Earthworms Enhance\nCrop Resistance to Insects Under\nMicroplastic Stress by Mobilizing Physical and Chemical Defenses

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