Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study

Aquatic biomass and essential nutrients can subsidize terrestrial food webs. However, stressors in the aquatic ecosystem, such as the non-chemical mosquito control agent Bti (Bacillus thuringiensis israelensis), may affect such subsidies by changing the dynamics and diversity of emergent aquatic ins...

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Main Authors: Agnes Schöndorfer, Sara Kolbenschlag, Peer Bauspiess, Jens Schirmel, Eric Bollinger, Alessandro Manfrin, Mirco Bundschuh
Format: Article
Language:English
Published: Elsevier 2025-05-01
Series:Ecotoxicology and Environmental Safety
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Online Access:http://www.sciencedirect.com/science/article/pii/S0147651325005445
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author Agnes Schöndorfer
Sara Kolbenschlag
Peer Bauspiess
Jens Schirmel
Eric Bollinger
Alessandro Manfrin
Mirco Bundschuh
author_facet Agnes Schöndorfer
Sara Kolbenschlag
Peer Bauspiess
Jens Schirmel
Eric Bollinger
Alessandro Manfrin
Mirco Bundschuh
author_sort Agnes Schöndorfer
collection DOAJ
description Aquatic biomass and essential nutrients can subsidize terrestrial food webs. However, stressors in the aquatic ecosystem, such as the non-chemical mosquito control agent Bti (Bacillus thuringiensis israelensis), may affect such subsidies by changing the dynamics and diversity of emergent aquatic insects. Such changes in emergence phenology may influence riparian predators with consequences for the terrestrial food web. Here we asked whether repeated Bti application over four consecutive vegetative periods cause similar impacts over these years (i.e., 2020–2023). We used floodplain pond mesocosms and measured insect emergence from control and Bti-treated ponds between April and August in each year. We found significant effects on insect emergence dynamics and community composition only during the first year. This effect disappeared over the three following years. Our observations suggest a shift in community composition, for example, by replacing more Bti-sensitive (i.e., Chironomidae) with more tolerant insect species – a hypothesis that is partially supported by changes in the wider community of emergent aquatic insects during the study. Alternatively, a reduced Bti activity could explain this pattern: The activity could be affected by changes in environmental factors such as the accumulation of organic carbon and fine sediment. All in all, our data point to a higher annual variability in insect emergence dynamics and the community of emergent aquatic insects relative to the impacts caused by Bti.
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spelling doaj-art-caa8cddfe9c54f29a74ec0ca338d9a362025-08-20T02:30:15ZengElsevierEcotoxicology and Environmental Safety0147-65132025-05-0129611820810.1016/j.ecoenv.2025.118208Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm studyAgnes Schöndorfer0Sara Kolbenschlag1Peer Bauspiess2Jens Schirmel3Eric Bollinger4Alessandro Manfrin5Mirco Bundschuh6iES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, Germany; Eusserthal Ecosystem Research Station (EERES), University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, Germany; Eusserthal Ecosystem Research Station (EERES), University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, GermanyiES Landau, Institute for Environmental Sciences, University of Kaiserslautern-Landau (RPTU), Landau, Germany; Corresponding author.Aquatic biomass and essential nutrients can subsidize terrestrial food webs. However, stressors in the aquatic ecosystem, such as the non-chemical mosquito control agent Bti (Bacillus thuringiensis israelensis), may affect such subsidies by changing the dynamics and diversity of emergent aquatic insects. Such changes in emergence phenology may influence riparian predators with consequences for the terrestrial food web. Here we asked whether repeated Bti application over four consecutive vegetative periods cause similar impacts over these years (i.e., 2020–2023). We used floodplain pond mesocosms and measured insect emergence from control and Bti-treated ponds between April and August in each year. We found significant effects on insect emergence dynamics and community composition only during the first year. This effect disappeared over the three following years. Our observations suggest a shift in community composition, for example, by replacing more Bti-sensitive (i.e., Chironomidae) with more tolerant insect species – a hypothesis that is partially supported by changes in the wider community of emergent aquatic insects during the study. Alternatively, a reduced Bti activity could explain this pattern: The activity could be affected by changes in environmental factors such as the accumulation of organic carbon and fine sediment. All in all, our data point to a higher annual variability in insect emergence dynamics and the community of emergent aquatic insects relative to the impacts caused by Bti.http://www.sciencedirect.com/science/article/pii/S0147651325005445BiocideBacillus thuringiensis israelensisFloodplainInsect community compositionFood webAquatic-terrestrial linkage
spellingShingle Agnes Schöndorfer
Sara Kolbenschlag
Peer Bauspiess
Jens Schirmel
Eric Bollinger
Alessandro Manfrin
Mirco Bundschuh
Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
Ecotoxicology and Environmental Safety
Biocide
Bacillus thuringiensis israelensis
Floodplain
Insect community composition
Food web
Aquatic-terrestrial linkage
title Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
title_full Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
title_fullStr Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
title_full_unstemmed Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
title_short Long-term consequences of Bti applications on aquatic insect emergence: Insights from a 4-year mesocosm study
title_sort long term consequences of bti applications on aquatic insect emergence insights from a 4 year mesocosm study
topic Biocide
Bacillus thuringiensis israelensis
Floodplain
Insect community composition
Food web
Aquatic-terrestrial linkage
url http://www.sciencedirect.com/science/article/pii/S0147651325005445
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