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Gypsy Moth Caterpillar Gedrag

Gypsy Moth Caterpillar Gedrag


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Ek het onlangs 'n redelike hoeveelheid aanlyn navorsing gedoen oor sigeunermotruspes en bronne waarna ek gekyk het sê dat ouer ruspes hoofsaaklik gedurende die nag aan die bome vreet en bedags afsak en in donker beskutte gebiede wegkruip.

Ek werk vir iemand wat verlede jaar 'n ernstige sigeunermotbesmetting gehad het en ons het jute om verskeie geïsoleerde bome vasgemaak om te kyk of ons die skade kon verminder. Op die hoogtepunt van die besmetting het ons opgemerk dat daar op 'n gegewe tydstip gedurende die dag 20-40 ruspes om die basis van die jute draai en soms suksesvol daaroor kruip. Dit het gelyk of hulle aktief besig was om gedurende die dag in die bome op te klim, wat blykbaar alles weerspreek wat ek gelees het.

Kan iemand enige insig gee in hierdie gedrag?


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Sigeunermot

Die sigeunermot het vier ontwikkelingstadia – eier, ruspe (larwe), kokon (papie) en volwassene. Manlike en vroulike sigeunermotte lyk baie anders. Die volwasse vroulike mot is wit en het golwende, donker bande wat van voor na agter van die voorste vlerke loop. Volwasse wyfies het 'n vlerkspan van ongeveer 2 duim, maar kan net kort afstande vlieg. Die wyfie se lyf is stewig en dig bedek met 'n kol goudkleurige hare op haar kop. Vroulike sigeunermotte is ook groter as mannetjies op 2 ½ duim lank wanneer hulle volwasse is. Mannetjiemotte is net sowat 3/4 duim en het gewone, bruingrys vlerke met groot, veeragtige antennas. Die antennas, soos baie ander motte, help om wyfies op te spoor om mee te paar. Volwasse larwes is maklik om te identifiseer, aangesien hulle baie groot is (ongeveer 2 ½-2 ¾ duim) met lang hare, vyf pare blou knoppe aan die voorkant en ses pare rooi knoppe agter in hul rug. Die wyfies lê 'n eiermassa wat gemiddeld 400-500 eiers bevat wat bedek is met hare wat losgemaak is en aan die eiermassa van die wyfie vasgeplak is terwyl sy die eiers lê.

Gedrag, dieet en gewoontes

Sigeunermotruspes verkies hardehoutbome en dit is bekend dat hulle op meer as 300 boomsoorte voed. Die boomsoorte wat hulle verkies, is egter eikebome, appels, 'n paar populiere, wilger, els en meidoorn. Hulle volledige lewensiklus word in een jaar voltooi. Die ruspes kan bome heeltemal ontbloot deur al die blare daarvan te eet. Sigeunermot-eiers broei uit en die larwes begin vreet op 'n tyd van die jaar wanneer baie van hul gasheerbome begin blaargroei verkry, gewoonlik rondom Mei. Voeding begin normaalweg op die top van die boom, dus ontblaring van sigeunermot kan nie op hoë bome gesien word totdat die graad van ontblaring swaar word nie. Jonger ruspes voed gewoonlik bo -op bome en kan op groot bome ongemerk bly. Soos die ruspes ouer word, bly oueres nie meer in die boonste dele van die boom, of die blaredak nie, maar beweeg op en af ​​in die boom, soek skuilplekke op die grond en die boomstam gedurende die dag en beweeg dan terug teen die boom op. snags om op die blare te voed.

Meer inligting

As ’n huiseienaar dink dat hulle dalk ’n probleem met sigeunermaande het, is die eerste ding om te doen om jou plaaslike voorligtingsdienskantoor te kontak vir hulp om die plaag korrek te identifiseer. Om die ruspes met insekdoders te behandel, kan moeilik wees vir 'n huiseienaar, so soek altyd die advies van jou plaagbeheerkundige. Huiseienaars en regeringsagentskappe gebruik soms 'n bakterie genaamd Bacillus thuringiensis om die insek se larfstadium dood te maak. Boombande deur gebruik te maak van jute, kleefband en taai stowwe om larwes wat op en af ​​teen die boomstam beweeg vas te vang, vang gewoonlik baie ruspes, maar verminder oor die algemeen nie die algehele bevolking aansienlik nie. Om eiermassas te verwyder deur dit van die boom af te krap voordat die eiers uitbroei is ook 'n goeie beheermaatreël.


'N Virus wat die gedrag van die ruspe beïnvloed

Wanneer 'n virus wat as baculovirus bekend staan, besmet word, klim sigeunermotruspes geheimsinnig na die boomtoppe. Hulle sterf dan en strooi virale deeltjies, wat hul kamerade hieronder besmet. Entomoloog Kelli Hoover bespreek die insekte se gedragsverandering en die voordele vir die virus.

Dit is WETENSKAP VRYDAG. Ek is Ira Flatow. Stel jou voor dat jy met 'n erge geval van griep afkom, maar in plaas daarvan om uitgeput te voel, wil jy in 'n boom gaan klim. Wel, dit is wat gebeur as jy 'n sigeunermotruspe is wanneer jy deur 'n baculovirus besmet is. Die ruspes verlaat hul skuilplekke, hulle klim helder oordag na die boomtoppe, en wat volgende gebeur is nie baie mooi nie.

My gas bestudeer al jare lank virus-geïnfekteerde insekinteraksies en het nou ’n virale geen gevind wat die gedrag in die ruspe beheer en in die boom laat klim, en sy het pas haar bevindinge in die joernaal Science gepubliseer.

Kelli Hoover is 'n professor in die Departement Entomologie in die Sentrum vir Chemiese Ekologie aan die Penn State University. Welkom terug by WETENSKAP VRYDAG, Kelli.

KELLI HOOVER: Ag, dis lekker om weer met jou te praat.

FLATOW: Wat gebeur daar bo-aan die boom?

HOOVER: Wel, besmette ruspes bly daar bo eerder as om gedurende die dag af te klim om vir roofdiere weg te kruip. Die geen wat hierdie virus uitdruk, wat EGT genoem word, laat hulle dus in 'n voedingstoestand bly deur die hormoon wat hulle laat vervel, inaktiveer.

Normaalweg stop die voeding van gypsy motte of insekte dan ook vir 'n lang tyd. En in die teenwoordigheid van hierdie geen, word die mol geblokkeer, en dus hou die insek, in plaas daarvan om vir 'n lang tyd op te hou voed, aan en word dus in die middel van die dag in die boom gevind wanneer jy normaalweg nie sou vind nie hulle.

As u dus gedurende die dag 'n gypsy mot -ruspe op die blare sien, is hulle byna altyd besmet.

FLATOW: Maar jy het ons nie vertel wat met hulle gebeur nie, jy weet, die laaste einde van die ruspe.

HOOVER: Wel, die arme ding vrek uiteindelik daar bo en word omgeskakel na 'n sak virus wat dan smelt of vloeibaar maak en virusdeeltjies op die loof hieronder laat reën sodat nuwe gashere besmet kan word deur die virus op die blare te eet.

FLATOW: Dit klink soos iets uit "Ghostbusters" of iets, jy weet, die slym wat. Dit slym die boom.

FLATOW: En - maar dit is hoe die virus homself dan versprei.

HOOVER: Ja, so dit vergemaklik die virus om nuwe gashere te besmet deur sy, jy weet, sy sak virusse hoër op in die boom te hê sodat wanneer dit reën, dit die blare kan tref en nuwe gashere kan besmet.

FLATOW: Dit klink of dit 'n baie wrede ding vir 'n virus is.

HOOVER: Dit is soort van wreed. Dit is - ek weet nie. Ek kan nie eers dink aan 'n virus wat soogdiere infekteer wat dieselfde soort ding doen in terme van om die gasheer in 'n sak goo te verander nie.

