To assess the ecological risk of microplastics (MPs) in agricultural systems, it is critical to simultaneously focus on MP-mediated single-organism response and different trophic-level organism interaction. Herein, we placed earthworms in soils contaminated with different concentrations (0.02% and 0.2% w/w) of polyethylene (PE) and polypropylene (PP) MPs to investigate the effect of earthworms on tomato against Helicoverpa armigera (H. armigera) under MPs stress. We found that earthworms alleviated the inhibitory effects of MPs stress on tomato growth and disrupted H. armigera growth. Compared to individual MPs exposure, earthworm incorporation significantly increased the silicon and lignin content in herbivore-damaged tomato leaves by 19.1% and 57.6%, respectively. Metabolites involved in chemical defense (chlorogenic acid) and phytohormones (jasmonic acid) were also activated by earthworm incorporation. Furthermore, earthworms effectively reduced oxidative damage induced by H. armigera via promoting antioxidant metabolism. Overall, our results suggest that utilizing earthworms to regulate above- and below-ground interactions could be a promising strategy for promoting green agriculture.

Heavy metal pollution in soil can impact the relationships between plants and their natural enemies. Enemy attack from herbivores and pathogens is predicted to be lower in metal-contaminated areas such as mine sites. However, whether this is the case is remains to be tested. It is also unknown how defense traits differ in polluted sites compared to adjacent sites. To address this gap in knowledge, we compared the standing leaf damage in populations of two invasive and five native plant species at the abandoned Jiuhua copper mine and an adjacent site. We also compared physical and chemical defense traits of the populations. Herbivory on four plant species was significantly lower in a copper mine than in an adjacent site. Overall, plants growing in the mine were more physically and chemically defended than plants growing adjacent to the mine. Copper hyperaccumulator species (Cynodon dactylon and Kummerowia stipulacea) increased defense levels in the mine for only one of the traits. In contrast, defenses were higher in the mine site for most traits relative to their respective adjacent populations in the non-hyperaccumulator species. Our results suggest that the damage herbivores inflict on plants may be strongly influenced by how plants respond to stressors in mine site environments, such as metal pollution. Metal hyperaccumulation and increased non-elemental defenses may be alternate responses used by plants to simultaneously deal with metal pollution and natural enemies in contaminated sites. (c) 2024 SAAB. Published by Elsevier B.V. All rights are reserved, including those for text and data mining, AI training, and similar technologies.