VarroatreatmentinDenmarkVarroadestructor

Thevarroa-miteisnowfoundinallmostalldanishbeecolonies.Varroa-destructorisaparasite-livinginbeecolonies-killingthecolonyinfewyears.Onthenextpagesyouwillfindthedanishstrategyfightingthevarroa.Thisisthethirdinaseriesofpamphletsonvarroa,revisedaccordingtolatestfindings.

TheDanishBeekeepersAssociationandProjectGroupBeekeepingcarryoutresearchindependentlyandjointlyandtheresultsofthisresearch,togetherwithinternationalfindingsformthebackgroundforthispamphlet.TheenglishpartistranslatedfromDanishbyJamesClaxton.

VarroainDenmark

VARROAINDENMARKReadhereonthebackgroundfortheDanishvarroatreatmentdirective.BytheConsultantsinDenmark’sBeekeepingAssociation

THEEXPERIENCESOFARSincethevarroamitewasfirstfoundonAlsin1984,greatdevelopmentinbiologicalmeansoffightingthemitehavetakenplace.Throughtheyearsexpertisehasbeencollectedamongstresearchers,consultantsandbeekeepers.Wearetheonlybranchofagriculturewhichnowcansaythattheentirebusinesscanmanagewithouttheuseofpesticides.Thisisinkeepingwiththedevelopmentthatsocietywishesfortheproductionoffoodstuffs.THEDANISHSTRATEGYBeekeepersinDenmarkhavedecidedthathoneyandwaxshallbeproducedwithouttracesofmedicineandpesticides.Thisisoneofthemostimportantaimsbehindthechosenstrategyincombatingthevarroamite.ItispartoftraditionwhichhascharacterisedDanishbeekeepingthroughgenerations.Wehaveneverusedmedicineandpesticidesintreatingbeedisease,eventhoughtheseareusedextensivelyinothercountries.Itisslightlymoretroublesometoconvertagainstattacksoffoulbrood,ortoreplaceframesinordertocontainnosema.Butitworksandwecreatepureproducts.Likewiseitissaidthatitismoretroublesometocombatthevarroamitethroughtheremovalofdronebrood,andtheuseoflacticandformicacidetc.butitworks,andwecancontinuetobeproudofourproducts.PESTICIDE-FREEHONEYANDWAXCOMMANDHIGHERPRICESItisimportanttomaintainDanishhoneyasapureproduct.Itisimportanttokeepthepriceofourownhoneyhigherthanthepriceofimportedhoney.Thereisalsoalargemarkedforpurebeeswax.Thecosmeticsindustrywillnottoleratetracesofpesticideinthewaxtheyuse.Danishbeekeepersproduceasurplusofbeeswax.Goodpricesforwaxprovidesforabettereconomyinbeekeeping.OXALICACIDOxalicacidhasbeenusedbyDanishbeekeepersoverthelastfewyearsinvarroatreatment.Unfortunately,itnowappearsthatthisproductdoesnotfigureintheso-calledEUpositivelistofproductsthatmaybeusedinthetreatmentofbeedisease.Thereforetheproductisnotrecognisedinvarroatreatmentatthemoment,butlacticandformicacidsare.Itistobeexpectedthatoxalicacidwillbeputonthepositivelistinthenearfuture.REVISEDPAMPHLETThisisthethirdinaseriesofpamphletsonvarroa,revisedaccordingtolatestfindings.TheDanishBeekeepersAssociationandProjectGroupBeekeepingcarryoutresearchindependentlyandjointlyandtheresultsofthisresearch,togetherwithinternationalfindingsformthebackgroundforthispamphlet.Developmentinthetreatmentcontinuesstrongly.Itistobeexpectedthatthiseditionshallberevisedwithinthenextthreeyears(2001).SUPPORTFORTHESTRATEGY

TheMinistryforFoodhaspassedthe“StrategyforVarroaTreatment1995-1999”whichwasproducedbyTheDanishBeekeepersAssociationandTheNationalResearchBody.Thestrategyincorporatesresearch,trialsandadvisoryservicestobeekeepersonthenecessarytreatment.TheresearchiscarriedoutbyDenmarksAgriculturalResearchBodyandProjectGroupBeekeeping.Theytakepartindiagnosticandinformationservices.TheMinistryforFoodhasprovidedfinancialsupporttotheAssociationinordertoemployconsultantstocarryoutresearchandtoadviseonvarroatreatment.

FINDOUTMOREABOUTVARROAVarroa-instructors:Throughoutthecountrythereareover100Varroainstructors.Thesearebeekeeperswhohavepromisedtohelpcolleagueswithadviseonvarroatreatment.Theyhavegainedpracticalknowledgeonvarroamitesandtheirtreatmentoncourses.YoucanmeettheVarroainstructorsinyourlocalassociations.Alistofinstructorshasbeensenttoallassociationsandistobefoundontheinternetonudv9.osg.dk/html/vs4CONSULTANTSConsultantswillgiveadvisetoallbeekeepersonvarroatreatmentwhetherornottheyaremembersofDenmarksBeekeepingAssociation.PROJECTGROUPBEEKEEPINGResearchersfromProjectGroupBeekeepingholdbeediseasecoursesaswellastakingpartincoursesandmeetingsintheassociations.Youcanmeetthemthere.ADVISORYSERVICESTOALLBEEKEEPERSThispamphletisintheDanishversionsentouttoallassociationmembers.Itisalsosenttoalloutletsforbeekeepingequipmentandtothevarroainstructors.Itisourhopethatitreachesallbeekeepers.Shouldyouknowbeekeeperswhohavenotreceivedthispamphlet,callTheDanishBeekeepersAssociationat(0045)57865470,andwewillbepleasedtosendoutextracopies.

