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1、1Lesson9ForensicEntomology(法医昆虫学法医昆虫学)2Activity9.1IntroductionofForensicEntomologyIntroductionofForensicEntomology()(anon-linevideobyMartinHallofNaturalHistoryMuseumofLondon)(suggestedepisodeforvideowatching:00:00-16:27)3TaxonomyofinsectsKingdom(界)Animalia(动物界)Phylum(门) Arthopoda(节肢动物门)Class(纲) Inse
2、cta(昆虫纲)Order(目) X,Y,ZFamily(科) A,B,C,Genus(种)D,E,F,Species(属)G,H,I,4TaxonomyofTrueFliesKingdom(界)Animalia(动物界)Phylum(门)Arthopoda(节肢动物门)Class(纲)Insecta(昆虫纲)Order(目)Diptera(双翅目)Family(科) Calliphoridae(BlowFlies)Sarcophagidae(FleshFlies)Genus(种)Species(属) 5TrueFliesofHongKong6亚麻蝇HouseFly(Parasarcophag
3、esp.)Source:HongKongInsects(2007)(FriendsoftheCountryParks&CosmosBooksLtd)GenusnameSpeciesname7金蝇BlowFly(Chrysomyasp.)Source:HongKongInsects(2007)Source:HongKongInsects(2007)(FriendsoftheCountryParks&CosmosBooksLtd)GenusnameSpeciesname8南亚寡鬃实蝇PumpkinFruitFly(Bactrocera tau)Source:HongKongInsects(2007
4、)(FriendsoftheCountryParks&CosmosBooksLtd)GenusnameSpeciesname9Source:http:/(PestsandDiseasesImageLibrary)Chrysomya megacephala(红头丽蝇)(Bluebottle)10Chrysomya megacephala(FoundinHK)Order(目)Diptera(双翅目)Family(科)CalliphoridaeGenus(种)ChrysomyaSpecies(属)megacephala11Pupa6-10mmEgg2-3mmLifeCycleofaBlowFly(C
5、ompleteMetamorphosis)NOTTOSCALEAdultLarva1stinstar2-4mm2ndinstar5-8mm3rdinstar10-15mmSource:12Remarks:1stinstar1slitwithineachspiracle2ndinstar2slitswithineachspiracle3rdinstar3slitswithineachspiracleAmaggot(larvalstage)Posteriorbluntpart(spiraclesforbreathing)Anteriorpointedpart(mouthforeating)Twos
6、piracles(eachwith3slits)3rdinstar13Thepuparialcaseisusuallyovalinshapeandchangescolourovertime.Thecolourofthepuparialcaseofdifferentblowflyspeciesvaries.14ForensicEntomologyKitSource:(SIRCHIE)15PMI(PostMortemInterval)PMIthetimeelapsedsincedeathPMIusuallycorrelateswiththeageoftheoldestimmatureblowfly
7、stagedevelopingonthecorpse.Dependingonthespeciesoftheblowfliesandtheenvironmentsuchasambientairtemperaturethedevelopmentoftheblowfliesmaytakeseveralweeksormonths.16Adeadbodyisarichsourceforcarrionanimalswhichincludeinsectsandotherarthropodssuchasbeetles.17Effectoftemperatureontherateofdevelopmentofi
8、nsectslInsects(e.g.blowflies)arecold-bloodedanimalsandtheirlevelofactivityincludingthegrowthratedependsonthetemperatureofthesurroundingenvironment.lInsectsrequireacertainamountofheatenergytodevelopfromonestageintheirlifecycletoanotherstage.lTheheatenergyisrequiredfortheenzyme-controlledbiochemicalre
9、actionsofinsects18EffectoftemperatureontherateofdevelopmentofinsectslForfliestodevelopthetemperaturemustremainbetweenaminimumtemperature(minimumdevelopmentalthreshold)andamaximumtemperature(upperdevelopmentalthreshold)foracertainamountoftimelTheminimumthresholdtemperatureformanyflyspecies=10oC(gener