FLATOW: Wel, so is dit 'n spesiale soort sigeunermot, of is dit elke sigeunermot wat.

HOOVER: Alle sigeunermotte is vatbaar vir hierdie virus. Dit is 'n virus wat natuurlik voorkom. Jy vind dit heeltyd in die veld uit. Dit is op 'n lae vlak in die bevolking totdat daar 'n bevolkingsontploffing is, en dan kan die bevolking soms in duie stort omdat tonne insekte met hierdie virus besmet raak.

VLAK: Weet u, ons hou regtig nie van sigeunermotte nie, want hulle kom, en hulle neem die bome oor en eet die blare en dinge, reg.

HOOVER: Ja, en hulle kan duisende hektaar bos ontblaar sodat dit lyk soos, jy weet, winter wanneer dit die middel van die somer is.

FLATOW: Lyk dit nie so nie - wel, ek dink aan, ek sê hey, hier is 'n sigeunermot, anti-sigeunermot ding. Kan ons nie, weet jy, leer hoe om hierdie virus dalk geneties te manipuleer en van die sigeunermotte ontslae te raak nie?

HOOVER: Wel, ons het dit eintlik ondersoek. Daar - die gypsy mot het 'n immuunrespons op hierdie virus, en dit kan dit afweer as dit op die regte ouderdom is, en as die dosis nie hoog genoeg is nie, as dit nie genoeg virus inneem om dit dood te maak nie.

En daarom het ons na maniere gesoek om die immuunstelsel te onderdruk sodat dit nie gebeur nie.

FLATOW: En gewoonlik klim gypsy motte net bo -op die boom en smelt daarbo?

HOOVER: Ja, hulle sal vervel, en dan sal hulle, jy weet, op die blare eet, maar sekerlik snags is hulle uit op die blare, maar gedurende die dag sal jy hulle sien, jy weet, in die oggend klim hulle terug om in die basskeure weg te kruip, of as hulle groter ruspes is, gaan hulle tot in die grond om weg te kruip.

FLATOW: Jy weet, dit klink 'n bietjie soos hondsdolheid. Jy weet, daar is hondsdol wasbeer en dinge wat veronderstel is om gedurende die dag te slaap, en hulle is gedurende die dag uit, en jy weet dat hulle dalk besmet is. Dit klink so iets.

HOOVER: Dit doen dit beslis. Omdat jy reg is, wat met hondsdolheid-infeksie gebeur, is dat hierdie diere sal, soos jy gesê het hulle is nagdiere, maar hulle sal op die verkeerde tyd uit wees. Hulle sal gedurende die dag uit wees. En hulle raak meer aggressief. Hulle sal 'n ander dier nader en hulle probeer byt.

FLATOW: En doen virusse - soos u voorheen aangedui het, ken u ander diere wat geraak word, word die gedrag beïnvloed deur virusse?

HOOVER: O beslis. Daar is - wel, daar is 'n hele paar virusse wat kan - en ander parasiete en patogene wat gedrag kan manipuleer. Maar u weet dat toksoplasmose wat ek dink die meeste mense in gedagte hou, is: dit is nie 'n virus nie, dit is 'n protosoïese, maar u weet hoe swanger vroue nie hul rommelbakke moet skoonmaak nie , hulle moet iemand anders kry om dit te doen, en dit is omdat hulle dit uit die rommelbak kan optel.

Katte word hiermee besmet, en hulle kry dit dikwels van muise wat hulle eet. So muise wat hiermee besmet is, verloor hul ingebore vrees vir katte, en hulle is meer geneig om geëet te word. So hul gedrag verander wel. En dit is selfs bespiegel dat mense wat met toksoplasmose besmet is, dat hul gedrag ook verander kan word.

Dit is soort van, sou ek sê, kontroversieel, maar dit is beslis voorgestel.

FLATOW: Is daar enige ander virusse wat menslike gedrag kan beïnvloed?

HOOVER: Daar kan wees, maar ek - jy weet, ek kan nie aan een dink wat soortgelyke tipes invloede op sy gasheer het nie.

FLATOW: En so is dit wat jy doen, jy bestudeer virale gene?

HOOVER: Ja, ek doen. Ek werk al vir 'n hele paar jaar daaraan om na verskillende gene in hierdie spesifieke virus te kyk en hoe dit met die sigeunermot in wisselwerking tree. En dit is 'n baie interessante stelsel.

FLATOW: Kom ons kry 'n vraag of twee van ons luisteraars. Derrick(ph) in Grand Rapids, hi Derrick.

DERRICK: Hallo, Ira, hoe gaan dit met jou?

FLATOW: Hallo daar, hoe gaan dit met jou?

DERRICK: Goed. Ek is net besig om "Die oorsprong van die spesie" klaar te maak, en hierdie evolusionêre skakel het my soort van laat wonder hoe die virus ontwikkel het om die gedrag van die insek te manipuleer. En is daar nie 'n - daar is een wat die mier ook affekteer, waar dit tot bo op die gras klim.

HOOVER: Regtig, zombie -miere wat met swam besmet is, ja.

DERRICK: Okay, right, right, so ..

DERRICK: Ja, wonder net hoe dit eintlik ontwikkel het om die gedrag te kry wat dit wil hê.

HOOVER: Wel, daar word gedink dat hierdie geen waarskynlik in 'n insek ontstaan ​​het, want daar is gene wat soortgelyk is aan hierdie wat gevind word in insekte wat soort van 'n soortgelyke funksie het, maar hulle beïnvloed nie noodwendig gedrag nie. Hulle doen soortgelyke tipes chemie.

Maar ek sou dink wat sou gebeur, is jy, as jy verskillende stamme van dieselfde virussoort het, laat ons sê, en een van hulle verkry hierdie geen, en dit gee hulle 'n voordeel omdat dit jou gasheer verhoed om te smelt, dit hou dit voed en veroorsaak ook dat dit sterf in 'n posisie wat jou toelaat om oordrag na nuwe slagoffers te verbeter, dan het jy 'n selektiewe voordeel. Dit sal dus gekies word en kan dan nie net na jou eie stam versprei nie, maar dit kan uiteindelik 'n geen wees wat jy uiteindelik ook in ander virusse sien.

Trouens, die meeste baculovirusse het hierdie geen, ten minste dié wat in hierdie groep is.

DERRICK: So dit bestendig die virus?

HOOVER: Ja, dit verhoog die hoeveelheid virus wat jy uit 'n gegewe ruspe kan kry, want deur te keer dat dit smelt en dit aanhou voed, kry jy 'n groter ruspe, sodat jy meer virus uit 'n gegewe insek kry.

FLATOW: Derrick het die zombiemier genoem. Ek kan dit nie laat verbygaan nie.

FLATOW: Sonder om ons daarvan te vertel.

HOOVER: Om die waarheid te sê, een van die mede-outeurs op hierdie koerant, David Hughes, is die ou wat aan zombiemiere werk. En sy werk het getoon dat wanneer miere met hierdie cordyceps-swam besmet is, die swam hulle veroorsaak om in die boom op te klim net na die regte plek sodat die humiditeit en temperatuur perfek is vir wanneer die mier doodgaan, dit - die swam begin nie net groei nie uit die mier se kop, wat regtig vreemd is in time-lapse fotografie, maar dan sporuleer dit en reën spore neer op niksvermoedende miere hieronder om hulle te besmet.

Die baie gawe ding is ook dat die swam die mierbekke op die aar van 'n blaar laat klem. Dit is baie moeilik om hulle los te ruk. En op dié manier hou jy die mier vir 'n lang tyd op daardie plek, want dit neem die swam 'n paar dae, jy weet, om uit te groei en te spoor. Dit is nogal grof.

FLATOW: Daar is 'n draaiboekskrywer wat hier luister, ek is seker.

