To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extrac...To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extract effects on activities of several enzymes.In addition,to improve the stability of the extract,microcapsules were prepared by complex coacervation and phase separation with the extract as core material,and gelatin and gum arabic as wall material.With the embedding rate as the evaluation index,the response surface method was used to optimize the preparation process of the microcapsules.The results show that the extract had a strong insecticidal activity on the larvae,with inhibitory effects on several enzymes examined of carboxylesterase,acetylcholinesterase,glutathione-S transferase,catalase,and superoxide dismutase.The inhibition rate increased with time.The best preparation process of tobacco extract microcapsules was 25% mass fraction of emulsifier,2.05% mass fraction of gelatin,3% mass fraction of gum arabic,1.34 wall core ratio,36 min of complex coacervation time.The embedding rate was 58.4% which is approximately the theoretical embedding rate(58.9%).The microcapsules prepared by this method have a smooth surface,good combining form and particle size distribution,and a median diameter of 8.6 μm.Infrared characteristic peaks of the extracts were preserved at 877.55 cm^(-1) and2922.13 cm^(-1).Microencapsulation can improve the thermal stability of the tobacco extract.Indoor toxicity tests showed that LC_(50) of extract microcapsules was 20.2 mg·mL^(-1),equivalent to the toxicity level of the tobacco extract itself,indicating that microencapsulation did not reduce extract insecticidal effects.This research may provide a reference for the optimization of the tobacco extract microcapsule preparation process.展开更多
To study the insecticidal activity and toxicity mechanism of spinosad,we assayed bioactivity of spinosad by leaf membrane method and its effects on the activities of detoxifying and protective enzymes in Malacosoma ne...To study the insecticidal activity and toxicity mechanism of spinosad,we assayed bioactivity of spinosad by leaf membrane method and its effects on the activities of detoxifying and protective enzymes in Malacosoma neustria testacea larvae by spectrophotometry.The results showed that spinosad had an extremely high toxicity against the 4th and 5th instar larvae.The glutathione S-transfer (GST) activity in 4th and 5th instar larvae was firstly inhibited,then induced,and finally inhibited,while the mixed-functional oxidase(MFO) activity was inhibited and then enhanced.The induced effect on carboxylesterase(CarE),the induced and inhibited effect on acetylcholinesterase (AchE) and peroxidase(POD),and the complicated effects on superoxide dismutase(SOD) and Catalase(CAT) were determined in 4th instar larvae with spinosad treatment.However,the obvious inhibition effects were found on the activities of CarE,AchE,SOD and POD in the 5th instar larvae whereas the catalase(CAT) activity was inhibited, then increased,and inhibited finally.Therefore, spinosad could effectively disrupt and interfere not only the detoxifying and protective enzymes but also normal physiological metabolism of M.neustria testacea and show extremely high toxicity against this pest.展开更多
基金funded by the Fundamental Research Funds for the Central Universities (2572019AA04)the Central Financial Fund for Forestry Science and Technology Promotion (JLT[2019]HZT02)the Forestry Science and Technology Project of Key State-owned Forest Management Bureau in Daxing 'anling,Inner Mongolia (2018003)。
文摘To understand and improve the stability of the insecticidal activity of tobacco extract,the 3 rd instar larvae of Malacosoma neustria testacea was determined by the leaf film method.Spectrophotometry identified extract effects on activities of several enzymes.In addition,to improve the stability of the extract,microcapsules were prepared by complex coacervation and phase separation with the extract as core material,and gelatin and gum arabic as wall material.With the embedding rate as the evaluation index,the response surface method was used to optimize the preparation process of the microcapsules.The results show that the extract had a strong insecticidal activity on the larvae,with inhibitory effects on several enzymes examined of carboxylesterase,acetylcholinesterase,glutathione-S transferase,catalase,and superoxide dismutase.The inhibition rate increased with time.The best preparation process of tobacco extract microcapsules was 25% mass fraction of emulsifier,2.05% mass fraction of gelatin,3% mass fraction of gum arabic,1.34 wall core ratio,36 min of complex coacervation time.The embedding rate was 58.4% which is approximately the theoretical embedding rate(58.9%).The microcapsules prepared by this method have a smooth surface,good combining form and particle size distribution,and a median diameter of 8.6 μm.Infrared characteristic peaks of the extracts were preserved at 877.55 cm^(-1) and2922.13 cm^(-1).Microencapsulation can improve the thermal stability of the tobacco extract.Indoor toxicity tests showed that LC_(50) of extract microcapsules was 20.2 mg·mL^(-1),equivalent to the toxicity level of the tobacco extract itself,indicating that microencapsulation did not reduce extract insecticidal effects.This research may provide a reference for the optimization of the tobacco extract microcapsule preparation process.
文摘To study the insecticidal activity and toxicity mechanism of spinosad,we assayed bioactivity of spinosad by leaf membrane method and its effects on the activities of detoxifying and protective enzymes in Malacosoma neustria testacea larvae by spectrophotometry.The results showed that spinosad had an extremely high toxicity against the 4th and 5th instar larvae.The glutathione S-transfer (GST) activity in 4th and 5th instar larvae was firstly inhibited,then induced,and finally inhibited,while the mixed-functional oxidase(MFO) activity was inhibited and then enhanced.The induced effect on carboxylesterase(CarE),the induced and inhibited effect on acetylcholinesterase (AchE) and peroxidase(POD),and the complicated effects on superoxide dismutase(SOD) and Catalase(CAT) were determined in 4th instar larvae with spinosad treatment.However,the obvious inhibition effects were found on the activities of CarE,AchE,SOD and POD in the 5th instar larvae whereas the catalase(CAT) activity was inhibited, then increased,and inhibited finally.Therefore, spinosad could effectively disrupt and interfere not only the detoxifying and protective enzymes but also normal physiological metabolism of M.neustria testacea and show extremely high toxicity against this pest.
