| 1. |
- Lundström, Jan O., et al.
(författare)
-
Production of wetland Chironomidae (Diptera) and the effects of using Bacillus thuringiensis israelensis for mosquito control
- 2010
-
Ingår i: Bulletin of entomological research. - Cambridge : Cambridge University Press. - 0007-4853 .- 1475-2670. ; 100:1, s. 117-125
-
Tidskriftsartikel (refereegranskat)abstract
- Massive mosquito nuisance problems, caused by the flood-water mosquito Aedes sticticus, occur after floods in the flood plains of the River Dalalven, central Sweden. Since 2002, the biological mosquito larvicide Bacillus thuringiensis var. israelensis (Bti) has been used to control these mosquitoes. Here, we report results from the first six years of monitoring Chironomidae, the most Susceptible non-target organisms, in three wetlands with Bti-treatment against mosquitoes and in three wetlands without treatment. Emergence traps were used for continuous insect sampling from May to September each year, 2002-2007, and were emptied once a week. A total of 21,394 chironomids of 135 species were collected, and the Subfamily Orthocladiinae dominated the fauna followed by Chironominae and Tanypodinae. The annual chironomid production in the wetlands was low, with ail average of 1.91.7 individuals per m(2) and 42 g ash-free dry weight per m(2) We found no reduced production of chironomids at neither family, nor subfamily level, in Bti-treated as compared to untreated wetlands. This is the first long-term follow-up study of the possible effects of Bti-based mosquito larval control oil chironomid species production. In the short-term view, one species had higher production in treated areas. In the long-term view, four species had higher and one species had lower production in treated areas. We conclude that the B3ti-based control of floodwater mosquitoes does not cause and, major direct negative effects on chironomid production, and therefore does not seem to induce any risk for indirect negative effects on birds, bats or any other predators feeding on chironomids.
|
|
| 2. |
- Schäfer, Martina, et al.
(författare)
-
Influence of landscape structure on mosquitoes (Diptera : Culicidae) and dytiscids (Coleoptera
- 2006
-
Ingår i: Wetlands (Wilmington, N.C.). - 0277-5212 .- 1943-6246. ; 26:1, s. 57-68
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Patterns of species diversity and community structure depend on scales larger than just a single habitat and might be influenced by the surrounding landscape. We studied the response of two insect families, mosquitoes (Diptera: Culicidae) and dytiscids (Coleoptera: Dytiscidae), to landscape variables at five spatial scales. We studied adult mosquito and dytiscid abundance, diversity, and species assemblages in relation to water permanence (area of permanent water bodies versus temporary wetlands) and forest cover (area covered by forest versus open land) within nested circles of 100 to 3000 m around trap sites in four wetlands in southern Sweden and in five wetlands in central Sweden. We found that mosquito abundance was greatest in areas with plentiful forest cover and a high proportion of temporary water, while most dytiscids favored open areas with a high proportion of permanent wetlands. However, diversity of both mosquitoes and dytiscids was positively correlated with high permanence and little forest cover. Mosquito species assemblages were mainly influenced by forest cover at a large spatial scale, whereas permanence was more important at local scales. Dytiscid species assemblages were mainly influenced by water permanence, especially at intermediate spatial scales. These results can be explained by the flight capability and dispersal behavior of mosquito and dytiscid species. The observed landscape associations of mosquitoes and dytiscids could be useful when creating new wetlands. Mosquito colonization could be reduced by creating permanent wetlands in an open landscape, which would favor colonization by dytiscids, a potential predator of mosquito larvae, while also supporting the diversity of both taxa.
|
|
| 3. |
- Schäfer, Martina L., et al.
(författare)
-
Influence of landscape structures on mosquitoes (Diptera: Culicidae) and dytiscid (Coleoptera: Dytiscidae) at five spatial scales in Swedish wetlands
- 2006
-
Ingår i: Wetlands (Wilmington, N.C.). - 0277-5212 .- 1943-6246. ; 26:1, s. 57-68
-
Tidskriftsartikel (refereegranskat)abstract
- Patterns of species diversity and community structure depend on scales larger than just a single habitat and might be influenced by the surrounding landscape. We studied the response of two insect families, mosquitoes (Diptera: Culicidae) and dytiscids (Coleoptera: Dytiscidae), to landscape variables at five spatial scales. We studied adult mosquito and dytiscid abundance, diversity, and species assemblages in relation to water permanence (area of permanent water bodies versus temporary wetlands) and forest cover (area covered by forest versus open land) within nested circles of 100 to 3000 m around trap sites in four wetlands in southern Sweden and in five wetlands in central Sweden. We found that mosquito abundance was greatest in areas with plentiful forest cover and a high proportion of temporary water, while most dytiscids favored open areas with a high proportion of permanent wetlands. However, diversity of both mosquitoes and dytiscids was positively correlated with high permanence and little forest cover. Mosquito species assemblages were mainly influenced by forest cover at a large spatial scale, whereas permanence was more important at local scales. Dytiscid species assemblages were mainly influenced by water permanence, especially at intermediate spatial scales. These results can be explained by the flight capability and dispersal behavior of mosquito and dytiscid species. The observed landscape associations of mosquitoes and dytiscids could be useful when creating new wetlands. Mosquito colonization could be reduced by creating permanent wetlands in an open landscape, which would favor colonization by dytiscids, a potential predator of mosquito larvae, while also supporting the diversity of both taxa.
