Publication
Title
Effect of tick parasitism on the health status of a passerine bird
Author
Abstract
1. Little information is available on the ecological interactions between ticks and their hosts under natural conditions, and particularly so for avian hosts. To understand this hostparasite interaction it is necessary to assess the physiological harm ticks can do to their host. 2. We combined observational and experimental (field and laboratory) data to examine the effects of a common tick species with major economic importance, the sheep tick (Ixodes ricinus), on the health status of a common passerine bird, the great tit (Parus major). 3. In the laboratory experiment a parallel group design was carried out in which the birds of the experimental group were infested with 310 nymphs, whereas the birds of the control group were kept free of ticks and received a sham treatment. Both groups were stratified according to age and sex. Health parameters were measured the day before and 3 days after infestation or sham treatment: haematocrit level, erythrocyte sedimentation rate, leucocyte concentration and general body condition (body mass corrected for body size). 4. No effects of age were observed on any of the health parameters. The decrease in haematocrit level in the experimental group was significantly greater than in the control group. Moreover, infested males suffered more blood depletion than infested females. The increase in sedimentation rate was greater in the experimental group than in the control group. Surprisingly, no treatment effects were found on leucocyte concentrations, which may indicate immunoregulation by the ticks on components of the birds' cellular immune response. Also no difference in general body condition between the treatment groups was found. None of the infested birds died during infestation. 5. Lower haematocrit levels in infested birds, but unaffected leucocyte concentrations and general body condition are confirmed by field data (experimental and observational) of adult birds during breeding season. 6. Neither haematocrit level nor general body condition was associated with parasite intensity among infested birds, suggesting that immature Ixodes ricinus are not resource limited at high natural densities. Still, the measurable direct harm caused by sheep tick infestations calls for further study on its importance for the evolutionary ecology of passerine hosts.
Language
English
Source (journal)
Functional ecology / British Ecological Society. - Oxford
Publication
Oxford : 2008
ISSN
0269-8463
Volume/pages
22:6(2008), p. 1099-1107
ISI
000260670000019
Full text (Publisher's DOI)
UAntwerpen
Faculty/Department
Research group
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 19.11.2008
Last edited 01.08.2017
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