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The Research Of Trapping Techniques And Antennal Transcriptome On Olfactory Genes In Drosophila Suzukii Matsumura

Posted on:2019-05-22Degree:DoctorType:Dissertation
Country:ChinaCandidate:P M CaiFull Text:PDF
GTID:1363330572953963Subject:Agricultural Entomology and Pest Control
Abstract/Summary:PDF Full Text Request
Drosophila suzukii Matsumura originated from Southeast Asia,recently had invaded many countries and areas in America and Europe and caused severe economic loss to the local fruit industries.Drosophila suzukii have emerged as a cosmopolitan pest,but the researches on this pest in China is still at initial stage and has not attracted enough attention.Hence,its risk in China were quantitatively and qualitatively analyzed for arousing the attention of the relevant departments in China;The responses of D.suzukii to different colors,host plants and their volatiles and protein bait were determined to develop a series of effective,species-specific,and steady trapping techniques for attracting this pest;The antennal transcriptome of D.suzukii females and males were sequenced and analyzed to establish foundation for researching molecular mechanism of olfactory reception in this pest.The main results are listed as follow:1.Its risk in China was qualitatively and quantitatively analyzed based on the procedure of pest risk analysis(PRA)of international standards for pest measurements(ISPM)and the model mainly focused on five aspects—potential damaged degree,spreading and colonization possibility,economical importance of damaged host plants,the current distribution and risk management difficulty in China.The result shows that the comprehensive risk value of this pest is 0.84791,which means that D.suzukii is a highly dangerous pest in China.Last,the relevant risk management measures were built up to reduce the risk at the accepted levels.2.The behavioral responses of D.suzukii female and male adults to a variety of colors in no-choice and choice tests under laboratory condition and the attractiveness of trap bottles with various colors to D.suzukii in field were investigated.The results showed that the spotted wing drosophila females and males were significantly attracted to purple,black,and red in no-choice tests and choice assays under laboratory and field conditions.Moreover,D.suzukii males and females adults responded identically to these tested colors.This research aimed at providing references for optimizing high-attractiveness and species-specific traps for spotted wing drosophila,contributing to better understanding the role of vision in D.suzukii host orientation.3.The ovipositional characteristics,olfactory responses and ovipositional preference of this pest to host fruits like cherry,strawberry,grape,blueberry,apple and banana,to attacked by D.suzukii were determine.The results shows that 5th to 7th day after adult emergence is the spawning peak stage of this pest,the flies at this stage laid most eggs at 14:00 to 16:00.In a six-choice olfactometer study,D.suzukii female responses to the six tested fruit types were ranked in the following order:strawberry= cherry>banana= apple= blueberry=grape,whereas in Y-tube olfactometer study,the ranking were listed as following:banana=cherry>grape>strawberry=blueberry=apple;however,in no-choice and choice tests,the ovipositional preferences of D.suzukii for these tested fruits were ranked as follows:cherry>strawberry>blueberry>banana>grape>apple.Furthermore,we reconfirmed that D.suzukii females showed equal olfactory preference to either fresh or rotten fruit,this pest targets rotten fruit mainly for feeding and targets ripe fruit for oviposition.Moreover,D.suzukii females preferred fruits like cherry,blueberry and grape with intensive mechanical damage.4.The composition of fruit volatiles from different host plants of D.suzukii were analyzed by GC-MS.The results shows that the blueberry volatiles consist of 21 compounds,the most compounds is ethyl hexanoate(29.63%),followed by trans-2-hexenal(12.20%)and isoamyl acetate(11.42%);the cherry volatiles consist of 18 compounds,the most compounds is(E)-2-hexenal(35.52%),followed by isoamyl acetate(13.60%);the strawberry volatiles consist of 20 compounds,the most compounds is ethyl hexanoate(42.41%),followed by methyl hexanoate(7.27%).Moreover,the most compounds in blueberry and strawberry is esters,alcohols come second;the most compounds in cherry is aldehydes,esters