Professor University of California, Santa Cruz Santa Cruz, California, United States
Abstract: Vegetative connectivity is an important aspect of habitat complexity that may impact species interactions at local scales. However, agricultural intensification reduces connectivity in agroforestry systems, including coffee agroecosystems, which may hinder movement of natural enemies and ecosystem services that they provide. Ants play an important role in removing the coffee berry borer (CBB), the most damaging coffee pest. For Azteca sericeasur arboreal ant communities, connections between trees are important structures that facilitate ant mobility, resource recruitment, foraging success, and pest control ability. To better understand how connectivity impacts arboreal ants in coffee agroecosystems, we developed an experiment to assess the impact of artificial (string) and vegetative (vines, leaves, branches) connectivity on A. sericeasur behavior on coffee plants. We compared ant activity, resource recruitment, and CBB removal rates across three connectivity treatments connecting coffee plants to A. sericeasur nest trees: vegetative connectivity, string, and control (not connected) treatments.
We found that the highest rates of ant activity, resource recruitment, and CBB removal occur on plants with naturally occurring vegetative connections to A. sericeasur nest trees. Artificial connectivity (string) increases ant activity, resource recruitment, and CBB removal but to a lesser extent than vegetative connectivity. Secondly, ants are willing to travel farther distances to coffee plants that are vegetatively connected to their nest tree. These results reinforce how habitat complexity in the form of vegetative connectivity impacts interspecific interactions at the local scale. These findings also suggest that leaving some degree of vegetative connectivity between coffee plants and shade trees can promote ant-mediated biological pest control in coffee systems.
