Effects of agroforestry on pest, disease and weed control: a meta-analysis

Abstract

Agroforestry practices may influence pest incidence and abundance both through increased top-down regulation by natural enemies and via bottom-up factors such as moderation of microclimate, soil nutrients and water content. We conducted a meta-analysis of the effects of agroforestry on the abundance of invertebrate pests, weeds, natural enemies and plant damage due to pests and diseases. We also tested whether effects of agroforestry were dependent on crop type (annual or perennial), type of pest association (above or belowground) and weed type (parasitic Striga weeds or non-parasitic weeds). Agroforestry practices resulted in lower abundances of both parasitic and non-parasitic weeds, and in higher abundances of natural enemies. The effects of agroforestry on invertebrate pests and diseases were dependent on crop type. In perennial crops (e.g. coffee, cocoa and plantain), agroforestry was associated with lower pest abundances and less plant damage. However, the effects were not significant in annual crops (e.g. maize, rice and beans). Despite the limited number of crop-pest systems available for the analyses, overall our results suggest that agroforestry is beneficial in terms of pest, disease and weed management