Plant community composition and functional characteristics define invasion and infestation of termites in cocoa agroforestry systems

Abstract

The effects of farm management on non-native species and the structure and function of native communities and ecosystems on crop yield is poorly documented especially in the cocoa agroforestry systems of West Africa. We assessed termite damages, cocoa plantations structural characteristic and local farmer knowledge to refine the critical role of shade trees management on subterranean crops pests and the consequences on marketable yield in five cocoa agroforestry systems. Farmers recognized termites as the most damaging subterranean pests and clearly described the type of damages they cause on cocoa trees and seedlings. Complete shade removal or very heavy shade on very old cocoa trees were responsible of the invasion of termites with negative effect on marketable yield. Some tree species, specifically fruit tree species planted in high proportion or solely may act as termite attractants and reservoirs by facilitating the building of galleries on cocoa trees. Many plant parts from roots to pods are preferred by termites with higher incidence on stems (52%), roots (34%) and young branches (27%). Damages on plant parts varied significantly with shade management. We found that the relationship between yield and the infestation of termites was weak in unshaded systems and very strong under shaded systems. We also found that the sales of agroforestry products significantly contribute to offset yield loss due to termite infestations. We conclude that intermediate shaded cocoa agroforestry systems with a diversity of shade trees will limit the outbreaks of termites. The intermediate shaded systems provide agroforestry products that offset marketable yield loss due to termites with positive impacts on income and the sustainability of cocoa production.