HOOVER: Wel, jy weet, ek dink dit is regtig creepy vir mense om te dink dat 'n parasiet of patogeen jou gedrag kan manipuleer. Dit is 'n bietjie creepy.

FLATOW: Jy het nie "The Tingler" jare gelede gesien nie - in die 50's, waar.

HOOVER: Nee, ek dink ek het nie.

FLATOW: "Die inval van die liggaam Snatchers."

HOOVER: O, ek het dit gesien, ja, ja.

HOOVER: Maar dit is nie werklik nie.

HOOVER: Ja, maar jy kan dit inhandig - miskien is dit hoe hulle die idee gekry het, jy weet, om na wetenskap te kyk.

FLATOW: So soos jy sê, jy weet nie van 'n hele klomp ander virusse wat gedrag of mikrobes kan beïnvloed nie, maar hulle kan wees, en ons weet dit dalk nie, daar is dalk ander? Jy moet dink ons ​​ken nie almal van hulle nie, reg?

HOOVER: Reg, en daar is eintlik 'n hele paar wat is - verskillende parasiete en patogene wat dit doen. Weet u, daar is hierdie organisme wat - 'n patogeen of ek sou dit 'n parasiet noem dat dit slakke besmet en veroorsaak dat hulle nie net op die blare bly nie, maar dit verander hulle - dit veroorsaak dat hul tentakels pulseer en, soos , adverteer hul teenwoordigheid aan voëls sodat hulle dan deur 'n voël geëet kan word en die voël kan besmet. Dit is regtig 'n reis.

FLATOW: Sjoe, wel, as 'n voël hierdie ruspe met die virus eet, sal dit dit so versprei?

HOOVER: Ja, dit sal, want die virus bly lewensvatbaar wanneer dit soos voëls deur roofdiere gaan. So as hulle bedags op die blare is, en hulle adverteer dat hulle daar is, sal die voël hulle eet, en as hulle hul mis op plante laat rondgooi, sal dit ook die virus versprei.

FLATOW: Wel, moet hulle kry voordat hulle in slym verander.

FLATOW: Kelli, dit was heerlik. Dankie vir - en, jy weet, dit gee ons hierdie naweek iets anders om oor na te dink.

HOOVER: Wel, jy is baie welkom.

FLATOW: Kelli Hoover is 'n professor in die Departement Entomologie aan die Sentrum vir Chemiese Ekologie aan die Penn State University. Ons sien jou weer. Geniet die naweek.

FLATOW: Ons gaan 'n blaaskans neem, en wanneer ons terugkom, gaan ons van ratte verander en praat oor 'n hernieude bevinding van fossiele, baie interessante bevinding van gefossileerde bene wat ons kan dwing om menslike evolusie te herevalueer. Bly by ons. Ons sal dadelik terug wees.

Ek is Ira Flatow. Dit is SCIENCE FRIDAY van NPR.

Kopiereg & kopie 2011 NPR. Alle regte voorbehou. Besoek ons ​​webwerf se gebruiksvoorwaardes en toestemmingsbladsye by www.npr.org vir verdere inligting.

NPR-transkripsies word op 'n haastige sperdatum geskep deur Verb8tm, Inc., 'n NPR-kontrakteur, en vervaardig met behulp van 'n eie transkripsieproses wat met NPR ontwikkel is. Hierdie teks is dalk nie in sy finale vorm nie en kan in die toekoms bygewerk of hersien word. Akkuraatheid en beskikbaarheid kan verskil. Die gesaghebbende rekord van NPR&rsquos-programmering is die klankrekord.


Koöperatiewe uitbreiding: Insekplae, bosluise en plantsiektes

Sigeunermotruspes voed op die meeste hardehoutbome, behalwe as. Hulle verkies eike-, populier-, grysberk- en vrugtebome. As die larwes halfgroot of groter is, sal hulle waarskynlik ook van immergroen voed. Soos die aantal sigeunermotlarwes in 'n gebied toeneem, raak hul gunsteling voedselbronne uitgeput. Die larwes voed dan waarskynlik op ander sierbome en struike.

Gesonde hardehout kan gewoonlik twee tot drie jaar se ontblaring weerstaan, maar sekondêre aanvalle deur insekte of siektes kan die lewe van verswakte bome verkort of beïnvloed. Verswakte, siek, insekbeskadigde of skadu bome, veral dié wat reeds sukkel met swak grond- of vogtoestande, is veral kwesbaar. Ernstige ontblaarde groenblare is minder geneig om te oorleef as ander bome.

Zigeunermotbesmettings is die swaarste in sentraal- en suidelike Maine. Benewens die ontblaring van bome, is hulle ook lastige plae as gevolg van rondlopende ruspes, mis, papieskas en eiermassas op huise en die afspin van jong ruspes. Klein haartjies van die ruspes kan sommige mense se vel irriteer. In sommige gevalle lei erge reaksies tot uitslag en/of jeuk. As dit geraadpleeg word, moet 'n dokter in kennis gestel word van die moontlikheid van kontak met zigeunermot -rusperhare.

Oorwinterende sigeunermot-eiers broei in Mei uit. Die jong, 1, 16 duim, harige, swart ruspes het 'n klein knop aan elke kant van die kop en word die eerste keer naby trosse eiers gesien. Dit neem tot 'n maand vir al die eiers om uit te broei. Om hierdie rede is dit algemeen om ruspes van verskillende groottes op dieselfde tyd te vind. Die larwes kruip gou in boomtoppe, waar hulle op sylyne draai om na ander plekke geblaas te word.

Voeding deur die jong ruspes aan die onderkant van blare gaan gewoonlik ongemerk verby. Teen die tyd dat hulle half gegroei is, 3/4 tot 1 duim lank, word hele blare geëet. Op hierdie stadium is die ruspes meestal swart, behalwe vir oranje merke op hul rug. Sorgvuldige seleksie en gebruik van insekdoders en biologiese beheermaatreëls in hierdie tyd kan effektiewe beheer van windverwaaide ruspes verskaf.

Die ruspes vervel vyf of ses keer voor verpopping. Wanneer die ruspes 1 duim of meer lank is, is hul voeding meer opvallend. Hulle beweeg op in die bome om snags of op koel dae te voed. Gedurende warm, droë, sonnige dae beweeg hulle af om op die onderste takke, stamme of grasperke te rus.

Die laatstadiumruspes is harig, donker en word maklik onderskei deur vyf pare blou kolle op die voorlyfsegmente en ses pare rooi kolle op die agterlyfsegmente. Volgroeide larwes is 1 ½ tot 2 ½ duim lank. Ongeveer 70 persent van hul kos word verbruik gedurende hierdie stadium van ontwikkeling, hulle is in staat om 'n boom oornag te stroop.

In Julie soek die volwasse larwes beskermde gebiede wat amper enige plek kan wees, waar hulle rooibruin papies vorm. Manlike papies is ongeveer 3/4 duim lank wyfies ongeveer 1 duim lank. Oor 10 tot 15 dae, nog in Julie, kom die motte te voorskyn.

Mannetjiesmotte is uitstekende vlieërs. Hulle is gewoonlik donkerbruin. Voorvlerke vertoon swart golwende bande en V-vormige merke. Agtervlerke is ligbruin afgewerk met donkerbruin. Hul vlerkspan is ongeveer 1½ duim. Mannetjiemotte het opvallende, veeragtige antennas.

Wyfiemotte is groter as mannetjies en oorwegend wit met 'n paar dowwe, golwende bruin of swart bande en V-vormige merke op die voorste vlerke. Marginale donker kolle word op beide voor- en agtervlerke gevind. Vroulike motte het 'n vlerkspan van 2 tot 2 ½ duim, maar hulle kan nie vlieg nie.

Omdat hulle nie kan vlieg nie, beweeg wyfies nie ver van die verpakkingsplek om hul 500 of meer eiers te lê nie. Die eiers is bedek met 'n bruin fluweelagtige massa wat van die wyfie se liggaamshare gemaak is. Eiers is die stadium waarin die sigeunermot oorwinter. Mot sterf kort na paring en eierlegging. Daar is net een generasie sigeunermot elke jaar.

