Preparation of Fluopyram-Loaded Nanofiber Nematicide and Its Biological Activity Against Meloidogyne incognita
[Objective]Root-knot nematode disease has become an important influencing factor restricting the development of protected agriculture in China,among which Meloidogyne incognita has caused the most serious yield loss.At present,there are few types of nematicides in China,the objectives of this study are to prepare the fluopyram-loaded nanofiber nematicide based on the electrospinning technique,evaluate its biological activity against M.incognita,and to enrich the types of effective nematicides for controlling root-knot nematode disease of crops and expand the application field of nanofiber agents.[Method]Two kinds of fluopyram-loaded nanofiber nematicide(Flu@NF)were prepared by coaxial electrospinning technology with different biodegradable materials as shell materials and solvated fluopyram as core materials.The morphology,structure,elemental composition,functional components and thermal stability of Flu@NF were characterized by SEM,EDS,TEM,FTIR and TGA.With 41.7%fluropyram suspension as control agent,the biological activity of Flu@NF against 2nd stage juveniles(J2)and egg mass of M.incognita was evaluated.[Result]PEG/PCL-Flu@NF and CA-Flu@NF using polyethylene glycol(PEG),polycaprolactone(PCL)and cellulose acetate(CA)as shell materials were successfully prepared under high pressure+15 kV,core-shell solution flow rate 1﹕4 and receiver side distance of 24 cm.The average diameter of two kinds of agents was 316 and 440 nm,respectively.Fibers were in accordance with the inner and outer microstructure of core-shell,and the shell thickness was separately 71.15 and 24.84 nm.The loading capacity of two kinds of fluopyram-loaded fibers was 15.32%and 20.37%,respectively.Moreover,the thermal stability of fluopyram was significantly improved after shell coating by coaxial electrospinning.Compared with fluropyram suspension,the slow-release performance of fluopyram-loaded fibers was significantly improved,and the mortality of J2 was significantly increased with the extension of treatment time at different concentrations.The lethality rate of the two fiber agents against J2 was higher than 98%after 24 h treatment at high concentration(25 mg·L-1).After treatment with low concentration(4 mg·L-1)for 24 h,the lethality rate of the two fiber agents against J2 was 91.4%and 79.6%,respectively.The two kinds of nematicides had good inhibition effects on the hatching of nematode eggs,after 3 d treatment at high concentration(25 mg·L-1),the unhatched rate of eggs was 71.8%and 89.2%,respectively,and after 3 d treatment at low concentration(4 mg·L-1),the unhatched rate of eggs was 59.4%and 76.2%,respectively.[Conclusion]Based on coaxial electrospinning technology,the nanofibers prepared with PEG/PCL and CA as shell materials have excellent coating effect on fluopyram,and the fluopyram-loaded fibers have high biological activities on M.incognita through slow-release action,which has great potential to prevent and control root-knot nematode disease through crop root protection.
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