Toxicity test and control effects of several pesticides against Hyphantria cunea(Drury)

Several pesticides were used against 3rd-instar larvae of Hyphantria cunea(Drury).According to the experimental results under laboratory conditions,the toxicity of Propylene Glycol Alginate 0.12% was the highest whose LC50 to the larvae was 0.053 5 mg/L,the others were Matrine 0.38%(LC50=0.259 mg/L),Matrine Nicotine 1.2%(LC50=0.574 mg/L),Emamectin Benzoate 1%(LC50=0.78 mg/L),Avermectins 1.8%(LC50=1.38 mg/L),beta-cypermethrin 4.5%(LC50 =2.58 mg/L) and eucalyptol 5%(LC50=3.85 mg/L).The experimental results under field conditions showed that the final mortality was all 100% for the 10 pesticides applied.Beta-cypermethrin 4.5% caused the highest mortality 12 hours after the applieation,followed by Matrine Nicotine 1.2%,eucalyptol 5%,Matrine 0.38%,Propylene Glycol Alginate 0.12%,Avermectins 1.8% and Emamectin Benzoate 1%.Triflumuron 5% had the least knockdown effect among the 3 bionic pesticides.the residual period of bionic pesticides was over 49 days,subsequently that of beta-cypermethrin 4.5% was about 14 days.The residual periods of Emamectin Benzoate 1%,eucalyptol 5%,Matrine Nicotine 1.2%,Matrine 0.38%,Avermectins 1.8% and Propylene Glycol Alginate 0.12% were about 7 days.It's essential to alternate pesticides periodically so as to keep Hyphantria cunea from developing resistance.