The Research On Tea Aphid Infestation Reduce The Defensive Response Of Tea Plant To Tea Geometrid Larvae

Longjing43# Camellia sinensis and insects feeding on it, including tea aphids and tea geometrid larve, were investigated in this paper. By examining the development of tea geometrid larvae on the tea plants which have been attacked by tea aphid in different densityfor 6 days or different time duration in 50 densitycompared with those on healthy tea plants.Then the volatiles emitted from the tea plant infested by tea geometrid alone or previously infested by tea aphid for six days were measured,as well as the relative expression of Csi PI, Csi LOX, Csi PAL, Csi ADH genes in the tea leaves which have been infested by single or combined population. The influence of aphid infestion on induced defense of tea plants to tea geometrid larves can be revealed in these respects.The content and main conclusionsare as follows:(1) The influence of tea aphid attack on the development of tea geometridlarvae.On the 10 th day, the tea geometrid larvae developed 14.7% or 29.4% faster respectively on tea plants that previously attacked by aphids for 4 or 6 days than control,and there was no significant difference on the 13 th day.While the facilitation on tea plant infested by tea aphid simultaneously or previously for 2 days is not differ significantly; The tea plant infested by aphids in 25, 50 or 100 density promote the development of cartipillars can be observed on the 7th day,but the effect caused by 25 tea aphids in desity elimated as the cartipillars growed up.(2)The influence of tea aphid attack on tea plant volatiles induced by tea geometrid larvae.Bycomparing the volatiles emitted from tea plant upon single and multi-species herbivory attack,the results show the tea aphid infestation inhibits release of jasmonic acid(JA)-mediated volatiles induced by Ectropis larvae, such as the(Z)-3-hexenol,(E)-β-ocimene, DMNT,(E, E)-α-farnesene and(E)-nerolidol have great difference after 12, 24 and 48 hours tea geometrid larvae feeding respectively. Also, the release of Salicylic acid(SA)-mediated benzaldehyde and indole reduced at each time point, but the release of methylis salicylas increased. After taking away the tea geometrid larvae, the release of benzaldehyde, methylis salicylas,DMNT and(E, E)-α- farnesene increased instead of decreased. This may be closely related to the important role they play in the indirect defense.(3)Expression pattern analysis of Csi PI, Csi LOX,Csi PAL,Csi ADH under different treatments in tea leaves.The tea geometrid larvae attack of 3, 12, 24 hours induce high expression of Csi LOX and Csi PAL genes, and has no significance on Csi PI gene. The combined attack reduce the expression of Csi PI, Csi LOX and Csi PAL genes. So antagonistic effect may exist in different defense signals caused by tea geometrid larvae and aphid. Tea aphid attack increases the expression of Csi ADH gene, so aphid infestation not only has certain inhibitory effect on defense signaling mediated by JA, but also involves ethylene(ET) and other defense signaling probably.The result suggests that aphid infestation reduces the defense response of tea plant to the tea geometrid larvae. After a period of infestation, Aphids reduced defense responses associated with JA pathway caused by tea geometrid larvae, raising the suitability of tea geometrid larvae,The majority of volatiles release caused by tea geometrid larvae was inhibited,This kind of infestation has antagonistic action to defense genes activated by tea geometrid larvae. This study willfurther our understanding of mechanisms of induced insect resistance induced by multiple phytophagous insects with different feeding guilds.