Elevation and grassland cover shape natural enemy communities in Kenyan maize crops

Natural enemies, including arthropod predators and parasitoids, provide essential pest control services in agricultural systems by reducing pest populations below harmful levels. However, studies examining how natural enemies respond to environmental gradients, such as elevation and grass cover, are limited in sub-Saharan Africa. This study investigates the effects of elevation (1200–1950 meters above sea level) and grassland cover in the surrounding landscape (2–30%) on natural enemy communities in maize fields in western Kenya over two sampling seasons. We selected maize plots along gradients of elevation and percentage of grassland and conducted field surveys using pitfall traps to assess the diversity and composition of natural enemies.  Natural enemy diversity, richness, evenness, abundance, and community structure were compared across gradients using generalized linear models (GLMs) and Non-Metric Multidimensional Scaling (NMDS). Overall, ants were the most abundant group. Lower elevations supported more diverse and evenly distributed natural enemy communities, while higher elevations were dominated by Myrmicaria ants.  Grassland cover exhibited limited overall effects, showing a marginally positive impact on species evenness during the second sampling season, which contributed to changes in community composition. The dominance of Myrmicaria ants at high elevations and low grass cover may reduce overall pest control resilience, emphasizing the need for integrated pest management strategies with a focus on multiple landscape variables and responses to climate change. Our findings highlight the importance of environmental gradients in shaping natural enemy biodiversity in agricultural fields with implications for pest control in western Kenya.