The Effects Of Tabacco Volatiles On Behavioral Orientation Of Aphidius Gifuensis

This research was based on a tritrophic system involving the tobacco Nicotiana tabacum L.,the aphid Myzus persicae?Sulzer?and the parasitoid Aphidius gifuensis Ashmead.The behavioral responses of the parasitoid to the tobacco with different treatments and their volatile were determined by a six-choice olfactometer,and the components and relative contents of volatile from host plants infested by aphids after different times intervals were analyzed by the chromatography mass spectrometry?GC-MS?.The main results were as follows:?1?The role of volatile from hurt tobacco of different treatments on the olfactory behavior of parasitoids was evaluated with the six-choice olfactometer.The results indicated that both the female and male parasitoid adults were significantly attracted by hurt tobacco with 50mechanical damage holes.And the olfactory behavioral responses of parasitoids to tobaccos of different mechanical hurt levels were not increased as the hurt level increased.Moreover,the behavioral responses of parasitoids were strengthened as the aphid density increased.The tobacco with more aphids attracted more parasitoids.The most active period occurred at 14:00 to 20:00 for parasitoids searching hosts.?2?The behavioral responses of parasitoids to different concentrations of tobacco volatile were determined.The results indicated that different concentrations of benzaldehyde,cis-3-Hexen-1-ol,hexanal,methyl salicylate and trans-2-hexenal had significant effects on the behavioral responses of parasitoids,the significantly attractive concentration ranges of these chemicals were were 10^-210^-1,10^-11,10^-410^-2,10^-310^-11 and10^-310^-2,respectively.?3?The GC-MS analysis showed that healthy tobacco volatiles mainly consisted of 10 compounds,the most compound was undecane?5.23%?,followed by naphthalene?5.17%?.The volatiles from tobacco suffered from 24 hour aphid infestation mainly consisted of 14 compounds,the most compounds was?+?-?-funebrene?8.14%?.The infested tobaccos newlyproducedtridecane,1H-3a,7-methanoazulene,tetradecane,pentadecane,hentriacontane,nonane and 1,8-Nonadien-3-ol.The volatiles from tobacco suffered from 48 hour aphid infestation mainly consisted of 16 compounds,the most compounds was undecane?11.54%?.The infested tobaccos newly produced tridecane,1H-3a,7-methanoazulene,tetradecane,heneicosane,sulfurous acid,limonene,cedrene,dichloro acetaldehyde and 1,8-Nonadien-3-ol.Moreover,the total contents of volatiles from aphid-infested tobaccos were higher than healthy plants,especially fatty acid derivatives and terpenes.The results indicated that both female and male adults of A.gifuensis were significantly attracted to N.tabacum with 50 mechanical damage holes.The behavioral responses of A.gifuensis to N.tabacum were increased as the aphid density increased.Different concentrations of five chemicals had significant effects on the behavioral responses of A.gifuensis.The total contents of volatiles from aphid-infested plants were higher than healthy plants,especially fatty acid derivatives and terpenes.