Ecological and Functional Consequences of Landscape Fragmentation on Beneficial Arthropod Communities Supporting Horticultural Systems in Ogun State

Agricultural landscape fragmentation, driven by urbanization and land use intensification, alters the community structure and functional roles of beneficial arthropods including pollinators and natural enemies of crop pests. In Ogun State, the rapid conversion of natural habitats surrounding horticultural production zones is hypothesized to be disrupting beneficial arthropod services that underpin crop productivity. This dissertation tests the hypothesis that landscape-level fragmentation metrics predict beneficial arthropod community composition and functional service delivery in horticultural farms of Ogun State, using landscape ecology and community ecology frameworks. Arthropod sampling using pan traps, pitfall traps, and sticky cards was conducted at 45 horticultural farms stratified across a gradient of landscape fragmentation intensity. Landscape metrics including percent natural habitat within 500 m, 1 km, and 2 km radii were derived from classified drone imagery. Structural equation modeling was applied to link landscape, arthropod diversity, and crop productivity outcomes. Results demonstrate that natural habitat cover within 1 km radius is the strongest positive predictor of predatory arthropod species richness and biological control service intensity, with a threshold at 15 percent habitat cover above which functional service delivery is maintained. The study provides landscape ecology evidence for designing pollinator-friendly and pest-suppressive agricultural landscapes in Ogun State. Keywords: landscape fragmentation, beneficial arthropods, biological control, pollination, Ogun State