Effects Of Host And Non-host Plant Volatiles On Host Selection Of Dictyoploca Japonica

During long term coevolution,insects and plants have formed a variety of interactions and established complex biological community,but these interactions are focused from a perspective of nutritional relationships.Hosts of most insects have been demonstrated to be genera-or species-specific.In order to select the suitable hosts,insects have to tend to host plants and avoid non-host plants.However,in natural ecosystems their host plants are often exist with non-host plants,so non-host plants have mediated effects on insect behavior.Especially,plant volatiles play an important role in the localization and selection host plants of insects.Therefore,better understand the effects of host plant and their neighboring non-host plant volatiles is essential for identifying potential mechanisms on how insects to choose their host.Dictyoploca japonica Moore(Saturniidae: Dictyoploca)is an important pest of the forest and medicinal plants,because larvae cause serious damage on their host by eating leaves,and they already become one of the key monitor and control targets.Its host plant——Juglans mandshurica,often forms mixed forest with its non-host plants.So,in this study,D.japonica,and its host plant and non-host plants(Pinus koraiensis,Ulmus davidiana var.japonica,Phellodendron amurense,Quercus mongolica,Populus koreana,Fraxinus mandschurica,Tilia amurensis)as study organisms,the main composition and content of plant volatiles were analyzed by solid-phase microextraction(SPME)technique collecting the volatiles of host and non-hosts,and were determined by gas chromatography-mass spectrometry(GC-MS)identifying chemicals.Effective compounds that attract or deter D.japonica were determined by the electroantennogram(EAG)and olfactory behavioral test.And then,possible effects of different volatiles from host plant and non-host plants were analyzed.Main conclusions are as follow:1.Results found that there were 120 major plant volatiles(relative content ?0.5%)from eight tree species,including alcohols,aldehydes,ketones,esters,fatty acids,alkynes,alkenes,alkanes,aromatics,monoterpenes,sesquiterpenoids and diterpenoids.Plant volatiles of J.mandshurica include alcohols,aldehydes,esters,alkenes,aromatics,monoterpenes,sesquiterpenoids,with higher content for monoterpenes(44.25%)and sesquiterpenes(39.42%).Among the non-host plants,the volatiles of P.koraiensis are mainly monoterpenes(70.03%)and sesquiterpenoids(23.39%),while volatiles of the deciduous broadleaved trees are mainly alcohols,esters and aromatics.In terms of the content of volatiles,the contents of(1R)-(+)-?-pinene(13.61±3.22%),?-pinene(12.29±1.04%)and caryophyllene(11.36±1.57%)in J.mandshurica are more higher than that of others volatiles;The contents of Terpinolene and ?-Myrcene respectively are 12.228±1.985% and 12.08±4.786% in P.koraiensis,which are more higher than others volatiles;The content of Naphthalene(33.67±3.67%)is the highest in U.davidiana;The contents of ?-Phellandrene,(E)-?-Ocimene,Naphthalene are more higher in P.amurense and the contents respectively are 11.38±3.63%,10.78±2.2%,10.11±0.64%;The contents of(E)-3-Hexen-1-ol acetate,(Z)-3-Hexen-1-ol acetate,(Z)-3-Hexen-1-ol in Q.mongolica are more higher than that of others volatiles,and the contents respectively are 19.4±12.28%,10.27±9.71%,14.44±3.27%;The contents of Styrene(11.15±4.3%)and Hexano(9.84±3.31%)in P.koreana are more higher than that of others compound;(Z)-3-Hexen-1-ol acetate and ?-Farnesene are main components of F.mandschurica and T.amurensis,the contents of former in F.mandschurica and T.amurensis respectively are 33.07±7.33% and 44.69±13.62%,the latter respectively are 19.11±6.38%,20.25±11.66%.In terms of volatile components,all studied tree species contains the similar components,and 2-Hexenal appeared in host and 7 non-hosts.And moreover,volatile of each tree species has species-specific,J.mandshurica specific components have 9 species,P.koraiensis include 15 species,P.amurense include 13 species,U.davidiana include 9 species,Q.mongolica include 2 species,P.koreana include 15 species,F.mandschurica include 3 species,and T.amurensis include 3 species.2.Determine the effects of host and non-host plant volatiles on D.japonica by EAG experiment.EAG results indicated the D.japonica responds differently to different compounds.The responses of female were higher to the stimuli of(Z)-3-Hexen-1-ol,(E)-2-Hexen-1-ol,Hexanol,(E)-2-Hexenal,Styrene.The responses of EAG of D.japonica female were depended on the concentration of tested chemicals,with increasing with the concentration gradient of chemical:(Z)-3-Hexen-1-ol,(E)-2-Hexen-1-ol,(E)-2-Hexenal,Styrene,Ocimene,?-Pinene,1S-?-Pinene,(E)-2-Hexen-1-ol acetate,Salicylaldehyde,?-Phenylethanol,Linalool,with decreasing for other chemicals: Terpinolene,Geranyl acetate,Hexanol.The responses of male were higher to the stimuli of ?-Myrcene,Ocimene,(-)-?-Pinene,(E)-2-Hexen-1-ol.The responses of EAG of D.japonica male were also depended on the concentration of tested chemicals,with increasing with the concentration gradient of chemical: Caryophyllene,?-Caryophyllene,1R-(+)-?-Pinene,Ocimene,D-Limonene,(Z)-3-Hexen-1-ol acetate,Acetic acid hexyl ester,(E)-2-Hexen-1-ol acetate,(Z)-3-Hexen-1-ol,(E)-2-Hexen-1-ol,?-Pinene,?-Phellandrene,Terpinolene,Salicylaldehyde,Benzaldehyde,Styrene,with decreasing for 1S-?-Pinene.The responses of EAG by D.japonica male and female moths were significantly different in ?-Myrcene,D-Limonene,Terpinolene,Acetic acid hexyl ester,cis-3-Hexenyl butyrate and 1-Nonanol.3.The volatiles which caused the significant EAG reaction of D.japonica were selected to determine whether the volatiles of host and non-host plants have attract or evasive function on D.japonica by olfactory behavioral test.Results indicated,the female moth could be attracted by(Z)-3-Hexen-1-ol,(E)-2-Hexen-1-ol,and Styrene,and be detered by Hexanol.The male moth could be attracted by(-)-?-Pinene,and be detered by(E)-2-Hexen-1-ol.In host plant J.mandshurica and the non-host plants: P.koraiensis,P.amurense,Q.mongolica,T.amurensis and P.koreana include volatiles that could attract D.japonica;U.davidiana and F.mandschurica include volatiles which can deter.Therefore we speculate that population size of D.japonica may be higher when J.mandshurica coexist with non-host plants of P.koraiensis,P.amurense,Q.mongolica,T.amurensis and P.koreana because these trees could release volatile to form associate susceptibility odor complex.In total,our results showed that there were significant effects of host and non-host plant volatiles on the directional behavior of D.japonica from a perspective of chemical ecology.The volatile category of each tree species is similar,but the compositions of that are different.The population of D.japonica were easy increased in mixed forest when which could be attracted by the chemical constituents of host plants and non-host plants.Thus,this study can provide a theoretical basis for interactions of insects and plants,and it can provide a theoretical basis for predicting the population dynamics of D.japonica in the mixed forest of host plant with non-host plants.