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

Elevated CO(2) may reduce the tolerance of Nilaparvata lugen (N. lugens) to adverse environmental factors through the biological and physiological degeneration of N. lugens. In an artificial climate box, under 375 and 750 μL L(-1) CO(2) 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 CO(2) were studied. The results showed that rice stems had significantly higher protein and total amino acid levels under ambient than elevated CO(2) levels. Nymphs had significantly higher protein levels in the ambient CO(2) treatment, while their glucose levels were significantly lower under ambient CO(2) conditions. Significantly higher trypsin activity was observed in nymphs grown in elevated CO(2). Significantly lower activities of the protective enzymes total superoxide dismutase and catalase were observed in the nymphs under ambient CO(2). Meanwhile, the activity of the detoxification enzyme glutathione S-transferase was significantly higher in the ambient CO(2) treatment. Measuring how energy and resources were allocated to enzymes in N. lugens nymphs under elevated CO(2) conditions can provide a more meaningful evaluation of their metabolic tolerances to adverse climatic conditions.