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Modification of Antipredator Behavior of Caecidotea Intermedius by Its Parasite Acanthocephalus Dirus
Author(s) -
Hechtel Laura J.,
Johnson Cheryl L.,
Juliano Steven A.
Publication year - 1993
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1940798
Subject(s) - biology , foraging , predation , ecology , predator , host (biology) , zoology
The isopod Caecidotea intermedius serves as the intermediate host for the acanthocephalan Acanthocephalus dirus. C. intermedius is preyed upon by the northern creek chub, Semotilus atromaculatus, which also serves as the definitive host for A. dirus. The effects of the parasite on the antipredator behavior of C. intermedius were examined. We tested the hypothesis that behavioral changes induced in C. intermedius by the parasite are by—products of increased energy demands induced by the parasite (i.e., increased hunger). Infected and uninfected C. intermedius were placed in a divided aquarium with 0, 1, or 2 creek chubs. Leaf discs provided both a food source and a refuge from the predator. In the presence of the creek chubs, uninfected C. intermedius avoided the predator, and were found more frequently in refugia as the number of creek chubs increased. However, infected C.intermedius were associated with the side of aquarium containing the predator, and spent significantly more time out in the open away from the refuge regardless of the number of creek chubs. These data show that the antipredator behavior exhibited by C. intermedius is altered by A. dirus, and that such alterations are unlikely to be simply products of increased energy demands. Parasite—induced behavioral changes appear to increase C. intermedius' vulnerability to predation, thereby increasing the likelihood of A. dirus completing its life cycle. We find little evidence for greater foraging need as the mechanism indicating changes in antipredator behavior.