10、ally6oCto10oC)lOneithersideoftheminimumthresholdtemperaturetheinsectwillnotdeveloportherateofdevelopmentwilldecrease19ItisfoundthatrateofdevelopmentofinsectsisdirectlyproportionaltotemperatureThehigherthetemp.,thelesstimeneededforthedevelopmentofinsects2021AccumulatedDegreeHours/DaysADH/ADDAccumulat
11、edHeatacombinationoftemperatureabovetheminimumdevelopmentalthresholdmultipliedbytimeismeasuredasphysiologicaltime(“physiologicalenergybudget”),inunitscalleddegree-days(oD)ordegree-hours(ohr)ADH=(T-Tmin)oCXtime(inhr)ADD=(T-Tmin)oCXtime(inday)22Eachinsectspeciesrequiresacertainnumberofdegree-days/degr
12、ee-hourstocompleteitslifecycleTheamountofheatenergyrequiredforthedevelopmentofaspecificinsectspeciesisconstant(i.e.theADD/ADHfordevelopmentisspecificforacertaininsectspecies)TheADHfortheblowflyPhormia reginaandSarcophaga bullataare5160ADHand8317ADHrespectively23Asthetemperatureincreasesordecreases,t
13、hechemicalreactionsgoverningthegrowthofaninsect(blowfly)increaseordecreasecorrespondingly.However,thetotalamountofADHforablowflytoreachaspecificgrowthstageisthesamewhetherithappensquicklyathighertemperatureorslowlyatlowertemperature.24Forinstance,thetotalADHfortheblowflyPhormia regina todevelopfromt
14、heeggstagetotheendof1stinstar=567.8ADHIftheeggsoftheblowflyarerearedat26.7oC,itwilltake34hoursfortheeggstodevelopintothebeginningof2ndinstar.ADHofthedevelopment=34(hr)X(26.7-10)oC=567.8ADH25IftheeggsoftheblowflyPhormia regina arerearedatalowertemperature,20oC,theflywillneedmoretimetodevelopfromtheeg
15、gstagetothebeginningof2ndinstar.(20-10)oCxYhrs=567.8ADHY=56.7826ReferencefortheDerivationofADD/ADHGennard,D.E.(2007).Forensic Entomology: An Introduction.UK:JohnWiley&SonsLtd.27Activity9.2SimpleCalculationofADD(Quiz1)1.UsingthedatabelowcalculatetheADDofaflyspeciesforday1and2.Minimumthresholdtemperat
16、ure=10oCAveragetemperatureofday1=12oCAveragetemperatureofday2=14oC2.CalculatethetotalADDforthetwodays.28Quiz1(Solution)1.Day1:ADD=(12-10)(degree)x1(day)=2degree-daysDay2:ADD=(14-10)(degree)x1(day)=4degree-days292.TotalADD=2+4=6(degree-days)Remarks:Temperatureusuallyfluctuateswithinaday.Hence,themean
17、(average)temperatureistakenforaday.30Activity9.2(Quiz2)ApplicationofADHtoinferPMIAcorpsewasdiscoveredat10:00am,25September2009.MaggotsofPhormia regina, a blow fly species (atthebeginningstageof2ndinstar),werepresentandcollectedbytheforensic.entomologistat11:00am,25September2009Ittakes34hours(26.7oC)
18、torearPhormia reginafromtheeggstagetothebeginningof2ndinstarinthelaboratory.31lAverageTemp.on25,24,23,22Sept.2009were20oC,21oC,22oC,18oCrespectively.lEstimatethePostMortemIntervalofthedeadbody(i.e.Whendidtheblowflyfirstarriveatthescene?).32Quiz2(Solution)Workingbackwards:TotalADHfromeggstagetobeginn
19、ingstageof2ndinstarofthefly=34hrsx(26.7-10)oC=567.8ADHFor25Sept.2009(0:00am11:00am)ADH=11(hr)x(20-10)oC=110ADHFor24Sept.2009(0:00am12:00midnight)ADH=24(hr)x(21-10)oC=264ADH33TotalADHfor25&24Sept.2009=110+264ADH=374ADHTherefore,therewere567.8374ADH(i.e.193.8ADH)contributedfromdaysbefore24Sept2009LetY