Verskeie faktore kan die weer van sigeunermotpopulasies, roofdiere, parasiete en siektes beïnvloed. Een nag van -20 ° F of kouer maak baie oorwinterende eiers dood wat nie met sneeu bedek is nie.

Bestuur

Meganies

Eiers kan fyngedruk word, maar dit is moeilik om al die eiers in 'n eiermassa op bas of ander growwe oppervlaktes fyn te druk. Eiers kan ook geskraap of andersins verwyder en vernietig word. Hulle moet nie toegelaat word om op die grond te val nie, waar beskermende sneeubedekking die kans op uitbroei verhoog.

Jute kan om die stamme van bome gedraai word om ruspes te versamel en te verhoed dat hulle op takke klim om te voed. Versamelde ruspes kan dan doodgemaak word. Om enige vroulike mot, ruspe, papies of eiers fyn te maak help om sierbome te beskerm, maar slegs as 'n hoë persentasie van die bevolking doodgemaak word.

Hindernisse

Kommersieel beskikbare taai petroleummateriaal is beskikbaar om te verhoed dat ruspes in bome kom. Blik, plastiek, ens., Kan om die boomstam geplaas word om dieselfde doel te bereik. Sommige mense sit petroleumjellie, olie of vet op die omhulsels vir ekstra beskerming, maar vetterige stowwe moet van die bome gehou word en verwyder word as die ruspes weg is. Die meeste petroleumprodukte, taai produkte, olie, ghries of diesel moet nie direk op bome gegooi word nie, want dit sal die bas binnedring, veral van jonger bome. Bome van vier duim in deursnee is in een seisoen doodgemaak toe ghries op hul bas toegedien is. As jy vet op die bas kry, skraap dit so gou as moontlik af en hou dit van die grond af om te verhoed dat die boomwortelsone besoedel word. Versperrings is die doeltreffendste op geïsoleerde bome, as slegs 'n paar ruspes in die boom is wanneer die versperring toegedien word, en as 'n insekdoder vroeër toegedien is.

Insekdoders

Die insekdoders Bt (Bacillus thuringiensis) vir jong larwes, neem, spinosad, carbaryl (Sevin), cyfluthrin, ortheen, en malathion kan ook gebruik word om ruspes te beheer. Spuit ruspes enige tyd, maar vir die beste resultate spuit voordat hulle half gegroei word op 3/4 tot 1 duim lank. Blare moet laatmiddag of vroegaand gespuit word vir die beste resultate en die beste beskerming van bye, roofdiere en parasiete.

Wanneer plaagdoders gebruik word

VOLG ALTYD ETIKETAANWYSINGS!

Plaagbestuurseenheid
Koöperatiewe Uitbreiding Diagnostiese en Navorsingslaboratorium
17 Godfrey Drive, Orono, ME 04473
1.800.287.0279 (in Maine)

Die inligting in hierdie publikasie word bloot vir opvoedkundige doeleindes verskaf. Geen verantwoordelikheid word aanvaar vir enige probleme wat verband hou met die gebruik van genoemde produkte of dienste nie. Geen goedkeuring vir produkte of ondernemings is bedoel nie, en kritiek op produkte of maatskappye sonder naam word ook nie geïmpliseer nie.

Bel 800.287.0274 (in Maine), of 207.581.3188, vir inligting oor publikasies en programaanbiedinge van die Universiteit van Maine Cooperative Extension, of besoek extension.umaine.edu.

Die Universiteit van Maine is 'n EEO/AA -werkgewer en diskrimineer nie op grond van ras, kleur, godsdiens, geslag, seksuele oriëntasie, transgenderstatus, geslagsuitdrukking, nasionale oorsprong, burgerskapstatus, ouderdom, gestremdheid, genetiese inligting of veterane nie status in indiensneming, onderwys en alle ander programme en aktiwiteite. Die volgende persoon is aangewys om navrae oor nie-diskriminasiebeleide te hanteer: Sarah E. Harebo, Direkteur van Gelyke Geleenthede, 101 North Stevens Hall, Universiteit van Maine, Orono, ME 04469-5754, 207.581.1226, TTY 711 (Maine Relay) Stelsel).


Sigeunermot

Die sigeunermot (GM) is 'n indringende nie-inheemse insek met larwes wat woes op die blare van baie Noord-Amerikaanse plante voed. GM ruspes verkies eike en aspe, maar eet nie koniferenaalde nie, tensy hulle honger ly. Voorkeurgashere is gekonsentreer in die Noordooste, Midde-Weste en suidelike Appalachians en Ozarks. GM is sowat 130 jaar gelede naby Boston bekendgestel en het sy pad deur New England en Mid-Atlantiese streke gesny, die huidige &ldquoinvalfront&rdquo strek van Noord-Carolina tot by Minnesota.

By die invalsfront word bome vir die eerste keer aangeval en word gewoonlik heeltemal ontblaar, soms vir 'n tweede keer as hulle weer blaar. Agter die voorkant leef GM in verskillende digthede, en die bevolking kan elke 5 tot 10 jaar vinnig toeneem (of & ldquoerupt & rdquo). Ontblaring verminder bome se groei, groeikrag en weerstand teen biotiese en abiotiese stressors en veroorsaak direkte mortaliteit. Alhoewel minder as 20% van die bome in die meeste woude sal vrek, kan boomsterftes op sommige plekke swaar wees. Boomsterftes verminder houtwaarde residensiële koste word geassosieer met GM ontblaring en oorlas— ruspehare veroorsaak allergiese reaksies by mense en ruspe &ldquofrass&rdquo (in wese ontlasting) kan letterlik van bome af reën.

Gelukkig, in woude agter die invalsfront, hou verskeie van die biologiese beheermaatreëls wat op verskillende tye ingestel is, oor die algemeen GM-bevolkings op redelike getalle, hoewel uitbrake wel voorkom. Chemiese insekdoders word nie meer vir bespuiting gebruik nie, slegs biobeheermiddels soos die lepidoptera-spesifieke bakterie Bacillus thuringiensis (Bt) 'n virale patogeen (Gypchek) en paringsontwrigters word nou meestal gebruik. Vir meer as 100+ jaar was die GM die fokus van intensiewe studie, aangesien federale, staats- en akademiese entomoloë, ekoloë en ander wetenskaplikes gewerk het om hierdie vraatsugtige plaag te beheer en te verstaan ​​en die verspreiding daarvan te stop.

Baie van die biologie en gedrag van GM is bestudeer en gerapporteer in die wetenskaplike literatuur en baie beheermaatreëls is ontwikkel, hulle sal in die afdelings hieronder bespreek word. Tans fokus navorsing op die Northern Research Station op nuwer doelwitte en#8212 (1) vertraag die verspreiding van hierdie insek in nuwe vatbare habitats (2) ontwikkel en verbeter biologiese beheermaatreëls en (3) bepaal watter faktore uitbarstings of uitbrake beïnvloed.


Proteus

Habitat

Proteus myxofaciens is slegs van die larwes van die sigeunermot geïsoleer (Porthetria dispar) en sal dus nie verder oorweeg word nie. Die ander Proteus spp. kom egter wyd in die natuur voor en vorm 'n belangrike deel van die flora van ontbindende materie van dierlike oorsprong. Hulle is voortdurend teenwoordig in vrot vleis en riool en baie gereeld in die ontlasting van mense, diere en plae soos kakkerlakke en vlieë. Hulle word ook algemeen in tuingrond en op groente en vrugte aangetref. Benewens hul wye saprofitiese bestaan, is isolate van Proteus spp. is die oorsaak van 'n aantal septiese infeksies by mense en diere.


