Effects of Pesticide Use Intensification on Beneficial Arthropod Communities in Intensive Vegetable Farming Systems in Ogun State, South West Nigeria

Intensification of pesticide use in peri-urban vegetable farming threatens beneficial arthropods including natural enemies and pollinators, with downstream consequences for crop system sustainability. Ogun State's peri-urban agricultural belt supplies fresh vegetables to Lagos markets under conditions of escalating chemical input use. This study examines how pesticide use intensification influences the abundance and diversity of beneficial arthropods across vegetable farms in Ogun State. Farm-level pesticide use data (frequency, active ingredient classes, dose) will be collected from 80 farms through farmer interviews, and farms classified into pesticide intensity quartiles. Beneficial arthropod communities including predatory beetles, parasitic wasps, spiders, and bees will be sampled using yellow sticky traps and sweep nets during three sampling rounds. Generalized additive models will test monotonic and threshold relationships between pesticide intensity and beneficial arthropod community metrics. The study tests whether a pesticide intensity threshold exists beyond which natural enemy communities collapse, using an empirical data-driven approach not previously applied to Nigerian vegetable systems. Findings will be submitted to the Ogun State Ministry of Agriculture as evidence for incentivized IPM adoption programs in the Lagos-Ogun peri-urban vegetable corridor. Keywords: beneficial arthropods, pesticide intensification, vegetable farming, natural enemies, Ogun State