Explaining the distribution of Rhabdopterus jansoni in coffee plantations: insights from diet breadth and preference

Abstract

Understanding the factors that influence the dynamics of herbivory becomes a particularly important challenge when considering agricultural systems. Here we use the regionally specific herbivore of Coffea spp., Rhabdopterus jansoni (Jacoby) (Coleoptera: Chrysomelidae) and explore the potential factors which contribute to its dynamics and relative densities in coffee agroecosystems. Our experiments have shown that R. jansoni did not feed differentially on varieties of Coffea arabica, but preferred all varieties of Coffea arabica to Coffea canephora. No difference was found in R. jansoni’s preference for young or old coffee leaves, R. jansoni was more abundant in plantations of C. arabica relative to C. canephora, and finally, R. jansoni was found on 15 of 18 shade trees surveyed in the agroecosystem. Interestingly the lab preference experiments correspond to the relative densities of R. jansoni in the field, suggesting to us that field surveys may represent a metric of preference for some herbivores in agroecosystems. Additionally we discuss various factors to be considered when attempting to understand the role that shade trees may play in agroforestry systems.