Insectivorous predators: Inter and intra-trophic interactions between frogs, lizards, and ants

Abstract

Small vertebrate predators of herbivores have complex roles in ecosystem composition and functioning, but a review of existing studies concerning two of these small vertebrates, lizards and frogs, has yet to be conducted. Lizards and frogs are abundant in ecosystems across the globe, and many species of these vertebrates are generalist insectivores that can influence multi-trophic interactions and pest and non-pest arthropod abundance. In my f irst chapter, I review the predation dynamics of these two small vertebrates, identifying the patterns of classification in literature concerning the effects of lizards and frogs on arthropod abundance. In my second chapter, I investigate how multiple predators influence pest control in coffee agroecosystems. In a laboratory experiment, I examined how two predators, the lizard Anolis cristatellus, and the ant Solenopsis invicta, affect a common coffee pest, the coffee leaf miner Leucoptera coffeella (CLM). I recorded the predatory effect of A. cristatellus and S. invicta together and in isolation and compared it to a control treatment with no predators. S. invicta consume far more CLM than A. cristatellus, and when the ants and lizards co-occur, their effect on the CLM is less than when ants predate alone. This result indicates that there is a negative effect when both predators occupy the same space, indicating possible intraguild predation or a trait mediated indirect interaction (TMII) between these two species. Multi-predator dynamics in both agricultural and nonagricultural systems can have complex effects on herbivore abundance and this research have pratical implications for S. invicta and A. cristatellus are both highly abundant on coffee farms in Puerto Rico, where the CLM is one of the main pests. The results of this research demonstrate the complexity of biocontrol services and the importance of informed management decisions in both agricultural and non agricultural ecosystems.