| Omphisa plagialis is a major pest to the branches of Catalpa bungei,which brings serious losses to its young plantation,new afforestation and nursery.In this paper,the1-year-old seedlings of 13 clones,2-year-old seedlings of 11 clones and 3-year-old seedlings of 17 clones of C.bungei were used as experimental materials.Based on the investigation of the number of defecation holes,galls and eclosion holes,and the height and DBH of1-year-old seedlings of 13 clones of C.bungei,the percentage of plants with pests,the density of population,the index of damage,the amount of growth and the coefficient of activity of different clones were calculated.At the same time,on the basis of these indexes,the insect resistant grades of different clones were analyzed,and the clones with strong insect resistance were screened.On this basis,the species and relative content of the volatile substances related to insect resistance in the branches of C.bungei were further analyzed by solid phase microextraction and GC-MS,and the content of total phenol,soluble protein and proline of the non-volatile substances were determined,in order to preliminarily reveal the relationship between these substances and insect resistance of C.bungei clones,and the impact of insect resistance.This study can provide a theoretical basis for the selection and popularization of resistant varieties of C.bungei,and provide an effective way for the sustainable control of O.plagialis.The main results are as follows:1.The 1-2-year-old seedlings of C.bungei are susceptible to infection of the O.plagialis,while the 3-year-old seedlings are less damaged,which may be related to the different number of insect sources in different places.2.Percentage of plants with insects,density of plant population,damage index and relative growth rate can be used to evaluate the resistance of different C.bungei clones.Among the clones investigated,9-1,63 and 1-3 showed strong resistance to pests,while19-01,2-7 and 5-8 were more susceptible,and the resistance to pests was weak.3.The main volatile substances in the branches of C.bungei clones are alcohols,hydrocarbons,esters and ketones.Among them,alcohols accounted for the highest proportion,the main substance was 1-octene-3-ol,ketones and esters followed,the main substances were 3-octyl ketone and methyl salicylate respectively,while acids and phenols were only detected in individual clones.The relative contents of alcohols and ketones in resistant clones 63 were significantly higher than those in susceptible clones 5-8(P<0.05),while the contents of hydrocarbons and esters were significantly lower than those in susceptible clones 5-8(P<0.05).4.The contents of total phenol,soluble protein and proline in different clones of C.bungei all reached significant difference levels,but there was no obvious law of change.Among them,the total phenol content of resistant clones 63 was significantly higher than susceptible clones 2-7 and 5-8(P<0.05),but there was no significant difference with susceptible clones 19-01(P>0.05).The soluble protein and proline content were significantly higher than 19-01 and 2-7(P<0.05),but significantly lower than 5-8(P<0.05).5.Combined with the index of insect resistance and the kinds and contents of secondary metabolites related to insect resistance in the branches of C.bungei,63 clones were preliminarily determined as insect resistant,while 5-8 clones were susceptible. |
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