Graphene Oxide As Pyrethroid Pesticide Delivery Carrier And Its Application In Tetranychus Urticae Koch Control

Pyrethroid pesticides are widely used in agricultural production and pest control because of their high efficiency,low toxicity and wide insecticidal spectrum.However,its application is limited due to its fast release rate,unstable performance and easy photolysis.At present,the use of nanomaterials to develop new sustained-release formulations of nano-pesticides is of great significance for improving pesticide dispersion,increasing pesticide deposition rate on crop leaves,improving its stability and effective utilization rate,and reducing environmental pollution.Graphene oxide（GO）has the characteristics of hydrogen bonding,π-electron system and large specific surface area,which is widely used in the field of biomedical materials,and is also a hot carrier material for the study of nano pesticide sustained release agents.In this thesis based on GO nanomaterials,aiming at the drawbacks of existing pesticides,the multifunctional GO-pesticide sustained release agent was studied,and the biological activity of GO-pesticide against Tetranychus urticae Koch in greenhouse and field was studied.The main research results are as follows:GO-pesticides were prepared by physical adsorption method.The drug loadings of GO on Cyhalothrin（Cyh）,Bifenthrin（Bif）and Fenpropathrin（Fen）were 122.10%,77.13%and 74.03%,respectively.Compared with the original pesticide,the absorbance,crystallinity and thermal stability of GO-pesticide are better.With methanol-water（6:4,v/v）as the release medium,GO-pesticides showed better sustained-release performance than pesticides at different temperatures（25℃,30℃,35℃）and pH values（5.0,7.0,9.0）,which effectively improved the utilization rate of pesticides.The UV resistance of GO-pesticides was enhanced,and the half-life of GO-pesticides was significantly prolonged.After long-term storage for 2 years,cold storage at 0℃for 7 days,and hot storage at 54±2℃for 14 days,the decomposition rate of active ingredient content of GO-pesticides was below 5%,showing good physical stability.The synergistic index was evaluated by the ratio SR of LC₅₀of pesticides to GO-pesticides.The results showed that adding GO into the three pesticides could significantly improve the biological activity of Tetranychus urticae.In greenhouse experiments,the acaricidal activities of GO-Cyh,GO-Bif and GO-Fen were 2.80,3.55 and 2.85 times higher than those of Cyh,Bif and Fen,respectively.In the field experiment,the SR can still reach 2.67,3.16 and 2.51.The synergistic mechanism may be that GO nanocarriers improve the dispersion and adhesion of pesticides,so that the prepared GO-pesticides have similar functions to’double-sided glue’,so that pesticides can be well adsorbed on the surface of Tetranychus urticae and the cuticle of leguminous plant leaves through GO carriers,thereby increasing the contact opportunities between pesticides and Tetranychus urticae.