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Nikolaev KE, Fedorov DD, Vinogradova AA, Levakin IA, Galaktionov KV. No time to relax: Age-dependent infectivity of cercariae in marine coastal ecosystems. J Helminthol 2023; 97:e102. [PMID: 38130206 DOI: 10.1017/s0022149x2300086x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2023]
Abstract
Age dynamics of the ability of cercariae of two digenean species, Himasthla elongata (Himasthlidae) and Renicola parvicaudatus (Renicolidae), to infect the second intermediate host (SIH), mussels (Mytilus edulis), was investigated experimentally. This is the first study of this kind made on cercariae transmitted in the intertidal of the northern seas. The larvae of all tested ages (from 0.5 to 6 hr) were equally successful in infecting mussels. This finding disagrees with the literature data on cercariae of several freshwater digeneans, which are practically incapable of infecting the SIH during the first 1-3 hr of life. The presence of a time delay before the attainment of the maximum infectivity (TDMI) may be associated with the need for physiological maturation of cercariae in the very beginning of their life in the environment, the need for their broad dispersion, and the prevention of superinfection of the downstream host. The absence of TDMI in the cercariae examined in our study could be associated with the instability of environmental factors in the marine intertidal (wave impact, tidal currents). These factors promote a broad dispersion of cercariae in the intertidal biotope and prevent superinfection of potential SIHs. Biological and behavioural features may also play a role. We hypothesize that the presence or absence of TDMI does not depend on the taxonomic affiliation of the cercariae but is determined by the transmission conditions.
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Affiliation(s)
- Kirill E Nikolaev
- White Sea Biological Station, Zoological Institute, Russian Academy of Sciences, St. Petersburg199034, Russia
| | - Daniil D Fedorov
- Laboratory for the Study of Parasitic Worms and Protists, Zoological Institute, Russian Academy of Sciences, St. Petersburg199034, Russia
| | - Anna A Vinogradova
- Laboratory for the Study of Parasitic Worms and Protists, Zoological Institute, Russian Academy of Sciences, St. Petersburg199034, Russia
| | - Ivan A Levakin
- Laboratory for the Study of Parasitic Worms and Protists, Zoological Institute, Russian Academy of Sciences, St. Petersburg199034, Russia
| | - Kirill V Galaktionov
- Laboratory for the Study of Parasitic Worms and Protists, Zoological Institute, Russian Academy of Sciences, St. Petersburg199034, Russia
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2
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Roper MJ, Arnold RE, Storer KE, Green JP. Transmission of parasitic mites (Riccardoella oudemansi) between limacid slug hosts: the role of parasite and host behaviour. Symbiosis 2023. [DOI: 10.1007/s13199-023-00909-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/28/2023]
Abstract
AbstractTransmission between hosts is crucial to the growth, development and reproduction of many parasites. As a consequence, parasites are under selection to maximise transmission success and exhibit many behavioural and morphological adaptations that allow detection of, and movement between, hosts. However, transmission success is not determined by parasites alone, but is also shaped by host behaviours. Often, host behaviours function to minimise the risk of exposure to parasites; in some cases, however, host behaviours may be manipulated by parasites to increase transmission success. In this study, we investigated transmission of the parasitic mite Riccardoella oudemansi between slug (Limacus maculatus) hosts, considering the role of both host and parasite behaviour in determining transmission success. Host-host transmission occurred when slugs were in physical contact, but mites were also capable of moving across the substrate to locate new hosts, a process facilitated by mucus trails. We found no strong evidence that slugs avoid parasitised conspecifics, or that mites manipulate slug behaviour to increase transmission. Finally, mites showed a preference for the mucus of parasitised slugs, but did not discriminate between mucus from their own host and another parasitised slug. A general preference for mucus from parasitised slugs is likely to be important in encouraging mites to remain in close contact with their host and may also facilitate host-switching and outbreeding. We encourage further study of parasitism by Riccardoella in limacid slugs, where cross-species variation in host social behaviour may drive differences in the rate and success of parasite transmission across slug species.
