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Araujo Filho JA, Teixeira AAM, Teles DA, Rocha SM, Almeida WO, Mesquita DO, Lacerda ACF. Using lizards to evaluate the influence of average abundance on the variance of endoparasites in semiarid areas: dispersion and assemblage structure. J Helminthol 2020; 94:e121. [PMID: 31964431 DOI: 10.1017/S0022149X19001147] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The distribution of parasites within host populations and communities, and the mechanisms responsible for these patterns, are poorly understood aspects of wildlife parasitology. Here, we evaluate the influence of the average abundance of endoparasite variance, using endoparasites of lizards from the Caatinga domain (semiarid region), north-eastern Brazil. We hypothesized that, due to the high number of generalist endoparasite species, they may occur randomly throughout host populations in an aggregate pattern. In addition, we evaluated the degree to which sample variance is influenced by the average abundance of endoparasite species, patterns of co-occurrence and dominance among endoparasite species and similarities between abundance and the richness of endoparasite infracommunities in several host species. Between September 2015 and February 2016, 2141 lizards (1233 infected) from 16 species were collected from six Caatinga areas. In total, 25,687 endoparasites were collected, which belonged to 13 species including nematodes, pentastomids, cestodes, trematodes and acanthocephalans. Parasite-host associations documented here included 39 newly identified interactions. Endoparasites occurred in a typical aggregate pattern of distribution within their hosts; there was no measurable preference related to the acquisition of hosts by endoparasites. Despite the new records, endoparasites found were commonly associated with lizards in Caatinga environments, which may reflect fauna composed of generalist endoparasite species.
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Bernot JP, Caira JN. Site specificity and attachment mode of Symcallio and Calliobothrium species (Cestoda: "Tetraphyllidea") in smoothhound sharks of the genus Mustelus (Carcharhiniformes: Triakidae). PeerJ 2019; 7:e7264. [PMID: 31338258 PMCID: PMC6628880 DOI: 10.7717/peerj.7264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2019] [Accepted: 06/06/2019] [Indexed: 11/20/2022] Open
Abstract
Previous studies suggest that cestodes (i.e., tapeworms) of the sister genera Symcallio and Calliobothrium attach in different specific regions of the spiral intestine of their triakid shark hosts, with species of Symcallio attaching in the anterior region of the spiral intestine and species of Calliobothrium attaching with a broader distribution centered around the middle of the spiral intestine. In the present study, we tested the generality of this pattern of site specificity in two additional species pairs: Symcallio peteri and Calliobothrium euzeti in Mustelus palumbes and S. leuckarti and C. wightmanorum in M. asterias. Finding that these cestodes also exhibit the aforementioned pattern, we investigated a series of functional explanations that might account for this phylogenetically conserved pattern of site specificity. The mucosal surface of the spiral intestine of both shark species was characterized, as were the attachment mechanisms of all four cestode species. Although anatomical differences in mucosal surface were seen along the length of the spiral intestine in both shark species, these differences do not appear to correspond to the attachment mode of these cestodes. We find that while species of Symcallio, like most cestodes, attach using their scolex, species of Calliobothrium attach with their scolex and, to a much greater extent, also with their strobila. Furthermore, attachment of Calliobothrium species appears to be enhanced by laciniations (flap-like extensions on the posterior margins of the proglottids) that interdigitate with elements of the mucosal surface of the spiral intestine. The role of proglottid laciniations in attachment in species of Calliobothrium helps reconcile a number of morphological features that differ between these two closely related cestode genera.
