| Herbivorous insects often use host plants volatiles in search of food and spawning sites. The smell of plants, kairomones used in insects host location, is information compounds in the process of two nutritional relationship building between plants and herbivorous insects. Many factors affect on insects in its choice of host plants, such as the chemical composition of plants, plant morphological characteristics, environmental factors (light, temperature, humidity, etc.) and other organisms and so on. However, chemicalreceptors are mainly used to identify the signal substances (primarily plant secondary metabolites) of plants for herbivorous insects. We selected several common host plants of Apriona swainsoni (Hope) based on historical records in our study. We further clarified the host range of A. swainsoni by observation on its host selection behavior indoor and outdoor. Then, we analysis the volatile compounds in different host in order to understand the host selection mechanism. Application of the solvent distillation trapped the VOCs from the twigs and leaves of Sophora japonica Linn., then the extracts were used to field trapping tests in preliminary study of of plant attractants for prevention and control of A. swainsoni. The following description will be divided into seven parts:1. By"Y"-tube Olfactometer, we studied the response of A. swainsoni adult towards odor sources from seven different trees, such as S. japonica, Robinia pseudoacacia cv. idaho, Salix babylonica Linn., Koelreuteria paniculata, Koelreuteria paniculata var. intergrifola, Caesalpinia decapetala (Roth) Alston and Dalbergia hupeana Hance respectively. The results showed that, the twigs and leaves of S. japonica have a strong attractiveness to adult A. swainsoni. The same to R. pseudoacacia, K. paniculata, K. paniculata var. intergrifola and C. decapetala to female adult, but there is no obvious difference among these four species. Twigs and leaves of S. japonica have the strongest attractiveness to male adult, twigs of R. pseudoacacia and K. paniculata var. intergrifola are also attractive to the male adult, but the leaves of two species did not show the attractiveness. In addition, the other trees have no obvious attractiveness to male adult. Overall, A. swainsoni adult showed the same preference order, S. japonica> R. pseudoacacia> K. paniculata var. intergrifola> K. paniculata> D. hupeana> C. decapetala> S. japonica, to twigs and leaves of host plants on the host selection. 2. Field observations showed that A. swainsoni adult chose S. japonica and R. pseudoacacia first, with largest amount of feeding and spawning, than K. paniculata var. intergrifola. But there was no feeding and spawning behavior occurred on S. japonica. The feeding and oviposition of A. swainsoni preference on these four species given the same order: S. japonica> R. pseudoacacia> K. paniculata var. intergrifola> S. japonica.3. Observation on the attraction of fresh twigs and leaves of S. japonica to A. swainsoni adult in the Wind Tunnel. The results showed that twigs, the rate of male and female adult which was attracted to feed is 85.33% and 77.33% respectively, are more attractive adult beetles than leaves, the latter is 64.00% and 41.33% respectively. Results are consistent with the bioassay tests.4. Extraction of twigs and leaves volatile compounds of S. japonica treated by Steam Distillation and Solvent Distillation were tested in "Y"-tube Olfactometer. The results are as follows: (1) In Steam Distillation extraction tests, all twigs extracts within 4 hours have a strong attractiveness to A. swainsoni female adult, but only the 3h and 4h extracts given a strong attractiveness to male adult. On the other hand, the 4h extracts of leaves, which is the strongest, is more attractive than the others to female adult, and the 1h, 2h and 3h extracts are more attractive than the 4h's to male adult. (2) In Solvent Distillation extraction tests, twigs extracts at 90min showed more stronger attractiveness to female adult than 40min's, while the leaves extracts at different times just showed the opposite effect, and the leaves extracts at 40min is more stronger than twigs; Both twigs and leaves extracts at 90min are all have stronger attractiveness to male adult than 40min's, and the twigs extracts at 90min have more stronger attractiveness.5. SPME/GC/MS hyphenated technique was used to extract the volatile substances from natural materials and Steam Distillation and Solvent Distillation extracts. The results are as follows: (1) Volatiles in host plant twigs contain a large number of terpenes, mainlyα-Pinene,β-Pinene, 3-Carene, Ocimene, D-Limonene and Copaene, in addition, it also contains a small amount of terpenes. such asβ-Damascone,α-Phellandrene,β-Phellandrene,β-Myrcene, (+)-Cycloisosativene, Germacrene D, Aromadendrene,α-Amorphene, Cedrene, trans-.alpha.-Bergamotene,α-Farnesene and Caryophyllene, and some alcohols, such as Cedr-8-en-13-ol, Linalool and Eucalyptol. Volatiles as terpenes in host leaves of are less than in twigs, among them no terpenes were detected from leaves of S. japonica. (2) Volatiles in leaves and twigs Steam Distillation extracts of S. japonica are mainly alcohols, such as Maltol, (E)-2-Hexen-1-ol, (E)-3-Hexen-1-ol, (E)-4-Hexen-1-ol, (E)-2-Decen-1-ol, (E)-5-Decen-1-ol, 1-Octanol, Linalool and cis-.beta.-Terpineol, and ketones, such as cis-Jasmone, 2-Octanone, beta.-Damascenone and beta.-Damascone. In addition, leaves extracts also contains some esters, such as (E)-4-Hexen-1-ol, acetate. (3) Volatiles in leaves and twigs Solvent Distillation extracts of S. japonica are mainly alcohols, such as Maltol, Inositol and Menthol, and esters, such as trans-.beta.-Terpinyl pentanoate and Methyl (Z)-5,11,14,17-eicosatetraenoate. Extracts also contains a small amount of Estragole, Eugenol and .gamma.-Hydroxyisoeugenol.6. By Y-tube Olfactometer, we studied the response of A. swainsoni adult towardsα-Pinene, (1S)-(-)-α-Pinene, (-)-β-Pinene, R-(+)-Limonene, S-(-)-Limonene, DL-Limonene, (+)-3-Carene, Mycrene and mixtures as Mix 1(DL-limonene:(1s)-(-)-α- pinene:(+)-3-carene =4:4:1) and Mix 2(Mycrene : (+)-3-carene =6:1). The results showed that Mycrene, (+)-3-Carene, (1S)-(-)-α-Pinene and DL-Limonene have attraction to female adult, the first two is stronger, however, Mix 1 and Mix 2 have no obvious attractiveness effect to female adult. And R-(+)-Limonene,α-Pinene and S-(-)-Limonene given repellent effect to female adult. All the terpenes and mixtures did not show obvious effect to male adult.7. Leaves and twigs Solvent Distillation extraction of S. japonica was used to field trapping tests. The results showed that both of them have a certain attraction to A. swainsoni adult, twigs extraction at the dose of 100ml showed the highest capacity for 7.42 adults per week each trap.
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