摘要:

There is an inverse correlation between sodium concentration ([Na]) and larval densities of insects in water-filled treeholes, suggesting that sodium might be a limiting resource or that it is controlled by biota. The effects of water [Na] and population density on the growth of the culicidAedes triseriatusand the scirtid beetlesHelodes pulchellaandPrionocyphon discoideuswere studied in a laboratory experiment. At low densities, microcosms high in [Na] produced significantly larger adultA. triseriatusthan those low in [Na]. Scirtids showed the opposite trend. Sodium level had no impact on size at high density for either mosquitoes or scirtids. Dry masses of adult mosquitoes and larval scirtids were significantly smaller at high than at low density. High densities were also associated with longer development and lower survival of mosquitoes. Despite the fact that mosquitoes at low density grew faster at high [Na], the negative effects of high density were not alleviated by high [Na]. High densities of scirtids decreased the [Na] of the water in the microcosms, indicating that the insects may regulate water [Na].

ISSN:0270-5060    

DOI:10.1080/02705060.1999.9663660

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

Before treatment with a 3 mg/1 Noxfish (0.15 mg/1 active ingredient; rotenone) for 48 hours, benthic invertebrate communities were quantitatively sampled with a modified Surber net. Then spring, summer, and fall post-rotenone samples were taken monthly at each of four Strawberry River stations for five years. Statistical analyses of the data indicated that the application of rotenone had a significant effect on the following species density:Cinygmula sp., Pteronarcella badia,Hesperoperla pucifica, Hydropsyche sp., and Brachycentrus americanus.Thirty-three percent of the benthic invertebrate taxa at the four stations showed resistance to rotenone. Up to 100% of Ephemeroptera, Plecoptera and Trichoptera species were missing after the second rotenone application. Forty-six percent of the taxa recovered within one year, but 21% of the taxa were still missing after five years. Of the 19 taxa still missing, 47% were Trichoptera, 21% were Ephemeroptera, 16% were Plecoptera, 11% were Coleoptera, and 5% were Megaloptera.

ISSN:0270-5060    

DOI:10.1080/02705060.1999.9663661

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

摘要:

FemaleParagordius variuswere collected in a slough of the Mississippi River in Grant County and a small trout stream in Kewaunee County. The Kewaunee County specimen was laying eggs on July 25, later than reported for the species elsewhere in its range.Paragordius variusis much less common thanGordius robustusin Wisconsin, at least in small cold springs or springfed streams.

ISSN:0270-5060    

DOI:10.1080/02705060.1999.9663662

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1999.9663663

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1999.9663649

出版商:Taylor & Francis Group    

年代:1999

数据来源: Taylor