Primary Research On Prevention Mechanism Of Emamectin Benzoate Trunk Injection Against Pine Wilt Disease

The prevention of pine wilt disease had not made breakthrough progress. All countries are tryingtheir best to seek effective control methods. The control practice showed that Emamectin benzoate trunkinjection had good control effect against pine wilt disease. In the paper, the insecticidal activity ofEmamectin Benzoate on Bursaphelenchus xylophilus and Monochamus alternatus, and the preventionand treatment effect of Emamectin Benzoate against pine wilt disease were determined systematically.Prevention mechanism of Emamectin benzoate trunk injection against pine wilt disease was disscussedpreliminary, from the aspects of Monochamus alternatus population change, residue of EmamectinBenzoate in pine and duration of the efficacy.1. The insecticidal activity of Emamectin Benzoate on Bursaphelenchus xylophilus was determinedby the dipping method. The24h LC50and LC90were0.23mg/L and0.75mg/L respectively. The contacttoxicity of Emamectin Benzoate to4th larvae of Monochamus alternatus was determined by the dropmethod. The LD50of24h and48h were0.70mg and0.43mg each one. The prevention and treatmenteffect of Emamectin Benzoate trunk injection against pine wilt disease were researched. The preventioneffect was100%, inoculating Bursaphelenchus xylophilus after trunk injection. The treatment effect oftrunk injection in10days after inoculation was100%, while it was only20%on the twentieth day.2. The growing development and population change of Monochamus alternatus were investigatedin injection forest. Trunk injection of emamectin benzoate did not influence the oviposition behavior,but reduced the hatching rate significantly and18.72%of the larvae grew abnormally. The result of themonitor from2010to2012showed the number of Monochamus alternatus in the treated forestdecreased significantly, and difference between the treated and control forest was extremely significant.It showed that Emamectin Benzoate trunk injection could reduce the population of Monochamusalternatus effectively, and depress the transmission chance of Bursaphelenchus xylophilus.3. The residue of Emamectin Benzoate in pine and duration of the efficacy were studied. Pinesawdust was first extracted with acetone and water (1:1,V/V), filtrated with C18-SPE columns, and thendetermined by HPLC(UVD) with the mobile phase of methanol/acetonitrile/0.1%triethylamine watersolution (40:45:15,V/V). Emamectin Benzoate recovery of this method was90.18%-100.76%, andrelative standard deviation was3.70%-7.62%. The lowest detectable quantity and concentration were2 ×10-10g and0.01mg/L respectively. The residue of Emamectin Benzoate in pine of injection0.5a,1a,2a,3a ago were38.28mg/kg,8.46mg/kg,2.73mg/kg,1.02mg/kg respectively, higher thanLC50(0.23mg/L), LC90(0.75mg/L). The prevention effect of trunk injection was significant. Injectiononce could control pine death rate between0.19-0.58%for three consecutive years. The pine death ratewas6.33-7.71%by cleaning up the dead tree year by year. The results showed that the prevention effectof Emamectin Benzoate trunk injection lasted for at least3years.Emamectin Benzoate trunk injection controlled the happen of pine wilt disease effectively fromtwo aspects of pathogens and transmission, by killing Bursaphelenchus xylophilus in pine and reducingthe population of Monochamus alternatus. Emamectin Benzoate trunk injection could be popularizedand used in practical control, because of the good effect and long efficacy duration.