Landscape and farm-level management for conservation of potential pollinators in Indonesian cocoa agroforests

Abstract

Cocoa (Theobroma cacao L.), a major commodity globally, depends on insects for pollination. However, the cocoa pollinator identity is largely unknown and there are important knowledge gaps regarding landscape and farm-level management driving pollinators. Here we analyzed flower visitation with two approaches to quantify how landscape and farm-level factors affect potential pollinators (flower visitors) of cocoa in Central Sulawesi, Indonesia. In the first approach (landscape and farm-level) we selected 18 farms and focused on the relative importance of distance to forest (m), potential-pollinator habitats surrounding the farm (i.e. secondary forests and cocoa agroforests [%]), canopy cover (%), leaf-litter amount (kg/m2), and cocoa flower abundance for flower visitors. In the second approach (experimental farm management) we manipulated leaf-litter in 24 farms, because high leaf-litter is suggested to enhance flower visitors. We found that ants and Diptera were the most common flower visitors, and although previous studies suggest ceratopogonids as main cocoa pollinators, none were captured in this study. In the landscape and farm-level approach, potential-pollinator habitats surrounding the farm, and increased canopy cover enhanced ant and Diptera abundance, whereas distance to forest had no effect. In the experimental farm management approach, potential-pollinator habitats surrounding the farm rather than leaf-litter manipulation increased Diptera and ant abundance. In summary conservation of forests and agroforests surrounding the farm, maintaining canopy cover and minimum leaf-litter enhance cocoa flower visitors. Thus, farms with shade trees embedded in a biodiversity-friendly landscape are important for conservation of potential pollinators and pollination services and, thereby, promotion of sustainable cocoa.