Beyond predator richness: How diversified cropping can enhance pest regulation

Research Highlight discussing: Heinen, J.; Dominguez, V.; Aguilera, G.; Malsher, G.; Vesterinen, E.; Roslin, T.; Bommarco, R.; Bartomeus, I. (2024). Diversified cropping strengthens herbivore regulation by providing seasonal resource continuity to predators. Journal of Applied Ecology, https://doi.org/10.1111/1365-2664.14674. Crop monocultures consist of homogenous agroecosystems highly dependent on pesticides for pest regulation and mineral fertilisation for maintaining plant nutrition, representing the least resilient system. Agricultural diversification practices can increase heterogeneity in agroecosystems, resulting in greater richness of arthropod predators and enhanced ecological services. Among natural enemies of pests, generalist predators are important for pest regulation as they prey on diverse arthropod pests and be present throughout the season. However, since they consume other predators (intraguild predation) and soil fauna, it is uncertain whether enhanced richness of generalist predators translates into improved pest regulation. The study by Heinen et al. examined how diversified crop rotation and organic fertilisation influenced predator–prey interactions throughout the cropping cycle in cereal fields. The predators' diet preference shifted over the growing season, indicating that soil fauna is an important resource for recruitment and maintenance of predators early in the season. Although intraguild predation was considerably high, it decreased across the season in fields with the greatest level of diversification, where predation of pests remained stable. This study demonstrated how diversified cropping is important for providing resource continuity with alternative prey (soil fauna and predators) over crop-growing season, enhancing predator richness and herbivore regulation.