Hoe 'n slim virus 'n baie honger ruspe doodmaak

'n Gesonde sigeunermotruspe op 'n blaar. Uitbrake van sigeunermotte beskadig elke jaar ongeveer 1 miljoen hektaar bos in die VSA.

Wetenskaplikes sê hulle het uitgepluis hoe 'n baie slim virus 'n baie honger ruspe uitoorlê.

Die ruspe is die sigeunermot in sy larfstadium, en die indringersoort beskadig jaarliks ​​ongeveer 'n miljoen hektaar bos in die VSA deur boomblare te verslind.

Maar die skade sou groter wees as dit nie was vir iets wat 'n baculovirus genoem word nie, wat hierdie ruspes kan besmet en veroorsaak dat hulle roekelose, selfs selfmoordgedrag beoefen, sê wetenskaplikes. Die virus is so effektief dat die regering dit eintlik op bome spuit om die uitbrake van sigeunermot te help beheer.

Nou dink 'n span wetenskaplikes dat hulle ontdek het hoe die baculovirus beheer neem oor sigeunermotruspes. Die sleutel is 'n spesiale geen wat deur die virus gedra word en die ruspe se eetgedrag beïnvloed, volgens die span se nuwe studie in Wetenskap.

Die ontdekking verduidelik 'n verskynsel waaroor wetenskaplikes al dekades lank gewonder het.

Normaalweg voed sigeunermotruspes snags op boomblare wanneer roofdiere, insluitend voëls en eekhorings, hulle nie kan sien nie. Dan klim die ruspes bedags af en skuil in die boombas of selfs onder blare op die grond.

Maar ruspes laat vaar daardie sinvolle strategie wanneer hulle met 'n baculovirus besmet is, sê Kelli Hoover, 'n entomoloog aan die Pennsylvania State University en die hoofskrywer van die koerant.

“Soos hulle siek word, klim hulle na verhewe posisies en bly daar en sterf,” sê sy. Wat volgende gebeur, is nogal grusaam. "Die binnekant van die ruspe word redelik omgeskakel na miljoene en miljoene virusdeeltjies. Dan is daar ander ensieme wat die eksoskelet laat smelt. En dit maak die ruspe vloeibaar, en dan kan dit virusse op die blare onder neerreën."

Wanneer ander ruspes daardie blare eet, word hulle ook besmet.

'n Slim patogeen

Hoover en 'n span navorsers het vermoed dat die virus beheer oor die ruspe neem deur 'n geen te gebruik wat betrokke is by vervelling, wat die sigeunermotlarwes verskeie kere moet doen terwyl hulle groei. Die geen beïnvloed ook eetgedrag, want om te vervel, moet larwes ophou eet.

Om hul hipotese te toets, het die wetenskaplikes sommige ruspes besmet met 'n baculovirus wat die normale weergawe van hierdie geen dra, en ander ruspes met 'n baculovirus met 'n geïnaktiveerde weergawe van die geen. Toe sit hulle die ruspes in hoë plastiekhouers wat met ’n skerm uitgevoer is.

"Elke keer as die ruspes met die normale geen besmet is, sou hulle op 'n verhoogde posisie in die houer doodgaan," sê Hoover. "As die geen uitgeslaan is, het hulle nie."

Rupes wat met baculovirus besmet is, klim na die toppe van bome, waar hulle smelt en die virus op die blare onder drup. Daar word dit deur ander ruspes geëet. Michael Grove/Wetenskap/AAAS versteek byskrif

Rupse wat met baculovirus besmet is, klim tot bo -op bome, waar hulle smelt en die virus op die blare hieronder laat drup. Daar word dit deur ander ruspes geëet.

Dit is waarskynlik omdat hierdie geen 'n hormonale stelsel ontwrig wat die ruspe vertel wanneer om op te hou eet," sê Hoover. "En om te voed, moet jy bo in die boom wees."

Die resultaat is verwoestend vir die gypsy mot, maar goed vir die virus, sê David Hughes, 'n entomoloog en bioloog van Penn State en mede-outeur van die studie. As jy dus na die wêreld kyk vanuit die oogpunt van 'n baculovirus, is dit maklik om te sien hoe dit sou ontwikkel het om hierdie geen te dra.

"Die belangrikste uitdaging vir 'n virus is om ander virusse uit te kompeteer," sê Hughes. So 'n virus wat sy gasheer kan laat sterf op 'n plek wat die infeksie na ander gashere versprei, sal 'n groot voordeel hê, sê hy.

Ander wetenskaplikes sê die bevinding toon hoe slim 'n patogeen kan wees.

"Wie het geweet dat 'n virus die gedrag van sy gasheer sou kon manipuleer?" sê Jim Slavicek, 'n navorsingsbioloog by die Amerikaanse Bosdiens, wat ook bygedra het tot die nuwe studie.

Virus as 'n wapen teen uitbrake

Slavicek sê om te weet presies hoe baculovirus die sigeunermot oorweldig, kan wetenskaplikes help om kragtiger stamme van die virus te ontwikkel. Dit kan hulle ook help om te bepaal wanneer in die sigeunermot se lewensiklus dit die kwesbaarste is vir infeksie.

En hy sê alles wat kan help om die koste van bespuiting met baculovirus te verlaag. Right now, he says, land managers often use cheaper methods, such as insecticides or a deadly fungus.

"The advantage of the virus is that it is specific for gypsy moth larvae, and so it will impact no other animal, insect, plant in the treatment zone."

Gypsy moth outbreaks in the U.S. are less severe than they were a couple of decades ago, thanks to better treatments, Slavicek says. But he says the pest remains a major threat that can leave a forest bare in a matter of weeks.

During an outbreak, Slavicek says, there are so many caterpillars that their remains make some roads so slippery that road crews have to apply sand.

And if you drive on those roads at night, he says, "millions of moths will fly to the car, and it can be so dense that it's like a snowstorm. You can't see what's in front of you."


Zombie Caterpillars Rain Death From Treetops

A single gene in a caterpillar virus sends its victims running for the treetops, where they die and their bodies liquefy, sending an ooze of virus particles on their brothers and sisters below.

This species of baculovirus infects only gypsy moth caterpillars, essentially turning them into zombies. It stops the caterpillars from molting and sends them up into the tree leaves during the day (a behavior they normally save for the cover of darkness), where they die among the leaves as they wait to molt.

"They die there, and then they melt within hours after they die, and they are dripping virus down onto the leaves below," said study researcher Kelli Hoover, of Pennsylvania State University. "We knew before that this behavior benefits the virus, but we didn't know how it was causing the behavior." [See images of zombie caterpillars]

Strange wanderings

The strange caterpillar behavior was first observed 100 years ago, and was blamed on infection from a virus. Now researchers, led by Hoover, have discovered that a single gene in the virus causes this effect. The gene, named egt, interferes with the caterpillar's molting hormone and seems to play a role in the caterpillar's urge to climb.

They discovered this amazing property by infecting caterpillars with a normal baculovirus and the same virus lacking the egt gene. The caterpillars infected with the virus that didn't have egt died at the bottom of specially made enclosures (tall soda bottles) meant to mimic their natural environments. Those caterpillars infected with the virus containing egt died clinging to the top of the bottles, with little chance of spreading the virus to siblings since that would mean others would have to walk over a puddle of goo to get infected.

Not only does the virus send the caterpillars crawling upward, it also stops them from molting, which is a major help to the virus since molting caterpillars don't eat, don't grow, and therefore produce less virus-containing goo.

Spreading virus

The virus multiplies fiercely in almost every cell of the caterpillar's body. When the caterpillar dies among the leaves, it undergoes a natural liquefaction process in which its exoskeleton disintegrates. Each drop of caterpillar goo contains millions of viruses.

Birds even help disperse the virus when they scarf a caterpillar snack from the leaves, they bash it on branches to remove some of its hair. Slow-motion video shows this action not only dispenses of hair, but also expels droplets of liquefied caterpillar. The virus can even survive in the gut of the birds, to be rained down like viral bombs from above in their feces.

