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Chinese Journal of Biological Control ›› 2021, Vol. 37 ›› Issue (2): 385-393.

• GREEN PREVENTION AND CONTROL TECHNOLOGY •

### Fluorescence Quenching Method for Determining the Content of Sexual Attractants of Grapholitha molesta Busck and Its Field Application

DOU Rui1, DU Shaofang1, WANG Yang1, JING Xiaoyuan1, MA Ruiyan2, LIU Jinlong1

1. 1. College of Foundation/Institute of Chemical Ecology, Shanxi Agricultural University, Taigu 030801, China;
2. College of Plant Protection, Shanxi Agricultural University, Taigu 030801, China
• Received:2020-04-14 Published:2021-04-14

Abstract: The aim of this research was to build a new way to determination of cis-8-dodecenyl acetate (Z8-12:Ac) content by fluorescence quench. In alkaline medium, β-cyclodextrin (β-CD) and neutral red (NR) formed an inclusion complex (β-CD-NR) to enhance the fluorescence intensity of neutral red (NR). However, the fluorescence of β-CD-NR system undergoes quench after adding Z8-12:Ac, the main component of sex attractant of Grapholitha molesta Busck. The solutions, which including NaH2PO4-Na2HPO4 buffer solution (pH 7.4, 0.2 mol/L,7.0 mL), neutral red solution (1.0×10-3 mol/L, 1.0 mL) and β-CD solution (1.0×10-2 mol/L, 5.0 mL), were pipette into 25.0 mL volumetric flask, mix the solution thoroughly and bring to volume after adding a certain amount of Z8-12:Ac. The mixture solution was ultrasonic reaction 20 minutes in an ultrasonic cleaner and kept at 4℃. The fluorescence intensity F of the above solution and the fluorescence intensity F0 of the β-CD-NR system were analyzed by Fluorospectro Photometer (RF5301PC, JPN) under the conditions of excitation wavelength of 460 nm and emission wavelength of 580 nm. The fluorescence quenching value ΔF was calculated by the quotation:ΔF=F0-F. It was compared and analyzed that the relationship between different concentrations of Z8-12:Ac standard solutions and the corresponding fluorescence quenching value ΔF. The results showed that the fluorescence quenching value ΔF showed a good linear relationship with the concentration of Z8-12:Ac in the range of 1.0×10-4-4.0×10-4 mol/L. The linear equation is ΔF=28.3c-16.8, R2=0.9978. ΔF value of 2.0×10-4 mol/L Z8-12:Ac solution was measured parallelly 11 times to determine the method detection limits. The method detection limits was 1.25×10-5 mol/L (S/N=3), RSD=±1.5%, indicated that the method has good precision. The spiked recoveries ranged from 98.0% to 103.0%, the method has good accuracy. This new method was used to test the concentrations of Z8-12:Ac in field experiments from lures and the amount of insects trapped corresponding to different residues was counted. This study elucidates that this method successfully determined the residual amount of Z8-12:Ac in the trap cores at different days and knew the decay trend of Z8-12:Ac in the trap cores. Its attenuation trend is basically consistent with the change trend of insect trapping quantity in the field. This method can provide technical support for the field monitoring of G. molesta trap cores, the accuracy of insect forecasting, and ensure the trapping effect of the cores.

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