Auflistung nach Autor:in "Walther, Bernd"

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    Baiting location affects anticoagulant rodenticide exposure of non-target small mammals on farms
    (2020) Walther, Bernd; Geduhn, Anke; Schenke, Detlef; Schlötelburg, Annika
    BACKGROUND Commensal rodents such as Norway rats (Rattus norvegicus Berk.), black rats (R. rattus L.) and house mice (Mus musculus L.) damage stored produce and infrastructure, cause hygienic problems and transmit zoonotic pathogens to humans. The management of commensal rodents relies mainly on the use of anticoagulant rodenticides (ARs). ARs are persistent and bioâ€Ìaccumulative, which can cause exposure of nonâ€Ìtarget species. We compared the baiting strategies to use brodifacoum (BR) in bait boxes indoors only versus in and around buildings in replicated field trials at livestock farms to assess resulting BR residues in nonâ€Ìtarget small mammals. RESULTS When bait was used indoors only, the percentage of trapped nonâ€Ìtarget small mammals with BR residues as well as BR concentration in liver tissue was about 50% lower in comparison to bait application in and around buildings. These effects occurred in murid rodents and shrews but not in voles that were generally only mildly exposed. During the baiting period, BR concentration in murids was stable but decreased by about 50% in shrews. CONCLUSION Restricting the application of BR bait to indoors only can reduce exposure of nonâ€Ìtarget species. The positive effect of this baiting strategy on nonâ€Ìtarget species needs to be balanced with the need for an effective pest rodent management within a reasonable time. More research is needed to clarify which management approaches strike this balance best. © 2020 The Authors
  • Vorschaubild nicht verfügbar
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    Effects of anticoagulant rodenticide poisoning on spatial behavior of farm dwelling Norway rats
    (2021) Walther, Bernd; Ennen, Hendrik; Geduhn, Anke; Schlötelburg, Annika
    Commensal rodent species cause damage to crops and stored products, they transmit pathogens to people, live-stock and pets and threaten nativeflora and fauna. Tominimize such adverse effects, commensal rodentsare pre-dominantly managed with anticoagulant rodenticides (AR) that can be transferred along the food chain. Wetested the effect of the uptake of the AR brodifacoum (BR) by Norway rats (Rattus norvegicus) on spatial behaviorbecause this helps to assess the availability of dead rats and residual BR to predators and scavengers. BR was de-livered by oral gavage or free-fed bait presented in bait stations. Rats were radio-collared to monitor spatial be-havior. BR residues in rat liver tissue were analyzed using liquid chromatography coupled with tandem massspectrometry. Norway rats that had consumed BR decreased distances moved and had reduced home rangesize. Treatment effects on spatial behavior seemed to set in rapidly. However, there was no effect on habitat pref-erence. Ninety-two percent of rats that succumbed to BR died in well-hidden locations, where removal by scav-enging birds and large mammalian scavengers is unlikely. Rats that ingested bait from bait stations had 65% higher residue concentrations than rats that died from dosing with two-fold LD50.Thissuggestsanoverdosingin rats that are managed with 0.0025% BR. None of the 70 BR-loaded rats was caught/removed by wild preda-tors/scavengers before collection of carcasses within 5-29 h. Therefore, and because almost all dead rats diedin well-hidden locations, they do not seem to pose a significant risk of AR exposure to large predators/scavengers at livestock farms. Exposure of large predators may originate from AR-poisoned non-target small mammals. Thefew rats that died in the open are accessible and should be removed in routine searches during and after the ap-plication of AR bait to minimize transfer of AR into the wider environment. © 2021 The Authors. Published by Elsevier B.V.