These zombie caterpillars are just one example where a parasite can control another organism. For instance, fungus-infected zombie ants are lured to their death to spread their parasite, and similarly, a protozoan called toxoplasmosis makes infected mice approach cats, the parasite's ultimate host.

We may not even be safe from such mind control.

"Who knew that a virus could change the behavior of its host?" study author Jim Slavicek, of the U.S. Forest Service, said in a statement. "Maybe this is why we go to work when we have a cold."

A poopy problem

Learning more how the virus interacts with its host could help forestry researchers design better control methods for gypsy moth caterpillars, which can become pests as their populations skyrocket and plummet.

In fact, the forestry service uses these viruses to control outbreaks of gypsy moth caterpillars in areas where pesticides might harm endangered insects.

Hoover has even been affected by out-of-control gypsy moths, which took over a hickory tree in her yard. "I needed a hat because there was so much frass, insect feces, raining down out of the tree," Hoover told LiveScience. "I would sit there and watch them march up and down the trunk."

You can follow LiveScience staff writer Jennifer Welsh on Twitter @microbelover. Follow LiveScience for the latest in science news and discoveries on Twitter @livescience and on Facebook.


2 MATERIAAL EN METODES

2.1 Experimental area and gypsy moth population surveys

The experiment was set up in the region of Franconia, in north-western Bavaria, Germany, within an approximately 2400 km 2 area delimited by the cities of Würzburg in the West, Schweinfurt in the North, Bamberg in the East and Bad Windsheim in the South (Figure 2). The landscape is dominated by a matrix of agricultural land (arable land, vineyards and grasslands) surrounding forest patches of variable size (Figure 2). Forests are dominated by deciduous oaks (Quercus robur Land Quercus petraea Mattuschka) and have been subjected to cyclical and spatially synchronous gypsy moth outbreaks since the early 1990s (Lemme et al., 2019 ).

Local district foresters carried out surveys of gypsy moth egg masses in four administrative regions – Upper Franconia, Middle Franconia, Lower Franconia and Swabia – during fall 2018, following a standardized protocol. The number of gypsy moth egg masses were counted on the lowest 2 m of tree trunks along a transect comprising, in most cases, 10 trees of the dominant social class. The abundance of egg masses on the underside of lower canopy branches of each tree, stand vitality, stand age and history of previous outbreaks were also reported. These data were used to calculate a ‘defoliation risk index’ (DRI) to identify areas at high or low risk of defoliation in the summer 2019 (Supplementary Information, file S1). In total, 26823 single trees were surveyed along 2802 transects.

2.2 Experimental design

2.2.1 Plot selection

We searched for oak-dominated areas at both high (DRI>1) and low (DRI<0.5) risk of defoliation for 2019, excluding young stands (i.e. average overstory tree age <70 years old) as well as sites with a recent spray history, based on the centrally stored application records of Bavaria. Candidate plots were individually checked by on-site visits for stand-structural homogeneity, and heterogeneous areas were excluded. Candidate blocks were to include a minimum of four comparable plots (two high DRI and two low DRI) of at least five hectares each, such that insecticide treatment could be attributed to one random plot per defoliation risk class in a full factorial fashion, that is each block consists of the four following plots: high defoliation risk, unsprayed (further referred to as ‘high-control’) high defoliation risk, sprayed (‘high treatment’) low defoliation risk, unsprayed (‘low-control’) and low defoliation risk, sprayed (‘low-treatment’) (Figures 1 and 2). Overall, 142 areas based on 778 transects (7534 trees) were inspected, of which 22 candidate blocks comprising 108 plots were retained.

2.2.2 Plot validation

Once a block was considered suitable for the experiment, approval of landowners was sought to include the nested plots into the experimental design. As the aim was to include in each block one sprayed and one unsprayed plot from high risk and low risk stands, attribution of the insecticide treatment was initially done by drawing a random number. However, the process was challenged by several constraints. First, insecticide treatment is generally only allowed in stands at high risk of defoliation. The denomination of stands to be sprayed (‘treatment setting’) is done by the Bavarian State Institute of Forestry (LWF) and is the legal basis for insecticide application in Bavaria. Thus, for all low-treatment plots, and all high-treatment plots falling outside of the treatment setting, permission had to be applied for to the authorities. Second, landowners can decide whether to follow the recommendation of the LWF or not. Owners’ objections to treatment allocation led to the exclusion of 18 candidate plots and two treatment shifts between plots (Figure S2-1 in the Supporting Information). Third, concurrent with the negotiations, all plots selected for spraying have to be checked for compliance with state guidelines for nature protection. These guidelines prohibit spraying of a stand and apply to a shortlist of species with local conservation value and which populations may be negatively impacted by insecticides either directly (e.g. Euplagia quadripunctaria, Lepidoptera: Erebidae) or indirectly (e.g. Bubo bubo, Strigidae). We obtained permissions to spray stands falling under this rule for eight plots in which the threat posed by spraying was considered minimal (i.e. indirect threat only and unsprayed habitat available in close vicinity to the plot Figure S2-1 in the Supporting Information Supplementary Information, file S3). A final 48-plot study design covering a total area of 647 ha, with 311 ha to be sprayed with tebufenozide, was established as the outcome of the validation process (Figure 2). Around the centre of each plot, we established a 4.5-ha subplot where all investigations will be conducted. A detailed description of all selected plots, that is location, size, tree species composition, soil type, management type, spray date and spray history, is provided in Table S4-1 in the Supporting Information.

2.2.3 Insecticide application

Tebufenozide was applied in spray plots as Mimic® (Spiess-Urania Chemicals, Hamburg, Germany 240 g L −1 active ingredient [a.i.]) at the maximal legal rate of 750 mL diluted in 50 L of water per ha (i.e. 180 g a.i. ha −1 ), between 3 and 23 May 2019. The length of the spraying window was significantly extended due to legal procedures and unfavourable weather conditions. Treatment was applied by a Bell 208 helicopter equipped with a Simplex spraying system (Simplex Aerospace, Portland, Oregon, USA) with nozzle size 5 according to German regulations (German Federal Office of Consumer Protection and Food Safety, 2019 ) on an area ranging from 6.7 to 27.8 ha, for a total area of 314 ha (Table S4-1 and Figure S5-1 in the Supporting Information). Application proceeded in dry weather and low wind conditions (i.e. wind speed below 2.5 m s −1 ) and block-wise when applicable.

2.3 Data collection

During the treatment year (2019), we intensively sampled the study plots in order to measure the response of different components of the ecosystem (trees, non-target fauna) to insecticide and gypsy moth outbreaks. We hereby describe the data collection procedures carried out during the first year of the experiment. These surveys shall be repeated in the post-treatment years to assess the effects of continuing outbreaks and post-treatment recovery. Photographs of all survey methods, an example map of a plot and a list of the associated variables can be found in the Supplementary Information, file S6.

2.3.1 Tree growth monitoring

We marked 20 oaks in each plot, that is 44 × 20 = 880 trees (11 blocks block T could not be included due to time constraints). In addition to the central tree, its six nearest neighbours with a diameter at breast height higher than 7 cm were included to account for competitive influences (Prodan, 1968 ). Starting from the centre of each plot, 20 of these ‘six-tree samples’ were taken along transects in the four cardinal points (Figure 3(a)). Sample circles were positioned at 25, 50, 75, 100 and 125 m from the centre of the infested area (origin of the coordinate system in Figure 3(b)). These sample circles served to record the stand characteristics (e.g. basal area, standing stock). Within each sample circle, the tree with medium diameter was selected as the sample tree for the detailed sampling. Species, diameter, position and crown transparency of the neighbour trees were scored.