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Affiliation(s)
- James P. Bernot
- Institute for Biomedical Sciences, George Washington University, Washington, D.C., USA
| | - Janine N. Caira
- Department of Ecology & Evolutionary Biology, University of Connecticut, Storrs, CT, USA
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Paladini G, Hansen H, Williams CF, Taylor NGH, Rubio-Mejía OL, Denholm SJ, Hytterød S, Bron JE, Shinn AP. Reservoir hosts for Gyrodactylus salaris may play a more significant role in epidemics than previously thought. Parasit Vectors 2014; 7:576. [PMID: 25526740 PMCID: PMC4287164 DOI: 10.1186/s13071-014-0576-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2014] [Accepted: 11/27/2014] [Indexed: 11/24/2022] Open
Abstract
BACKGROUND Gyrodactylus salaris Malmberg, 1957 has had a devastating impact on wild Norwegian stocks of Atlantic salmon Salmo salar L., and it is the only Office International des Epizooties (OIE) listed parasitic pathogen of fish. The UK is presently recognised as G. salaris-free, and management plans for its containment and control are currently based on Scandinavian studies. The current study investigates the susceptibility of British salmonids to G. salaris, and determines whether, given the host isolation since the last glaciation and potential genetic differences, the populations under test would exhibit different levels of susceptibility, as illustrated by the parasite infection trajectory over time, from their Scandinavian counterparts. METHODS Populations of S. salar, brown trout Salmo trutta L., and grayling Thymallus thymallus (L.), raised from wild stock in UK government hatcheries, were flown to Norway and experimentally challenged with a known pathogenic strain of G. salaris. Each fish was lightly anaesthetised and marked with a unique tattoo for individual parasite counting. A single Norwegian population of S. salar from the River Lærdalselva was used as a control. Parasite numbers were assessed every seven days until day 48 and then every 14 days. RESULTS Gyrodactylus salaris regularly leads to high mortalities on infected juveniles S. salar. The number of G. salaris on British S. salar rose exponentially until the experiment was terminated at 33 days due to fish welfare concerns. The numbers of parasites on S. trutta and T. thymallus increased sharply, reaching a peak of infection on days 12 and 19 post-infection respectively, before declining to a constant low level of infection until the termination of the experiment at 110 days. CONCLUSIONS The ability of S. trutta and T. thymallus to carry an infection for long periods increases the window of exposure for these two hosts and the potential transfer of G. salaris to other susceptible hosts. This study demonstrates that G. salaris can persist on S. trutta for longer periods than previously thought, and that the role that S. trutta could play in disseminating G. salaris needs to be considered carefully and factored into management plans and epidemics across Europe.
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Affiliation(s)
- Giuseppe Paladini
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| | - Haakon Hansen
- Norwegian Veterinary Institute, Section for Parasitology, P.O. Box 750, Sentrum, NO-0106, Oslo, Norway.
| | - Chris F Williams
- Environment Agency, National Fisheries Laboratory, Bromholme Lane, Brampton, PE28 4NE, UK.
| | - Nick G H Taylor
- Centre for Environment, Fisheries & Aquaculture (Cefas), Weymouth Laboratory, Barrack Road, Weymouth, DT4 8UB, UK.
| | - Olga L Rubio-Mejía
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| | - Scott J Denholm
- Animal Breeding and Genomics, Animal & Veterinary Sciences, SRUC, Roslin Institute Building, Easter Bush, Midlothian, EH25 9RG, UK.
| | - Sigurd Hytterød
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| | - James E Bron
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
| | - Andrew P Shinn
- Institute of Aquaculture, School of Natural Sciences, University of Stirling, Stirling, FK9 4LA, Scotland, UK.
- Fish Vet Group Asia Ltd., 99/386, Chaengwattana Building, Chaengwattana Rd., Kwaeng Toongsonghong, Khet Laksi, Bangkok, 10210, Thailand.
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Dezfuli BS, Giari L, Shinn AP. The role of rodlet cells in the inflammatory response in Phoxinus phoxinus brains infected with Diplostomum. Fish Shellfish Immunol 2007; 23:300-4. [PMID: 17182257 DOI: 10.1016/j.fsi.2006.11.003] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Revised: 11/07/2006] [Accepted: 11/08/2006] [Indexed: 05/13/2023]
Abstract
European minnows, Phoxinus phoxinus L., are commonly infected with Diplostomum phoxini Faust, 1918 metacercariae. A sub-sample of 34 minnows collected from the River Endrick, Stirlingshire, Scotland revealed that 50% of the population were infected (n = 17), with the cerebellum, medulla oblongata and the optic lobe regions of the minnow brain bearing the heaviest infections (13.7 +/- 2.6 mean +/- S.E.; 1-38 range). Serial histological sections through the brains of both uninfected and infected minnows revealed the presence of rodlet cells in the latter, which were occasionally observed in close proximity to the tegument of a metacercaria. Rodlet cells were the only type of host inflammatory cells found in this study and their role in the host's immune response to parasitic infection is commented upon.
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Affiliation(s)
- Bahram S Dezfuli
- Department of Biology, University of Ferrara, Via Borsari, 46, 44100 Ferrara, Italy.
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Affiliation(s)
- John Janovy
- School of Biological Sciences, University of Nebraska-Lincoln, 68588-0118, USA.