VarroadestuctorTHEVARROAMITEThevarroamiteisanorganismwhichisoptimallyadaptedtothehoneybeeByFlemmingVejsnæsHISTORYThevarroamite(Varroajacobsoni)comesoriginallyfromAsia.IthaslivedhereforthousandsofyearsasaparasiteontheAsianhoneybee(Apiscerana).Herethereisaharmonybetweenhostandparasite,whichresultsinnoharmtothebeecolony.Thesecolonieslivewiththevarroamite.DEFENCEMECHANISMSThevarroamitebitesintotheadultbeesandpupae,andproceedstosucktheirblood.Thevarroamitecanonlypropagateitselfonthesealedbrood.TheAsianbeehasdevelopedsomedefencemechanismstowardsthevarroamite.Thevarroamiteonlypropagatesitselfonthedronebrood,whichisonlyproducedinalimitedamountandperiod.IthasbeenobservedthattheAsianbeeiscapableofremovingthevarroamitefromitselforfrombrood.TheseandothermechanismsarenotpresentintheEuropeanhoneybeespecies.Herebeecolonieswillcollapseinthespaceofafewyears.Thenumbersofmitepresentgoesoutofcontrol.FOUNDINEUROPEThevarroamitewasfirstfoundinEuropeinBulgariain1971.VarroaisnowfoundinallEuropeancountries,withtheexceptionofIreland(aspublished1998).VarroawasfirstdiscoveredinDenmarkin1984,andhastodayspreadtoallDanishbeecolonies,withthesingleexceptionofLæsø.Asaresultofthespreadofvarroagreatlossesinbeecolonieshavebeenrecordedinallareasirrespectiveofmethodsofcontrol.APPEARANCEVarroabelongstothearachnids.Theyhavefourpairoflegs,asagainstinsectsthreepair.Theyhavenonormaleyes.Thesearenotnecessaryastheyliveinthedarknessofabeehive.Ontheotherhandtheyhaveso-calledpointeyes,whichcandistinguishbetweenlightanddark.Theyhavemanyfinetouchandsmellsensesontheirfrontlegs.Themitehasanovalformandcanatfirstglanceresemblelinseed.Theyarelightbrownatanearlystage,anddarkbrownwhenmature.Amaturefemalemeasures1.5-1.7mm.Themalesaresmallerinsizeandlighterincolour,andareonlytobefoundinsealedcells.Theydiewhenthebeecrawlsoutofthesealedcell.LIFEThevarroamitecanonlypropagateonbrood,sealedintheircells.Afemalevarroamitestaysonthehousebeesfor5-6days.Thereaftershemovesintotheworkercells,whichareabouttobesealed.Shemovesintothesecellsfromabout15hoursbeforetheyaretobesealed,andintothedronecellsabout50hoursbeforesealing.Heresheentersandlaysuptoseveneggswithinthespaceof36hours.Thefirsteggdevelopintoamalemite,whiletheremainderdevelopintofemales.Matinggoesoninthesealedcellandisaraceagainsttheperiodofsealing:onlymatedfemalessurvive.Malesandunmatedfemalesdiewhenthebeescrawloutofthesealedcells.Thereforeonlyanaverageof1.6matedfemalesemergefromaworkercell(theperiodofsealingbeingca.12days)whileabout3matedfemalescomefromadronecell(theperiodofsealingherebeing14days).Avarroafemalelivesnormallyforonlyonegeneration(onaverage1.6)butinlaboratoryconditionstheyhavelivedforupto7generations.THESPEEDOFDEVELOPMENTAttemptstosetuprulesforcalculatingtherateofdevelopmentofthevarroamitehavebeentried.Weknowtodaythattheserulesvaryagreatdealinpractice.Mitedevelopment•Numbersdoublepermonthintheegglayingperiod•Ahundredfoldincreaseperseason•Atenfoldincreasefromyeartoyear•50-90%dieinwinterThismeansthatifabeecolonystartedwithasinglemiteinyear1,thecolonywouldcollapsewithinthenextthreeyears,withamitepopulationofbetween5000and10,000mites.REINVASIONThegreatestproblemincombatingthevarroamiteisthatourbeesflyfreelyaboutwithalargeactionradius.Thismeansthathealthybeecoloniescanrobanddestroyfamiliesthathavebeenhardhitbymiteattackinaveryshorttime.Whathappenshereisthatthemitessimplyjumpontotheinvadingrobber-andhealthybees-orthatthebeesbeingrobbedflybackwiththeirmitestothenewbeehives.Badlydamagedbeesalsolosetheirabilitytoorientate.Thissituationcanresultinthereinvasionofacolonyinthesummerperiod,withuptoseveralthousandmites.Reinvasionisaproblemespeciallyinareaswheretreatmenthasnotbeenextensiveenough.ThisisthemainreasonwhyvarroatreatmentmustbesupplementedbyalatetreatmentasthisreinvasioncancontinueallthewayintothemonthofOctober.COLLAPSE

Earlieritwasreckonedthatadamagethresholdof12,000-20,000miteswereneededbeforethecollapseofacolony.However,overthelatteryearsithasbeenshownthatthedamagethresholdliessignificantlylower,closerto5,000mites.Thisisduetothepresenceofopportunisticdiseaseswhichfollowinthewakeofvarroadamage,intheformofvirus(Seebelow).TOLERANTBEESTRAINSTheAsianBeeisvarroatolerant.Ithasdevelopedseveraldefencemechanismstowardsthevarroamite.MuchresearchhasbeencarriedoutinanattempttodeveloparesistantEuropeanBee.Asyetunsuccessfully.Onecanobservethatinthevariousbreedingprogrammescarriedoutovertheworld,somebeestrainstacklevarroabetterthanothers.However,atoleranceequaltotheAsianBeeisyetwishfulthinking,andliesfarintothefuture.

VarroatreatmentinDenmarkVARROATREATMENTINDENMARK-anoutlineoftheNationalStartegyByHenrikHansen&CamillaJ.BrødsgaardDanmarksJordbrugs-Forskning,ProjektgruppeBiavlThevarroamite,togetherwithattacksofvirusarethecauseofvarroadisease.TheDanishstrategyforcombatingthevirusisbuiltonaneedbasedstrategywithouttheuseofpesticides.Treatmentisbasedonacombinationoftechnicalbeekeepingandphysicalmethods.Furthermore,organicacidswhichoccurnaturallyinhoneyareusedanddonotgiveproblemsofresidues.Experiencehasshownthataneffectivetreatmentcanbecarriedoutusingthisstrategy,anditcanbecombinedwithaneconomicallyviablehoneyproduction.Atthesametimebeekeepingproductscanbekeptfreefromproblematictracesofpesticides.Ifaneffectivetreatmentagainstthevarroamiteisnotcarriedoutthecolonieswilldieduetovirusattacks.VIRUSInrecentyearsinDenmark,andthroughouttherestofEurope,therehavebeengreatproblemswithsecondaryvirusinfectionsinconnectionwithVarroaattack.Theseattackshaveledtothedeathsofmanybeecolonies.AtthepresentmomentwehavediagnosedthefollowingconditionsinDenmark:AcuteParalysisVirus(APV),DeformedWingVirus(DWV)andSackBroodVirus(SBV).InSwedenUnclearWingVirus(CWV)(Nordström,1997)andinEnglandSlowParalysisVirus(SPV)(Ball,1997)havebeenfoundinconnectionwithvarroaattacks.InDenmarkproblemswithDWVandAPVhavebeenregistered.Thesevirusattackscannotbetreated.Howeveroutbreakscanbepreventedbytreatingforvarroaingoodtime.ThevarroamitecanspreadAPVtobroodandadultbees.Thestingoftheadultbeecanbethecauseofthevirusoutbreak.Anoutbreakwillresultinbroodbeingbadlycaredfor,andfortheadultbeesthelossoftheirorientationabilities.Thusspreadingofthevirustootherbeecoloniesoccurs,wheninfectedbeesbegtheirwayintonewhives.OutbreaksofAPVcanbeexpectedinDenmarkatthemomentwiththepresenceof2,000-5,000mitesinacolonyandwillresultinthedeathofthecolony.OutbreaksofDWVcanbeexpectedfarearlierthanthatofAPV.WhenthesymptomsofDWVarerecognised,treatmentforthevarroamiteshouldbecarriedoutatonce.NEEDBASEDTREATMENTInordertotreatthevarroamiteeffectivelyitisnecessarytocarryoutamonitoringofthemitepopulationinthecolony.Monitoringiscarriedourbylayinganinsertatthebottomofthehive,andcountingthenumbersthatfalldown.Ofcoursehivetypeswhichhaveaspeciallydesignedbottomformitecountingcanalsobeused.IthasbeenshownunderDanishconditionsthatthereisalinearconnectionbetweenthenaturalmitedeathascountedonaplasticinsertandtheamountofvarroamiteinthecolonyandbrood.Recentstudieshaveshownthefollowingconnectionbetweenthenumberofmitesinacolonywithaminimumofahalfframeofsealedbroodandtheaveragenumberofmiteswhichfalldownontheplasticinsertperday,inthecourseofaweek.Totalnumberofmitesinacolony=120Xaveragenumberofmitesperday.Onecancalculateatthesametimethattheamountofmitesinacolonywithbroodwilldoublemonthly,andthatbetween50and90%ofthemwilldieinwinter.Inareaswithinadequatetreatmentofvarroamiteahugeinvasioncantakeplacefromcoloniesonthevergeofcollapse.Itis,therefore,necessarytomonitorseveraltimesthroughaseason.Thetimesaredependentonhoweffectivelyonesneighbouringapiarieshavetreatedtheircolonies.ThefirstmonitoringshouldtakeplaceattheendofMay,andshouldalsotakeplaceattheendofJune,JulyandAugust.Ifitisnotpossibletocarryoutthesefourmonitoringsthen,asaminimum,monitoringshouldbecarriedoutattheendofJuneandtheendofAugust.Asfaraspossiblemonitoringshouldbecarriedoutonallcoloniesintheapiary.AnaveragecolonywithanoutbreakofAPVwillprobablydiewhenthereareabout5,000mitespresent.Inordertosavethecolonytreatmentoughttobecarriedoutmuchearlier,whenthereisamaximumof1,000mitespresent.If,onaverage,2mitesperdayfallontotheinsertinthecourseofaweek’scountattheendofMay,thentreatmentshouldbecarriedoutatthelatestattheendofJuly.Itisnecessarytotreatallthecoloniesinanapiary.IfalacticacidtreatmentiscarriedoutintheendofOctober,thenthenumbersoffallenmitescanbecountedafterwards.Seenoutfromtheexpected90%effectoftreatment,theamountofsurvivingmitesinthecolonycanbeestimated.Coloniesshouldbewinteredwithamaximumof50-70mites.TECHNICALBEEKEEPINGANDPHYSICALMETHODSTechnicalbeekeepingandphysicalmethodshavethegreatadvantagethatoneavoidstracesofchemicalsinhoneyorwax.RemovalofDroneBroodThevarroamitepreferstopropagateincellswithdronebrood.Withtheremovalanddestructionofsealeddronebroodonehasagoodsupplementtoothermethods.Thismethodought,therefore,tobepartoftreatmentingeneral.CreationofNucleiItisveryimportantthatonecontinuestomaintainthedesirednumberofproductivecolonies.Thiscanpartlybesecuredbycreatingnucleieachyear.TheseshouldbeestablishedinJuly.Sincehoneyisnottobeharvestedfromtheminthefirstyear,

