Caddis larvae cases (Trichoptera, Limnephilidae) as anti-predatory devices against brown trout and sculpin

Abstract

Brown trout (Salmo trutta L.) and sculpin (Cottus gobio L.) predation on the cased limnephilid larvae Glyphotaelius pellucidus (Retz.) (weak, broad leaf case), Limnephilus pantodapus McLachl. (weak, long cylindrical leaf case), L. rhombicus (L.) (rigid, 'hedgehog' case) and Potamophylax cingulatus (Steph.) (rigid, cylindrical mineral case) was studied in the laboratory. The proportion of larvae ingested was significantly higher in brown trout than in sculpin for all four prey species. Brown trout captured larvae of all four species with equal success, but the higher number of unsuccessful captures resulted in a higher survival rate for P. cingulatus. It was significantly more difficult for sculpin than for brown trout to capture L. pantodapus larvae and to ingest all species except L. rhombicus. P. cingulatus larvae were never ingested by sculpins, and had the highest survival rate after capture by both fish species. In brown trout, the handling time of L. pantodapus was significantly longer than that of P. cingulatus. Sculpin had a significantly longer handling time of G. pellucidus than brown trout. L. pantodapus and L. rhombicus larvae feigned dead significantly longer than did those of G. pellucidus and P. cingulatus upon attacks from sculpins. L. rhombicus larvae also feigned dead for a long time upon attacks from brown trout. The survival rate of a larva attacked by sculpin or brown trout depends on both case rigidity as well as its behaviour. Brown trout was a more successful predator of cased caddis larvae than sculpin.

Stream mosses as chemically-defended refugia for freshwater macroinvertebrates

“…Selective feeding by large, generalist herbivores, including waterfowl (Sondergaard et al 1996, Van Donk and Otte 1996, Weisner et al 1997, Santamaria 2002, crayfish (Lodge and Lorman 1987, Lodge 1991, Lodge et al 1994, Dorn and Wojdak 2004, mammals (Qvarnemark and Sheldon 2004), and fish (Van Donk and Otte 1996), can alter the abundance and species composition of freshwater plant communities and drive plant assemblages towards dominance by chemically defended plants (Parker et al 2006). Although macroinvertebrates are often abundant on submersed aquatic plants (Brusven et al 1990, Bowden 1999, Hutchens et al 2004, and suffer intense predation from omnivorous crayfish (Lodge et al 1994), fish (Sheldon 1987, Johansson 1991, Flecker and Townsend 1994, and waterfowl (Marklund et al 2002), the feeding and host-plant preferences of small, plant-associated grazers relative to the feeding preferences of larger consumers in the same freshwater system have rarely been considered.…”

Case selection by a limnephilid caddisfly [Potamophylax latipennis (Curtis)] in response to different predators

“…This dissimilar pattern is consistent with the different hunting techniques of those predators. Dragonfly naiads and brown trout rely on physically damaging the case (puncturing, rupturing or crushing) for successful predation (personal observation), and mineral cases offer greater protection than organic ones against them (Otto and Svensson 1980;Johansson 1991; Nislow and Molles 1993;Johansson and Englund 1995). In contrast, fire salamander larvae need to separate the larvae from its case to consume it (see above), as shown for ambystomatid salamanders (Holomuzki 1983;Wissinger et al 1999), and both organic and mineral cases seem to be of the same anti-predator value against them.…”

“…Previous studies have shown that the mineral cases of the genus Potamophylax and other limnephilids are of greater defensive value than organic ones against brown trout and dragonflies that rely on crushing or puncturing the case for successful predation (Otto and Svensson 1980;Johansson 1991;Otto and Johansson 1995;Nislow and Molles 1993). Gut content analyses have revealed that brown trout eat larvae of Potamophylax and other limnephilids with their cases (Rincón 1993).…”

“…Some animals, such as cased caddisfly larvae and hermit crabs, decrease predation risk through the use of exogenous materials to cover the softer, more vulnerable parts of their bodies (Otto and Svensson 1980;Johansson 1991;Conover 1978;Borjesson and Szelistowski 1989;Cote et al 1998). This phenomenon represents an interesting interface between morphology and behaviour, as behavioural processes yield what could be functionally regarded as morphological structures (Nislow and Molles 1993).…”

General activity and foraging tactics in a water bug

“…The degree to which Notonecta larvae opt for safety instead of better food is dependent upon agespecific vulnerability (Sih 1981). It has been suggested that odonate larvae have evolved 2 main life-styles in response to vertebrate predators: a "slow" life-style with low activity in the presence of vertebrate predators and a "fast" life-style with high activity and rapid energetic rates in the absence of predators (Johansson 1991). A higher level of activity may be related to a lower reaction time (Johansson & Johansson 1992).…”