20、bethetimeintervalbetweenthetimetheflylaideggsonthecorpseandmidnight(24:00)of23Sept2009.(22-10)oCxY(hr)=193.8ADHY=16.15(approx.16)Theflylaideggsonthecorpsearound8am(24-16=8)on23Sept.200934ThePMIofthedeadisaround8amon23September2009.35BasicAssumptionsinusingADHtocalculatePMIBlowflieswilllayeggsontheco
21、rpseassoonastheydiscoverthedeadbody.Weatherconditions(e.g.temperature)recordedatasitedistantfromthecrimescenereflecttheconditionsatthecrimescene.Surroundingairtemperaturesarethemajorfactorsaffectingtherateofthedevelopmentoftheblowflies.36Whydoforensicentomologistsneedtocollectandrearblowflies?Aforen
22、sicentomologistwillcollectseveralspecimensofblowflyspeciesfoundatthecrimesceneforlateridentificationatalaboratorybecausethelarvaeofmanyblowflieslookmuchalike.Thelarvaewillberaisedinatemperature-controlledchamberuntilthefliesemergedasadults(fortheexactspeciesidentification)37Manyfactorsotherthantemp.
23、mayaffectdevelopmentofblowflies:BuriedbodiesBodiesfoundinenclosedspaces(e.g.aroom,awardrobe)BodiesexposedtosunBodiesinwaterBodiesinacarBodieswrappedwithacarpet,etc.38SeasonsUrbanvsruralscenes39Activity9.3ApplicationofForensicEntomologytofindthePMIinaCrimeCaseCaseIntroductionAwomansbody(MissDianaWong
24、)wasfoundinabushatnoonon13thOctober2009.Dr.AndyTse,aGovernmentforensicentomologistwascalledbythepolicetohelpinvestigatethecrime.Dr.Tsearrivedatthecrimesceneat1pmthatdayandhistaskwastodeterminethetimesincedeath(PMI,PostMortemInterval)ofthevictim.40AttheCrimeScene1.Dr.Tsecollectedsomeadultblowfliesfly
25、ingoverthecorpsebyahandnetandplacedtheminasmallbottlecontaining70%alcohol.2.Hemeasuredtheairtemperature(=270C).3.Healsofoundthatthereweresomelargemaggotsonthecorpse.Hethencollected2dozenlargemaggotsandputtheminacleanbottle.414.Healsofoundsomepupaefromtheclothesofthevictimandcollectedthepupaeinanothe
26、rbottle.5.Hetooksomesoilfromunderneaththecorpse.6.Henotedthatthecrimescenewaswetandshady.7.Finally,heleftasmallweatherstationatthecrimescenetocollecttheweatherdata(max.andmin.temperature)forthenext7days.42Atthelaboratory1.Theadultblowfliescaughtatthecrimescenewereexaminedanditwasfoundthatallofblowfl
27、iesbelongedtothespeciesChrysomya megacephala.2.Theadultflieswerepreservedin70%alcohol.3.Mostofthemaggotscollectedwereidentifiedvisuallyas3rdinstarmaggots.434.Onedozenofthemaggots(larvaestage)werekilledinhotwaterandthentransferredto70%alcoholforidentificationofspecies.5.Theotherdozenofmaggots(larvaes
28、tage)wererearedat270Candallowedtodevelopandhatch.6.Noemptypupaecasesfound.7.Allcollectedpupaewerealsorearedat270Candallowedtodevelopandhatch.8.Remarks:Thenumberofpupaefoundfromthecorpsewassmallerthanthatofthemaggots.44CaseNoteThelowerdevelopmentthresholdwasconsideredtobe100Cforallspeciesofblowflies.
