The Olfactory Responses Of Diaphorina Citri To The Volatile Compounds Of Nanfeng Mandarin

Citrus,an important economic crop in China,could be destroyed once infected by Huanglongbing disease which spread rapidly by Diaphorina citri Kuwayama(D.citri).In general,the areas where the D.citri occur are also the distribution areas of Huanglongbing.Therefore,one of the important means to prevent Huanglongbing is to control D.citri,which currently relies largely on chemical insecticides.Although intensive chemical control can reduce the population of D.citri in a short period of time,the side effects,such as development of insecticide resistance and pollution of environment,were following.Plant volatiles are natural chemical substances that derive from nature and environmentally friendly.They play an important role in the habits of pest about their host selection,feeding,and oviposition.Hence,it is significant for the development of D.citri traps to evaluate the attraction of voliates componds to D.citri in plants.In this research,we used Simultaneous Distillation Extraction(SDE)and Solid Phase Microextraction(SPME)to extract the volatile compounds from young shoots of Nanfeng mandarin in spring,summer,autumn and winter,and the compounds were identified by Gas chromatography-mass spectrometry(GC-MS).Then,common components were screened from the volatile compounds of young shoots.And tests were conducted in a vertically oriented Y-tube olfactometer to evaluate the olfactory responses of D.citri to the volatile compounds and common components.The main results were as follows:A total of 48 volatile compounds were extracted from young shoots of four seasons by SDE,and 90 volatile compounds by SPME.The most abundant compounds was terpenoids extracted by two methods,followed by alcohols.From young shoots of four seasons,12common ingredients were extracted by SDE,16 common ingredients by SPME,and 5common constituents by two methods which respectively were terpinolene,γ-terpinene,linalool,α-terpineol and o-cymene.There were significant positive tendency in the olfactory responses of Diaphorina citri adults to volatile compounds from young shoots of four seasons.The volatiles from summer shoots exhibited the strongest attraction to females(χ~2=9.60,P<0.01).The volatiles of shoots from spring,autumn and winter showed the strong attraction to males(spring:χ~2=11.27,P<0.01;autumn:χ~2=15.00,P<0.01;winter:χ~2=13.07,P<0.01).Among 10 common compounds with 1.0μl/ml,only terpinolene andγ-terpinene were able to significantly attract D.citri.In addition,among 8 concentration gradients of two standards,terpinolene with1.00μl/ml,0.50μl/ml and 0.20μl/ml exhibited significant attraction to females,and 0.10?l/ml and 0.20μl/ml significant attraction to males;γ-Terpinene showed significant attraction to males at the concentration of 1.00μl/ml.These results indicate that the volatiles emitted by young shoots of Nanfeng mandarin in spring,summer,autumn and winter are attractive to D.citri significantly.Moreover,terpinolene andγ-terpinene which show obvious attraction to D.citri are selected from the volatile compounds of Nanfeng mandarin.