Contrasting diel activity and feeding patterns of four species of carnivorous stoneflies

Abstract

1. The hypothesis under test was that larvae of Dinocras cephalotes (Curtis), Perla bipunctata Pictet, Isoperla grammatica (Poda), and Perlodes microcephalus (Pictet) differed markedly in their diel activity and feeding patterns.Mature larvae collected about 1 month prior to adult emergence were used either for gut analyses or for observations of their activity and feeding patterns in three stream tanks with natural substrata and glass bottoms, so that activity could be observed above and below the substratum. A dull red light was used for observations in the dark. Food (larvae of Ephemeroptera, Simuliidae, and Chironomidae) was provided in excess.2. Larvae for gut analyses were taken 1 h before dusk or dawn (n = 30 larvae per species for each day or night sample). The only species with food in the gut for the day samples was P. microcephalus. All species fed at night, the mean number of prey per larva being very similar for D. cephalotes, P. bipunctata, and I. grammatica but signi®cantly higher for P. microcephalus. Most prey were insect larvae, especially Simuliidae and Chironomidae.3. Diel activity patterns of single larvae differed interspeci®cally but not intraspeci®cally. Larvae of D. cephalotes and P. bipunctata were rarely active during the day; their activity increased at dusk and decreased at dawn, and was highest during the night; their success at prey capture was highest at dusk and dawn, with an ambush rather than a search strategy. Isoperla grammatica was rarely active during the day, most active at dusk and dawn when prey capture was highest, using a search strategy, and less active for the rest of the night. Perlodes microcephalus was active during the day, but only below the substratum, and very active from dusk to dawn with a high prey-capture success, using a search strategy. These experiments provided support for the hypothesis under test. The discussion concludes that the results could also help to explain known differences in growth rate and the length of the life-cycle in these four species.

Trophic Behavior of Two Perlidae Species (Insecta, Plecoptera) in a River in Southern Spain

“…A smaller niche breadth (inferred from the reduced number of consumed prey) for P. bipunctata was suggested, but not completely demonstrated due to the low sample size, only 14 studied nymphs of P. bipunctata, in a study in an Ireland stream (LUCY et al, 1990). This could not be explained by differences in foraging activity between both species, as experimentally demonstrated by ELLIOTT (2000). Despite the relatively low number of individuals, our results seem to support the general pattern suggested by LUCY et al (1990).…”

“…Plecoptera have diversified their food habits filling almost all major trophic categories in streams (STEWART and STARK, 2002; MERRITT et al, 2007). Large Perlid nymphs play an important role as the main predators among macroinvertebrates in many European streams (e.g., BERTHÉLEMY and LAHOUD, 1981;ELLIOTT, 2000ELLIOTT, , 2004BO and FENOGLIO, 2005;BO et al, 2007;FENOGLIO et al, 2007b). Additionally, resource partitioning among different predaceous stonefly species has been investigated (SHELDON, 1980;PECKARSKY, 1984;ELLIOTT, 2003;BO et al, 2007;THORP et al, 2007).…”

Velocidade da água e a distribuição de larvas e pupas de Chirostilbia pertinax (Kollar) (Diptera, Simuliidae) e macroinvertebrados associados

“…Os testes foram realizados no programa Systat (2004) versão 11. Referências bibliográficas Castaldi & Gutiérrez 1981;Crisp 1956;Crosskey 1990;Elliott 2000;Gorayeb & Mok 1982;Gorayeb & Pinger 1978;Jenkins 1964;Laird 1981;Wotton et al 1993. Crosskey 1990Damalt 1956;Gorayeb & Pinger 1978;Jenkins 1964;Kuralová & Olejnícek 1985;Laird 1981;Malmqvist 1994;Service 1974.…”

Feeding of Perla grandis nymphs (Plecoptera: Perlidae) in an Apennine first order stream (Rio Berga, NW Italy)

“…Unfortunately, the knowledge of great part of their ecology is still incomplete. In particular, the analysis of the diet and the study of trophic ecology could represent important source of data, that can be employed to improve our knowledge of the ecology of diff erent species (Elliott 2000), the structure of stream food webs (Huhta et al 1999), and the functional organization of lotic systems (Rosi-Marshall & Wallace 2002).…”