29、On19thOct2009Dr.Tsecollectedthedatafromtheweatherstationleftatthecrimescene.HeenteredthemaximumandminimumtemperaturesintoTable1a&1bfortheperiod13-19Oct2009.45Themeteorologicalinformation(maximumandminimumtemperatures)inOct2009wasobtainedfromthelocalobservatorydepartmentandthecorrespondingmaximumandm
30、inimumtemperatureswerealsoenteredinTable1a&1b.46Table1aLucilia sericataADHofthe13hours(13thOct.,00:00-13:00)47Table1bChrysomya megacephalaADHofthe13hours(13thOct.,00:00-13:00)48Table2Thedayandtimeofadultflyemergencesfromthelarvaeandpupaebeingrearedinthelaboratoryat270C.Maggotsrearedinthelaboratorysi
31、nce13thOct2009DayandTimeofAdultEmergencesNumberSpeciesofblowfliesCollectedaspupae 21stOct2009(13:00)12Lucilia sericataCollectedaslarvae(3rdlateinstar)29thOct2009(03:21)12Chrysomya megacephala49Table3Developmentaldataforablowfly(Chrysomya megacephala)at270CThresholdMinimumTemperature:100CStageDevelop
32、mentTime(h)ADHEgghatch183061stinstar-2ndinstar305102ndinstar-3rdinstar721224Late3rdinstar1442448Pupationadultemergence2343978Source:J.D.Wells,H.Kurahashi.Chrysomya megacephala(Fabricius)(Diptera:Callipohoridae)development:rate,variationandimplicationsforforensicentomology,JapaneseJournalofSanitaryZo
33、ology,45(4):303-309.50Table4Developmentaldataforablowfly(Lucilia sericata)at270CThresholdMinimumTemperature:100CStageDevelopmentTime(h)ADHEgghatch11.82001stinstar-2ndinstar203402ndinstar-3rdinstar20340Late3rdinstar17.1290Pupationadultemergence2594400TotalADH(eggadultfly)(5570)51Task1Usingtheprovided
34、informationofthecrimecaseandtheadditionalinformationfromTables1a,1b,2,3and4calculatethePMI(PostMortemInterval)ofthevictim(i.e.whendidMissDianaWongdie?)accordingtothedatafromLucilia sericata.52Task2UsingtheprovidedinformationofthecrimecaseandtheadditionalinformationfromTables1-4calculatethePMI(PostMo
35、rtemInterval)ofthevictim(i.e.whendidMissDianaWongdie?)accordingtothedatafromChrysomya megacephala. 53Task1(Solution)Lucilia sericata(i)WhatisthetotalADHforthedevelopment(fromeggtoadultfly)?Ans.:200+340+340+290+4400=5570(ADH)(ii)Howmanydaysdidthecollectedpupaeneedforitsdevelopmentinthelaboratoryuntil
36、adultemergence?Ans.:8days(Thetimegapbetween13thOct2009(1pm)and21stOct2009(1pm)54(iii)CalculatetheADHofthepupationinthelaboratory.Ans.:8(days)X24(hours)X(27-10)(oC)=3264ADH55(iv)HowmanyADHwouldaccountforthepupationinthewild?Ans.:FromTable4theADHforpupation=4400ADH,hencetheADHforpupationinthewild=4400
37、3264=1136ADH56(v)Calculatethedateoftheeggdeposition.Answer:FromTable4theADHrequiredforthedevelopmentfromeggtoendoflarvalstage=200+340+340+290ADH=1170ADH57CheckingTable1aandaddtheADHbackwardfrom13th,12th,11th,10th,9th,etcsuchthatthesumofADHjustexceeds1136+1170=2306ADH58SumofADHfromOct13,1pmto7thOct(0
38、0:00)=2231.5ADHSumofADHfromOct13,1pmto6thOct(00:00)=2657.5ADH2306ADHy/24x426ADH+2231.5ADH=2306ADHy=4.20Theflydepositedtheeggson6thOct2009(19:48)(usingthedata24-4.20)59Lucilia sericata60(vi)WhendidMsDiannaWongdie?MsDianaWongdiedon6thOct2009(19:48)(i.e.8pm).61Task2(Solution)Chrysomya megacephala (i)Wh