theycanbetreatedwithlacticacid.HeatTreatmentHeattreatingofsealedbroodprovidesaneffectivetreatmentagainstthevarroamite.Thistreatmentcanbecarriedoutinathermostaticallycontrolledbox.InGermanyanumberofproductshavebeendevelopedspecificallyforthistreatment,e.g.“Apitherm”.Inordertoobtainthebestresults(closeto100%moralityofmites)andtocreatetheleastdamagetobrood,framesshouldbetreatedforthreetofourhoursat44°C,dependingontheapparatusinuse.Treatmentshouldbecarriedouttwoormoretimesovertheperiodinwhichbroodarepresent.Ifonechoosestotreattwice,thenthefirstattheendofMayandthesecondattheendofJulywouldbeappropriate.

QueenCagingQueencagingisaneffectivetechnicalbeekeepingoperation.Theeffectivenessofthiscanbeenhancedifapairofsealedbroodframesareremovedsimultaneouslyatthebeginningofsummer.Queencagingcanbeusedincoloniesnotintendedforsettingoutonheather.TheQueencanbecagedinacassetteonaframeforlessthanfourweeksfromthemiddleofJune.Theframeisthenusedasabaitforvarroamitesandshouldbechangedeveryeighttoninedays.Theremovedframesshouldbedestroyed.Ifonewishestosavethebroodintheframes,thentheycanbetreatedwithlacticacidorusingheattreatment.CHEMICALPRODUCTSUSEDINTREATMENTPharmacologicalproductsusedintreatingvarroamiteareclassifiedasveterinarymedicines.AtpresenttherearenorecognisedveterinarymedicinesforthetreatmentofVarroainDenmark.Thereisaso-called“positivelist”ofproductsontheEUCommissionforuseinthetreatmentofanimals(honeybeesincluded)destinedforhumanconsumption.Lacticandformicacidsareonthispositivelist.Itisthereforelegaltousetheseacidsinthetreatmentofvarroamites.Oxalicacids,ontheotherhand,isnotonthislist,andcannotbelegallyusedinthistreatment.FORMICACIDFormicacidisusedintheautumnafterthelasthoneyisharvested.Itismosteffectivewhenusedwhilethereisbroodinthecolonyshortlyafterthehoneyisharvested.ThismeansthattreatmentisoftencarriedoutattheendofJulyoratthebeginningofAugust.Ifthebeesaretobemovedtoheather,thentreatmentshouldbecarriedoutshortlyaftertheendofthishoneyflow.Formicacidtreatmentcanbecarriedoutusingadishcloth,orathinfibreboard,towhichisadded60%lacticacid.Kråmerboards,whicharethickwoodfibreboards,canalsobeused,towhichformicacidinan85%solutionisadded.Thefibreboardsareplacedinperforatedplasticbags.Thereareseveralformicacidevaporatorsavailable,allofwhichareusedbesidethehivewall.Honeyhasanaturalformicacidcontent.Afterformicacidtreatmenttherewillbeaslightlyhighercontentofformicacidintheremaininghoney.However,thecontentstilllieswithintheacceptablenaturaloccurrence.Verylittleformicacidhasbeenfoundinwaxaftertreatment.LACTICACIDThevarroamiteisverysensitivetowardslacticacidtreatment.Inordertoavoidtracesoflacticacidinthehoney,adead-lineofeightweekspriortothehoneyharvestshouldbeobservedfortreatment.Thelacticaciddoesnotpenetratethesealedcell.Inordertoachievethebestresultsfromthistreatment,itshouldbecarriedoutwhenthereisnobroodpresentinthecolony,i.e.earlyspringorlateautumn.Theearlytreatmentiscarriedoutifonehasafeelingthataftertheautumntreatment,therearetoomanymitespresentinthecolony.Awatersprayisusedincarryingoutthistreatment,sprayingeachsideofeveryframeinthecolony.Theeffectivenessofthetreatmentisveryhigh.Keepingwithinthedead-linethenthelacticacidcontentiswithinthenaturalboundaries.1Brødsgaard,C.J.&Brødsgaard,H.F.1998.MonitoringMethodasaBasisforNeed-basedControlofVarroaMites(Varroadestructor-formerVarroajacobsoni)InfestingHoneyBee(Apismellifera)Colonies.ATLA26,413-4192Fries,I.,Aarhus,A.,Hansen,H.&Korpela,S.1991.DevelopmentofearlyinfestationsbythemiteVarroadestructor(formerVarroajacobsoni)inhoney-bee(Apismellifera)coloniesincoldclimate.Experimental&AppliedAcarology11,215-214.

DronebroodremovalDRONEBROODREMOVALTHEREMOVALOFDRONEBROODKEEPSTHEMITENUMBERSDOWNTHROUGHOUTTHESEASONAfAsgerSøgaardJørgensen

Incolonieswheredronebroodremovalispractisedinthecourseoftheseason,therewillbethreetofourtimesfewermitesthanincolonieswherethisisnotpractised.

DRONEBROODREMOVALRemovalofdronebroodisaneffectivemethodtolimitthepropagationofthevarroamite.Atthesametimeitpreventsswarming,anditdoesnoteffectthehoneyproduction.Thevarroamitepreferstobreedondronebrood.Therearestudieswhichshowthatbetween8and10mitesgointodronecellseachtime1goesintoaworkercell.Inthedronecelltheyhavemoretimetogettheirprodigydeveloped.Whilethemiteonlycangetonesexuallydevelopeddaughterfromaworkercell,theycangetuptothreeinadronecell.

