Developing an Original Framework for the Quantification of Pollination Ecosystem Services and Their Economic Value in Cocoa Agroforestry Systems of South West Nigeria

This dissertation develops and validates an original framework for quantifying pollination ecosystem services and their economic values in cocoa agroforestry systems of South West Nigeria, encompassing Ondo, Ekiti, Oyo, Osun, Ogun, and Lagos States. Cocoa is Nigeria's most economically important tree crop, and its production is entirely dependent on insect pollination, yet the specific contribution of biodiversity to pollination service delivery and the economic cost of biodiversity loss to cocoa yields have never been quantified in Nigeria. The dissertation employs a three-phase design: ecological characterisation of pollinator communities across 48 cocoa farms representing a gradient of shade tree diversity using standardised pan trapping, hand netting, and floral visitor observation; experimental manipulation of pollinator access using exclusion bags on cocoa flowers to measure the contribution of different pollinator groups to fruit set; and landscape-scale analysis integrating farm-level pollination data with GIS-derived habitat and crop yield data to estimate pollination service values at state level using net present value and replacement cost methods. An original Cocoa Pollination Service Model (CPSM) is constructed and validated against independent yield data. Ceratina bees and midges Forcipomyia spp. are confirmed as the primary pollinators, with their combined activity explaining 68 percent of variance in cocoa fruit set across farms. Shade tree diversity positively predicts bee pollinator diversity. The CPSM estimates that pollination service values range from 18,000 to 47,000 naira per hectare annually, substantially exceeding current investment in synthetic pest management in the sector. Keywords: pollination ecosystem services, cocoa agroforestry, South West Nigeria, economic valuation, bee diversity.