Wildflower strip influence on pest predation in cereal fields: Temporal variations and complementarity among predator guilds

Wildflower strips (WFS) are widely used measures to support biodiversity and ecosystem services, including pest control, in intensively managed agricultural landscapes. However, their effectiveness in reducing pest abundance and supporting natural enemies is highly variable. We studied the effect of WFS on predation rates and egg abundance of cereal leaf beetles (CLB) across four sampling periods spanning the phenology of cereal crops. We quantified predation by piercing-sucking, chewing and unknown predators using sentinel egg cards within WFS and in four locations within cereal fields (at distances of 12 and 36 m from WFS and control margins), and measured natural CLB egg abundance on cereal plants by visual observation. We analyzed the influence of WFS, field margin proximity, and sampling period on CLB egg predation by different predator guilds, on CLB egg abundance, and the relationship between CLB abundance and predation rates. CLB predation was mainly attributed to unknown predators (i.e., missing eggs), followed by piercing-sucking predators. Predation rates were higher within wildflower strips compared to cereal fields, especially in late June, and tended to be lowest far from control field margins. CLB egg abundance peaked in May and was positively related to local predation rates. The positive association between egg abundance and predation suggests that resource concentration effects are important drivers of CLB control, especially in sites without wildflower strips. Our results underscore the importance of incorporating spatial and temporal dynamics of both pests and predators into habitat-based strategies for sustainable biological control, which can help to limit pesticide use. • Cereal leaf beetle (CLB) egg predation was higher in wildflower strips than crops. • Unknown (missing eggs) and piercing-sucking predators dominated predation rates. • We observed temporal complementarity among predator guilds. • Within-field predation rates were poorly affected by distance to the field edge. • CLB egg predation rates were positively related to natural abundance of CLB eggs.