Biological and Biochemical Responses of Panonychus Citri (acari: Tetranychidae) Exposed to Sublethal Concentrations of Cyflumetofen

Citrus red mite, Panonychus citri (McGregor 1916) (Acari: Tetranychidae), is a major devastating pest in fruit orchards worldwide. Currently, the control of this pest remains to depend mainly on using various chemical insecticides and acaricides in agricultural systems. In this study, the sublethal (LC10, LC30 and LC50) effects of cyflumetofen exposure on the life history traits, together with enzyme activity measurements of P. citri larvae and adult females were assessed in order to determine if there were adverse or stimulating effects of sublethal stress on mites' fitness. After treatment with LC10 (larvae:1.767 mg/L; adult females:2.254 mg/L), LC30 (larvae: 7.017 mg/L; adult females: 9.473 mg/L) and LC50 (larvae: 18.238 mg/L; adult females: 25.610 mg/L), the survival and reproduction of P. citri larvae and adult females were decreased. Additionally, the gene expression levels of vitellogenin and its receptor were reduced in these concentrations. In addition, malondialdehyde levels were significantly increased at the LC30 and LC50 as compared to LC10 and the control. Then, the antioxidant enzyme activity assays suggested that superoxide dismutase, catalase and peroxidase activities of LC30 (SOD: larvae35.22 +/- 1.63, adult females-52.90 +/- 2.64; CAT: larvae-111.81 +/- 12.41, adult females-197.88 +/- 2.53; POD: larvae-68.64 +/- 5.19, adult females-131.38 +/- 4.48) were significantly increased, comparing with the control (SOD: larvae-25.34 +/- 2.19, adult females-25.60 +/- 2.06; CAT: larvae-66.74 +/- 7.30, adult females-139.04 +/- 5.43; POD: larvae-55.07 +/- 2.37, adult females-105.55 +/- 4.15). Moreover, cytochrome P450 monooxygenases (P450s), carboxylesterases (CarEs) and glutathione-S-transferase (GSTs) were up-regulated at LC30 (P450s: larvae-127.24 +/- 5.67, adult females-142.11 +/- 5.65; GSTs: larvae-88.55 +/- 2.18, adult females-139.88 +/- 6.33; CarEs: larvae55.66 +/- 4.43, adult females-86.58 +/- 1.22) compared to the control (P450s: larvae-103.72 +/- 4.44, adult females112.27 +/- 9.82; GSTs: larvae-55.34 +/- 2.19, adult females-109.92 +/- 7.67; CarEs: larvae-26.88 +/- 4.78, adult females -40.78 +/- 2.19). Additionally, our results also indicated that different developmental stages of P. citri differed in antioxidant and detoxification defences to cyflumetofen, larvae being more susceptible than adult females. These findings showed cyflumetofen can affect the biological and physiological biochemistry process of not only larvae but also adult females of P. citri, which will provide a further understanding of biochemical mechanism underlying antioxidant and detoxifying systems.