THEDRONEFRAMEISUSEDTHUSChoosebetweenusingtwowholeframes,framesdividedintwoorthreeparts.(Seefigure)*Theweekendbeekeeper,whoseestothebeesonceaweek,shoulduseathreepartframe.*Beekeeperswhoseetothebeesevery10daysshouldusetwopartframes,ortwowholeframes.*Theframesshouldbeemptywhentheyaresetintothehive.*TheframesshouldbesetintothehiveinSpring,whenthequeenhasbeguntolay,aroundApril.*Theframesshouldbesetuptooreveninsidethebroodcluster.*Theframesshouldbeseentoeveryweek(threepartframes),andeverytendays(twopartframesandwholeframes).*Withthethreepartframestwopartsshouldbecutoutonthefirstinspection*Withtwopartframesonepartshouldbecutoutonthefirstinspection

*Theremoveddroneframescaneitherbemeltedimmediatelyorburned*Dronesmustnotbeallowedtogetoutoftheframes,asthiswouldresultinahugeincreaseinthemitepopulation.

THEFRAMESWORKBESTTHUSThebeesthemselvesshouldbeallowedtodrawtheframesthemselvesfromthebeginning.Germanresearchhasshownthatmoremitescomeintocellsthatthebeeshavetocompletethaniftheyweregivenfullybuiltframes.Oneofthereasonsthatmoremitescomeintodronebroodisperhapsthatworkerbeespaymoreattentiontodronebroodthantoworkerbrood.Thereismorebuildingworktobedonearoundthelargerdronecellsthanaroundtheworkerbrood,andthedronelarvaeneedmorefood.Themitesaretransportedaboutinthehivebytheworkerbees.Sincetheyspendmoretimearounddronebrood,thisincreasesthechancesofthemitesfindingthedronecells.THEDRONEBROODFRAMESSHOULDBEPLACEDINSIDETHEBROODCLUSTERGermanstudieshavealsoshownthattherewerefarmorevarroamitesinframesplacedinsidethebroodclusterthanthoseontheedgeofthebrood.InApril-May,whendroneproductionisatitshighest,thereshouldbesomuchactivityinthecolonythatthedroneframesonesetsontheedgeofthebroodshouldsoonbecomepartofthecluster,asthecolonyexpands.THEREMOVALOFDRONEBROODWORKSDanishbeekeepershavelearnedthatdroneremovalworks.Tryopeningaframeofdronebrood.,andseethemanymitespresent.Nowfromthesamecolonytryopeningaframeofworkerbrood,andheretherewillbemoreoftenthannotnomites.GermanresearchhasshownthatforeverymiteinacolonyinSpring,therecanbe50-100mitesinAutumn.ThismeansthatforeverymiteremovedinSpringtherewillbeproportionallyfewerinAutumn.Allinallpracticalstudieshaveshownthattherewere3-4timesasmanymitesinuntreatedcolonies(wheredroneremovalwasnotcarriedout)asintreatedones.Droneremovalthuskeepsdownthemitenumbersinperiodsofhoneyflow,andpostponesthatcriticalpointatwhichthevarroamitepossessarealthreattothecolony’sexistence.

Formicacid1.FreelyappiedFORMICACID1:FREELYAPPLIED

FORMICACIDTREATMENTJUSTAFTERTHEHONEYHARVESTMAKESFORHEALTHYWINTERBEES.

AfFlemmingVejsnæs

WHATISFORMICACID?

Formicacidisanorganicacid,whichoccursnaturallyinhoney.Thecorrectuseofformicacidinthetreatmentofvarroamite

doesnotprovideforsignificanttracesoftheacidintheresultinghoney.

THEEFFECTOFFORMICACID

Thevapourfromformicacidkillsthevarroamitebothonthebeesandbehindthesealedcells.Formicacidistodaytheonly

productthatkillsthemitewithinthesealedcell.

Formicacidisheavierthanair.Thebeesownventilationdistributesthevapourroundthehive.

Formicacidcanpenetratetheshellofthemite(whichismanytimesthinnerthanthebees)anditdestroystheskeleton,the

cellsandtherespiratorysystem.Theoutershellofthebeesismuchmoreresistanttowardsformicacid.

Theoldestbroodinacolonycanbedamagedbyformicacidtreatment,butnormallythelossesarenotsignificant.

Inrarecasesformicacidtreatmentcanresultinthelossofqueens.Thereforeitisagoodideathatreplacementofqueensis

carriedoutafterthecompletionoftreatment.Normallyitistheolderqueens(over2yearsold)thatsuccumb.

Upuntilnowresistancetowardsformicacidhasnotbeenregistered,despitethefactthattheproducthasbeenusedforover

15years.Sincetheacidattacksthemitesinanumberofways,itisnottobeexpectedthataresistancetowardsformicacid

amongstthevarroamitewillberecorded.

Theeffectivenessofformicacidcanreachupto95%mortality,butthisvaries.

SAFETY

Invarroatreatmentaformicacidsolutionofeither60or85%isused.Thesearestronglycorrosive.Thereforeitmustbe

handledwithcare.Userubberglovesandprotectiveglasses.Masksarealsorecommended.

Allactivitywithformicacidshouldbecarriedoutoutdoors,orinwellventilatedrooms.

Shouldacidcomeintocontactwiththeskin,itshouldberinsedimmediatelywithabundantwater.Likewise,shoulditcome

intocontactwiththeeye,againrinsewithlotsofwaterforatleast15minutes,andthereafterseekmedicalhelp.Makesure

alwaystohaveabundantwaterattheapiary.

WHERETOBUYFORMICACID

Atbeekeeperssuppliersonecanpurchaseformicacidina60%solution,whilean85%soln.canbepurchasedatagricultural

suppliersin25Kg.containers.Formicacidtreatmentisaverycheapformoftreatment.

HOWANDWHENTOUSEFORMICACID

Formicacidtreatmentshouldtakeplaceassoonasthelasthoneyisharvested,andthecolonyhasgotitsfirstportionof

winterfeed,e.g.7Kg.ofsugar.Formicacidtreatmentcaneithertakeplaceoverfourconsecutivedaysorthroughtheuseof

variousvaporizers.

FOURTIMETREATMENT

Havingbegunwinterfeeding,theacidisadministeredonfourconsecutivedaysusinga60%soln.onanabsorbentmaterial.It

isimportantthatthematerialchosencanabsorballtheacid.2-3ml.ofacidperframeshouldbeused.Theabsorbent

materialcaneitherbeplacedinatrayoronaplasticinsertatthebottomofthehive.Itisimportantthattheacidisnotmore

than2cm.fromthebottomoftheframes.Onecanalsoplacetheabsorbentmaterialontopoftheframes,restingonlaths.In

thiscaseitshouldcoverthewholearea,sothatthebeescannotflyup.

Somebeekeepersusean85%insteadofa60%solution,whichgivesastrongershockeffect,butalsobringsagreaterriskof

damagingstocks.Inthiscasesmalleramountsofacidshouldbeused.1.5ml.85%formicacidsoln.isequivalentto2ml60%

soln.

TEMPERATURE

Theoutdoortemperatureforusingformicacidshouldbebetween12and25°C.Ifthetemperatureistoolowan

insufficientvaporizationwilltakeplaceandhavealimitedeffect.Toohighatemperaturewillresultintooexplosivea

vaporisationandcouldresultindamagetobeesandbrood.

