| This study investigated the population dynamics of the main pests and their natural enemies in the Apple Engineering Center, South Campus of Shandong Agricultural University, on identifying the main pests and natural enemies species basis, in order to study the sensitivity of main natural enemies to insecticides and the effects of insecticides on protective enzyme of natural enemies,The sensitivity of Propylaea japonica and Chrysoperla sinica to insecticides was determined, and the effect of imidacloprid and Pymetrozine on superoxide dismutase, peroxidase, catalase and glutathione peroxidase activity of Propylaea japonica was aslo determined. The results are as follows:1. The main pests in the Apple Engineering Center, South Campus of Shandong Agricultural University were apple leaf curling aphid, Aphis citricola, Spilonota lechriaspis Meyrick, Adoxophyes orana Fisher von Roslerstamm, Lithocolletis ringoniella, Tetranychus viennensis Zacher, Tetranychus urticae; The main natural enemies were Propylaea japonica, Harmonia axyridis, Chrysoperla sinica, aphidiidae and hoverflies etc. The Investigation method we used was sampling on five points., Through this method we knew the population dynamics of the main pests and their natural enemies:Aphis citricola occurred in2013more seriously than that in2012, the number of aphis was3525per branch when it occurred seriously in2013,which was1.89times of2012.apple leaf curling aphid and Spilonota lechriaspis Meyrick mainly occurred in2012, and in2012the Spilonota lechriaspis Meyrick whose bug grafting yield was up to37%has occurred throughout the year,the number of apple leaf curling aphid was89per branch in clean tillage orchard, in2013apple leaf curling aphid was not a serious matter; The natural predators occured mainly between June to August, the decrement of predators in the tree was far more than that in grass after Spraying pesticide in apple orchards. The investigation can provide1basic data for integrated pest management.2. Relative toxicity indexs of9insecticides against Propylaea japonica were surveyed with Spraying method, For the adults the results indicated that the toxicity order was Avermectins> Imidacloprid> Acetamiprid>Emamectin benzoate> Tebufenozide> Pyridaben> Chlorpyrifos> Buprofezin> Pymetrozine,for Propylaea japonica larvae the toxicity order was Avermectins> Acetamiprid> Imidacloprid>Emamectin benzoate> Pyridaben> Tebufenozide> Chlorpyrifos> Buprofezin> Pymetrozine; Relative toxicity indexs of5insecticides in Tai’an area against chrysoperla sinica larvae were also surveyed by spraying method, the toxicity order was acetamiprid> imidacloprid> chlorpyrifos>Pymetrozine> buprofezin. The results showed that Pymetrozine had high safety to Propylaea japonica, the LC50values of the Propylaea japonica larvae was1387.4mg/L, and the LC50values of the Propylaea japonica adults was1243.4mg/L;In addition Abamectin had low safety to Propylaea japonica, the LC50values of the Propylaea japonica larvae was0.69mg/L, and the LC50values of the Propylaea japonica adults was1.1mg/L. Buprofezin was safe to chrysoperla sinica, the LC50values was211.64mg/L; acetamiprid had low safety to chrysoperla sinica, the LC50values was9.5mg/L.3. Spectrophotometer was used to measure the effect of imidacloprid and Pymetrozine on superoxide dismutase, peroxidase, catalase and glutathione peroxidase activities of Propylaea japonica,and we studied the changes of activities of four kinds of enzymes after exposing imidacloprid and Pymetrozine for different time. The results showed that Low concentration of Pymetrozine can activate the activity of four kinds of enzymes,after72hours, high concentration can activate the activity of catalase, but the activity of peroxidase, superoxide dismutase and glutathione peroxidase was inhibited.Imidacloprid has an inhibitory effect on the activity of peroxidase of Propylaea japonica adults; low concentration of imidacloprid can activate the activation of catalase and superoxide dismutase, the effect of high concentration is inhibition; treated with imidacloprid for24hours, the glutathione peroxidase activity was inhibited, for48hours and72hours, low concentration showed activation effect,high concentrations had the opposite effect.,low concentration of imidacloprid has activation effect on four kinds of enzyme of Propylaea japonica larvaes, high concentration has inhibiting effect and the inhibitory effect of size is different with treatment time. |
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