Effects of elevated CO2 on activities of protective and detoxifying enzymes in Frankliniella occidentalis and F. intonsa under spinetoram stress.

Background Elevated CO2 can directly affect toxicity of insecticides to insects and the physiological response of insects to insecticides. Frankliniella occidentalis and Frankliniella intonsa are highly destructive pests that target horticultural crops. Spinetoram is an effective pesticide against thrips. This study sought to explore the effect of elevated CO2 on efficacy of spinetoram against F. occidentalis and F. intonsa and effect of the spinetoram on activities of protective and detoxifying enzymes under elevated CO2 . Notably, these enzymes can be exploited in further studies to develop interventions for thrips resistance management. Results Toxicity bioassay showed that the LC50 values of F. occidentalis and F. intonsa exposed to spinetoram at elevated CO2 (800 μL·L-1 concentration) for 48 h was 0.08 and 0.006 mg·L-1 , respectively, they are 0.62 and 0.75 times of those at ambient CO2 (400 μL·L-1 concentration). The findings showed that elevated CO2 decreased activities of the superoxide dismutase and acetylcholinesterase in thrips, while increased the activities of carboxylesterase and glutathione-S-transferase. However, spinetoram increased activities of protective and detoxifying enzymes in both thrips under the two CO2 levels. It has synergistic effect of elevated CO2 and spinetoram treatment on the physiological enzyme activity of thrips, and the activities of analyzed enzymes were generally higher in F. occidentalis than those in F. intonsa. Conclusion Elevated CO2 amplifies the efficacy of spinetoram on thrips, F. intonsa is more susceptibility to spinetoram than F. occidentalis, and the latter showed better adaptation to adverse conditions than the former. This article is protected by copyright. All rights reserved.