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Temperature Effect On Toxicity Of Insecticides To Apolygus Lucorum(meyer-dür) And The Related Mechanism On Detoxification Enzymes

Posted on:2016-06-17Degree:MasterType:Thesis
Country:ChinaCandidate:J LiuFull Text:PDF
GTID:2283330461996344Subject:Pesticides
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Reports indicate that temperature is an important factor influencing the toxicity and field control effect of insecticides. The influence mechanism of temperature on insecticides activity is very complex, which can change the toxicity and control effect by influencing the physicochemical property of the insecticides as well as the metabolism of insects, thus produced different temperature effects. Changes of physical and chemical properties of insecticides can directly influence the absorption and distribution of insecticides in insects. While the changes of metabolism in insects at different temperatures can significantly influenced their metabolic detoxification. According to the preliminary findings of previous research, there have obvious temperature effect of chemical insecticides about on Apolygus lucorum(Meyer-Dür)which is the important cotton insect has obvious influence to its toxicity. And the activity of detoxifying enzymes changed significantly in different temperatures. In this study, the same temperature were kept throughout the whole experiment in a series of precision temperature control chambers(250cm×150cm×180cm, ±0.5℃). The temperature effect of different insecticides with different action mechanism and different action mode and the joint action of different temperature coefficient insecticides to A. lucorum were measured. With the change of temperature, the activities of the three main detoxification enzymes of A. lucorum the long-term temperature influence of detoxifying enzymes in this insect, and also the insecticide-induced activity and the change of the detoxification enzymes of A. lucorum after the treatment of the detoxification enzyme inhibitors were all determined. The main results are as follows:1. The toxicities of seven different action mechanism insecticides, endosulfan, dichlorvos, fenvalerate, buprofezin, tebufenozide, abamectin, chlorfenapyr and hexaflumuron, to the third instar nymphs of A. lucorum were measured at 15℃, 20℃, 25℃, 30 and 35 respectively by food℃ ℃-dipping method. The results show that most of the insecticides showed a strong or weak positive temperature effect besides chlorfenapyr, which belongs to oxidative phosphorylation uncoupler, showed a slight negative temperature effects.2. The food dipping method and topical application method, artificial feed mixed insecticides method and fumigation method were selected to determine the temperature effect of phoxim, β-cypermethrin, imidacloprid, hexaflumuron and DDVP to the third instar nymphs of A. lucorum. In the temperature range from 15 to 35℃ ℃, by adopting the topical application method, temperature coefficient of poxim and β-cypermethrin was respectively +7.34 and-5.33, and which was +1.14 and-51.35 respectively by food dipping method. Temperature coefficient of imidacloprid and hexaflumuron was +8.75 and +46.91 respectively by using artificial feed mixed insecticides method, and which was +22.45 and +26.42 by food dipping method. By fumigation method, the temperature coefficient of DDVP was +3.89, and was +1.30 by food dipping method.3. The influence of temperature effect to CTC values, which indicate the joint action of different insecticides to A. lucorum, were measured at different temperatures by food impregnation method. The results indicated that after imidacloprid and hexaflumuron which are all with positive temperature coefficient are mixtured, the synergy value of different mixed proportion is decreased with the rise in temperature, the synergy effect is largest for 5:1; after methomyl and β-cypermethrin which are all with negative temperature coefficient are mixtured, the synergy value of different mixed proportion is rised with the rise in temperature, the synergy effect is largest for 25:1-30:1; after imidacloprid and β-cypermethrin which are with obvious positive and negative temperature effect are mixtured, the effect of temperature on mixed effect is not obvious; after phoxim and β-cypermethrin which are with weak positive and obvious negative temperature effect are mixtured, the synergy value of different mixed proportion is decreased with the rise in temperature; after methomyl and imidacloprid which are with weak negative and obvious positive temperature effect are mixed, the synergy value of different mixed proportion is rised with the rise in temperature.4. About the research on the influence mechanism of detoxification enzymes on temperature effect of insecticide toxicity, the temperature-dependent "bell shaped" curves of three main detoxification enzymes of A. lucorum were measured firstly. The results of the "bell shaped" showed that the activities of three main detoxification enzymes were all significantly higher at 25 ℃ than other temperatures, and the activities of three detoxifying enzymes were positively correlated with the temperature when the range of 10℃ to 25℃, but that were all negatively correlation with the temperature during at 25℃ to 40℃. However, from the results of the influence of long-term temperature on A. lucorum detoxification enzymes, the activity of GST and Car E declined significantly and the activity of MFO demethylase increased first and then decreased with the increase of temperature. The research on the activities of three detoxifying enzymes induced by sublethal doses of insecticides showed that GST may be subject to be induced by chlorfenapyr and took part in the change process of the negative temperature effect at different temperatures. In the low temperature about 15℃, the activities of Car E and MFO demethylase were susceptible to be induced and increased by the insecticides, hexaflumuron and chlorfenapyr. But the activities of these two kinds of detoxification enzyme were not induced by the tested insecticides easily during 20℃-35℃. In addition, the activity of MFO demethylase could be inhibited by hexaflumuron and imidacloprid by the tested concentration. The verification test by the inhibitors of detoxification enzymes showed that the GST activity was induced by phoxim and significantly higher than the treatment induced by inhibitors DEM and the blank at 25℃; however, the MFO demethylase activity, which was induced by imidacloprid, did not rise comparing to the control and PBO inhibitor treatment within the range of test temperature.Overall, the temperature effect of insecticides were influenced by detoxification enzymes to some degree, such as the GST may be subject to be induced by chlorfenapyr and took part in the change process of the negative temperature effect. But it still need more systematic and comprehensive research to complement and be more perfect.The results of this paper can provide experimental basis for more rational use of pesticides and improve its control effect.
Keywords/Search Tags:insecticide, temperature effect, detoxifying enzyme, mechanism, Apolygus lucorum
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