Ingestion and effects of cerium oxide nanoparticles on Spodoptera frugiperda (Lepidoptera: Noctuidae).

ABSTRACT

The objective of this study was to evaluate the biological and nutritional characteristics of Spodoptera frugiperda (Lepidoptera Noctuidae), an arthropod pest widely distributed in agricultural regions, after exposure to nano-CeO2 via an artificial diet and to investigate the presence of cerium in the body of this insect through X-ray fluorescence mapping. Nano-CeO2, micro-CeO2, and Ce(NO3)3 were incorporated into the diet (0.1, 1, 10, and 100 mg of Ce L-1). Cerium was detected in caterpillars fed with diets containing nano-CeO2 (1, 10 and 100 mg of Ce L-1), micro-CeO2 and Ce(NO3)3, and in feces of caterpillars from the first generation fed diets with nano-CeO2 at 100 mg of Ce L-1 as well. The results indicate that nano-CeO2 caused negative effects on S. frugiperda. After it was consumed by the caterpillars, the nano-CeO2 reduced up to 4.8% of the pupal weight and 60% of egg viability. Unlike what occurred with micro-CeO2 and Ce(NO3)3, nano-CeO2 negatively affected nutritional parameters of this insect, as consumption rate two times higher, increase of up to 80.8% of relative metabolic rate, reduction of up to 42.3% efficiency of conversion of ingested and 47.2% of digested food, and increase of up to 1.7% of metabolic cost and 8.7% of apparent digestibility. Cerium caused 6.8-16.9% pupal weight reduction in second generation specimens, even without the caterpillars having contact with the cerium via artificial diet. The results show the importance of new ecotoxicological studies with nano-CeO2 for S. frugiperda in semi-field and field conditions to confirm the toxicity.