ecosystem services provided by pest predators, which can lead to the overabundance of herbivorous insects and, consequently, increased herbivory, especially in highly urbanized areas. To investigate this, we placed 2555 artificial sentinel prey in 73 sampling units in the Greater João Pessoa region, Northeast Brazil, covering different types of urban and rural landscapes to verify how differences in land use and cover in a tropical city may affect predation on herbivorous caterpillars. Urban landscapes were located within the urbanized perimeter of the city. Rural landscapes included areas with monocultures, small livestock farmers, and smallholder farmers, and were noncontiguous. Arthropods emerged as the primary group controlling herbivorous insect populations, but built-up land cover and fragmented habitats strongly affected this ecosystem service. Birds were the second most common taxon providing pest control and were not affected by differences in land use and cover. Although rural areas were far apart and differed in land cover, predation rates were similar between each other. Contrary to our prediction, temporary plantations did not impact predation rates, probably due to the presence of small forest fragments. Birds might play a key role in controlling herbivorous insects in tropical cities since they can forage over considerable distances and endure highly built-up landscapes. While there is no one-size-fits-all solution to improve habitats for pest control providers, urban planners should aim to increase the number of trees in streets and plazas to encourage the presence of predators.