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3
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Born-Torrijos A, van Beest GS, Vyhlídalová T, Knudsen R, Kristoffersen R, Amundsen PA, Thieltges DW, Soldánová M. Taxa-specific activity loss and mortality patterns in freshwater trematode cercariae under subarctic conditions. Parasitology 2022; 149:457-468. [PMID: 35331353 PMCID: PMC11010473 DOI: 10.1017/s0031182021002006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2021] [Revised: 09/24/2021] [Accepted: 11/02/2021] [Indexed: 11/07/2022]
Abstract
Cercarial activity and survival are crucial traits for the transmission of trematodes. Temperature is particularly important, as faster depletion of limited cercarial energy reserves occurs at high temperatures. Seasonal climate conditions in high latitude regions may be challenging to complete trematode life cycle during the 6-month ice-free period, but temperature effects on the activity and survival of freshwater cercariae have not been previously identified. After experimentally simulating natural subarctic conditions during warmer and colder months (13 and 6°C), a statistical approach identifying changes in the tendency of cercarial activity loss and mortality data was used to detect differences in three trematode genera, represented by four taxa (Diplostomum spp., Apatemon spp., small- and large-sized Plagiorchis spp.). A strong temperature-dependent response was identified in both activity loss and mortality in all taxa, with Diplostomum spp. cercariae showing the most gradual changes compared to other taxa. Furthermore, whilst activity loss and mortality dynamics could not be divided into ‘fish- vs invertebrate-infecting cercariae’ groups, the detected taxa-specific responses in relation to life-history traits indicate the swimming behaviour of cercariae and energy allocation among larvae individuals as the main drivers. Cercariae exploit the short transmission window that allows a stable continuance of trematodes’ life cycles in high-latitude freshwater ecosystems.
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Affiliation(s)
- Ana Born-Torrijos
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005České Budějovice, Czech Republic
| | - Gabrielle S. van Beest
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005České Budějovice, Czech Republic
- Cavanilles Institute for Biodiversity and Evolutionary Biology, Science Park, University of Valencia, P.O. Box 22085, 46071Valencia, Spain
| | - Tereza Vyhlídalová
- Faculty of Science, University of South Bohemia in České Budějovice, Branišovská 31, 37005České Budějovice, Czech Republic
| | - Rune Knudsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N9037Tromsø, Norway
| | - Roar Kristoffersen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N9037Tromsø, Norway
| | - Per-Arne Amundsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N9037Tromsø, Norway
| | - David W. Thieltges
- Department of Coastal Systems, NIOZ Royal Netherlands Institute for Sea Research, P.O. Box 59, 1790, AB Den Burg, Texel, The Netherlands
| | - Miroslava Soldánová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, 37005České Budějovice, Czech Republic
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Gunn MA, Allen PJ, Rosser TG, Wise DJ, Griffin MJ. CERCARIAL LONGEVITY AND INFECTIVITY OF BOLBOPHORUS DAMNIFICUS, WITH NOTES ON METACERCARIAL PERSISTENCE AND SITE SPECIFICITY IN CHANNEL AND HYBRID CATFISH. J Parasitol 2022; 108:217-225. [PMID: 35446406 DOI: 10.1645/20-123] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Advances in hybridization practices in U.S. catfish aquaculture have led to increased production of channel (Ictalurus punctatus) × blue catfish (Ictalurus furcatus) hybrids to capitalize on their more favorable production characteristics. However, the effects of typical channel catfish pathogens on hybrids are not well understood, including the digenean Bolbophorus damnificus, which has caused significant losses in channel catfish production. Three experiments were conducted to assess the longevity and site specificity of 2 life stages of B. damnificus impacting catfish production. The first experiment investigated the cercarial longevity and infectivity of B. damnificus over time. Channel catfish were individually challenged with 100 cercariae/fish with cercariae aged in 12-hr time intervals over 5 days (n = 5 fish/time point), with metacercarial cysts excised and enumerated 14 days postchallenge. There was a decrease in cercaria viability and encysted metacercariae over the first 36 hr, with the 12-hr time point having both the greatest cercaria survival and the highest number of metacercariae in exposed fish. The second experiment investigated the longevity of metacercariae within both channel and hybrid catfish. Fish (n = 30) were exposed to 2 treatments (75 or 150 cercariae/fish), and 2 fish from each treatment were sampled every 3 mo for 13 mo. Live metacercariae, based on motility observed after excystment, were found in both species up to 13 mo postchallenge, indicating the metacercariae of B. damnificus can persist throughout an entire growing season in both channel and hybrid catfish. The third experiment investigated the site specificity of metacercariae within both channel and hybrid catfish. Fish (n = 60/species) were challenged with 300 cercariae/fish and 9 fish/species were sampled after 90 days. Metacercariae were excised and enumerated from the anterior midsection (head and body), posterior midsection (trunk/caudal peduncle), ventral (belly), and caudal fin (tail) sections of each fish. Overall, the trunk/caudal peduncle had a 2-fold increase in the number of metacercariae excised, and although not significantly higher, results indicate this region should be the focal point of pondside assessment for the presence of B. damnificus because of ease of detection of encysted metacercariae.
