| Phauda flammans（Walker）is an oligophagous pest,which only feed on Ficus concinna Miq.and F.Benjamin L.Gotra octocinctus Ashmead is its dominant parasitoid.The role played by the blades volatiles from Ficus species in the tritrophic nutrient system of Ficus-P.flammans-G.octocinctus is still unclear.Therefore,chemical constituents of the blades volatiles from the healthy and infested leaves of Ficus species were identified,using the techniques and/or methods of physiology,biochemistry,electrophysiology and behavior.The blades volatile compounds which brought physiological activities to the moth and parasitoid were screened out,and the chemotaxis of the moth and parasitoid to the active compounds were determined.The results not only lay a foundation for further study on the regulation mechanism of plant volatiles in the tritrophic nutrient system of Ficus-P.flammans-G.octocinctus,but also provide technical support for the implementation of"push-pull"control strategy,which has important theoretical and practical value.The main research results are as follows:（1）Based on the gas chromatography mass spectrometry（GC-MS）,a total of 53 volatile compounds were isolated from the healthy leaves of Ficus concinna and Ficus benjamina.The main components were terpenes and aromatic compounds,among which the relative quantities of 3-ethylacetophenone andβ-ocimene were the highest.A total of 58 volatile compounds were isolated from the infested leaves of F.concinna and F.benjamina,and the main components were terpenes and aromatic compounds,among which the relative quantities ofβ-ocimene andα-gold complex were the highest.The results showed that the content of terpenes in the volatiles of Ficus species increased significantly and the aromatics decreased significantly after being damaged by the moth,and some volatiles,e.g.,α-farnesene,3-ethylbenzaldehyde,（E）-β-ocimene,etc.were added.It is suggested that the components and contents of the volatiles of Ficus species would be changed after infested by the moth.（2）Electroantennography（EAG）,gas chromatography-electroantennogram detection（GC-EAD）and gas chromatography-mass spectrometry were used to screen six electrophysiological active substances from healthy/infested leaves of F.concinna and F.benjamina,which areβ-myrcene,d-limonene,β-ocilene,（-）-α-pinene,β-caryophyllene andα-farnesene（healthy leaves:β-myrcene,d-limonene,β-ocillene,（-）-α-Pinene andβ-caryophyllene;infested leaves:β-myrcene,β-ocimene,（-）-α-pinene,β-caryophyllene andα-farnesene）.The relative values of the maximum EAG responses of male and female adults were 10-2～10-1,10-3,10-1,10-4～10-2,10-2～10-1and 10-2～10-1,respectively.The results showed that the sensitivity of male and female to different concentrations of volatile compounds from Ficus species are different.When the concentration of different substances reached critical value,the activity of volatiles to EAG did not increase or even decreased.（3）Based on the“Y”olfactometer,the behavioral responses of male and female adults to volatiles from healthy/infested leaves were measured.The results showed that d-limonene,β-ocimene andβ-myrcene were attractive to both male and female,andα-farnesene was repellent to both male and female adults.Compared with the control,the mixture of volatiles from healthy leaves/infested leaves of F.concinna and F.benjamina had attractive effect on male and female of P.flammans,and the mixture of volatiles from damaged leaves had stronger attraction.The results showed that the blades volatiles from the leaves of Ficus species has an attractive effect on male and female,especially for the infested leaves are more attractive to male and female than those from healthy leaves.（4）Based on the responses of GC-EAD,“Y”olfactometer and field trapping methods,the GC-EAD and behavioral responses of male and female adults of G.octocinctus to the volatiles of F.concinna and F.benjamina were determined.The results showed that both male and female had obvious GC-EAD response to the mixture,and the preference of G.octocinctus to the mixture of volatiles from the damaged leaves was stronger than that of the mixture of volatiles from healthy leaves.In conclusion,the blades volatiles of F.concinna and F.benjamina has significant attraction to both male and female adults of P.flammans and G.octocinctus after they were damaged by P.flammans larvae,indicating that the blades volatiles of Ficus species played a positive role in the host localization of both herbivorous insects and parasitic wasps in the tritrophic nutrient system among Ficus-P.flammans-G.octocinctus. |
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