Intercropping enhances beneficial arthropods and controls pests: A systematic review and meta-analysis

Agricultural land use is a major driver of biodiversity decline worldwide, but adopting sustainable farming practices can help to restore or maintain biodiversity and associated ecosystem services. The common biodiversity declines in monocultures may be mitigated by intercropping, which means diversification with multiple crops in the same field. Here, we conducted a systematic review and meta-analysis, using data from 18 countries published in 63 articles, to quantitatively assess the overall effect size of intercropping on beneficial arthropods and pest populations. We also evaluated whether the effect of intercropping varies between different crop combinations and with the spatial arrangement of crops. We used monoculture as a control system, which served as a proxy for agricultural intensification. We found that intercropping, compared to monoculture, significantly increased the overall abundance of beneficial arthropods by 36%, density by 94%, and species richness by 27%. Intercropping reduced 38% of the abundance and 41% of the density of arthropod pests, while their species richness was not affected. Intercropping consistently affected positively the species richness of pollinators, parasitoids, and predators. The combination of cereal-legume outperformed cereal-cereal in promoting beneficial arthropods while reducing pests. Regarding spatial arrangement, row and strip were more effective than mixed and relay intercropping in supporting beneficial arthropods and controlling pests. According to our results, intercropping is an effective practice to mitigate the adverse impacts of agricultural intensification on beneficial arthropods in agroecosystems. Our findings may encourage farmers to adopt intercropping over intensive monoculture and policymakers to consider incentives for intercropping in agri-environmental schemes.