|
|
| 4. |
- Vinnersten, Thomas Z. Persson, et al.
(författare)
-
Diving beetle assemblages of flooded wetlands in relation to time, wetland type and Bti-based mosquito control
- 2009
-
Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 635:1, s. 189-203
-
Tidskriftsartikel (refereegranskat)abstract
- 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.
|
|
| 5. |
- Lundström, Jan O., et al.
(författare)
-
High species richness of Chironomidae (Diptera) in temporary flooded wetlands associated with high species turn-over rates
- 2010
-
Ingår i: Bulletin of entomological research. - 0007-4853 .- 1475-2670. ; 100:4, s. 433-444
-
Tidskriftsartikel (refereegranskat)abstract
- Species richness and species turn-over of Chironomidae was studied in irregularly flooded wetlands of the River Dalalven flood-plains in central Sweden. The chironomid fauna, sampled with emergence traps in six wetlands over six summers, contained as much as 135 species, and the cumulative species curves indicated that the regional species pool contain several more species. Recurrent irregular floods may have induced this high chironomid species richness and the high species turn-over in the temporary wetlands, as the dominance between terrestrial and aquatic species shifted between years. Half of the wetlands were treated with Bacillus thuringiensis var. israelensis (Bti) against larvae of the floodwater mosquito Aedes sticticus. These treatments had no significant effect on chironomid species richness, but there was a higher species turn-over between years of primarily low abundance species in the treated wetlands. The cumulative number of species was also higher in the Bti-treated experimental wetlands than in the untreated reference wetlands. Thus, Bti treatment against mosquito larvae seemed to have only small effects on chironomid species richness but seemed to increase the colonisation-extinction dynamics.
|
|
| 6. |
|
|
| 7. |
- Lundström, Jan O, et al.
(författare)
-
The geographic distribution of mosquito species in Sweden
- 2013
-
Ingår i: Journal of the European Mosquito Control Association. - 2054-930X .- 1460-6127. ; 31, s. 21-35
-
Tidskriftsartikel (refereegranskat)abstract
- Surveillance of the actual distribution of mosquito species in Northern Europe is fundamental for evaluating risk for emerging pathogens, and for research on potential vectors. The Swedish mosquito fauna composition and geographic distribution, originally described by Professor Christine Dahl in the 1970´s, included 43 species. We have compiled the information published from 1978 to 2012, and our own surveillance data from 2001 to 2013, and compared this with the species list and geographic distribution provided in "Taxonomy and geographic distribution of Swedish Culicidae" by Dahl (1977). New species detected during these 36 years were Culiseta (Culicella) ochroptera (Peus, 1935) published 1984, Aedes (Aedes) rossicus Dolbeskin, Goritzkaja & Mitrofanova, 1930 published 1986, Anopheles (Anopheles) beklemishevi published 1986, Aedes (Ochlerotatus) euedes (Howard, Dyar & Knab, 1912) published 2001, Aedes (Ochlerotatus) nigrinus (Eckstein, 1918) first recorded in 2012, and Anopheles (Anopheles) algeriensis Theobald, 1903, first recorded in 2013. We provide maps with the distribution by province for each species, including historic information up until 1977, and new records from 1978 to 2013, showing the similarities and differences between the old and the new records. Important findings in recent years include the wide distribution of the Sindbis virus enzootic vector Culex (Culex) torrentium Martinii, 1925, and the more limited distribution of the potential West Nile virus vector Culex (Culex) pipiens Linnaeus, 1758. The updated list of mosquito species in Sweden now includes 49 species.
|
|
| 8. |
- Persson Vinnersten, Thomas, 1972-
(författare)
-
Long Term Studies of Insect Abundances in Temporary Wetlands in Relation to Hydrology, Predation and Bti
- 2013
-
Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- 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.
|
|
| 9. |
|
|
| 10. |
|
|
