Virulence Determination Of Two Kinds Of Pesticides To Neoseiulus Barkeri And The Effect Of Abamectin Sublethal On Detoxifying Enzymes

Neoseiulus barkeri is a polyphagous phytoseiid mite, which mainly prey on small suck juice pest mites, such as spider mites, aphid, thrips and so on. It is a kind of important biological control and, and also be able to mature commercial production of one of the important natural enemies. In the present thesis, the toxicity of pesticides of abamectin and imidacloprid to Neoseiulus barkeri and Tetranychus truncates were tested, then the predation ability, both of Neoseiulus barkeri sensitive strain and after the abamectin LC50 processing, which preyed on different stages of Tetranychus truncates(female, nymph and egg),at the same time, the effect of abamectin sublethal on detoxifying enzymes of Neoseiulus barkeri were obtained.The main results were as follows:1 Two insecticidal(mites) agent for different measuring method of Neoseiulus barkeri and Tetranychus truncates toxicityIn order to indicate the toxicity of pesticides of abamectin and imidacloprid to Neoseiulus barkeri and Tetranychus truncates, LC50 and toxicity selective ratios(TSR) of the two pesticides were tested by using residual film method and Slide-dip method. The results of using residual film method showed that LC50 of abamectin to Neoseiulus barkeri and Tetranychus truncates were 0.1041mg/L and 1.2233mg/L respectively, and that of imidacloprid were 0.0814mg/L and 6.3567mg/L respectively.The toxicity selective ratios of abamectin and imidacloprid were 1.2789 and 0.1924respectively; The other method results indicate that LC50 of abamectin to Neoseiulus barkeri and Tetranychus truncates were 0.0352mg/L and 0.1401mg/L respectively,and that of imidacloprid were 0.0272mg/L and 0.1316mg/L respectively. The toxicity selective ratios of abamectin and imidacloprid were 1.2941 and 1.0646 respectively.The selective toxicity of two kinds of mites is abamectin>imidacloprid. So abamectin can be recommended to use preferentially in order to achieve predatory mites protection, especially the field spider mites and other pests mixing occurs should useless imidacloprid. Avoid resistant against mites and in order to improve the effectiveness of prevention and cure, realize coordinate with biological control and chemical control.2 Determing the predation ability of Neoseiulus barkeri to Tetranychus truncatesTo determine the predation ability of Neoseiulus barkeri sensitive strain and after the abamectin processing preyed on different stages of Tetranychus truncates under 5 different temperatures. The results showed that curves of functional response of Neoseiulus barkeri to various stages of Tetranychus truncates are equal belonging to the type of Holling Ⅱunder 5 temperatures. Among 16 to 28 ℃, the average daily predacious number of Neoseiulus barkeri to adult mites increased from 0.6852 to3.0320, the number of nymph changed from 1.8680 to 4.1973, and the feeding mount of eggs from 4.3583 up to 17.1394. Under the same temperature condition, the predation ability and attack coefficient goes on to the list were egg, nymph, and adult mites. The processing time was on the contrary. The average daily predacious number and the attack coefficient of Neoseiulus barkeri were decreased with the processing time added under 32 ℃.The curves of functional response of Neoseiulus barkeri to various stages of Tetranychus truncates processing in abamectin LC50 are equal belonging to the type of Holling Ⅱunder 5 temperatures. In 16 to 28 ℃, the average daily predacious number of Neoseiulus barkeri to adult mites increased from 0.1613 to 2.6390, the number of nymph changed from 0.8587 to 4.9693, and the feeding mount of eggs from 2.8789 up to 9.6562. These results were all lower than Neoseiulus barkeri sensitive strain. So in a word, this is necessary to rear resistance Neoseiulus barkeri before released into the filed.3 Effect of abamectin sublethal on detoxifying enzymes of Neoseiulus barkeri.The Neoseiulus barkeri were treated by different sublethal concentrations of abamectin after 24 hrs, the mixed function oxidases(MFO) specific activity with the rising of the sublethal gradually increased, processing in LC20, LC30 is significantly higher than control and processing in LC10. LC10, LC20 and LC30 are respectively 1.09,2.10, and 2.47 times. The acetylcholinesterase(ACh E) specific activity which processing in LC30 is significantly higher than other treatment groups, is 2.63 times as in control group, while LC10,LC20,no significant difference compared with controls,and is 1.19, 1.52 times to the control treatment respectively. The glutathione S-transferases(GSTs) specific activity with the increase of the sublethal exist differences, LC10, LC20, LC30 are respectively 1.036, 1.116, and 1.115 times to control treatment.