Masters Thesis

Quantifying pest control services by birds and ants in Kenyan coffee farms

Ecosystem services, such as pest control and pollination, are critical benefits of biodiversity necessary for agricultural production. Predators, including insectivorous birds and ants, can provide important biological controls in agroecosystems, boosting crop yield and helping to offset the need for expensive inputs such as pesticides. With agricultural demand projected to increase in the future, two broad management strategies, termed land sparing and land sharing, have been proposed to conserve biodiversity while still meeting increased agricultural demand. Understanding the related impacts of habitat and landscape characteristics on the delivery of ecosystem services can better inform managers seeking to promote these benefits of biodiversity. In order to better understand these relationships, I conducted a sentinel pest experiment to investigate predation levels in response to a novel pest on coffee farms in central Kenya. The frequency of predation decreased significantly with increasing distance from adjacent forest fragments and was correlated with bird species richness. Predation was also significantly higher on shade compared to sun coffee farms. The mechanism through which the bird and ant communities are effecting pest removal is less clear, but encouraging particular preferential predators could positively influence pest control. In conclusion, a land sharing approach, via both the integration of shade trees and the conservation of small forest fragments within a farm, can support increased levels of pest control services provided by both birds and ants in Kenyan coffee farms.