Abstract
Non-toxigenic strains of Aspergillus flavus (Link) can be used as biological control agents to reduce the contamination of grains such as maize with carcinogenic and immunotoxic aflatoxins. Based on its sclerotial morphology, A. flavus is commonly divided into two types: L strains and S strains. In this study, we applied the non-toxigenic A. flavus L strain BN030D to the soil of five maize fields in Djidja, central Benin, to investigate its effects on the composition of the prevailing fungal communities, on the ratio of A. flavus L strains and S strains, and on the vegetative compatibility of L strains with BN030D. Soil samples were taken before the strain application, and soil and cob samples were taken after BN030D treatment, i.e., at maize harvest. BN030D did not affect the composition of A. flavus, Fusarium spp., Penicillium spp. and A. niger in the soil. There was no significant difference between the number of A. flavus L and S strains in the control and (subsequent) treatment plots before treatment, but significantly more L than S strains in soil and maize after BN030D treatment. About 1% of all L strains isolated from the untreated soil samples were vegetatively compatible to BN030D, confirming the natural presence of the non-toxigenic A. flavus L strain in the study area. Additionally, 59% (soil) and 26% (maize) of all strains isolated from the treated samples belonged to the BN030D vegetative compatibility group. BN030D spread over time and space from the release area into the non-treated buffer area. The implications of these findings for strategies to reduce aflatoxin contamination of maize and the potentials of such a competitive replacement approach for biological control of A. flavus in West Africa are discussed.
Zusammenfassung
Aspergillus flavus (Link)Infektionen von Maispflanzen können zur Kontamination der Körner mit krebserregenden und immunotoxischen Aflatoxinen führen. A. flavus wird auf Grund der Morphologie seiner Sklerotien in so genannte L und S Stämme aufgeteilt. In der vorliegenden Studie wurde der nicht-toxische A. flavus L Stamm BN030D als Bodenappli-kation in fünf Maisfeldern in Djidja, Zentralbenin, freigesetzt, um Effekte bezüglich der Zusammensetzung der vorhande-nen Pilze, der Relation zwischen A. flavus L und S Stämmen und der vegetativen Kompatibilität der L Stämme mit BN030D zu untersuchen. Dazu wurden Bodenproben sowohl vor der Stammapplikation genommen, also auch zusammen mit Proben der Maiskolben bei der Ernte. Die Zusammen-setzung der Arten A. flavus, Fusarium und Penicillium spp. und A. niger innerhalb der Bodenproben wurden durch das Ausbringen des nicht-toxischen A. flavus L Stammen nicht verändert. Vor der Applikation von BN030D konnten zwi-schen Kontroll- und Behandlungsflächen keine signifikanten Unterschiede im Verhältnis der A. flavus L und S Stämme ge-funden werden. Nach der Ausbringung von BN030D konnten jedoch in zwei Behandlungsparzellen signifikant mehr L als S Stämme in Boden- bzw. Maisproben verzeichnet werden. Innerhalb der A. flavus L Stämme, konnte bei ca. 1% aller Isolate der Bodenproben, die vor der Applikation von BN030D genommen wurden, eine vegetative Kompatibilität mit BN030D festgestellt werden, was die natürliche Herkunft des nicht-toxischen A. flavus L Stammes BN030D im Unter-suchungsgebiet beweist. In den Behandlungsparzellen zur Erntezeit, konnte bei 59% bzw. 26% aller Isolate der Boden-bzw. Maisproben eine vegetative Kompatibilität mit dem Stamm BN030D festgestellt werden. Darüber hinaus wurde die Ausbreitung von BN030D von den Behandlungsparzellen in eine Pufferzone in Zeit und Raum dargestellt. Die Bedeu-tung dieser Ergebnisse werden bezüglich einer möglichen Reduktion von Aflatoxin-kontaminierten Maiskolben und bezüglich der möglichen Nutzung des Ansatzes der konkur-renzbetonten Verdrängung für die biologische Bekämpfung von A. flavus in Westafrika diskutiert.
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Klueken, A.M., Borgemeister, C. & Hau, B. Field release of a non-toxigenic Aspergillus flavus L strain in central Benin. J Plant Dis Prot 116, 17–22 (2009). https://doi.org/10.1007/BF03356281
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DOI: https://doi.org/10.1007/BF03356281