RESUMO
Complex life cycle parasites can manipulate the behavior of intermediate hosts in order to reduce their fitness and increase the chance of completing life cycle. In order to understand the effects of the trematode parasites of the genus Clinostomum on host fish Loricariichthys platymetopon, a filmed experiment was carried out to quantify the foraging activity of hosts with different intensities of infection. The results suggest that hosts with higher parasite intensities reduced foraging activity early in the morning when compared to hosts with low intensities. This period may be critical for hosts since birds, the target hosts of such trematodes, forage intensively at dawn.
Assuntos
Peixes-Gato/fisiologia , Peixes-Gato/parasitologia , Doenças dos Peixes/parasitologia , Trematódeos/fisiologia , Infecções por Trematódeos/veterinária , Adaptação Biológica , Animais , Comportamento Animal , Evolução Biológica , Brasil , Comportamento Alimentar , Doenças dos Peixes/epidemiologia , Doenças dos Peixes/fisiopatologia , Interações Hospedeiro-Parasita , Prevalência , Rios , Infecções por Trematódeos/epidemiologia , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/fisiopatologia , Gravação em VídeoRESUMO
Traira (Hoplias malabaricus) is a neotropical fish that is widely distributed in freshwater environments in South America. In the present study, we documented the occurrence of metacercariae of Austrodiplostomum spp. (Diplostomidae) in the eyes and cranial cavity of H. malabaricus and described parasite-induced behavioral changes in the host. The fish were collected from the upper São Francisco River, in the Serra da Canastra mountain range, Minas Gerais, transported alive to the laboratory, observed for 2 weeks, and subsequently examined for parasites. Of the 35 fish examined, 28 (80 %) had free metacercariae in the vitreous humor (mean intensity=95.4; mean abundance=76.3), and 24 (68.57 %) had free metacercariae in the cranial cavity, mainly concentrated below the floor of the brain, at the height of the ophthalmic lobe (mean intensity=12.91; mean abundance=8.85). Specimens of H. malabaricus with a high intensity of infection in the brain displayed changes in swimming behavior.
Assuntos
Comportamento Animal , Caraciformes/fisiologia , Caraciformes/parasitologia , Doenças dos Peixes/fisiopatologia , Trematódeos/isolamento & purificação , Infecções por Trematódeos/veterinária , Animais , Encefalopatias/parasitologia , Encefalopatias/fisiopatologia , Brasil , Helmintíase do Sistema Nervoso Central/parasitologia , Helmintíase do Sistema Nervoso Central/fisiopatologia , Helmintíase do Sistema Nervoso Central/veterinária , Olho/parasitologia , Infecções Oculares Parasitárias/parasitologia , Infecções Oculares Parasitárias/fisiopatologia , Infecções Oculares Parasitárias/veterinária , Doenças dos Peixes/parasitologia , Metacercárias/isolamento & purificação , Metacercárias/fisiologia , Rios , Natação , Trematódeos/fisiologia , Infecções por Trematódeos/parasitologia , Infecções por Trematódeos/fisiopatologiaRESUMO
The swimming behavior of Poecilia vivipara was evaluated using an image analysis system comparing laboratory-reared uninfected fish before and after experimental infection with different intensities of cercariae of the trematode Acanthocollaritrema umbilicatum. Two experiments were performed, each with 30 fish which were individually exposed to 30 and 50 cercariae, respectively, shed from experimentally infected molluscs, Heleobia australis. Before and after (17-27 days) infection, the behavior of each fish was monitored in terms of Distance travelled, Ambulatory time, Stereotypic time, Resting time and Average speed. At the end of the experiments, the fish were dissected to count the number of metacercariae recovered. In the experiment with 30 cercariae, fish with 2-10 metacercariae did not exhibit any significant differences in their swimming activity, but those with 11-22 metacercariae had a significantly enhanced Stereotypic time and a reduced Time Resting. In the experiment with 50 cercariae, fish with 5-22 metacercariae had an enhanced Distance travelled and a reduced Average speed; highly significant differences occurred with regard to all behavioral parameters when considering the subgroup 23-36 metacercariae: Distance travelled, Stereotypic time, Resting time, Ambulatory time and Average speed. The swimming behavior of P. vivipara changed influenced by an intensity-dependence on metacercariae of A. umbilicatum, supporting the prediction that parasites are able to alter the behavior of their hosts.