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Abstract
Habitat selection may be the basis of some of the most exciting questions in behavioural ecology today, but parasites are being excluded from this debate. Parasites are not aberrant; they form a large proportion of the diversity of life on earth, and one estimate suggests that parasitism is more common than all other feeding strategies combined. We still do not understand the adaptive value of habitat selection behaviours in these organisms, even though the literature is full of examples of parasites migrating and navigating through hosts to their specific habitats. Parasites must make the same decisions that every animal has to make regarding food acquisition, shelter and reproduction. However, we cannot even make reasonable guesses on the habitat selection strategies and critical resources that influence their decision-making. The purpose of this review is to provide examples of experiments and methods of incorporating critical resources into the ecological analyses of habitat selection by gastrointestinal parasites. Information on parasite resources is simply not available for most parasites, and these ideas might stimulate and guide future research. In addition, parasites are ideal models to test theoretical assumptions of habitat selection. Experimental manipulations of parasites are ideal models to test theoretical assumptions of habitat selection. Experimental manipulations of parasite populations are simple, and habitats of endoparasites can be precisely altered by surgical methods. Few tests of habitat selection theory have been attempted in free-living environments because of the difficulty of assessing the correlations between environmental variations and organismal success in real-world situations, but this is not a problem with parasites because their habitats are replicated exactly in each host.
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Affiliation(s)
- M V Sukhdeo
- Cook College, Rutgers University, New Brunswick, NJ 08903, USA.
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Janovy J, Clopton R, Clopton D, Snyder SD, Efting A, Krebs L. Species density distributions as null models for ecologically significant interactions of parasite species in an assemblage. Ecol Modell 1995. [DOI: 10.1016/0304-3800(93)e0087-j] [Citation(s) in RCA: 51] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Abstract
Helminth parasites of vertebrates usually select very specific regions or habitats in their hosts, and this is often preceded by a tortuous migration through various host organs. However, the proximate mechanisms of migration and habitat selection have remained enigmatic despite considerable effort by parasitologists. In this paper a new approach to studying helminth behaviour in the host is proposed. The core idea is that behaviour strategies must be considered from the perspective of the parasites and their perceptions of their environment. A guiding principle is that the environmental features to which an animal responds, and the actions which are required for responding to the environment, form a fundamental unit of behaviour. Thus, we can deduce an animal's behavioural strategy from the details of its response to environmental signals and from its sensory capabilities. The evidence presented suggests that helminth behaviours in the host often occur as fixed (or modal) action patterns which are usually seen in response to constant, or predictable environmental features. Thus, a working hypothesis is that the mechanisms of physiological and biochemical homeostasis within the host provide an extremely predictable environment for the parasite. Under these conditions, a parasite needs to perceive only small subsets of the total information available from the environment to respond appropriately. Studies on sensory and nervous systems of these organisms are critical to understanding parasite perception, but there are formidable technical obstacles that prevent easy access to parasite nervous systems. Therefore, a multidisciplinary approach, using ideas from parasitology, ecology, evolutionary biology and neuroethology, is considered requisite for reconstructing the parasites' behaviour strategies. It is suggested that future directions should pursue integration of studies on sensory physiology with the behavioural ecology of these organisms.
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Affiliation(s)
- M V Sukhdeo
- Department of Animal Sciences, Rutgers, State University of New Jersey, New Brunswick 08903
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Abstract
Host location by parasites can be achieved by either active or passive mechanisms. In spite of their significance, the efficacy of these methods has been little researched. High fecundity in parasites is discussed in terms of the role it plays in dispersal and transmission. Some concepts developed by mainstream behavioural ecologists are outlined and their relevance to parasitology is indicated. 'Reproductive value' is recommended as an appropriate measure of the costs and benefits of behavioural cts. Although costs of reproduction have been rarely studied in parasites, they are likely to occur in cosexual insects, nematodes and crustaceans. Experiments using captive hosts and/or in vitro cultivation could help in the construction of realistic optimality models. We suggest that r- and K-selection theory could assist in the study of the evolution of parasite behaviour. We discuss how parasite populations are dispersed and controlled and consider the implications of overdispersion. We outline three sources of signals to which parasites may respond and suggest that understanding evolutionary mechanisms and community organisation of parasites and hosts requires evaluation of fundamental behavioural responses to environmental signals. The study of closely related groups of parasites and their hosts may advance our knowledge of the evolution of parasite life cycles and the evolutionary costs and benefits of behavioural acts.
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Affiliation(s)
- J G Rea
- Department of Biological and Biomedical Sciences, University of Ulster, Jordanstown, Ireland
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Abstract
How do liver worms find the liver? Why are heartworms always found in the heart? Attempts to answer these questions have invariably yielded inconclusive results. A major problem has been the use of models or hypotheses derived from studies of free-living organisms. The parasite's environment is distinct from free-living environments in several fundamental ways and these differences will impact on the evolution of parasite behaviours. In this article, Michael Sukhdeo outlines a hypothesis for habitat selection behavior of helminths that is based on the specific environmental conditions within the host.
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Affiliation(s)
- M V Sukhdeo
- Department of Animal Sciences, Rutgers, The State University of New Jersey, Cool College, New Brunswick, NJ 08903, USA
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