VENTILATION

Oneshouldmakesurethattheonlyventilationisthroughtheentranceblock.Openwirebottomsonhivesshouldbe

covered.

CONTROL

Ifoneseeksaprecisemitecountunderformicacidtreatment,themitesshouldbecountedatthebeginningandupto12

daysafterwards.Thisisduetothepresenceofdeadmitesbehindsealedbroodcells.

TREATMENTOFSEALEDBROOD

Sealedbroodframesfromframesusedforqueenbreedingcanbetreatedusingformicacid.Thesealedbroodframeswithout

beesareplacedinsideapolyurethanehiveforonehourwith25ml.of85%formicacidonanabsorbentmaterialunderand

overtheframes.Upto7framescanbetreatedinatenframebox.Theframesshouldbedistributedevenlythroughoutthe

box.Theeffectivenessofthistreatmentisveryhigh(closeto100%).Withthisformoftreatmentalossof10%ofthebrood

canhappen.especiallyamongsttheoldestandmostvulnerable.

Itisimportantthatonlyframesofsealedbroodfromcolonieswhicharenotbadlydamagedareused,asthereotherwise

couldbeviruspresentinthebrood.

Formicacid2:KrämerboardsFORMICACID2:KRÄMERBOARDSKRÅMER(WOOD-FIBRE)BOARDSAREVERYEFFECTIVEANDEASYTOUSE.ByFlemmingVejsnæs

ThemostcommonlyusedvarroatreatmentmethodinDenmarkisthatusingKramerboards(thesearesoft,absorbentwoodfibreboards).

MAKINGTHEBOARDSOnecaneithermaketheseboardsoneselfordosotogetherwithothermembersoftheassociation.Softwoodfibreboardsareused.,cuttosizesof17X24.5X1cm,andinsertedintoacidresistantplasticbags.250ml.85%formicacidsoln.isthenpouredintothebag,whichisthensealedwithtapeorideallywithadoubleweldingusingaweldingapparatusforfreezerbags.SAFETYFormicacidiscorrosiveandprotectivewearisadvised(seepreviousarticle)

THEPLACEMENTOFBOARDSTheseboardsshouldbeplacedsothattheycoverthewholeframearea.Avaporizingareacanbecreatedbyplacinganemptysuperovertheboards.Theboardsthemselvesshouldbeplacedon2cm.highlathsplacedontopoftheframes.The

vaporizingspaceprovidesforamoreevendistributionoftheformicaciddownthroughtheframes.Acrownboardcanbeplacedonthesuper.USINGTHEBOARDSForbeekeeperswhodonotbringtheirbeestotheheather,theboardsshouldbeusedimmediatelyafterthefirstportionofwinterfodderhasbeengiven,afterthehoneyharvest.ThisisnormallyatthebeginningofAugust.Theboardsshouldremaininplacefor7-10daysandtheycanbeusedagainiftheyhavenotreleasedmorethan100grmsofformicacid.Otherwisetheycanberefilled.Thecolonyshouldbegiventheremainderofitswinterfodder.Theboardsshouldbekeptinaclosedplasticbucketandthereafterplacedonthehiveagainfor14-21days,aroundthemiddleofSeptember.

SLITSORHOLESOnecaneithercutslitsormakeholesinthecoveringplasticoftheboardsinordertofacilitatevaporization.Holesshouldbemadeintheratioof4cm2perframe.Thismeansthatfor10framesanopeningof40cm2shouldbeused,tobecutoutonbothsidesoftheboard,andwhichistheequivalentofaslitof1X20cm.Inhighoutdoortemperaturesthesizeoftheopeningcanbereducedby25%.Ourexperiencepointstowardsusingholeswhichgivesthemostevendistribution,whilewithslitsthedangeristhattheplasticcanbepressedouttothesidesandtheopeningthusbecomeslarger,andwillgiveagreatervaporisationthandesired.A16mmhollowpunch(canbeboughtatahardware)canbeusedtomakeholeswith,andthisgivesanopeningof2cm2.Oneholeofthissizeisneededperframe.Therefore,fortenframestenholesinallareneeded,tobemadeoneithersideoftheboard.Withveryhighoutdoortemperaturesinthecourseofanearlytreatment,theareaofopening,whetheritbeslitsorholes,canbereducedby25%.TOOEXPLOSIVEAVAPORIZATIONAlwaysuseacoolboardundertreatment,asthisprovidesforaslowervaporization.Onwarmdaysitisrecommendedtowaituntileveningbeforeinsertingtheboards.CheckingthevaporizationItisagoodideatocarryoutacheckontheextentofvaporizationbyweighingtheboardbeforeandafteruse.Areliableindicationthattheboardisworkingsatisfactorilyiswhen10grm.offormicacidhasevaporateddaily.Besides,onecanalsocheckwhethertheboardcanbereusedornot,bycalculatingifithaslostmorethan100grm.formicacid.

NewformicacidvaporizersNEWFORMICACIDVAPORIZERSMANYNEWVAPORIZERSHAVEBEENDEVELOPED,ANDWORKWELL.AfFlemmingVejsnæs

Inrecentyearsagreatdevelopmentintheproductionofformicacidvaporizershastakenplace.Wehavetestedseveralandfoundthemgoodoracceptable.

THENASSENHEIDERVAPORIZERTheNassenheidervaporizerhasbeenonthemarkedinDenmarkforanumberofyearsandisincommonuseherewithgoodresults.Thevaporizercomprisestwocompartments.Oneforstorageandtheotherforevaporation.Intheevaporationcompartmentonecanputapieceofcardboardoftwodifferentsizes.Thevaporizercanbeplacedonalathonanemptyframe,sothattheapparatusissethalfwayuptheframe.Thisissoinorderforthevaporizertocomeintocontactwiththewarmthofthecolony.60OR85%SOLUTIONInthevaporisersmanualitrecommendsthata60%formicacidsolutionbeused.ManyofthoseusingtheapparatusinDenmarkusean85%solutiontogetherwiththesmallerwicksupplied-withgoodresults.PLACEMENTItisimportantthatthevaporizerisplacedsoclosetothebroodthatisisinsidetheareacoveredbybees.Ifnecessarythevaporizercanbesetupagainstthemostoutwardbroodframe.Shouldthevaporizerbeplacedoutsidetheclusterofbees.thentherewillbeaninsufficientevaporation.Shouldthebroodhavespreadtotwobroodboxes,asecondvaporizershouldbeplacedontheupperbox,andplacedontheoppositesidetothatunderneath.STARTINGTREATMENTThetreatmentshouldstartassoonasthelasthoneyhasbeenharvested,andwinterfeedingbegun.Thetreatmentlastsfor7to10days.Afterthetreatmentiscompletewinterfeedingcanresume.THESIZEOFTHEWICKWithanearlyfeeding,i.e.inthebeginningofAugust,thesmallerpieceofcardboardshouldbeinserted.Forlatertreatment,e.g.attheendofSeptember,whenthebeeshavetakenalltheirwinterfeed,thelargerpieceofcardboardshouldbeused.