In order to investigate long-term effects on the growth pattern of the oaks due to defoliation, the central oaks were additionally equipped with a permanent girth tape. During the 2019 growing season, the tapes were read and checked five times (April, June, July, September and November). The assessment was repeated in 2020 and should be extended for up to three additional years. In the future, the reading and checking will be carried out annually in autumn after completion of annual ring formation and in spring immediately before the start of the growth, in order to eliminate artefacts caused by winter swelling and shrinkage, and defects caused by manipulation or overstretching of the tension springs.

In January 2020, four fences (5 × 5 m) were installed within 30 m of the centre of each plot to address the effects of defoliation on the development of natural regeneration (Figure 3). An area outside the fence is used as a control to analyse the influence of browsing. Within the fences and on the adjacent control areas, all individuals up to a maximum height of 2 m, separated by tree species, were counted in height intervals of 20 cm. Additionally, the browsing was addressed on each individual. In order to estimate the biomass of the regeneration, undamaged representative individuals were taken over the entire height spectrum found on the regeneration plots, outside the regeneration areas and separated by tree species. These individuals were dried to constant weight and weighed separately according to root and shoot. The regeneration recordings will be repeated in 2021 and should be extended for another 3 years if possible.

2.3.2 Periodic changes in vegetation

Met i representing the focal time point: 2 = defoliation peak, 3 = refoliation.

TLS surveys were repeated in 2020 and should be extended for at least one extra year, if possible.

2.3.3 Non-target fauna

To assess the effect of gypsy moth outbreak and the use of insecticide on other animal species, several measures will be taken: (a) sampling of canopy arthropods by pyrethrum knockdown, (b) sampling of ground-dwelling Carabid beetles with pitfall traps, (c) sampling of adult Lepidoptera with light traps, (d) sampling of the bird community using songbird recorders and nest boxes, and (e) sampling of bat communities using bat call recorders.

Canopy arthropods. Crown-dwelling arthropods are sampled by pyrethrum knockdown with SwingFog SN50 fogging machines (Swingtec GmbH, Isny, Germany). In each plot, one mature oak tree from the dominant social class was selected as the centre of the fogging area. Fogging areas were also selected at least 30 m away from trees used for gypsy moth monitoring and assessment of tree response, to prevent pyrethrum knockdown from impacting the natural development of focal gypsy moth populations. Four tarpaulin sheets (3 × 5 m) are laid on the forest floor below the crowns of the focal tree and its neighbours, within a distance of 20 m, for a total sampled area of 60 m 2 . The tree canopy above the sheets is fogged for 3–12 min depending on the wind conditions, until the fog cloud coats the targeted tree crowns. Arthropods are collected from the sheets after a 30-min exposure period and stored at –18°C. In 2019, the operation was repeated at three different time points: pre-spray baseline (25 April–8 May 2019 38 plots), acute insecticide toxicity (i.e. 1–3 weeks post-spray, 23 May–7 June 2019 48 plots) and peak feeding by the gypsy moth (1–4 July 2019 48 plots) in different but comparable fogging areas. Gypsy moth caterpillars were counted and separated from the rest of the catch. Barcoding will be performed on all individual caterpillars, including gypsy moth, to identify each specimen and its associated parasitoids to species. The by-catch will be sorted to order for further analyses. The second and third sampling rounds, that is the acute toxicity phase and the peak defoliation sampling were repeated in 2020 in the same fogging areas that were swapped between both time points. As the post-treatment recovery of oak-dwelling Lepidoptera is expected to take more than 2 years, canopy arthropod surveys should be extended for at least one additional year.

Carabid beetles. Pitfall traps (i.e. 200 mL plastic yoghurt pots) are used to sample ground-dwelling arthropod fauna, in all 48 plots. In spring 2019, three traps were placed in individual holes in a line between the plot centre and the S1 tree under an alveolar polycarbonate plate mounted on 3 wooden sticks to protect them from rainwater. The traps are filled with 150 mL vinegar solution (5%) mixed a few drops of dishwashing liquid, acting both as a killing and conservation agent. In 2019, the traps were exposed for about 3 weeks and sampled continuously from spring to early summer (24 April–31 May 2019 31 May–25 June 2019 25 June–16 July) and one more time in late-summer (29 August–24 September 2019). As the main focal group, Carabid beetles were separated from the by-catch, counted and identified to species. The assessment was repeated in 2020 to measure potential recovery from insecticide impacts, with one additional trap per plot. For this second survey, the traps were moved inside the recently installed regeneration fences (one trap per fence section 2.3.2. ‘Periodic changes in vegetation’) to reduce trap losses to wildlife damage. Conditional on patterns observed in 2020, the survey may be continued in 2021 to investigate longer-term carry-over effects.

Adult Lepidoptera. Adult moths are sampled by automatic light trapping in 44 plots. One light trap per plot is mounted at the height of approximately 1.6 m in proximity to the plot centre. Each trap consists of one fluorescent tube (12 V, 15 W up to 40 m attraction range Truxa & Fiedler, 2013 ) powered by a lead storage battery (12 V, 12 Ah) and equipped with a light sensor to enable automated activation and switch-off controlled by daylight intensity. Insects attracted by the lighted fluorescent tube fall through a plastic funnel into a bucket containing a chloroform-soaked wick. During each survey campaign, traps are set up for a single night in each plot, under conditions favouring flying activity of insects, that is temperature above 9°C, low precipitation, wind speed below 27 km h −1 and fullness of the moon below 85%. We use 32 individual light traps so that up to eight blocks can be sampled in one night. Insects are collected in the following morning and stored at –20°C. Light traps were operated in five occasions throughout the spring and summer to cover most of the species assemblage. In 2019, light trapping was performed at the end of April, May, June, July and August 2019. Light trapping was repeated in 2020, excluding the May session, and will be repeated in 2021, with a survey frequency conditional of the results obtained in the previous years. Male and female gypsy moth are separately identified and counted in the laboratory, while other macrolepidopteran species are identified by an expert lepidopterologist. Full species composition of the samples is achieved by morphological identification of the Coleoptera and metabarcoding of the remaining by-catch.

Bats. We use autonomous bat call recorders of the type ‘Batcorder 2.0’ and ‘Batcorder 3.0’ (ecoObs, Nuremberg, Germany) to quantify activity and species diversity of bats in 44 plots. Batcorders are set up in the same nights as the light traps, that is we use up to 32 batcorders simultaneously. One batcorder is tied to a tree located near the plot centre at the height of 1.5 m with a distance of at least 15 m from the illuminated light trap in order to avoid interference. Batcorder microphones are set up to point towards an open space in the forest stand away from the light trap. Bat calls are automatically recorded from dusk until dawn for one night. Batcorders are set with a quality less than or equal to 20 and a maximum critical frequency of 16 kHz. From all recordings, bat calls within a threshold of –27 dB are automatically analysed and assigned to a species or species group using bcAdmin4, batIdent1.5 and bcAnalyze3 (ecoObs, Nuremberg, Germany). Bat activity indices of each species or group are generated in 1-min intervals using bcAdmin4. Bat recording was repeated in 2020 and is planned for the second post-treatment year (2021), simultaneously with light trapping sessions.

Birds. We intend to examine the reproductive success of cavity-nesting birds in nest boxes and monitor songbird communities using sound recorders. Bird monitoring was conducted during the treatment year (2019), repeated identically in 2020 and planned for one additional year (2021) to address recovery of birds following disturbance.

Cavity B1 nest boxes (entrance hole diameter: 32 mm Schwegler, Schorndorf, Germany) are used to study the breeding success of cavity-nesting species such as tits (Parus major, Cyanistes caeruleus), flycatchers (Ficedula hypoleuca, Ficedula albicollis) and nuthatches (Sitta europaea). In March and April 2019, eight nest boxes were deployed in 44 study sites for a total of 352 next boxes, with an inter-box distance ranging from 30 to 90 m. In each location, half of the next boxes were hung freely onto a tree branch while the other half was placed in direct contact to an oak trunk to measure the effect of nest invasion by gypsy moth caterpillars that commonly occurs early in the summer during outbreaks. Nest boxes were checked four times between late April and mid of July 2019, covering the first and second broods of nesting birds. Breeding success was measured by the number of fledged nestlings and the number of successful broods, which we defined as broods with at least one fledged nestling.

