Bottom-up effects of polyethylene microplastics on the growth and development of potato, Colorado potato beetle and Stinkbug predators

With the widespread adoption of agricultural cultivation technologies, the continuous accumulation of microplastics (MPs) in agroecosystems poses a major threat to the growth, development, yield, and food chains in crops. To evaluate how polyethylene microplastics (PE-MPs) affect the food chains in potatoes, we simulated polluted field environments by treating potted potatoes with PE-MPs and by studying an herbivore (Leptinotarsa decemlineata) and its predator (Arma chinensis) within this system. The herbivore was exposed to potato leaves from plants treated with different PE-MPs particle sizes for 15 days. The effects of PE-MPs on potato growth and yield, as well as their impact on L. decemlineata and the potential predation ability of A. chinensis, were evaluated. We found that: 1) Adding PE-MPs to the soil not only prolonged the emergence time of potato plants but also reduced plant height and stem diameter, ultimately reducing potato yield. 2) Potato plants exposed to PE-MPs led to a significant decrease in the survival rate and vitality of L. decemlineata adults. 3) Arma chinensis were more likely to prey on PE-MPs-exposed L. decemlineata, however, A. chinensis were also affected, with a noticeable increase in mortality. These results suggest that PE-MPs have a bottom-up negative impact on crop-pest-natural enemy systems, which may affect the balance of the food chain, providing new insights for the risk assessment and toxicity of microplastics on terrestrial food chains.