Research On Green Chemical Control Of Bursaphelenchus Xylophilus

Pine wood nematode disease is a devastating forest disease caused by the pine wood nematode Bursaphelenchus xylophophilus,posing a threat to the ecological health of pine forests worldwide.Currently,control measures for pine wood nematode disease include the removal of infected trees,the prevention and control of vector insects,and the use of dry injection pesticides.If dry injection pesticides are mainly used,the cost of these chemicals is high,and their residues and accumulation can easily cause pollution to the ecological environment,Moreover,long-term use can easily lead to resistance of pine wood nematodes,so it is urgent to find new green prevention and control methods for pine wood nematode disease.Finding green and safe nematicides in nature has become a research hotspot.In our preliminary work,our research team found that metabolic substances in the rhizosphere soil of pine trees have nematicidal effects.In order to develop a new type of green nematicidal agent,this study used some significantly different metabolic substances found in the rhizosphere soil of pine trees with different disease susceptibility levels as the source of the agent,further exploring the specific categories of these differential metabolic substances,and studying whether they have stable control effects in pine wood nematode infection,Screening out green substances with high toxicity to pine wood nematodes.In order to achieve a more stable control effect on pine wood nematodes,these green substances with potential for prevention and control were optimized and tested for the control of susceptible pine seedlings.The effectiveness and stability of these substances in practical application were evaluated,providing scientific basis for the development of nematicides and green prevention and control.At present,the main research results are as follows:(1)Analysis of Metabolomics in Rhizosphere Soil of Pine Trees with Different Susceptibility Levels.The results showed that by analyzing the metabolomics of rhizosphere soil of pine trees with different susceptibility levels,green nematicides with potential for controlling pine wood nematodes were obtained.This study analyzed and identified the significant differences in metabolic substances between the rhizosphere soil of susceptible and healthy pine trees,and identified nearly a hundred different categories of metabolic substances,including benzene,lipids,and lipid like molecules,organic acids and their derivatives,organic nitrogen compounds,organic heterocyclic compounds,organic phosphorus compounds,phenylpropanoids,and polyketones.The experiment found that among these metabolites with significant differences,there are green,low toxicity,or non-toxic metabolites that have control effects on pine wood nematodes.Five highly toxic green nematicides were obtained by screening for significantly different metabolic substances,namely ginkgo flavonoids,2,3-dichloro-5-(trifluoromethyl)pyridine,sodium silicate,arecoline,and amygdalin.(2)Screening,compounding,and optimization of green thread killing agents.The results indicate that,five highly toxic green nematicides,Ginkgo flavone,2,3-dichloro-5(trifluoromethyl)pyridine,sodium silicate,arecoline,and amygdalin,have LC80 concentrations of 0.865g·L-1,0.406g·L-1,0.616g·L-1,0.717g·L-1,and 0.979g·L-1 at 48 hours,respectively.Among them,2,3-dichloro-5-(trifluoromethyl)pyridine has the best efficacy and stability.Four compound green nematicides with optimized toxicity and stability,namely ginkgo flavonoid+amygdalin,ginkgo flavonoid+sodium silicate,ginkgo flavonoid+arecoline,and arecoline+amygdalin,have the highest LC80 of 0.723g·L-1,0.559g·L-1,0.709g·L-1,and 0.649g·L-1 after 48 hours,The optimization degree of the combination of ginkgo flavonoid and amygdalin with green chemicals is the highest.(3)Prevention and control experiments with green nematicides.The results indicate that the above green nematicides have good control effects on susceptible pine seedlings,and the control effects of various green nematicides are superior to their therapeutic effects.The single substance green nematicides have better control effects,and the combined nematicides have better therapeutic effects.In the prevention and control experiment,the single substance green nematicide 2,3-dichloro-5-(trifluoromethyl)had the most excellent effect,with a prevention and control rate of 87.82%after 28 days of treatment;In the efficacy experiment,the effect of compound green thread killing agents is better than that of single substance green agents,and the effect is relatively average.The prevention and treatment rate is about 70%under 28 days of treatment,which has the potential for alternating use and can effectively avoid the occurrence of drug resistance.The single substance green nematicides selected in this experiment have high toxicity effects on pine wood nematodes.The toxicity and stability of the optimized composite green nematicides have been improved to a certain extent.These research results have the potential to be applied in practical prevention and control work,with the aim of achieving better control effects on pine wood nematode disease.