| The study on selective toxicity ratio of Amblyseius barkeri (Hughes) and Panonychus citri (McGregor) to 9 insecticides that used in citrus orchard, screening out the insecticides of abamectin and pyridaben that was safe to A.barkeri but the high toxicity to P.citri, and period of relative safe to A.barkeri by means of the study of the maximal predatory capacities decline predatory rate, searching efficiencies and handing time at the laboratory. The major results as follows:1. Toxicity of two kinds of bioassay procedure to P.citri.Toxicity of abamectin, emamectin benzoate, pyridaben, fenpropathrin and phoxim were determined using slide dip method and leaf residue method in the laboratory, The result showed that The toxicity of abametin to P.citri was higher with LC50 0.0045mg/L of the slide dip method than the leaf residue method with LC500.0215mg/L, as well as other insecticides. The order of toxicities of five pesticides from high to low against the females of P.citri was abamectin>E m-amectin benzoate> pyridaben>fenpropathrin>phoxim.2. The toxicity and selection of 9 insecticides (acaricides) to P.citri and A.barkeriThe toxicity and selective toxicity of insecticides(acaricides) in common used in orchard to P.citri and A.barkeri were studied.The results showed that the selective toxicity of abamectin is the highest among 9 kinds of insecticides (acaricides) tested.then were emamectin benzoate and pyridaben, the selective toxicity ratio were 37364.28,894.02 and 108.38.. The selective toxicity ratio of 9 kinds of insecticides (acaricides) are abamectin> emamectin benzoate> pyridaben> dicofol> imidacloprid> phoxim> chlorpyrifos> malathion> fenpropathrin in turn. Therefore the high selective insecticides (acaricides), such as abamectin, emamectin benzoate and pyridaben, not only possessed the high toxicity to P.citri, but also were safe for the nature enemy A.barkeri, were relatively ideal insecticides (acaricides) for controlling P.citri3. The selective of safety cycle of A.barkeri to abamectin and pyridabenThis study about the selective of safety cycle of A.barkeri to abamectin and pyridaben,The result showed that as the treatment time of leaves treated by abamectin and pyridaben in different cycle,the maximal predatory capacities, predatory rates and searching efficiencies of A.barkeri was gradually increased, handing time was gradually shortened, also, the influence of safety cycle of A.barkeri to abamectin and pyridaben was different, The selective of safety cycle of A.barkeri to abamectin was about eleventh day and pyridaben was seventh day.4. Effects of pesticide residues of pyridaben in different safety cycle on Specific activity of A.barkeri,The effects of pesticide residues of pyridaben in different time after used on GSTs of A.barkeri were studied, and the result showed that, in different cycle, as the treatment time reduced, the specific activity of GSTs of the A.barkeri was increased. On the kinetic study, we found that the Km value of GSTs decreased indistinctively in A.barkeri treated with pyridaben compared with that of the control. |
