FromanIbrareprint(1993)byIngemarFriesattheattheDepartmentofEntomology,SwedishUniversityofAgriculturalSciencesEffectsfromNosemaapisonApismellifera
Oncolonylevel
increasedwintermortality；reducedhoneyyield；poorspringbuildup.
Onindividuallevel
reducedlifespan；fasterphysiologicalageing；atrophyofhypopharayngealglands；supersedureofinfectedqueens；aggrevatesdysenterea.
ThetracesofNosemacanbestbeseeninthespringwhenbeesareoldandweakafterwinter.Herearethefeacesontopofframes.Thebeescouldnotgetouttodeficateduringwinter.Whenthebeestrytocleanitupmoreindividualswillbeinfectedbythespores.
TheNosemasporesentersthehoneybeethroughthefoodcanal,andtheygerminateundertheinfluenceofthegutjuices.
Diagnosis
Diagnosisisdependentonmicroscopicexaminationoftheventricularcontentand/orfeacalmatter.Nospecificoutwardsignofdiseaseispresent,althoughindissectionstheventriculusoftenappearswhitishandswolleninalatestageofinfection.Thediseaseiseasilydetectedinsamplesofwholebeesmaceratedinwater.Thefluidisexaminedunderlightmicroscopeat250-500xmagnificationwherethecharacteristicNosemasporescanbeobserved.
Nosemasporestogetherwithapollengrain.
ThelifecycleofNosema.
Thelevelofinfectionfoundinacolonyishighlyvariable.Theseasonaltrendoftypicalinfectionsexhibitslowlevelsduringsummer,asmallpeakinautumn,andaslowriseofinfectionduringwinter.Inthespringthelevelofinfectionincreasesrapidlyasbroodrearingstartsandwhileflightpossibilitiesarestilllimited.
Newlyemergedbeesarealwaysfreefrominfection.Flightbeescollectedattheentrancearemoreinfectedthanhousebees.Infectedbeeshasatendencytocongregateinthewarmerpartsofthehive.
AlladulthoneybeesaresusceptibletoNosema.Agreaterproportionofworkerbeesbecomeinfectedthandronesorqueens,probablyduetothecombcleaningactivitiesofyoungbeesinwhichdronesandqueensdonotparticipate.Nosemainfectedbeesdonotattendorfeedthequeentothesameextentashealthybees,whichhelpsthequeentoescapeinfection.Whenthequeenbecomesinfectedherovariesdegenerateandheregglayingcapacityisreducedduetoatrophyoftheoocytes.Queensthatbecomeinfectedbytheparasiteduringthebroodrearingseasonaresupersededbythebees.
Nosemainfectionsarefrequentlypresentinmostapiarieswithoutcausingsignificantdamage.Itisaggravatedbystress.Colonydisturbanceinwinteraswellasduringsummerincreasetheriskofdetectablediseaselevel.
AdditionofproteintothebeespromotesthedevelopmentofNosemaincageexperimentssuggestingthatsupplementaryfeedingwithproteininthespringshouldbedonewithcaution.However,managingcoloniestoavoidproteindeficiencyhasalsobeenshowntobebeneficial.Supplementaryfeedingofproteinormovingtoareaswithagoodsupplyofpollenreducestheinfectionlevelininfectedcolonies,probablyduetoalargernumberofbeesbeingproduced.
Diseaseprevention
Nosemadiseasecanbetransmittedwithwax.ColoniestransferredinearlysummertowaxcontaminatedwithNosemasporesoftendevelopNosemadiseasethefollowingspring.Topreventdiseaseoutbreak,beescanbetransferredtonon-contaminatedequipmentearlyintheseason.However,goodresultsincoldclimateshavealsobeendemonstratedbywinteringbeesonlyonfoundation.Reportsfrommiddle-Europeonfoundationwinteringislessfavourable.
Robbingofhoneyfromweakcoloniesspreadsthediseasesincethestoresofheavilyinfectedcoloniesoftencontainsspores.OtherfactorsthatcontributetothespreadofNosemasporeswithinthebeecolonyincludemanagementwherebeesarecrushed.Theliquidremainsofcrushedbeesarereadilyingestedbyotherbees.
Toreducetheneedforchangingandmeltingcombs,aceticacidfumigationofcombshasbeenusedtokillNosemaspores.Ethyleneoxidehasalsobeenfoundeffectiveindecontaminatingequipment.Heattreatmentin49Cfor24hourscanbeusedtokillthespores,andsocangammaradiation.湖北天马养蜂场，加我们的微信一起学养蜂。
AsimplewaytomakecombsfreefromviableNosemasporesistouseaceticacid.A60%solutioncanbeusedforthispurpose,withapproximately2mlperlitrevolumetobetreated.Theacidisputontopofastackofboxesinanemptyboxthatisclosedwithalid.Theacidisallowedtoremaininanopencontaineronthecombsuntilithasevaporatedoruntilthecombsaretobeusedagain.
TheantibioticFumagillinkillstheactivestagesofNosema,butnotthespores,andit'seffectdiminishovertime.Experimentsshowthatevenwhenfumagillinisadministeredbothintheautumnandspring,infectionlevelsmightstillbeharmful.Winteringbeesoncleanordisinfectedcombsarethereforadvisablewithorwithoutmedication.