辣椒素橙皮油复方生物农药研制及其杀灭红叶螨作用机理OA

[Objective]Tetranychus cinnabarinus is a widely distributed mite pest that severely impacts various crops and tradi-tional Chinese medicinal plants.This study aimed to develop a biopesticide using capsaicin and orange peel oil as the primary active ingredients,clarify its acaricidal mechanism,and provide a theoretical support for the biological control of T.cinnabari-nus on Cremastra appendiculata.[Method]Combinatorial experiments were conducted using three factors:capsaicin diluent(4.0,4.5,5.0,5.5,6.0 mL),orange peel oil(2.0,2.5,3.0,3.5,4.0 mL),and emulsifiers(volume ratio of EL-40 to S-20 at 8∶2,8.5∶1.5,9∶1,9.5∶0.5,10∶0).These were used to screen the preparation process for a nano-emulsion of the cap-saicin-orange peel oil compound biopesticide.The acaricidal efficacy and mechanism were subsequently investigated under labo-ratory culture conditions.[Result]Screening revealed that only 4 out of 125 sample groups met the standards for cold storage stability,heat storage stability,emulsion stability,and dispersibility.Based on a comprehensive analysis of particle size,sample No.122 performed best,with a polydispersity index(PI)of 0.368 7,a particle size of 33.58 nm,and a relative standard devi-ation(RSD)of 0.29%.The LC50 value for capsaicin was 1.015 μg/mL.and the optimal dilution ratio for practical application was determined to be 500-fold.Seven days after application,the acaricidal efficiency of sample No.122 reached 91.50%,which was significantly superior to the single-ingredient groups and second only to the Abamectin positive control group.Micro-scopic and electron microscopic(SEM)observations demonstrated that the compound biopesticide exerted its lethal effect by in-terfering with the digestive system of T.cinnabarinus.qRT-PCR results indicated the compound biopesticide significantly in-hibited the expression of the CYP392E10 gene 6 hours(P<0.01)after treatment and highly significantly inhibited the CYP406A1 gene expression 2 hours(P<0.001)after treatment.Conversely,it significantly induced the up-regulation of the CYP392A6 after 12 h(P<0.05).[Conclusion]The optimal formulation for 100 mL of the compound biopesticide was deter-mined as:4 mL capsaicin diluent,4 mL orange peel oil,2 mL wintergreen oil,8 mL EL-40,2 mL S-20,2 mL ethylene gly-col,0.1 mL antifoaming agent,and ultrapure water to volume.This study confirmed that orange peel oil has a synergistic acari-cidal effect on capsaicin.The developed compound biopesticide kill T.cinnabarinus by damaging their digestive systems and in-hibiting the expression of the detoxification enzyme genes CYP392E10 and CYP406A1.