| Chinese gall aphids parasitize compound leaves of a number of species of Rhus in summer and induce the formation of galls——gallnut. In winter they move to an alternate host, moss. Chinese gall aphid is an important resource insect in China. Gallnut that induced by Gallnut aphids. is the important raw material of the production of tannic acid; gallic acid and other chemical products, which are widely used in pharmaceutical, chemical, food, environmental protection and other industries. In China, Chinese gall aphids comprised five genera and 14 species (subspecies) and mainly distributed.in the South-western China including Shaanxi, Guizhou, Sichuan, Chongqing, Hubei, Hunan, and Yunnan etc. Chinese gall aphid has strong host specificity, and the odor chemicals of host plants are considered to be an important positioning signal. The study of odor chemicals and host plant volatiles provides certain theoretical basis to explain the nature of Chinese gall aphids’activity phenomenon that locate the host plants, and benefit the development of attractants. The quality of the gallnut that formed by Kaburagia rhusicola Takagi parasitizeing Rhus potaninii Maxim is the best. The research objective of this article is to study the active ingredient of host that can attract K. rhusicola.This study considers K. rhusicola as a research object according to the characteristics that K. rhusicola migrates to summer host tree R. potaninii in spring, migrate to winter host moss Eurohypnum leptothallum in summer. During K. rhusicola migration period in spring, bellied gallnut growing period, and K. rhusicola migration period in summer, we collected the host plant volatiles using headspace volatile collection method, prepared extractions of host plants by solvent extraction, and experimented with a Y-shape olfactometer to observe the orientation behavior of K. rhusicola to the samples, then used gas’chromatography-mass spectrometry (GC-MS) to identify the volatile organic compounds emitted by host plant and extractions of host tissues.The orientation behavior data of K. rhusicola to different samples from Y-shape olfactometer test showed that the volatiles and extractions of summer host tree R. potaninii that we prepared in spring and summer attracted spring migrant aphids at different degrees. The volatiles and extractions of winter host moss E. leptothallum that we prepared in spring and summer repelled spring migrant aphids at different degrees. However, whether it is summer host tree R. potaninii or winter host moss E. leptothallum, samples of both hosts showed attractive effect on summer migrant aphids with different degrees.According to GC-MS analysis of the host plant volatile samples, during K. rhusicola migration period in spring the sample of R. potaninii tree was identified to be 23 compounds, the sample of R. potaninii treelet was identified to be 10 compounds. The sample of E. leptothallum was identified to be 18 compounds. During bellied gallnut growing period in summer the sample of R. potaninii tree we was identified to be 57 compounds. The sample of R. potaninii treelet was identified to be 46 compounds. The sample of E. leptothallum was identified to be 40 compounds. During K. rhusicola migration period in summer the sample of R. potaninii tree was identified to be 64 compounds. The sample of R. potaninii treelet was identified to be 24 compounds. The sample of E. leptothallum was identified to be 25 compounds. The main volatile components are Toluene; Ethylbenzene; 1-Xylene; 1,3,5-Trioxane; Dodecane; Butanoic acid, butyl ester; Benzene, l-ethyl-3-methyl-; Styrene; Benzene,1,4-diethyl-; Acetic acid,2-ethylhexyl ester; Formamide, N,N-diethyl-; 1-Hexanol,2-ethyl-; Tetradecane; Benzene, 1-ethenyl-3-ethyl-; Benzene, 1-ethenyl-4-ethyl-; Hexadecane; 2-Pyrrolidinone, 1-methyl-; Benzaldehyde,3-ethyl-; Ethanone, 1-(4-ethylphenyl)-; Caprolactam; Hexadecanoic acid, methyl ester; Ethanone, 1,1’-(1,4-phenylene)bis-; and 1-Octadecene etc.Three solvents were used to prepare extractions. These are hexane, methylene chloride and methyl alcohol. According to GC-MS analysis of the host plant extraction samples, when the samples were extracted with hexane, during K. rhusicola migration period in spring, the extractions of branches in crown, branches on basal stems and roots of R. potaninii were, respectively, identified to be 32 compounds,25 compounds, and 23 compounds. The extraction of E. leptothallum was identified to be 15 compounds. During bellied gallnut growing period in summer, the extractions of branches in crown, branches on basal stems and roots, leaves, petioles and bellied gallnuts of R. potaninii were identified to be 21 compounds,14 compounds,4 compounds,5 compounds,5 compounds and 3 compounds, respectively. The extraction of E. leptothallum was identified to be 9 compounds. During K. rhusicola migration period in summer, the extractions of branches in crown, branches on basal stems, roots, leaves, petioles and bellied gallnuts of R. potaninii were identified to be 23,16,24,29 compounds,36 and 17 compounds, respectively. The extraction of E. leptothallum was identified to be 28 compounds. When the samples were extracted with methylene chloride, during K. rhusicola migration period in spring, the extractions of branches in crown, branches on basal stems and roots of R. potaninii were identified to be 30,17, and 18 compounds, respectively. The extraction of E. leptothallum was identified 7 compounds. During bellied gallnut growing period in summer, the extractions of branches in crown, branches on basal stems and roots, leaves, petioles and bellied gallnuts of R. potaninii were identified to be 36,31,42,32, 46 and 15 compounds, respectively. The extraction of E. leptothallum was identified to be 17 compounds. During K. rhusicola migration period in summer, the extractions of branches in crown, branches on basal stems, roots, leaves, petioles and bellied gallnuts of R. potaninii were identified to be 23,23,23,26,35 and 17 compounds, respectively. The extraction of E. leptothallum was identified to be 22 compounds. When the samples were extracted with methyl alcohol, during K. rhusicola migration period in spring, the extractions of branches in crown, branches on basal stems and roots of R. potaninii were identified to be 51,38, and 30 compounds, respectively. The extraction of E. leptothallum was identified to be 16 compounds. During bellied gallnut growing period in summer, the extractions of branches in crown, branches on basal stems, roots, leaves, petioles and bellied gallnuts of R. potaninii were identified to be 46,35,39,38,46 and 35 compounds, respectively. The extraction of E. leptothallum was identified to be 14 compounds. During K. rhusicola migration period in summer, the extractions of branches in crown, branches on basal stems, roots, leaves, petioles and bellied gallnuts from R. potaninii were identified to be 30, 21,31,41,41 and 25 compounds. The extraction of E. leptothallum was identified to be 13 compounds.Y-shape olfactometer test showed that host plant volatiles played an important role in the process. When K. rhusicola was locating hosts, the sample collection and preparation method in this study can effectively collect the host plant volatile components. Plant volatiles that were activated for insects are usually common green leaf volatiles, but each of host plants can release different volatiles and the ratio is . also different. GC-MS analysis results showed that the compositions of host plant volatiles, and different solvents had different extraction ability for volatiles. |
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