Microplastics, as an environmental pollutant, are receiving increasing attention due to their ubiquitous presence in ecosystems and their ability to transfer and accumulate through food chains. Although it is well known that microplastics can enter plants through nutrient and water uptake by plant roots, the effects of microplastics on the growth, development and predation efficiency of herbivorous insects and predatory natural enemies after transfer from plants are still lacking. In order to investigate the impacts of polyethylene microplastics (PE-MPs) on the growth, reproduction of herbivorous insects and the predation efficiency of their predatory natural enemies, the quarantine pest globally - Leptinotarsa decemlineata and its predatory natural enemy - the Arma chinensis were selected as the research objects. Constructed a transfer system of polyethylene microplastics (PE-MPs) soil - potato plants - L. decemlineata and PE-MPs feed - Tenebrio molitor - A. chinensis. The key attention is paid to the reproduction, growth, and development of the L. decemlineata, as well as changes in the predation behavior and ability of A. chinensis against the L. decemlineata. We found that PE-MPs treatment reduced the egg production of adult L. decemlineata, prolonged their developmental time, and decreased their survival rate. Additionally, it extended the resting time, searching time, paralyzing time, and the latent period of A. chinensis, while decreasing the predation amount of A. chinensis on L. decemlineata larvae. Although the effects of PE-MPs on the growth and reproduction of L. decemlineata and the predatory efficiency of armpit A. chinensis were limited, our study still revealed the adverse effects of PE-MPs on phytophagous pests and predatory natural enemies. Finally, the mechanisms underlying these effects remain uncertain, necessitating further research to assess whether microplastics have potential long-term impacts on interactions between herbivorous insects and their predatory enemies. Collectively, these studies provide new insights into the effects of microplastics on herbivorous insects and predatory natural enemies.