摘要:

In this study, we present data on life history, distribution and coexistence among five backswimmer species,Notonecta glauca,N. lutea,N. maculata,N. obliquaandN. reuteri, from 72 waters in a study area on the Swedish west coast. Two temporal life history patterns were found; species reproducing in the autumn (N. reuteriandN. lutea) and those reproducing in the spring (N. glauca N. obliquaandN. maculata). Female backswimmers were generally larger than conspecific males, except forN. lutea, in which the sexes were similar in size. The sex ratio ofN. glauca,N. luteaandN. reuteridid not differ from 1/1. The most abundant species wasN. glauca(49% of the waters inhabited by backswimmers) and thenN. obliqua(19%),N. maculata(14%),N. lutea(10%) andN. reuteri(8%). In all, 972 individuals were recorded. The species were sequenced, with reference to their habitat use (from species occurring in temporal habitats to more stable and complex ones), as follows;N. maculata – N. glauca – N. obliqua – N. reuteri – N. lutea. N. glaucahad the widest habitat distribution pattern. Two species combinations in pools were most commonly found and the five species were never found together. Possible competition among adults, according to their habitat distribution, may occur for:N. glaucawith all species;N. obliquamainly withN. glauca;N. luteamainly withN. reuteri;N. reuterimainly withN. luteaandN. glauca;N. maculatamainly withN. glauca. If body size is an important factor in the competitive ability between individuals, not merely species but also sex and temporal aspects have to be considered. The most intense competition should then exist betweenN. luteaandN. reuterifemales.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT081

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A flood event in a river will redistribute the bed sediments and may bury benthic insect larvae. To test the responses of case-building caddis larvae under such circumstances, we buried fourth instar larvae ofPotamophylax cingulatus(Limnephilidae) in sediment of various grain size diameters (<1, 1–4, 4–10, >10 mm) to a depth of 1 or 2 cm. Depth of burial significantly affected time taken to emerge, individuals buried to 2 cm requiring longer to emerge, particularly if buried in fine (<1 mm) or coarse (>10 mm) sediment. Two thirds of those buried 2 cm deep in fine sediment abandoned their cases before emerging, whereas very few of those buried in coarser sediments and none buried to 1 cm depth emerged without a case. Burial in fine sediment is detrimental toP. cingulatusindividuals, to the extent that they will abandon their cases, increasing the risk of predation, in order to facilitate escape. The case mass probably acts as a physical impediment to movement in fine matter, particularly if the animals experience respiratory stress. In coarse sediment, weight of sediment particles may slow down emergence, but not to the extent that individuals resort to case abandonment.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT099

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

The life cycle ofE. shigae, including eclosion, nymphal growth, last instar recruitment and adult emergence, was studied in a Japanese river. The synchronization of nymphal development is discussed. Eggs hatched sporadically from mid-March to early April as determined from continuous sampling of eggs from the river substratum. Nymphs attained the last instar in mid- to late August and emerged in mid-September. Size of nymphs at the time of last instar recruitment decreased gradually as did the size of emerging mayflies. Smaller individuals entering the last instar later developed more quickly and required a smaller number of degree-days to complete the last instar than did larger individuals. Consequently, larval development synchronized during the period between last instar recruitment and adult emergence.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT108

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

A new species,Prosopistoma sinense(Ephemeroptera: Prosopistomatidae), is described and illustrated based on egg and larval material from Hong Kong and Guangdong Province, China

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT122

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Paravelia antasp.n. from Argentina and Paraguay is described and compared with its close relativeP. hungerfordi(Drake & Harris) from Brasil, which is redescribed. In addition, characteristics to separate these two from the remaining species ofParaveliaare given.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT129

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

In this study, three new species of the genusRhyacophila(Trichoptera, Rhyacophilidae) from France and Spain are described and illustrated:R. joanisp.n. belonging to thevulgaris-group is found in Cantabria (Spain) and two species belonging to thestigmatica-group,R. pongensissp.n. (Spain) andR. artiessp.n (France). Descriptive notes onR. eatoniMcLachlan, 1879 andR. vandeliDespax, 1933 are included.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT138

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor

摘要:

Guloptiloides(Ephemeroptera, Baetidae), gen.n., is described to accomodate the speciesG. gargantua(larvae) andG. spA(female imagoes) based on specimens from the Eastern coast of Madagascar. Larvae ofGuloptiloidesare remarkable by the adaptation of the mouthparts to a predatory diet. It is also distinct from other genera in that adults have hindwings with 3 well-marked longitudinal veins and a single extremely developed spur on the costal margin. Affinities and ecology are discussed.

ISSN:0165-0424    

DOI:10.1076/0165-0424(200004)22:2;1-P;FT148

出版商:Taylor & Francis Group    

年代:2000

数据来源: Taylor