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Sivault E, Kollross J, Jorge LR, Finnie S, Diez-Méndez D, Fernandez Garzon S, Maraia H, Lenc J, Libra M, Murakami M, Nakaji T, Nakamura M, Sreekar R, Sam L, Abe T, Weiss M, Sam K. Insectivorous birds and bats outperform ants in the top-down regulation of arthropods across strata of a Japanese temperate forest. J Anim Ecol 2024. [PMID: 39045801 DOI: 10.1111/1365-2656.14146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2023] [Accepted: 06/06/2024] [Indexed: 07/25/2024]
Abstract
Birds, bats and ants are recognised as significant arthropod predators. However, empirical studies reveal inconsistent trends in their relative roles in top-down control across strata. Here, we describe the differences between forest strata in the separate effects of birds, bats and ants on arthropod densities and their cascading effects on plant damage. We implemented a factorial design to exclude vertebrates and ants in both the canopy and understorey. Additionally, we separately excluded birds and bats from the understorey using diurnal and nocturnal exclosures. At the end of the experiments, we collected all arthropods and assessed herbivory damage. Arthropods responded similarly to predator exclusion across forest strata, with a density increase of 81% on trees without vertebrates and 53% without both vertebrates and ants. Additionally, bird exclusion alone led to an 89% increase in arthropod density, while bat exclusion resulted in a 63% increase. Herbivory increased by 42% when vertebrates were excluded and by 35% when both vertebrates and ants were excluded. Bird exclusion alone increased herbivory damage by 28%, while the exclusion of bats showed a detectable but non-significant increase (by 22%). In contrast, ant exclusion had no significant effect on arthropod density or herbivory damage across strata. Our results reveal that the effects of birds and bats on arthropod density and herbivory damage are similar between the forest canopy and understorey in this temperate forest. In addition, ants were not found to be significant predators in our system. Furthermore, birds, bats and ants appeared to exhibit antagonistic relationships in influencing arthropod density. These findings highlight, unprecedentedly, the equal importance of birds and bats in maintaining ecological balance across different strata of a temperate forest.
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Affiliation(s)
- Elise Sivault
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Jan Kollross
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Leonardo Re Jorge
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Sam Finnie
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - David Diez-Méndez
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Sara Fernandez Garzon
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Heveakore Maraia
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Jan Lenc
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Martin Libra
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
| | | | - Tatsuro Nakaji
- Sapporo Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Japan
| | - Masahiro Nakamura
- Tomakomai Experimental Forest, Field Science Center for Northern Biosphere, Hokkaido University, Sapporo, Japan
| | - Rachakonda Sreekar
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Centre for Biodiversity and Conservation Science, School of Environment, The University of Queensland, Saint Lucia, Queensland, Australia
| | - Legi Sam
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
| | - Tomokazu Abe
- Faculty of Science, Chiba University, Chiba, Japan
| | - Matthias Weiss
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
| | - Katerina Sam
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Ceske Budejovice, Czech Republic
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Horne GM, Manderino R, Jaffe SP. Specialist Herbivore Performance on Introduced Plants During Native Host Decline. ENVIRONMENTAL ENTOMOLOGY 2023; 52:88-97. [PMID: 36610403 DOI: 10.1093/ee/nvac107] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Indexed: 06/17/2023]
Abstract
Ash (Fraxinus spp.) is in rapid decline across the northeastern USA due to the invasive emerald ash borer (Agrilus planipennis Fairmaire). Three recently co-occurring confamilial species may serve as alternative larval host plants for ash-reliant Lepidoptera. These prospective hosts are nonnative shrubs often planted in managed suburban landscapes and are sometimes invasive or naturalized in North America. Given the imminent decline of ash trees, we considered potential downstream effects on insect herbivores historically specialized on ash foliage. We measured the performance of three ash-specialist hawkmoths (Lepidoptera: Sphingidae) on native white ash (Fraxinus americana L.) and alternative host plants: common lilac (Syringa vulgaris L.), weeping forsythia [Forsythia suspensa (Thunb.) Vahl], and European privet (Ligustrum vulgare L.). We found the nonnative host plants provided varied support for larval survival to pupation, with biomass and growth rate affected differently by both plant and insect identity. Nearly all caterpillars reared on one alternative host, European privet, exhibited distinct malformations of the wing buds at pupation. Given caterpillar presence on privet in the field, privet may constitute an ecological trap (i.e., when female moths select a sub-optimal host, offspring survival and fitness are reduced). This work demonstrates how performance testing can reveal species-specific effects of host plant loss on mono- or oligophagous insects. For some ash specialists, alternative nonnative host plants may be suboptimal, but some cultivated host plants may be able to support certain specialist insects during native host decline. We suggest that landscaping decisions can be tailored to support threatened insect species.
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Affiliation(s)
- Grace M Horne
- Department of Biology, Colby College, 4000 Mayflower Hill Drive, Waterville, ME, USA
- The Caterpillar Lab, 172 Main Street, Marlborough, NH, USA
- Department of Entomology and Nematology, University of California Davis, 458 Hutchison Hall, Davis, CA, USA
| | - Rea Manderino
- Oak Spring Garden Foundation, 1776 Loughborough Lane, Upperville, VA, USA
| | - Samuel P Jaffe
- The Caterpillar Lab, 172 Main Street, Marlborough, NH, USA
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