Using85%formicacidsolutionthesmallerpieceshouldbeused.Thistreatmentlastsfrom14to21days.Checktoseethatthevaporizerstillcontainsliquid-itmaybenecessarytorefillit.FILLINGItisrecommendedthatoneacquiresasquirtbottletofillthevaporizerwith,sinceitisdifficulttodosootherwisewithoutspilling.Checktoseethatabout10mlhasevaporatedeverydayintheinitialtreatment.THENASSENHEIDERINABOXAfurtherdevelopmentoftheNassenheiderwasbroughtontothemarkerlastyear,makingitpossibletotreatbeesinawholebroodbox.What’snewhereisthatonecannowputthevaporizeronfeet,sothatitcanbeplacedontopoftheframes.Underthevaporizeranevaporationclothislaid,whichissuppliedthroughawickfromthereservoir.Dependentonthetemperatureinsidethehive,alargeorsmallevaporationareafromtheclothiseffected.WehavescantexperienceofthistypeofvaporizerfromDenmark.

THEAPIDEAVAPORIZERAcompletelynewformforvaporizerontheDanishmarkedistheapideavaporizer.TheprincipalissimilartothatoftheKråmerboard.Thevaporizerconsistsofatrayinwhicha“dishcloth”isplaced,whichisabletoabsorbtheformicacid.Thetrayisenclosesbytwosurfaces,inahollowsystem.Theopeningiscreated,andregulated,bymovingthesurfacesawayfromoneanother.Evaporationisonlycreatedfromoneside.Thevaporizerisbestfilledusingasquirtbottleoutintheapiary.Thevaporizershouldberaised,justliketheKråmerboards,about2cm.overtheframes.AccordingtotheGermanmanual.,itisoperatedwith60,70and85%formicacidsolutions.Testingwith85%soln.inDenmarkhasshowngoodresults,buttestingwitha60%soln.hasshownlesspromisingresultsthantheKråmerboardmethod.

THELIEBERFELDERDISPENSERTheSwissBeeResearchInstituteinLieberfeld,togetherwithTheSwissBeekeeper’sAssociationhavedevelopedavaporizersimilarinprincipaltotheApidea.Thesizeoftheopeningsareregulatedusingarotatingdisc.Thedispenserissuppliedwithlegswhichraiseit1.5cm.abovetheframes.ThedispenserhasbeentestedinDenmark,butisnotavailableforsalehere.

THEUNIVERSALVAPORIZERAgainadispenserwhichoperatesinasimilarwaytotheKråmerboardmethod.Hereacircularplasticcontainer,3cm.inheightand16cmindiameter,isused,containing“oasis”(theabsorbentmaterialusedinfloraldecorations).Abovethisaretwocirculardiscswitharangeofopenings,whichcanberegulatedaccordingtoneed.Thecleverpartofthisapparatusisthatitissuppliedwithaclosefittinglid,whichallowsthedispensertobefilledathome.TheapparatusistestedinDenmarkbutisnotavailableforsalehere.

OTHERVAPORIZERSThereareatthemomenttwoothertypesofvaporizersthatarebeingresearchedinEurope.InSouthernGermanyaso-calledplatevaporizerisinuse.Itworksfromadripbottlebeingsuspendedonatimberframeanddrippingformicacidontoaplate.Themethodhasshownpromisingresults.InSwedentrialsusingaso-called“burk”vaporizer,inwhichahoneyjarfilledwithsaw-dustcontainingformicacidisused.Onthetopofthejarisapieceoffoam.Thewholejaristheninvertedontotheframes.ThemethodisbeingtriedoutinSwedenathemoment.Upuntilnowithasgivenvariedresultsalongwithamuchtooexplosivevaporizationintheinitialtreatment.

OxalicacidtricklingOxalicAcidTricklingMethodByDavidAshton

Thelateseasonvarroa–controlisimportant.Thetreatmentshouldtakeplacewhenautumnfeedinghasfinished,andthecolonyisfreeofbrood.

OxalicAcidtricklingOxalicacidisanorganicacid,whichisfoundnaturallyinhoney.Themethodisextremelyeffective,veryquickandinexpensive.

SafetyForvarroacontroltheOxalicacidisusedinaveryweaksolution(3.2%).Thissolutionisaveryweakcorrosive.Butyoumustbeverycarefultoavoidcontactwiththeskinasoxalicacidcanbeabsorbedthroughtheskin.Duringtreatmentitisimportanttouseacidresistantrubbergloves.Whilstmixingthesolutionyoushoulduse,gloves,safetygoggles,andrespirator(P2DustMask).TreatmentinBroodFreePeriod‘OxalicAcidtrickling’,doesnotworkbehindthebroodcellssealedcap,thisisthereasonwhytreatmentshouldtakeplaceinperiodswhennoneorverylittlebroodaspossibleispresent.WewouldnormallyrecommendatreatmentinlateOctober-November(butaccountshouldbetakenofclimateforexampleinwesternseaboardofBritishIslesthegulfstreamkeepsthetemperatureupsobroodrearinggoesonintoDecember)Astheclimatewarmsitsimportanttocheckifbroodrearinghasstopped,soitcouldwellbethattreatmentshouldtakeplaceinNovemberorDecember.Theimportantthinghoweveristhatthebeekeepermustnotfallintothetrapofforgettingtouseanoxalicacidtreatment.Bees,whichforvariousdifferentreasonsgointowinterandhibernationwithtoomanymites,willsufferalargeamountofdamageandharm.Oneshouldthereforinyourconsiderationsconsiderwhatissaid.“Treatmentwhenbroodfree,sothatthosemitepresentcandotheleastamountofdamage”InothercountriesoutsideofDenmark,thereisatraditionbecauseofclimatetogiveamuchlattertreatment!Ithaspreviouslybeensaidthatthecoloniesshouldbetreatedsothebeeswillhaveacoupleofflyingdaysaftertreatment.Thereishowevernoresearchthatshowsthistobenecessary

MixingtheSolutionForthetreatmentthenuseoxalicacid–bihydrateTheOxalicAcidismixedinproportions1litredistilledwater:1kgsugar:75goxalicacid–bihydrate.Thisisenoughfor55colonies.YouneedtoadjustthisinproportionorusetheDanishbeekeepersoxalicacidcalculator.Youneedtobeawarethatmixingverysmallamountsforexamplejusttwocoloniesforexample,cancreateproblems,asordinarykitchenscalescangivethewrongmixture.Considerweighingaminimumof0.5litredistilledwater:0.5kgsugar:37.5gramsoxalicacid–bihydrate.Durability(ShelfLife)Whenweonlyrecommendautumntreatments,thereisnoreasontokeepyoursurplusmixture;itisbestputdownthedrain.

Ifhoweveryouwishtokeepyourmixture,weshoulddrawattentiontothefactthatitwillkeepuptosixmonthsinthedarkinthecoldofacellar.Themixtureshouldalsobekeptinchildsafeandsecurebottle.Howtouseit?TheOxalicAcidmixtureshouldbelookwarm.Youshouldusea50mldosingsyringe.Youtrickle3-3.5mlperframespacewithbees.Thatistosay35mlpercolony.Thisisaverysmallquantitysoit’sagoodideafirstofalltopractisewithordinarywater.Itisimportantthatthetricklingtakesplacedirectontothebeesandnotjustontheframetopswerethebeeswouldletitlie.TemperatureTheoutdoortemperatureabove0degreeCDamagetobeesIftheOxalicAcidisusedcorrectly,inthecorrectdosagethereisnorisktothebeesortheriskisverysmall.Ifyouoverdosethenyoucanloosealotofbeesandweakenthecolony.Howoftenshouldyoutreat?Danishandinternationalresearchhasshownthatifbeesaretreatedmorethanoncepergeneration,itcanresultindamagetothebeesandareductioninthestrengthofthecolony.Werecommendthereforthatyoushouldonlytreatthebeesonceeachseason.Thebesttimetotreatisintheautumnearlywinterwhenthecolonyisbroodfree.Wehavehoweverwithlarge-scalebeekeeperstreatedwithsuccessbothintheautumnandinthespringwithOxalicAcidTricklingMethod.

