University of Michigan, School for Environment and Sustainability Ann Arbor, Michigan, United States
Abstract: Background/ Questions/ Methods
Understanding the dynamics of multi-predator communities has practical significance in agroecosystems where questions of biological control and biodiversity go hand in hand. Prior work has shown that both synergistic and antagonistic net effects can dominate the dynamics of biological control depending on the underlying ecology of the community. Here we use the coffee leaf miner, CLM, (Leucoptera coffeella), and its community of predators to understand how predator diversity impacts the success of this insect pest across ontogeny. We focus on the larvae and pupae stages of the CLM, which are attacked by parasitoids, ants, and anolis lizards. While prior work has shown antagonistic interactions between two important predators of CLM, an invasive ant, Wasmannia auropunctata, and anolis lizards, here we ask about the impact of the larger community of ants on the control of the CLM. For this, we conducted surveys of the CLM in coffee farms in Puerto Rico, which consisted of measuring the number of mines, the larval stage, and of the pupae, alongside the ant dominance on the coffee plants.
Results/Discussion
Our results show both net positive and negative effects of ants on the dynamics of CLM. Both dominant invasive ants in the community, W. auropunctata and S. invicta, have a net positive effect on CLM larvae and pupae. Although W. auropunctata and likely S. invicta, prey on the CLM, these results suggest that their interference with other predators outweighs any potentially beneficial biological control of the CLM. We suggest that these net positive effects emerge from trait-mediated indirect interactions between these two aggressive ants and anoles which are also known to be predators of CLM. Importantly this net positive effect was not found in other ant species in the community such as Pheidole morens and Technomyrmex dificilis, showing that interactions between CLM and the community are largely species-specific and the community of ant predators should not be considered generally. Further studies are needed to understand how interactions among all the predators in the community are structured and what their implications are for CLM dynamics.
