Extrafloral nectary-bearing leguminous trees enhance pest control and increase fruit weight in associated coffee plants

Plant diversification is a strategy for pest management in agroecosystems. However, a major hurdle in the adoption of this management practice by farmers is related to doubts concerning its effects on crop productivity. Here we assess coffee production and natural control of coffee pests in the presence or absence of leguminous trees bearing extrafloral nectaries (Inga edulis). We compared coffee yield, coffee damage caused by coffee leaf miners (Leucoptera coffeella) and coffee berry borers (Hypothenemus hampei) and parasitism and predation of coffee leaf miners in a replicated field experiment. To evaluate the effect of proximity of the nectar source on natural control, we also assessed pest control and production along transects of 50 m extending from the Inga trees. Production per coffee plant was equal in both systems but coffee fruits were heavier in coffee consorted with Inga trees. In the most productive year, coffee production was higher on plants closer to the Inga trees. Damage caused by coffee leaf miners and coffee berry borers was lower in coffee with Inga trees and increased with distance from the trees. Parasitism of coffee leaf miners and predation by wasps did not increase in coffee consorted with Inga, neither decreased with distance from the trees. Therefore, Inga trees enhanced coffee production and increased natural control of coffee pests.