Study On The Inhibition Of Pine Wood Nematode By Propylene Isothiocyanat

Pine Wood Nematode Disease is a destructive plant disease caused by Bursaphelenchus xylophilus,which occurs rapidly and spreads widely,causing serious damage to economy and ecology.Vegetable essential oil is a kind of secondary metabolites derived from plants.It is safe and environmentally friendly,and has strong activity in the control of plant pathogenic nematodes.It is important to study the control of plant pathogenic nematodes by using the monomer components of plant essential oil and essential oil.This paper mainly discussed the toxicity of plant essential oil and its monomer to Bursaphelenchus xylophilus,screened and evaluated the linecidal activity of 13 plant essential oil and its monomer components,and preliminarily explored the fumigation toxicity and linecidal mechanism of essential oil and its monomer components with better linecidal activity.It has been expected to provide experimental basis and numbers for the application of plant essential oil in plant-derived linecidal pesticides.According to accumulation.The main results are as follows:1.The nematicidal activity of 13 essential oils and their monomers against Bursaphelenchus xylophilus was determined by immersion test.The results showed that the nematocidal activity of six essential oils of oregano,thymol,eugenol,carvacrol,cinnamon and propylene isothiocyanate was strong,and the corrected mortality rate was over 90%within 72 hours of treatment at 0.1%.Among them,propylene isothiocyanate oil showed the strongest nematicidal activity against Bursaphelenchus xylophilus.The LC₅₀of pine wood nematode treated for 24 hours was 0.000271%.2.The activity of propylene isothiocyanate,the strongest nematicidal agent,against Bursaphelenchus xylophilus and Bursaphelenchus xylophilus associated fungi was investigated by plate fumigation.The results showed that propylene isothiocyanate had certain fumigation toxicity to pine wood nematode-associated fungi,but the fumigation toxicity was not very strong.The maximum inhibitory amount of propylene isothiocyanate on pine wood nematode-associated fungi was 9μL/dish at 0.1%,and the bacteriostatic rate reached 30%.The effects of fumigation time,fumigation dose and fumigation temperature on the reproductive rate of Bursaphelenchus xylophilus after fumigation were determined.According to the experimental results,the inhibition rate of reproduction of pine wood nematode could reach the maximum when the fumigation time was set for 9 hours,the fumigation dose was set for 9μL/dish and the fumigation temperature was set for 35℃.3.The mechanism of propylene isothiocyanate poisoning Bursaphelenchus xylophilus was preliminarily studied.The changes of catalase（CAT）,acetylcholinesterase（Ach E）and glutathione sulfotransferase（GST）activities in nematodes were measured before and after treatment.The results showed that the morphology of Bursaphelenchus xylophilus treated with propylene isothiocyanate was seriously distorted,and the movement morphology changed from normal S shape to multi-knot bending and spiral curl.The action of nematode became slow with the passage of time,and eventually appeared C-shaped,crescent-shaped or died directly.With the increase of propylene isothiocyanate concentration,the total sugar and protein content in nematode increased significantly,and the metabolism of sugar and protein in nematode was disordered;the activities of CAT,Ach E and GST in nematode decreased significantly,and were lower than those in control group,indicating that the oxidative and antioxidative effects of nematode were imbalanced and the cells were greatly affected;the activity of Ach E was inhibited,indicating that nematode activity was inhibited.The nervous system was destroyed and the activity of GST was decreased,which indicated that the detoxification ability of liver in nematode was destroyed.4.Using propylene isothiocyanate as experimental material and model organism Nematodes elegans as research object,the mechanism of toxicity was further explored by measuring the expression of several genes related to the normal life activities of nematodes.The results showed that propylene isothiocyanate in the experimental concentration decreased the expression of insulin signaling pathway related genes,oxidative stress related genes and cell apoptosis related genes,which may affect the normal life of nematodes and make the toxic substances in nematodes not cleared in time.This may be another reason for the toxicity of propylene isothiocyanate.