Implementation of practices shapes the effectiveness of agricultural diversification for arthropod related ecosystem services: a meta-analysis

Agricultural intensification has increased food production but has also caused significant environmental degradation and biodiversity loss. Diversification practices can mitigate these impacts while sustaining yields. While previous meta-analyses have examined their effects on arthropod populations and associated ecosystem services, focusing on individual practices or treating them as a whole, this is the first study to compare a wide range of diversification strategies across specific arthropod groups and assess how management factors, such as plant diversity, spatial configuration, and sowing time, modulate their outcome. Clarifying these mechanisms is crucial for optimizing diversification practices and enhancing their adoption by farmers. We conducted the most up-to-date and comprehensive meta-analysis to evaluate the effects of four diversification practices (agroforestry, intercropping, flower resource addition, and maintaining semi-natural habitats) on arthropods (parasitoids, predators, pollinators, and herbivores), their associated ecosystem services (predation, parasitism, pollination), and disservices (herbivory), using 19,421 data points from 449 publications. On average, all diversification practices increased beneficial arthropod populations and their services by 41%, compared to a non-diverse control, and reduced herbivore abundance and plant damage by 33%. Intercropping was particularly effective, reducing herbivore abundance and damage by 39% and 30%, respectively, while increasing predator and parasitoid populations by 48% and 56%. Other practices showed no consistent effects, likely due to high variability across studies. For the first time, we tested the influence of management factors and found complex effects on parasitoid abundance and parasitism, highlighting the need for context-specific approaches. These results highlight the importance of tailored policies and targeted research to support the adoption of diversification practices. Effective implementation can reduce reliance on insecticides while simultaneously promoting ecosystem services and supporting the transition to sustainable agricultural systems.