Electroantennogram And Behavioral Responses Of Agrilus Zanthoxylumi To Volatiles In Host Fruits During High-risk Period

Agrilus zanthoxylumi Hou(Coleoptera: Buprestidae),the main stem borer of Zanthoxylum bungeanum Maxim in the pepper producing area in Shaanxi and Gansu province.At present,we find Agrilus zanthoxylumi only damaged Zanthoxylum bungeanum,greatly reducing the yield and quality of Zanthoxylum bungeanum.In this study,solid phase microextraction(SPME)and gas chromatography-mass spectrometry(GC-MS)were used to analyze and identify the main volatile compounds and their components and relative content of three different varieties of Zanthoxylum bungeanum(Zanthoxylum bungeanum Dahongpao,Zanthoxylum bungeanum Feng,Zanthoxylum bungeanum Shizitou)fruit in the high-risk period of Zanthoxylum bungeanum(late June).Electroantennography and Y-tube olfactometer were used to test the electroantennographic(EAG)and behavioral responses of Agrilus zanthoxylumi adults to the volatiles of host fruit,in order to find out the volatile substances that are attracted or repelled to Agrilus zanthoxylumi and further improve the species of green biological control pheromone of Agrilus zanthoxylumi and develop a certain theoretical basis for the development of Zanthoxylum bungeanum attractant or insect repellent.The results of this study are as follows:(1)The results of solid phase microextraction(SPME)and gas chromatography-mass spectrometry(GC-MS)indicated that 74,64 and 77 volatile compounds were identified in the fruits of Zanthoxylum bungeanum Dahongpao,Zanthoxylum bungeanum Feng and Zanthoxylum bungeanum Shizitou,respectively.There were no significant differences in the volatiles of the three kinds of Zanthoxylum bungeanum,but their relative contents were different,mainly including alkenes,terpenes,alcohols and esters.The highest content of the three varieties of Zanthoxylum bungeanum fruits was d-limonene.Zanthoxylum bungeanum Dahongpao is mainly composed of olefinic compounds,and the relative content of d-limonene(30.87%),myrcene(17.88%)and sabinene(14.11%)is the highest;the Zanthoxylum bungeanum Feng is mainly composed of olefins and esters.The compounds were mainly composed of d-limonene(33.82%),linalyl acetate(20.99%)and sabinene(11.24%),respectively.The main content of Zanthoxylum bungeanum Shizitou was mainly olefinic compounds,respectively.The relative content of limonene(32.21%),myrcene(19.60%)and sabinene(14.28%)was the highest.The study found that piperitone is an unique component of the volatiles of Zanthoxylum bungeanum Dahongpao fruit;2-methyleicosan is an unique component of the volatiles of the Zanthoxylum bungeanumFeng fruit;Isobornyl thiocyanoacetate is the only component of the volatiles of the Zanthoxylum bungeanum Shizitou fruit.(2)The results of the electroantennographic(EAG)responses indicated that all the 10 volatiles of the host fruit caused different degrees of EAG response of Agrilus zanthoxylumi.At the concentration of 100 ?g/?L,the absolute EAG response of female and male,respectively,caused by piperone and decanal.D-limonene and myrcene caused maximum EAG value for male at the concentration of 100 ?g/?L,however,for female at the concentration of 10 ?g/?L.EAG response of(±)-?-terpinyl acetate and ocimene in 10 volatiles was relatively weak.Paired T-test showed that only trans-2-hexenal had a significant gender difference in EAG responses between male and female adults(P<0.01),however there was no significant gender difference between the two genders for the other volatiles tested.(3)The results of the behavioral responses indicated that male significantly repelled linalool at a concentration of 1~100 ?g/?L,decanal at the concentration of 10~100 ?g/?L had repellent effect on both male and female.Both piperitone at the concentration of 1~10?g/?L and ?-terpinene at the concentration of 10~100 ?g/?L had significant repellent effect on female(P<0.05),while both myrcene at the concentration of 10~100 ?g/?L and d-limonene at the concentration of 0.1~1 ?g/?L had significant repellent effect on male.At the concentration of 1~100 ?g/?L,male repellent trans-2-hexenal significantly,however,female is repelled significantly only at the concentration of 10 ?g/?L.Trans-2-hexen-1-ol at the concentration of 0.1~1 ?g/?L exhibited repellent effect on female,but at the concentration of 10~100 ?g/?L attracted female.