Effects of elevated CO2 on the nutrient compositions and enzymes activities of Nilaparvata lugens nymphs fed on rice plants

Elevated CO2 may reduce the tolerance of Nilaparvata lugen （N. lugens） to adverse environmental factors through the biologi- cal and physiological degeneration of N. lugens. In an artificial climate box, under 375 and 750 μL L-1 CO2 levels, the rice stems nutrient content, the nutrient content and enzyme activities of N. lugens nymph fed on rice seedlings exposed to ambient and elevated CO2 were studied. The results showed that rice stems had significantly higher protein and total amino acid levels under ambient than elevated CO2 levels. Nymphs had significantly higher protein levels in the ambient CO2 treatment, while their glucose levels were significantly lower under ambient CO2 conditions. Significantly higher trypsin activity was observed in nymphs grown in elevated CO2. Significantly lower activities of the protective enzymes total superoxide dismutase and cat- alase were observed in the nymphs under ambient CO2. Meanwhile, the activity of the detoxification enzyme glutathione S-transferase was significantly higher in the ambient CO2 treatment. Measuring how energy and resources were allocated to enzymes in N. lugens nymphs under elevated CO2 conditions can provide a more meaningful evaluation of their metabolic tol- erances to adverse climatic conditions.