Landscape-Scale Modelling of Biological Weed Control Through Natural Enemy Conservation in Nigerian Farming Systems

This study develops landscape-scale models for biological weed control through natural enemy conservation in Nigerian farming systems, contributing an original modelling framework and empirical evidence for landscape ecology-based weed management. Biological control of weeds through seed predators and herbivorous insects represents an underexplored dimension of sustainable weed management in Nigeria. Natural enemy communities that consume weed seeds and damage weed vegetative parts are sensitive to landscape structure, with high landscape heterogeneity and natural vegetation patches supporting the weed-suppressive natural enemy guilds. This study combines field measurement of weed seed predation rates, granivore community sampling, and herbivory assessments across 90 farm plots representing three landscape types: simple agricultural landscapes, heterogeneous crop mosaics, and landscapes with significant natural vegetation patches, in Ogun, Benue, and Zamfara States. Agent-based landscape models are developed to simulate the movement of seed-predating ground beetles and weevils across landscape types and to predict landscape management effects on weed seed bank reduction rates. Findings reveal that weed seed predation rates in heterogeneous landscapes with greater than 15 percent natural vegetation are 64 percent higher than in simple agricultural landscapes. Carabid beetle and ant densities are the strongest predictors of seed predation rates. Landscape model simulations project that targeted natural vegetation corridor establishment can increase weed seed predation by 42 percent landscape-wide at 8 percent natural vegetation coverage. The study contributes original biological weed control landscape models for Nigeria and recommends natural vegetation corridor integration into sustainable weed management policy.

Keywords: biological weed control, landscape ecology, natural enemies, weed seed predation, Nigeria.