39、atisthetotalADHforthedevelopment(fromeggtoadultfly)?(SeeTable3)Ans.:306+510+1224+2448+3978=8466(ADH)(ii)Howmanyhoursdidthecollectedlarvae(at3rdlateinstar)needforthepupationstagebeforeemergenceasadultsinthelaboratory?(SeeTable2forthetimegapbetween13thOct2009(1pm)and29thOct2009(3:21)62Answer:15x24+14+
40、21/60=374.35hours63(iii)CalculatetheADHrequiredforthestageofpupation(3rdinstar)andemergenceasadultsinthelaboratory.64Answer:ADHrequiredforthestageofpupation(3rdinstar)andemergenceasadultsinthelaboratory=374.35(hours)x(27-10)(oC)=6364ADH65(iv)CalculatetheADHoftheeggandlarvae(1stand2ndinstar)inthewild
41、.Answer:8466ADH6364ADH=2102ADH66(v)Whatisthedateofeggdeposition(Chrysomya megacephala)onthecorpse?67Answer:lCheckingTable1bthedateofeggdepositioncanbefoundbyaddingtheADHinthewild(13th,12th,11th,10th,9thofOct,etc.)andcomparingthesumoftheADHwith2102ADHlCalculationofADHfrom13thOct(13:00)to7thOct388.8x(
42、y)/24+(352.8+357.6+313.2+302.4+297.6+219.05)ADH=2102ADHy=16Chrysomya megacephalalaideggsonthecorpseon7thOct(08:00)68CalculationofADHfrom13thOct.(13:00)to7thOct.(08:00):388.8x(y)/24+(352.8+357.6+313.2+302.4+297.6+219.05)ADH=2102ADHy=16(i.e.Chrysomyamegacephalalaideggsonthecorpseon7thOct.(08:00)69(vi)
43、WhendidMsDiannaWongdie?Answer:7thOct2009(8am).70Activity9.4DiscussionQuestions1.WhatfactorswouldaffectthereliabilityoftheabovemethodsusedtocalculatePMI?71Answer:EnvironmentalfactorsSeasonalchangesDailytemperaturesSunexposureDeadbodyinsideoroutsideabuildingDeadbodyimmersedinwaterornotDeadbodyinurbana
44、reaorinruralareaDeadbodyburiedornotDeadbodywrappedinsideablanket72DiscussionQuestions2.DothePMIresultscalculatedfromthe2differentspeciesofinsects,Lucilia sericataandChrysomya megacephala supporttheestimatedPMIofthevictim?Hint:Lucilia sericataiscalledaprimaryblowflysinceitwillfirstlayeggsontoadeadbod
45、ywithin4hoursofapersondying.Chrysomya megacephalaiscalledasecondaryblowflysinceitwilllayeggsontoadeadbodywithin4daysofapersondying.73Answer:TheestimatedPMIsfromTask1(6thOct2009(8pm)andTask2(7thOct2009(8am)arereasonableandhencethefinalestimatedPMIofthevictimshouldbe6thOct2009(8pm).74DiscussionQuestio
46、ns3.Whatisthepurposeofusingtwospeciesofinsects,Lucilia sericataandChrysomya megacephala tocalculatethePMIofthevictim(i.e.CanweusejustonespeciesoftheinsectstocalculatethePMI)?75Answer:WeusethedataofthetwospeciesofinsectstocalculatetheestimatedPMIbecausethetwoPMIscalculatedfromthetwospeciesofinsectsca
47、nprovideuswithcounter-checkoftherealPMI.IfthePMIcalculatedfromthesecondaryblowflyisgreaterthanthatfromtheprimaryblowfly,theestimatedPMIsarenotreasonableandsomethingmighthavegonewronginthedatacollection,methodologyand/orcalculationinvolvedintheforensicinvestigation.76Remarks:ThesuggestedsolutionsofActivity9.3werecalculatedbyreferencetothemethodsillustratedinASISTMForensicInvestigations:ForensicEntomology(CentreforLearningTechnology,FacultyofLife&PhysicalScience,TheUniversityofWesternAustralia):