come second.5.The attractiveness of a certain proportion of ethanol and acetic acid mixtures combined with eleven volatile compounds from host fruits(hexanal,2-heptanone,trans-2-hexenal,linalool,ethyl acetate,methyl salicylate,hexanoic acid,(a)-ionone,hexanol,trans-2-hexen-1-ol and isoamyl acetate)to D.suzukii adults were determined respectively to find out the compounds with synergism for ethanol and acetic acid mixtures.Moreover,the selected compounds were evaluated by the orthogonal experiment to develop an optimal lure with the best attractive efficacy.The result showed that the ethanol and acetic acid mixtures combined with a certain concentration of hexanal,2-heptanone,trans-2-hexenal,linalool had significant synergism effects in attracting D.suzukii adults.Furthermore,the various volatiles were treated as solute and the ethanol and acetic acid mixtures were treated as solvent,the result from orthogonal experiment showed that mixing 1/5000 of hexanal(Vsolute/Vsolution),1/500 of 2-heptanone,and 1/5000 of linalool into ethanol and acetic acid was proved to have best attractiveness to D.suzukii adults with the highest proportion of flies captured(86.4%).6.We evaluated a protein bait based on enzymatically hydrolyzed beer yeast and two widely used baits including a sugar+vinegar+wine(SVW)mixture and apple cider vinegar(ACV)for their ability to trap D.suzukii in the laboratory and outdoors.The protein bait was a more attractive lure than the other tested baits,with the protein bait capturing significantly more female and male adults at different developmental stages than the other baits,and exhibit equal attractiveness to D.suzukii females and males.Furthermore,the protein bait with 20%vinegar attracted significantly more adult flies than the other baits,and the protein bait without dilution attracted the most adults.Except for the addition of 0.05%spinosad,increased insecticide content in protein bait reduced its attractiveness to adult flies.Moreover,we found that D.suzukii has a bimodal activity pattern in visiting protein bait,where maximum activity occurs during 8:00 to 10:00 A.M.and 14:00 to 16:00 P.M.Other sensory played an important role in detecting the chemicals emitted from the protein bait,as the number of intact flies that responded to new protein bait was significantly higher than the number of flies without antennae that responded,but 13.6%of defective flies still responded to the protein bait.Our results suggested that the protein bait based on spent brewery yeast could be a promising alternative for D.suzukii population monitoring as well as for managing this pest,providing guidance for using this protein bait as a component of IPM.7.The antennal transcriptome of D.suzukii females and males were sequenced through an Illumina HiSeq platform and subjected to bioinformatics analysis.A total of 38.1 Gb clean data were obtained,and the mean clean reads were 42.31 M with 16414 genes and 16416 new transcripts being identified.All genes in the antennal transcriptome of D.suzukii adults were annotated against the public databases.The results shows that most genes(15572 genes)were annotated to Nr database,followed by KEGG database,16687 genes were assigned to 44 known second level metabolic pathways.The least genes were annotated to GO database,and 8254 genes were divided into 22 subclass.In molecular function,the most genes were annotated to the function of binding,catalytic and transporter activity.By further screening,218 olfactory-related genes of D.suzukii including 52 odorant binding protein(OBP)genes,71 chemosensory protein(CSP)genes,78 odorant receptor(OR)genes,14 ionotropic receptor(IR)genes and 3 sensory neuron membrane protein(SNMP)genes were identified.The genes with different expression levels were analyzed using DEGseq.1723 genes were up-expressed and 1311 genes were down-expressed in female antennae compared with males.Total 26 olfactory-related genes were identified including 10 OBPs,10 CSPs and 6 ORs,no differences were found in IRs and SNMPs.This study obtained the antennal transcriptome data of D.suzukii for the first time,aim at providing the basic data and candidate target genes for biological control of this pest,establishing foundations for the research of olfactory reception mechanism and olfactory gene function analysis in D.suzukii.
Keywords/Search Tags:Drosophila suzukii, vision, olfactory, protein bait, transcriptome
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