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    Effektivität und Weiterentwicklung von Risikominderungsmaßnahmen für die Anwendung von als Biozid ausgebrachten antikoagulanten Rodentiziden mit hohem Umweltrisiko
    (Umweltbundesamt, 2020) Walther, Bernd; Schenke, Detlef; Jacob, Jens; Julius Kühn-Institut; Geduhn, Anke; Hein, Susanne; Schlötelburg, Annika
    Zur Regulierung von Schadnagerpopulationen werden im Biozidbereich in Deutschland in den meisten Fällen Fraßköder mit blutgerinnungshemmenden (antikoagulanten) Wirkstoffen eingesetzt. Antikoagulante Rodentizide wirken bei allen warmblütigen Tieren, also auch bei Organismen, die nicht bekämpft werden sollen oder dürfen. Zudem sind die meisten dieser Wirkstoffe persistent, bioakkumulierend und toxisch. Um Nichtzielorganismen zu schützen und Einträge in die Umwelt zu minimieren, wurden bei der Biozid-Zulassung von antikoagulanten Rodentiziden verbindliche Risikominderungsmaßnahmen festgeschrieben. Die Effektivität dieser Maßnahmen ist jedoch kaum empirisch untersucht, so dass Wissensdefizite auch im Hinblick auf eine mögliche Optimierung bzw. Weiterentwicklung von Risikominderungsmaßnahmen bestehen. Im Rahmen dieses Forschungs- und Entwicklungsvorhabens wurden daher drei zentrale Aspekte mit Bezug auf den Schutz von Nichtzielorganismen näher betrachtet. Im ersten Teil wurde untersucht, wie sich die Ausbringung antikoagulanter Rodentizide in Köderstationen ausschließlich innerhalb von Gebäuden im Vergleich zum Einsatz in und um Gebäude auf das Auftreten blutgerinnungshemmender Wirkstoffe in freilebenden Nichtzielkleinsäugern auswirkt. Weiterhin wurden die Bewegungsmuster und Sterbeorte vergifteter Wanderratten auf Bauernhöfen dokumentiert, um daraus Rückschlüsse auf die mögliche Exposition von Beutegreifern ziehen zu können. Im zweiten Teil wurden Rückstände antikoagulanter Rodentizide in Rotfüchsen aus ländlichen und urbanen Räumen untersucht, um mögliche Unterschiede in der Exposition zu identifizieren. Außerdem wurde das Auftreten blutgerinnungshemmender Wirkstoffe in verschiedenen Singvögeln während Rattenbekämpfungen auf landwirtschaftlichen Betrieben analysiert. Im dritten Teil wurde versucht, die Ausbringung von Fraßködern in Köderstationen so zu gestalten, dass Nichtzielorganismen von der Köderannahme ausgeschlossen werden. Quelle: Forschungsbericht
  • Vorschaubild nicht verfügbar
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    Exposure of passerine birds to brodifacoum during management of Norway rats on farms
    (2020) Walther, Bernd; Geduhn, Anke; Schenke, Detlef
    The exposure of non-target wildlife to anticoagulant compounds used for rodent control is a well-known phenomenon. Exposure can be primary when non-target species consume bait or secondary via uptake of poisoned animals by mammalian and avian predators. However, nothing is known about the exposure patterns in passerine birds that are commonly present on farms where rodent control is conducted. We used liquid chromatography coupled with tandem mass spectrometry to screen for residues of anticoagulant rodenticides (ARs) in liver tissue of passerine birds that were present during rodent control with a product containing brodifacoum (BR). The 222 birds of 13 species were bycatch of rodent snap trapping in 2011-2013 on 11 livestock farms run synchronously with baiting. During baiting, ARs were detected in about 30% of birds; 28% carried BR. In liver tissue of 54 birds that carried BR, concentrations ranged from 4 to 7809 ng/g (mean 490 +/- 169 ng/g). Among common bird species with AR residues, BR was most prevalent in robins (Erithacus rubecula) (44%) and dunnocks (Prunella modularis) (41%). Mean BR concentration was highest in great tits (Parus major) (902 +/- 405 ng/g). The occurrence and concentrations of BR residues were about 30% higher in birds collected close to bait stations compared to birds collected further away. The results demonstrate that several ground feeding songbird species are exposed to ARs used on farms. If BR was present in liver tissue, concentrations were variable, which may imply a combination of primary and secondary exposure of songbirds. Exposure was mostly restricted to the immediate surroundings of farms where bait was used, which might limit the transfer to the wider environment. Efforts should be made to reduce the access for birds to AR bait to prevent high exposure. © 2020 Elsevier B.V.