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Diving beetle assemblages of flooded wetlands in relation to time, wetland type and Bti-based mosquito control
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution.
2009 (English)In: Hydrobiologia, ISSN 0018-8158, E-ISSN 1573-5117, Vol. 635, no 1, 189-203 p.Article in journal (Refereed) Published
Abstract [en]

We investigated the abundance and taxonomic composition of the aquatic predatory insect fauna, with focus on adult diving beetles (Coleoptera: Dytiscidae), in eight temporary flooded wet meadows and two alder swamps in the River Dalalven flood-plains, central Sweden from 2002 to 2006. Diving beetles are generalist predators and often abundant in various waters, including temporary wetlands. In the River Dalalven floodplains, recurrent floods induce massive hatching of flood-water mosquitoes (Diptera: Culicidae), which constitute a superabundant patchy and irregular food resource for aquatic predatory insects. Our aims were (1) to characterize the assemblage of adult diving beetles occurring in the wetlands during floods in relation to time and wetland type and (2) to evaluate the effect on the aquatic predator assemblage of strongly reducing the abundance of a potential prey, flood-water mosquito larvae with Bacillus thuringiensis var. israelensis (Bti) during floods. We found diving beetles to be the dominating aquatic predatory insect taxa in all 10 wetlands. There was a difference in Dytiscidae species richness but not in diversity between wet meadows and alder swamps after rarefaction. The cluster analysis based on dytiscid species and abundances showed very high similarities between the wetlands. The variance component analysis was unable to distinguish any factor that could explain more than 7.4% of the variation in the dytiscid species assemblages. The only effect of Bti-treatment against flood-water mosquito larvae, potential food for the predatory dytiscids, was a slight increase in abundance of the medium-sized dytiscid species. Our results are in accordance with previous studies, suggesting that irregular and recurrent flood dynamic structure the dytiscid fauna more than food limitations and environmental factors.

Place, publisher, year, edition, pages
2009. Vol. 635, no 1, 189-203 p.
Keyword [en]
Diving beetles, Aquatic predatory insects, Flood-water mosquitoes, Temporary wetlands, Bti
National Category
Biological Sciences
Identifiers
URN: urn:nbn:se:uu:diva-127480DOI: 10.1007/s10750-009-9911-9ISI: 000270652200018OAI: oai:DiVA.org:uu-127480DiVA: diva2:330289
Available from: 2010-07-15 Created: 2010-07-13 Last updated: 2014-01-23Bibliographically approved
In thesis
1. Long Term Studies of Insect Abundances in Temporary Wetlands in Relation to Hydrology, Predation and Bti
Open this publication in new window or tab >>Long Term Studies of Insect Abundances in Temporary Wetlands in Relation to Hydrology, Predation and Bti
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Long-term insect abundances have been studied to investigate factors structuring the insect communities of the temporary wetlands around the River Dalälven floodplain. In the wet meadows and swamps in the River Dalälven floodplains recurrent floods are the ultimate prerequisite for high production of floodwater mosquitoes. In the larval stages these make up a superabundant potential prey for aquatic predatory insects while as adults they become nuisance for people and animals. Mosquito control with Bacillus thuringiensis israelensis (Bti) has been carried out in parts of the floodplain wetlands since 2002. This study investigate potential long-term effects of Bti on non-target insects in general, and non-biting midges (Diptera: Chironomidae) and aquatic predator insects in special in 10 temporary wetlands. Diving-beetles (Coleoptera: Dytiscidae) were the most common aquatic predatory insects in temporary flooded wetlands, and we found no indications that diving-beetles were negatively affected by mosquito larvae reduction with Bti-treatments. Non-target Bti-effects on the insect community in general, measured as increase or decrease of insect abundances, in general showed no effects of Bti except for Coleoptera. The non-biting midges were studied on species level, since this taxon previously has been associated with negative Bti non-target effects in the short-term. We found no reduced production of chironomids at neither family, nor subfamily level in Bti-treated as compared to untreated wetlands. We conclude that other factors than the occasional Bti-treatments dominate in structuring the chironomids fauna. For example, hydrology measured as floods and hydroperiod had substantial impact on insect emergence Increased hydroperiod was associated with lower insect emergence for the majority of the studied taxa, indicating an insect fauna adapted more to terrestrial conditions. In the final study, we developed and applied a molecular method to study interspecific predator – prey relationships between medium-sized diving beetles and floodwater mosquito larvae. Gut content analyses showed that floodwater mosquito larvae are a regular, but limited, part of the diet of medium-sized diving beetles. This thesis is one of the first long-term studies of insects of temporary wetlands in relation to mosquito control actions. The results indicate that hydrology is one of the major factors influencing and structuring the insect communities of the temporary flooded wetlands in the River Dalälven floodplains, and that mosquito control actions with Bti only have marginal effect on insect abundances.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 48 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1080
Keyword
floodwater mosquitoes, mosquito control, predation, aquatic insects
National Category
Ecology
Identifiers
urn:nbn:se:uu:diva-207841 (URN)978-91-554-8762-1 (ISBN)
Public defence
2013-11-08, Lindahlsalen, Evolutionsbiologiskt Centrum, Norbyvägen 18 B, Uppsala, 10:00 (English)
Opponent
Supervisors
Available from: 2013-10-18 Created: 2013-09-19 Last updated: 2014-01-23

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