Preparation And Biological Application Study Of Chitosan Nanopesticides

Providing enough food to meet the growing global population is one of the greatest challenges facing humanity.The use of pesticides is the primary precondition for increasing grain yield.However,conventional pesticides formulations will cause the degradation of soil health,the destruction of the ecological environment and the threat to human health.It restricts the safe and efficient use of conventional pesticides.Although nanotechnology has been studied in various fields of agriculture,the research of natural degradable nano-carriers as growth regulators and inducers for rice is rare.In this paper,two different molecular weights of biocompatible and degradable chitosan are used as starting materials.The CS/?-PGA and Cso-La nano-carriers were prepared by simple ionic cross-linking with poly-?-glutamic acid and La³⁺,respectively.Furthermore,the abamectin loaded CS/?-PGA?Abm-CS/?-PGA?and avermectins loaded Cso-La?Abm-Cso-La?were prepared.The main results were as follows:?1?Through the characterizations FTIR,TEM on the Abm-CS/?-PGA and CS/?-PGA,the mechanism of the form of nanoparticles and drug loading process were known.Meanwhile,The controlled-release and anti-photolysis ability of the Abm-CS/?-PGA were revealed.It was found that CS/?-PGA were able to release abamectin rapidly under weak alkaline conditions and reduce the sensitivity of abamectin to light.The biological test showed that the nematocidal activity of Abm-CS/?-PGA was nearly 30%higher than free abamectin under the water.FITC-labeled CS/?-PGA nanoparticles were revealed that the nanoparticles could enrich in intestines and head of nematodes?Bursaphelenchus xylophilus?.?2?The Cso-La and Abm-Cso-La nanoparticles were evaluated by FTIR,XRD,TEM,SEM,DLS,EDS and XPS to study the mechanism of the form of nanoparticles and drug loading process.The abamectin release and anti-photolysis assey showed that Cso-La nanoparticles could improve persistence and reduce photosensitivity of abamectin.In order to explore the other characteristics of Cso-La nanoparticles,different concentrations of Cso-La were used to cultivate rice?Oryza sativa?.It found that Cso-La nanoparticles were better to promote the growth of rice than Free Cso and La³⁺.Besides,Cso-La nanoparticles also had the stronge inducing effects against rice blast disease?Magnaporthe grisea?.In conclusion,the research proves that chitosan-based nanopesticides not only improve the water dispersibility,stability,persistence and insecticidal activity of the pesticides,but also effectively promote the growth and improve the disease resistance of crops.It expands the application of novel nanopesticides formulation used in integrated pest management and provides theoretical and scientific basis for the study of the new environmental friendly formulation.