Communities of vocalizing bird species were detected continuously from late April to September 2019 via autonomous recording units (Bioacoustic Audio Recorder, Frontier Labs, Salisbury, Australia). At 44 locations, one recorder per site was permanently mounted at the height of 2.5 m near the centre of the plot. On four occasions between late April and mid-June, 10 min of the recorded sounds were identified to species for each study site and occasion by an experienced ornithologist.

2.3.4 Gypsy moth population monitoring

We monitor gypsy moth populations by intensively sampling different life stages, including different larval instars. In 2019, all four life-stages (egg, larva, pupa and imago) were sampled throughout the spring and summer. In April, shortly before egg hatch, egg masses laid on oak trunks up to 2 m high were counted on 48 trees comprising the ‘six-tree samples’ centred around the trees 1 and 2 in each cardinal direction starting from the plot centre (Figure 3). To sample late-instar larvae, we installed 50-cm-wide burlap bands (polypropylene wood fleece, DuPont™ Plantex® Gold) on eight trees per site, that is two trees in each intercardinal direction starting from the plot centre, with an inter-tree distance ranging from 20 to 40 m. Live larvae, dead larvae and pupae sheltered below the bands were counted on two 300 cm 2 windows orientated north and south on each banded tree in two occasions (11–20 June and 02–18 July 2019) (Figure 3). This type of survey was conducted in 10 of the 12 blocks (i.e. 40 plots) in 2019. Early-instar larvae and imagines were sampled by pyrethrum knockdown and light-trapping together with the associated non-target species (see section 2.3.3. ‘Non-target fauna’). Gypsy moth monitoring was conducted at the same intensity in 2020. As no outbreak population remained in any plot after 2020, lighter surveys (e.g. on a smaller number of trees per plot) will be performed during the next years as routine monitoring of population density.

2.4 Statistical procedures

Statistical analyses will be performed in R 4.0.2 and upcoming versions (R Core Team, 2020 ).

2.4.1 Missing data

In cases of non-random missing data (e.g. an entire block could not be sampled) in independent variables, missing data will be dropped, and the analysis only performed on complete data. Covariates with non-random missing data could be dropped depending on their importance in the analysis. For data missing at random in essential variables, individual data points will be dropped when the proportion of missing values is below 5%. For randomly missing data ranging from 5 to 30% of the total, multiple imputations (n = 500) will be performed with the R package mice to impute NAs with realistic values computed based on information from relevant variables in the dataset (Buuren & Groothuis-Oudshoorn, 2011 ). Statistical models will then be applied to each of the imputed datasets and the results pooled by Rubin's rules (Rubin, 1987 ).

2.4.2 Statistical models

For variables with non-normal error distribution, generalized linear mixed models will be used with the family distribution that best fits the response variable. Zero-inflation models will be used to investigate the post-spray response of groups for which strong insecticide effects are expected, that is gypsy moth and non-target Lepidoptera. Adjustments to the core model, such as inclusions of relevant covariates or nested random effects (e.g. 1|block/plot) will be made on a model-to-model basis, considering the existence of specific hypotheses justifying the inclusion of additional variables and the hierarchical level at which the effects are investigated (e.g. plot or individual tree). Because our experiment has a full factorial design, (generalized) linear models may be performed instead of mixed effect models in the absence of nested structure (i.e. plot-level analysis) and strong block effect. Lastly, generalized additive (mixed) models may be used to fit nonlinear relationships between the dependent and independent variables.

To separate direct and indirect effects of tebufenozide on the various non-target groups under study, we will perform structural equation models with gypsy moth density or foliation rate as mediators of the relationship between treatment and the independent variable(s). The choice of the appropriate mediator(s) will be motivated by the pathways through which indirect effects on the independent variable are expected to occur, namely whether they are related to change in resources (foliage or caterpillars) or habitat degradation (Figure 4).

2.4.3 Covariates

A covariate will be included in a model only if it complies with the following criteria: (1) expected biological relevance, that is there is a sound hypothesis motivating its consideration in the analysis (2) independence, that is the effect of the focal variable is not confounded with that of treatment and other covariates. The presence of confounding effects will be tested for each covariate in regression models with treatment as a predictor. Failure to accept the null hypothesis (i.e. no significant correlation between the covariate and the treatment) will lead to the exclusion of the focal covariate. To test for multicollinearity of covariates, we will perform a principal component analysis (PCA) on all potential covariates using the subset of plots considered for the analysis. In cases when two or more covariates are highly correlated, we will favour the variable which best describes the expected relationship with the independent variable. The covariates potentially included in further analyses are listed in the overview of all measured variables in Table S6-1 in the Supporting Information.

2.4.4 Post-fitting procedures

Model diagnostics. (Generalized) linear (mixed) models and generalized additive (mixed) models must fulfil the assumptions of normality and independence of the residuals and homogeneity of the variance among groups. Each model will be graphically checked for compliance with these assumptions using base R plotting functions (linear models), and model diagnostic functions built-in the R package DHARMa (linear mixed models Hartig, 2020 ) and mgcv (additive models Wood, 2017 )

Influence measures. To assess the influence of outliers on the results of the regression models, we will compute Cook's distance (D) for each observation and examine the observations with values of D that are substantially outstanding from the rest. These observations will be dropped from the data, and the model refitted. Outliers will be considered influential if they substantially bias the estimates, in which case they will be dropped from the analysis.

Inference. To test our hypotheses, we will use t-, F-, Wald or likelihood ratio tests depending on the family error distribution and the structure of the focal model. For (generalized) linear mixed models, we will use the options currently available, following recommendations from Bolker ( 2020 ), namely Kenward–Roger F tests for the normal family, likelihood ratio tests for the Poisson family and Wald tests for the beta and negative binomial families and zero-inflation models. To test for differences among groups, we will perform comparisons of estimated marginal means with multivariate-t adjustment of bl-values for multiple comparisons.

2.5 Evaluation of the experimental design

In order to assess the suitability of the study design for addressing our research questions, we measured gypsy moth population density and the intensity of defoliation in the study sites during the treatment year (2019). We gathered data on gypsy moth population density at various stages of its development: egg masses, early-instar larvae (canopy pre-spray and post-spray), late-instar larvae (burlap bands live and dead), pupae (burlap bands) and imagines (see section 2.3 ‘Data collection’ for a description of the sampling methods). The data were analysed following the statistical procedures described in the previous section. Characteristics of the individual models are shown in Table S7-1 in the Supporting Information.


Adults

Moths &mdash the adult stage in the gypsy moth life cycle &mdash start emerging from their cocoons in late July. This emergence can continue into late August in south-coastal B.C.

Adult gypsy moths do not eat. They live only about a week &mdash long enough to mate and for the females to lay their eggs.

Male gypsy moths are brown. They have a small body and are strong fliers. Female gypsy moths are white with black markings on their wings. They are much larger than males and do not fly.

Females attract mates using chemicals called pheromones. After mating, the female lays her eggs before she dies. Her eggs will hatch the following spring. Egg-laying is usually complete by early September.

Adult male gypsy moth.
Note the feathered antenna.
Adult female gypsy moth.


Kyk die video: Gypsy Moth Caterpillar Workout (Junie 2022).


Kommentaar:

  1. Rorey

    skok kamentov

  2. Gozahn

    Kan nie wees nie

  3. Rush

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  4. Newton

    Presies! Dit lyk vir my na 'n goeie idee. Ek stem saam met jou.

  5. Kazrataxe

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  6. Orik

    Die uitstekende vraag



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