Reasearch On The Extraction And Structure- Activity Relationship Of Insect Repellent Ingredients From Ficus Carica L.

Ficus carica L. has a long cultivation history in our country, diseases and insect pests rarely occur on this plant. It may be due to the active substances in F. Carica, which have repellent efficacy against the insects or inhibit the growth of plant pathogenic fungi. The recent studies on biological control of F. Carica mainly focus on the antibacterial property, but not the insect repellency. In order to provide theoretical basis for the development and application of a new biological pesticide, the structure of compounds, insect repellency and extraction process of F. Carica extracts were studied in this paper.Two crystals were isolated from F. Carica leaves. They were identified by X-ray single crystal diffraction:Psoralen and 1-cyclohexyl-6,7-dimethoxyl-1,4-dihydronaphthalen (The latter was a new compoud and was called New Fig below). The crystal structure of psoralen was different from the recordation in CCDC. New Fig was isolated from plants for the first time, and has obtained patent license.The insect repellency of F. Carica was studied under the conditions of laboratory and field. Under the laboratory conditions, we investigated the olfactory responses of B-biotype Bemisia tabaci to different F. Carica extracts by four-armed olfactometer. The crude extract of F. Carica leaves showed stronger repellency than psoralen and New Fig to B-biotype B. tabaci. The repellency of New Fig was related to the concentration. At the concentration of 2.0 mg/ml and 4.0 mg/ml, New Fig showed effective repellency to B-biotype B. tabaci. The intercropping of F. Carica and Phaseolus vulgaris L. was able to reduce the degree of occurrence of major pests, Etiella zinckenella and Aphis craccivora Koch in P. Vulgaris fields. When the two plants intercropped within the greenhouse, the repellency was stronger than intercropped outside the greenhouse. The F. Carica extracts were sprayed on P. Vulgaris at the insect pests emergence period of P. Vulgaris. The results showed that the control effect against Etiella zinckenella was 87.36%, and 79.94% against Aphis craccivora Koch at the 7th day after treatment with crude extract of F. Carica leaves(10.0 mg/ml).The extracting concentration of New Fig was applied as the evaluation index in optimizing the extraction process. Response surface methodology (RSM) was used to optimize the process parameters of effective constituent extraction from F. Carica leaves. Design Expert 9.0.5.1 software showed the optimal extraction condition as follows:ultrasonic time 66 min, ratio of liquor to material 20.4:1, soaking time 59min.