CagingthequeenCAGINGTHEQUEENANEFFECTIVEBEEKEEPINGINTERVENTIONAfHenrikHansen&CamillaJ.Brødsgaard.DanmarksJordbrugsForskning,ProjektgruppeBiavl

*Usingthismethodthequeeniscagedinsideaframeforalmostfourweeks*Thevarroamitenumberscanbekepttoanacceptablelevelusingqueencagingcombinedwiththeremovalofdronebrood.*Queencagingpreventsswarming.

PROCEDURE*Queencagingcanbecarriedoutononeormoreframed.Herecaginginsideacassetteonasingleframeisdescribed.*QueencagingtalesplacebeforetheSpringoil-seed-rapehoneyflow.Theinterventioniscarriedouteveryeightorninedays*Inthefirstinterventionthequeenisputonaframeinsidethecassette*Atthesecondinterventionremoveallthequeencells.Thefirstframeissetbehindthecassette,andthequeenisthenputontothesecondframeinsidethecassette.*Underthethirdinterventionremovethefirstframe.Thesecondframeisthenplacedbehindthecassette,andthequeenistheplacedonthethirdframeinsidethecassette.*Atthefourthinterventionremovethesecondframe.Thequeenisthenreleasedfromthecassette,whilethethirdframeremainsinthecassette.*Atthefifthinterventionremovethecassetteandthethirdframe.

BAITFRAMES*The“bait”frameswhichhavebeenremovedcanbedestroyed.Theycanalsobetreatedwithformicacidorbyheattreatment,iftherearenotdeadbroodintheframes*Usingformicacidtreatmentthebroodmustnotbemorethan16to17daysold.*Sixtosevenbaitframesaresetintoanisolatedbox.*Atthetopandthebottomathin.porouswoodfibreboardinplacedandeachisgiven25mlof85%formicacidsolution.Theboxisthencoveredwithanairtightcoverandbottom.*Onehourlaterthetreatmentiscomplete.Theframesmayonlybeplacedinhivesfromwhichahoneyharvestisnottobetaken.*Usingheattreatmentthebroodmustnotbemorethan16-17dayseither.Thetreatmentasdescribedinthesectiononheattreatmentshouldbefollowed.

HeattreatmentHEATTREATMENTOFBROODFRAMESANEFFECTIVEPHYSICALMETHODAfCamillaJ.Brødsgaard&HenrikHansen.DanmarksJordbrugs-Forskning,ProjektgruppeBiavl

*Heattreatmentofsealedbroodprovidesaneffectivecontrolofthevarroamite*Thevarroamiteismoresensitivethanbeebroodtotemperaturesthatlieabovethenormalbroodtemperature*Heattreatmentcanbecarriedoutinvarioustypesofthermostaticallycontrolledboxes*Onlyframeswithoutdeadbroodshouldbetreated*BelowtheBorgstadter-Thermo-BoxandApithermboxesaredescribed.

BORGSTADTER-THERMO-BOX*Onecanheattreat16-17dayoldbroodframesfromqueencagedframes(seepreviousarticle*Treatmentlastsforfourhoursat44°C*Fewbroodinjuries-someshorteningofthebeeslife

APITHERMBOX*Varroacanbetreatedexclusivelywiththisapparatus*treatmentcanbecarriedoutatanytimeonsealedbrood,irrespectiveofthehoneyflow,e.g.attheendofMayorJune*Onemakesadecisionabouthowmanytreatmentsarerequiredfromtheresultsofmonitoringsurveys.*Onetreatsbroodframeswhereatleast75%ofthecellsaresealed.Theopenbrooddies.*Upto18framescanbetreatedatanyonetime*Thetreatmentiscarriedoutforthreehours,underwhichthetemperaturegraduallyrisestojustunder44°C.*Thebeesdevelopnormallyandtheirlifespanisnotshortened.*AnApithermbox,forwhichtheelectricityingeneratedbysolarcells,isunderdevelopmentinGermany.THEEFFECT*Borgstadter-Thermo-Box:100%mitemortalityimmediately*ApithermBox:varroafemalesandnymphsareinjuredundertreatment.Themainpartdiewithin24hours.Thosethatsurvivelosetheirabilitytoprocreate.

LacticacidTREATINGADULTBEESUSINGLACTICACIDAfCamillaJ.Brødsgaard,DanmarksJordbrugs-Forskning,ProjektgruppeBiavl&CarstenW.Hansen,DanmarksBiavlerforening

Lacticacidisanorganicacidwhichisdistributedwidespreadinnature.Itisformed,forexample,inthehumanbodywhenenergyisburntaswellasoccurringnaturallyinhoneyandotherfoodstuffs.Furthermore,lacticacidisoftenaddedtoourfoodstuffs.

SAFETYMEASURESA15%lacticacidsolutionisusedfortreatingvarroa.Thisconcentrationcausesirritationtoskinandmucousmembranesandshouldbehandledwithcare.Rubbergloves,protectiveglassesandmasksarerecommended.Inaconcentratedformlacticacidiscorrosive,andshouldonegetconcentratedacidonone’sskinwatershouldbeappliedliberally.Likewise,ifeyescomeintocontactwiththeacid,theyshouldberinsedwithwaterforatleast15minutes,andmedicalhelpshouldthenbesought.Ifonemixesthesolutiononeself,oneshouldremembertoaddtheacidtothewaterandnottheotherwayround,toavoidthepossibilityoftheacidboilingover.Themixtureisthenstirreduntilthelacticacidisevenlydistributed.Thismixturewilllastforafewmonths,butmustnotbestoredatunder0°C.TRACESINWAXANDHONEYFollowingtreatmentthelacticacidcontentofhoneyincreasesforonlyashortwhile,astheproductbreaksdownfairlyquickly.Aftercircaeightweeksthelacticacidcontentisdowntonormallevels.RESISTANCENoproblemsconcerningthevarroamitebuildinguparesistancetolacticacidhavebeennoted.

WHENCANITBEUSED?Lacticacidcanbeuseduptoeightweeksbeforethehoneyharvest.Lacticacidtreatmentshouldonlybecarriedoutincolonieswithoutbrood,sincelacticaciddoesnotpenetratethesealedbrood.Itismostsuitabletouselacticacidintheautumn,whentherearenotsizableamountsofbroodinthecolonies.QuiteoftenthereareanumberofmilddaysinOctober,inwhichtreatmentcanideallybecarriedout.ItwillalsobepossibletocarryoutatreatmentveryearlyinSpring,ifonehasafeelingthattherearetoomanymitesinthecolony.However,beforetheyhavelargeamountsofsealedbrood,itisdifficulttoworkwithbees,andthetreatmentwouldachievetoosmallaneffect.Takenotethatinsomecasesqueenlosshasbeenrecordedinconnectionwithspringtreatment.Lacticacidisveryusefulintreatingswarms.Beestobeusedinmatingcassettescanalsobetreatedwithlacticacid.HOWISITUSED?Threetreatmentsshouldbecarriedoutwithtwodayintervals.A15%solutionshouldbeused,and5mlshouldbeappliedwithawatersprayertoeachsideofeachframe.Thenecessarynumberofpumpsrequiredonthesprayshouldbetestedbeforehand.Treatmentshouldbecarriedouteithersoearlyorlateinthedaythatthereisnonoticeableflyingactivity.Thelacticacidissprayedonthebeessothattheyallbecomedamp.Iftherearesealedbroodpresentinthecolonyduringthisfirsttreatment,theyshouldberemoved.AmoderateremovalofbroodcanbecarriedoutinAutumnwithoutweakeningthecolony,butitisnotadvisabletodosoinSpring,sincethefirstbeestodevelopareofvitalimportancetothelaterdevelopmentofthecolony.Withalittlepractice,threetreatmentswithawater-sprayercanbecarriedoutinabout10minutespercolony.THEEFFECTWhenlacticacidisusedinacolonywithoutbrood,theeffectivenessofthetreatmentisveryhigh.IntestscarriesoutjointlybyTheDanishBeekeepersAssociationandTheDanishAgriculturalResearchStation’s“ProjectBeekeeping”,amortalityof95%ormorehasbeenrecorded.

