Identification And Functional Characterization Of The Sex Pheromone Compounds Of Tea Black Tussock Moth Dasychira Baibarana(Lepidoptera,Lymantriidae)

Tea camellia sinensis a popular beverage second to water with great economic importance.Tea plant is attacked by various insect pest species,which cause a huge reduction of tea production and quality.Tea black tussock moth Dasychira baibarana Matsumura is one of those pests,the larvae of this species feed on terminal shoots of tea plant and damage the tea plant by causing economical loss.Except the chemical pesticides there is no known control method for D.baibarana species.The application of chemical substances like sex pheromones is one of the ideal and eco-friendly control methods.To develop an efficient lure to control D.baibarana species their sex pheromone glands were analyzed by using GC-EAD and GC-MS.The larvae and eggs of D.baibarana were collected from Suichang County,Zhejiang,China,and a colony of this insect was established and maintained in the laboratory for experiments.Initially the calling behaviour of female moths was investigated to extract the sex pheromone glands,the peak calling behaviour was observed at 8.5^thhours of scotophase period and sex pheromone glands of female moths were extracted.The crude sex pheromone extract was analyzed by GC-EAD and GC-MS respectively for identification of the candidate compounds.In the GC-EAD analysis,three components elicited strong electrophysiological responses,and GC-MS analysis of the crude extract identified three EAG bio-active components:(3Z,6Z)-cis-9,10-epoxyheneicosa-3,6-diene(Z3,Z6,epo9-21:H,Compound I),(3Z,6Z,11E)-cis-9,10-epoxyheneicosa-3,6,11-triene(Z3,Z6,epo9,E11-21:H,Compound II),and(3Z,6Z)-heneicosa-3,6-diene-11-one(Z3,Z6-21:11-one,Compound III).These results revealed an unique sex pheromone of D.baibarana composed of an epoxydiene,epoxytriene,and dienone with the same 3,6-dienyl motif.The epoxytriene and dienone were characterized as an insect pheromone component for the first time.In the EAG analysis,each synthetic compound strongly stimulated male antennae,although Compounds II and III elicited higher responses than Compound I.In the wind tunnel bioassay and field trapping experiments,ternary blends of the identified compounds successfully attracted male D.baibarana.Efficient attraction was achieved in the field with a rubber septum baited with 500?g of a mixture of Compounds I,II and III in a 25:20:55 ratio,which could be a useful lure for integrated management of this pest in tea gardens.Furthermore,the tea plant volatiles were evaluated in EAG and behavioural bio-assays,the D.baibarana male moths significantly responded to tea plant volatiles(Z)-3-hexen-1-ol,ocimene,(Z)-3-hexenyl butyrate,linalool,and benzyl alcohol,and the female moths elicited significant response to,(Z)-3-hexenyl hexanoate,(Z)-jasmone,linalool,ocimene and benzyl alcohol in EAG and behavioural bio-assays.The tea plant volatiles influenced the behaviour of D.baibarana moths,which will greatly contribute to prepare efficient lure for D.baibarana,through the application of a blend of compounds that showed significant EAG and behavioural responses or a blend combined with female-produced sex pheromones.The findings of this dissertation are significant in the development of an eco-friendly control method by application of identified sex pheromone compounds in the field,which will not only contribute to our knowledge but will be helpful to farmers for the control of D.baibarana in tea gardens.