| Chestnut gall wasp (Dryocosmus kuriphilus Yasumatus) is one of the most important pests of henry chinquapin (Castanea henryi (Skan) Rehd. Et Wils). By analysis the resistant mechanisms of different resistant levels of henry chinquapin strains to chestnut gall wasp before and after being damaged by chestnut gall wasp, it provided us an theoretic evidence for selecting high yield and resistance strain to the pest, and carrying out the integrated pests management (IPM) for the pest.Based on the investigations of the indices of average number of gall, average weight of pupa, developmental duration and survival rate of imago of chestnut gall wasp on 8 main strains of henry chinquapin, a quantitative resistance index of strains of henry chinquapin against chestnut gall wasp obtained by factor analysis was suggested and applied to resistance evaluation on these8 strains. The formula of the index isAccording to the resistanceindex, the resistance of 8 main strains against chestnut gall wasp was divided into 5 grades.The activities of phenylalanine ammonia-lyase (PAL) in leaves of henry chinquapin strains with different resistance to chestnut gall wasp before and after being damaged by chestnut gall wasp were measured and the relationship between PAL activities and resistance to chestnut gall wasp was analyzed. The results indicated that PAL activities showed no differences between resistant strains and insect-attacked strains before being damaged, after injured, the PAL activities of the resistant strains increased, but the insect-attacked strains had no these effects.The Catalase (CAT) activities in leaves of henry chinquapin strains with different resistance to chestnut gall wasp before and after being damaged by chestnut gall wasp were measured by ultraviolet spectrophotometry. The results revealed that the resistant strains and the insect-attacked strains showed no significant difference before being damaged. The CAT activities of the resistant strains increased during the active period (during larval period to the period of adult in gall) of damage, and decreased during the resting period (during the period of adult out of gall to the period of egg) of damage. However, the CAT activities of the insect-attacked strains were completely contrary to the resistant strains.The activities of peroxidase (POD) in leaves of henry chinquapin strains with different resistance to chestnut gall wasp before and after being damaged by chestnut gall wasp were measured by guaiacol test. The results displayed that no matter before being damaged or after, the activities of POD in leaves were relatively high when harmed by chestnut gall wasp, and low when didn't. The POD activities of the insect-attacked strains would increase induced by the harm of chestnut gall wasp, but the POD activities of the resistant strains could not do so.The activities of Superoxide dismutase (SOD) in leaves of henry chinquapin strains with different resistance to chestnut gall wasp before and after being damaged by chestnut gall wasp were determined by NBT-illumination method. The results showed that the SOD activities of any resistant levels had similar dynamic trend following the time before injury. After injury, the SOD activities of the insect-attacked strains increased during the period of early larva after terminating dormancy then decreased while the damage continued; the SOD activities of the resistant strains increased both at the period of early larva and larva terminated dormancy.The volatile secondary substances in leaves of henry chinquapin strains with different resistance to chestnut gall wasp before and after being damaged by chestnut gall wasp was extracted by steam distillation (SD). The extract obtained was analyzed by gas chromalongraphy-mass spectrometry (GC-MS). In the four strains, there were no differences in the components of the volatile secondary substances before and after being damaged by chestnut gall wasp, which including alkanes, olefin, halohydrocarbon, acid, ester, aldehyde, alkone, alcohol, hydroxybenzene, aether, heterocyclic compounds and its derivatives, and complex functional group compound that contained several functional groups. Among them, the highest contents were ester substances, and the next were alcohol, heterocycle ring and its derivatives, and complex functional group compound. The content of Dibutyl Phthalate in different strains was the highest, and the content of 4-hydroxy-4-methyl-2-Pentanone was relatively high.During the larva period (the last ten days of April), the comparative contents of acid substances and complex functional groups compounds of the insect-attacked strains were higher than the resistant strains before injury by chestnut gall wasp. The variety of heterocyclic ring and its derivatives of the resistant strains were obviously more than of the insect-attacked strains. The comparative contents of phenol and linalool of the resistant strains were higher than the insect-attacked strains. During the period of larva, the changes of the compositions and contents of volatile secondary substances after injury were as follow: 1．The comparative contents of alkenes and complex functional groups compounds of all of strains increased; 2．The comparative contents of heterocyclic ring and its derivatives, and aldehydes substances of the resistant strains decreased, the comparative contents heterocyclic ring and its derivatives of the insect-attacked strains increased, but aldehydes substances did not change obviously; 3．Compared with the insect-attacked strains, the content of phenol of the resistant strains increased obviously; 4．The comparative contents of Linalool, (Z)-9-Octadecenal and 5,6,7,7a-tetrahydro-2(4H)-Benzo-furanone of the resistant strains decreased, the comparative contents of Linalool and (Z)-9-Octadecenal of the insect-attacked strains increased slightly or didn't change obviously while 5,6,7,7a-tetrahydro-2(4H)-Benzofuranone increased significantly.During the period of pupa (the first ten days of May), the composition of volatile secondary substances belonging to resistant and insect-attacked strains had no significant differences before injury. Compared with the insect-attacked strains, volatile secondary substances of the resistant strains contained more alpha-Cedrol. After injury, the changes of volatile secondary substances were as follow: 1．The contents of alkanes of any resistance levels increased while alcohols substances decreased. 2．The comparative contents of heterocyclic ring and its derivatives of the resistant strains increased while the insect-attacked strains decreased. 3．For the resistant strains, the comparative contents of 3-[1,3] dioxolan-2-ylpropyl-Acetic acid, 2,5-Hexanedione and 2,3-dihydro-7-hydroxy-3-methyl-1H-Inden-1-one increased while the insect-attacked strains did not change obviously or decreased slightly, Phenol and 5,6,7,7a-tetrahydro-2(4H)-Benzofuranone decreased ,but the insect-attacked strains did not change obviously or increased slightly.During the period of adult out of gall (between the last ten days of May and the first ten days of June), the contents of volatile secondary substances of the insect-attacked strains before being damaged were higher than the resistant strains. The content of Benzenacetic acid was high in the insect-attacked strains, and relatively low in the resistant strains. The effects of Dryocosmus kuriphilus were following: 1．The comparative contents of ester substances in the volatile secondary substances of different resistant levels dropped first and then rised, while the contents of alcohols rose first and dropped then. 2．The comparative content of Benzenacetic acid in the volatile secondary substances dropped in the insect-attacked strains, but did not change obviously in the resistant strains.During the period of egg (between the last ten days of June and the first ten days of July), the comparative content of 5,6,7,7a-tetrahydro-2(4H)-Benzofuranone of volatile secondary substances of each resistance levels were higher than the others before injury; The content of Diethylmethyl-Borane in the insect-attacked strains were much higher than the resistant strains without injury. After being damaged, volatile secondary substances changed as follow: 1．The comparative content of 5,6,7,7a-tetrahydro-2(4H)-Benzofuranone of the resistant and the insect-attacked strains both increased, while 4-hydroxy-4-methyl-2-Pentanone decreased; 2．The comparative content of IsoPhytol of the resistant strains increased while the insect-attacked strains decreased. During the period of the first instar larva (between the last ten days of July and the first ten days of August), the relatively high composition of volatile secondary substances of the resistant strains were similar to the insect-attacked strains. After injury, the comparative contents of acid substances of every resistance levels all decreased; the comparative contents of Benzothiazole of the insect-attacked strains increased because of being damaged, but the resistant strains did not change obviously. |
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