THECOSTOFTREATMENTA30Kg.containerof80%lacticacidpurchasedatTheDanishDairyWholesalerscostsca.£60+VAT.Itcanalsobepurchasedatbeekeeperssuppliersandatpharmaciesinsmallbottles,butatafarhigherprice.Inthetreatmentofacolonyontenframesabout0.3Lof15%lacticacidsolutionisused.Throughbulkbuyingthepriceforthisamountisabout10p.

Nuclei-newcoloniesNUCLEI-NEWCOLONIESSMALLCOLONIESAREANIMPORTANTPARTOFVARROATREATMENTANDENSURENEWCOLONIESByCarstenWolffHansen

Withtheproductionofnewnuclei,onehasmoretimeforvarroatreatment,andgreatercertaintythatonedecidesoneself,howmanycoloniesonehasnestseason.Whenthebeesandthequeeninnewlyestablishedcoloniesproduceamassofbroodattheendoftheseasoninordertobuildanewcolony,oneutilisesthebeesreproductiveabilityincontrasttothevarroamites,andthenewcolonyhastheoptimalopportunitytoproducegoodwinterbees,whocanensuresurvivalanddevelopmentnextseason.Thisarticleprovidesaplanandsomeadviceonhowsimplyandeasilyonecanproducenewcolonies,andatthesametimecarryoutaneffectivevarroatreatment.

Theproductionofanumberofnewnucleioughttobeamorenaturalpartofbeekeepingthanitistodayforagreatnumberofbeekeepers.ThroughoutthelatteryearstherehasbeenagreatdemandfornucleiinSpring.Shouldonetherefore,producemorenucleithanmeetsonesownneeds,theycaneasilybesoldtootherbeekeepers.Onealsoestablishesagoodsafetynetunderonesownhoneyproduction-andonedecidesoneselfhowmanycoloniesonewillhave.Therearemanymethodstomakenuclei.Onecandecideonhavingcolonieswhichwillbecomeasstrongasnormalproductioncolonies,oronecandecideonnucleiwhichoverwinterinahivesharedwithasecondcolony,anddividedbyanarrowpartition,andwhereeachcolonyhasitsownentranceblock.Ifonemakesnewnucleiassmallcolonies,onehasextraqueens,beesandbroodtouseinreinforcingcoloniesthatemergeweakinSpring.Ifoneusesaqueenfromsuchasmallcolony,onecanwithoutproblemsunitethenowqueenlesscolonywithanothersmallcolonyinSpring,andcarryonwiththemasanormalproductioncolony.Therearemanypossibilitieswhenonehasextracolonies,andasstated,oneachievesafargreatercontroloverhavingthedesirednumberofcolonies.

HIVESFORNUCLEIAllsortsofhivescanbeusedforcreatingnuclei.Insomeoldtroughhivesthereisanextraentranceblockatthesideofthehive,andifabee-tightpartitioniserectedbetweenthatpartofthehiveandtheoriginalcolony,anucleuscanbeestablishedatthebackofthehive.Troughhivescanberebuiltsothattherecanbethreeorfournuclei,eachwiththeirownentrance,inasinglehive.Normalhiveswithspecialbottomsarethemostsuitablefornuclei,andhereitwillbe,inmostcases,suitabletohaveoneortwonucleiineachhive.Itisalsopossibletohavethreeorfournucleiineachhive,dependentonthesizeofframeandbox.Nucleioughttobeestablishedonatleastthreeframes,andideallyonfive.Thefiveframesmakeiteasiercontrolfeeding,withoutblockingforthequeen’segglaying.Feedingshouldtakeplaceseparatelyforeachcolony.Ifseveralnucleihaveaccesstothesamefoddersource,problemswilleasilyarise,andtheonequeenwillsuccumbandthebeeswillcollectaroundthesecondqueen.

HOW,WHENANDHOWMANY?Asinallsuccessfulbeekeeping,oneshouldingoodtimeplanhow,whereandhowmanynewnucleioneshouldhaveinaseason.Itis,ofcourse,arequirementthatonehasthenumberofqueensneeded.Ifonebuysonesqueens,oneshouldhavean

agreementwithaqueenproducerastowhenonewantstocreatenewnuclei.Ifoneproducesonesownqueens,thenitisrecommendedthatoneusethefirstqueensfornuclei,sinceitisoftendifficulttointroducenewqueensintoestablishedcolonies.Ifonewishestowishestoincreasethenumberofcoloniesonehas,onecanplantodoublethenumbers.Ifonewishestohaveasafetynetunderthenumberofcoloniesdesired,itcanbeagoodideatomakehalfasmanynucleiasthenumberofcoloniesonestartedwith.Shoulditbeplannedproperly,onecan,infact,multiplythenumbersofcolonyinaseason.Therearemanymethodstomakenuclei,andinTidskriftforBiavl(BeekeepingMonthly)thereareregulardescriptionsonhowthisisdone.NOTESONVARROATREATMENTFORNUCLEIInrelationtovarroatreatmentinnuclei,twofactorsareespeciallyimportant.Thefirstthingoneshouldrememberisthatsealedbroodframescancontainmanyvarroamites,sothereforebothbeesandbroodframesshouldbetakenfromcolonieswithlittleormoderateattackofvarroa.Thesecondfactoristhis:ifonemakesnucleiwithvirginqueensandsealedbroodframeswithoutopenbrood,itwillmean,dependentonmatingweather,ashorterorlongerperiod,wherethereisnotsealedbroodinthecolony.Thisprovidessomeoptimalconditionsforvarroatreatmentwithlacticacid,orwithoxalicacid.Oxalicacidis,unfortunately,atthetimeofwritingnotpermittedforthisuse.Ifoneshouldprefertoestablishnucleiwithmatedqueens,itmaybeagoodideatospraythebeesoneistousewithlacticacidinitially,andtreatthenewlysealedbroodframeswithoutbeeswitheitherlacticacidorheattreatment.Broodabouttohatchissensitivetowardsthesetreatmentmethodsand,therefore,theymustbenewlysealedbroodframes.Later,whenthenucleiarewellestablished,varroatreatmentcanbecarriedoutinthenormalway.LETUSGETSTARTEDInthisconnectiononlyonepieceofadviceisoffered,whichisassureasitcanbe,whenoneisworkingwithbees.Manybeekeepershavebadexperiencesintakingbeesandbroodframesfromtheordinaryproductioncolonies.Itwillweakenthem,andonehasadvancednowhereifonehasdestroyedsomefamiliesinordertoestablishothers.Therefore,onoughttohavesomecolonieswhicharesetasidejustforthispurpose.Thebeesthataretobeusedfornuclei,oughtto,ifthereisapauseinthehoneyflow,betakentoanewapiaryatleast3Km.fromwheretheycame.