Trophic Transfer\nof Metal Oxide Nanoparticles in the\nTomato-Helicoverpa armigera Food Chain:\nEffects on Phyllosphere Microbiota, Insect Oxidative Stress, and Gut\nMicrobiome

Understanding the trophic transfer and ecological cascade\neffects\nof nanofertilizers and nanopesticides in terrestrial food chains is\ncrucial for assessing their nanotoxicity and environmental risks.\nHerein, the trophic transfer of La<sub>2</sub>O<sub>3</sub> (nLa<sub>2</sub>O<sub>3</sub>) and CuO (nCuO) nanoparticles from tomato leaves\nto Helicoverpa armigera (Lepidoptera:\nNoctuidae) caterpillars and their subsequent effects on caterpillar\ngrowth and intestinal health were investigated. We found that 50 mg/L\nfoliar nLa<sub>2</sub>O<sub>3</sub> and nCuO were transferred from\ntomato leaves to H. armigera, with\nparticulate trophic transfer factors of 1.47 and 0.99, respectively.\nWhile nCuO exposure reduced larval weight gain more (34.7%) than nLa<sub>2</sub>O<sub>3</sub> (11.3%), owing to higher oxidative stress (e.g.,\nMDA and H<sub>2</sub>O<sub>2</sub>) and more serious intestinal pathological\ndamage (i.e., crumpled columnar cell and disintegrated goblet cell)\nby nCuO. Moreover, nCuO exposure led to a more compact antagonism\nbetween the phyllosphere and gut microbiomes compared to nLa<sub>2</sub>O<sub>3</sub>. Specifically, nCuO exposure resulted in a greater\nincrease in pathogenic bacteria (e.g., <i>Mycobacterium</i>, <i>Bacillus</i>, and <i>Ralstonia</i>) and\na more significant decrease in probiotics (e.g., <i>Streptomyces</i> and <i>Arthrobacter</i>) than nLa<sub>2</sub>O<sub>3</sub>, ultimately destroying larval intestinal immunity. Altogether, our\nfindings systematically revealed the cascade effect of metal oxide\nnanomaterials on higher trophic consumers through alteration in the\nphyllosphere and insect gut microbiome interaction, thus providing\ninsights into nanotoxicity and environmental risk assessment of nanomaterials\napplied in agroecosystems.