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The influence of larval case design on vulnerability of Limnephilus frijole (Trichoptera) to predation
Author(s) -
NISLOW KEITH H.,
MOLLES MANUEL C.
Publication year - 1993
Publication title -
freshwater biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.297
H-Index - 156
eISSN - 1365-2427
pISSN - 0046-5070
DOI - 10.1111/j.1365-2427.1993.tb00775.x
Subject(s) - predation , caddisfly , predator , dragonfly , biology , larva , odonata , ecology , invertebrate , population , minnow , fish <actinopterygii> , fishery , demography , sociology
SUMMARY1 We examined the potential selective pressures exerted by different types of predators on morphological prey defences using the case‐building larvae of the limnephilid caddisfly, Limnephilus frijole . The predators were a predaceous minnow, Gila pandora , and an aeschnid dragonfly naiad, Oplonaeschna armata . 2 The influence of larval case design on vulnerability to predators was evaluated in a series of laboratory experiments. Larval L. frijole were collected from a stream without fish or dragonflies. In the laboratory, larvae still occupying their field‐built cases were exposed to the two predators, with which L. frijole co‐occurs in other streams. Following 24 h exposure of caddisfly larvae to a specific predator, the pre‐trial case length, case strength, case width, and case composition of victims and survivors were compared. 3 Principal components analysis (PCA) indicated substantial independent variation for all four case parameters in the study population. The cases of larvae surviving exposure to either dragonfly naiads or fish were significantly stronger and wider than cases of victims of predation. Cases of survivors were also longer and had a greater mineral fraction than those of victims, but differences were either marginally significant or not significant. 4 These results demonstrate that specific aspects of case design affect the vulnerability of caddisfly larvae. In addition, predaceous fish and predaceous invertebrates, using different predation techniques, may exert similar selective pressures on these defenses. Case aspects influencing vulnerability in these experiments are broadly consistent with natural variation in case design associated with predator‐rich and predator‐free habitats for related caddisfly species.