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Ecol Appl

Title:		Trait-mediated responses of caterpillar communities to spongy moth outbreaks and subsequent tebufenozide treatments
Author(s):		Leroy BML; Rabl D; Puls M; Hochrein S; Bae S; Muller J; Hebert PDN; Kuzmina ML; Zakharov EV; Lemme H; Hahn WA; Hilmers T; Jacobs M; Kienlein S; Pretzsch H; Heidrich L; Seibold S; Roth N; Vogel S; Kriegel P; Weisser WW;
Address:		"Terrestrial Ecology Research Group, Department of Life Science Systems, School of Life Sciences, Technical University of Munich, Freising, Germany. Field Station Fabrikschleichach, Department of Animal Ecology and Tropical Biology, Biocenter, University of Wurzburg, Wurzburg, Germany. Bavarian Forest National Park, Grafenau, Germany. Department of Integrative Biology, University of Guelph, Guelph, Ontario, Canada. Centre for Biodiversity Genomics, University of Guelph, Guelph, Ontario, Canada. Department of Forest Protection, Bavarian State Institute of Forestry, Freising, Germany. Chair of Forest Growth and Yield Science, Department of Life Science Systems, School of Life Sciences, Technical University of Munich, Freising, Germany. Ecosystem Dynamics and Forest Management Research Group, Department of Life Science Systems, School of Life Sciences, Technical University of Munich, Freising, Germany. Berchtesgaden National Park, Berchtesgaden, Germany"
Journal Title:		Ecol Appl
Year:		2023
Volume:		20230618
Issue:		6
Page Number:		e2890 -
DOI:		10.1002/eap.2890
ISSN/ISBN:		1051-0761 (Print) 1051-0761 (Linking)
Abstract:		"Outbreaks of the spongy moth Lymantria dispar can have devastating impacts on forest resources and ecosystems. Lepidoptera-specific insecticides, such as Bacillus thuringiensis var. kurstaki (BTK) and tebufenozide, are often deployed to prevent heavy defoliation of the forest canopy. While it has been suggested that using BTK poses less risk to non-target Lepidoptera than leaving an outbreak untreated, in situ testing of this assumption has been impeded by methodological challenges. The trade-offs between insecticide use and outbreaks have yet to be addressed for tebufenozide, which is believed to have stronger side effects than BTK. We investigated the short-term trade-offs between tebufenozide treatments and no-action strategies for the non-target herbivore community in forest canopies. Over 3 years, Lepidoptera and Symphyta larvae were sampled by canopy fogging in 48 oak stands in southeast Germany during and after a spongy moth outbreak. Half of the sites were treated with tebufenozide and changes in canopy cover were monitored. We contrasted the impacts of tebufenozide and defoliator outbreaks on the abundance, diversity, and functional structure of chewing herbivore communities. Tebufenozide treatments strongly reduced Lepidoptera up to 6 weeks after spraying. Populations gradually converged back to control levels after 2 years. Shelter-building species dominated caterpillar assemblages in treated plots in the post-spray weeks, while flight-dimorphic species were slow to recover and remained underrepresented in treated stands 2 years post-treatment. Spongy moth outbreaks had minor effects on leaf chewer communities. Summer Lepidoptera decreased only when severe defoliation occurred, whereas Symphyta declined 1 year after defoliation. Polyphagous species with only partial host plant overlap with the spongy moth were absent from heavily defoliated sites, suggesting greater sensitivity of generalists to defoliation-induced plant responses. These results demonstrate that both tebufenozide treatments and spongy moth outbreaks alter canopy herbivore communities. Tebufenozide had a stronger and longer lasting impact, but it was restricted to Lepidoptera, whereas the outbreak affected both Lepidoptera and Symphyta. These results are tied to the fact that only half of the outbreak sites experienced severe defoliation. This highlights the limited accuracy of current defoliation forecast methods, which are used as the basis for the decision to spray insecticides"
Keywords:		Animals *Moths *Insecticides Ecosystem *Bacillus thuringiensis DNA barcoding Lepidoptera Lymantria dispar Symphyta defoliation oak forest pest control tebufenozide;
Notes:		"MedlineLeroy, Benjamin M L Rabl, Dominik Puls, Marcel Hochrein, Sophia Bae, Soyeon Muller, Jorg Hebert, Paul D N Kuzmina, Maria L Zakharov, Evgeny V Lemme, Hannes Hahn, W Andreas Hilmers, Torben Jacobs, Martin Kienlein, Sebastian Pretzsch, Hans Heidrich, Lea Seibold, Sebastian Roth, Nicolas Vogel, Sebastian Kriegel, Peter Weisser, Wolfgang W eng Research Support, Non-U.S. Gov't 2023/05/22 Ecol Appl. 2023 Sep; 33(6):e2890. doi: 10.1002/eap.2890. Epub 2023 Jun 18"