Toxicity of Terpenoids to Bursaphelenchus xylophilus and Screening of Mixed Combinations
In order to find out the toxic effects of different terpenoids on Bursaphelenchus xylophilus,a green con-trol agent with high efficiency and low toxicity was developed.The direct contact killing method of nematode suspension and pesticide was used to determine the toxicity in the laboratory.Based on the previous research,four insecticides,a-pinene,β-pinene,limonene and Emamectin Benzoate and Imidacloprid,were selected,and their le-thal rate to PWD was observed by setting different concentration gradients and different combinations of insecti-cides.The results showed that the single pesticide treatment had different degrees of toxicity to PWD.With the in-crease of pesticide concentration,the mortality of PWD increased gradually,and the order of virulence was Em-amectin Benzoate and Imidacloprid＞limonene＞β-pinene＞a-pinene,and LC50 for 6 h was 0.36,0.45,6.08 and 90.92.After the combination of pesticides in pairs,all the combinations of pesticides showed synergistic or addi-tive effects in killing PWD,and the lethal rate of limonene(3.60 mg/mL)+Emamectin Benzoate and Imidacloprid(3.00 mg/mL)was the highest,reaching 99.87％.The optimum concentrations of four pesticides were determined by orthogonal experiment,namely a-pinene(90.00 mg/mL),β-pinene(6.00 mg/mL),limonene(3.60 mg/mL)and emamectin benzoate imidacloprid(3.00 mg/mL),and three combinations were selected as substitute pesticides.The results of laboratory tests on the control effect of different pesticides on PWD showed that α-pinene(90.00 mg/ml)+β-pinene(6.00 mg/ml)+limonene(3.60 mg/mL)+Emamectin Benzoate and Imidacloprid(3.00 mg/mL)had the best control effect within 21 days.Among the four insecticides,emamectin benzoate and imidacloprid have the strongest toxicity to PWD,and all the insecticides are more toxic than the single insecticide.It is recommended that(90.00 mg/ml)+β-pinene(6.00 mg/ml)+limonene(3.60 mg/mL)+emamectin benzoate and imidacloprid(3.00 mg/mL)are as the preferred agent,which can be used alternately with the other three groups of alternative a-gents to develop an efficient and low-toxicity green control agent for Bursaphelenchusxylophilus.
NETL
NSTL
万方数据