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Affiliation(s)
- Mackenzie A Gunn
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi 39762
| | - Peter J Allen
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi 39762
| | - T Graham Rosser
- Department of Basic Sciences, College of Veterinary Medicine, Mississippi State University, Mississippi State, Mississippi 39762
| | - David J Wise
- Department of Wildlife, Fisheries and Aquaculture, Mississippi State University, Mississippi State, Mississippi 39762.,Delta Research and Extension Center, Thad Cochran National Warmwater Aquaculture Center, Mississippi State University, Stoneville, Mississippi 38776
| | - Matt J Griffin
- Delta Research and Extension Center, Thad Cochran National Warmwater Aquaculture Center, Mississippi State University, Stoneville, Mississippi 38776.,Department of Pathobiology and Population Medicine, College of Veterinary Medicine, Mississippi State University, Stoneville, Mississippi 38776
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5
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Soldánová M, Kundid P, Scholz T, Kristoffersen R, Knudsen R. Somatic Dimorphism in Cercariae of a Bird Schistosome. Pathogens 2022; 11:pathogens11030290. [PMID: 35335614 PMCID: PMC8953619 DOI: 10.3390/pathogens11030290] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2022] [Revised: 02/20/2022] [Accepted: 02/22/2022] [Indexed: 11/16/2022] Open
Abstract
Phenotypic polymorphism is a commonly observed phenomenon in nature, but extremely rare in free-living stages of parasites. We describe a unique case of somatic polymorphism in conspecific cercariae of the bird schistosome Trichobilharzia sp. “peregra”, in which two morphs, conspicuously different in their size, were released from a single Radix balthica snail. A detailed morphometric analysis that included multiple morphological parameters taken from 105 live and formalin-fixed cercariae isolated from several naturally infected snails provided reliable evidence for a division of all cercariae into two size groups that contained either large or small individuals. Large morph (total body length of 1368 and 1339 μm for live and formalin-fixed samples, respectively) differed significantly nearly in all morphological characteristics compared to small cercariae (total body length of 976 and 898 μm for live and formalin samples, respectively), regardless of the fixation method. Furthermore, we observed that small individuals represent the normal/commonly occurring phenotype in snail populations. The probable causes and consequences of generating an alternative, much larger phenotype in the parasite infrapopulation are discussed in the context of transmission ecology as possible benefits and disadvantages facilitating or preventing the successful completion of the life cycle.
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Affiliation(s)
- Miroslava Soldánová
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic; (P.K.); (T.S.)
- Correspondence:
| | - Petra Kundid
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic; (P.K.); (T.S.)
- Department of Parasitology, Faculty of Science, University of South Bohemia in České Budějovice, 370 05 České Budějovice, Czech Republic
| | - Tomáš Scholz
- Institute of Parasitology, Biology Centre of the Czech Academy of Sciences, 370 05 České Budějovice, Czech Republic; (P.K.); (T.S.)
- Department of Parasitology, Faculty of Science, University of South Bohemia in České Budějovice, 370 05 České Budějovice, Czech Republic
| | - Roar Kristoffersen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N9037 Tromsø, Norway; (R.K.); (R.K.)
| | - Rune Knudsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, N9037 Tromsø, Norway; (R.K.); (R.K.)
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6
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Yu A, Vannatta JT, Gutierrez SO, Minchella DJ. Opportunity or catastrophe? effect of sea salt on host-parasite survival and reproduction. PLoS Negl Trop Dis 2022; 16:e0009524. [PMID: 35202408 PMCID: PMC8870500 DOI: 10.1371/journal.pntd.0009524] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2021] [Accepted: 01/24/2022] [Indexed: 11/18/2022] Open
Abstract
Seawater intrusion associated with decreasing groundwater levels and rising seawater levels may affect freshwater species and their parasites. While brackish water certainly impacts freshwater systems globally, its impact on disease transmission is largely unknown. This study examined the effect of artificial seawater on host-parasite interactions using a freshwater snail host, Biomphalaria alexandrina, and the human trematode parasite Schistosoma mansoni. To evaluate the impact of increasing salinity on disease transmission four variables were analyzed: snail survival, snail reproduction, infection prevalence, and the survival of the parasite infective stage (cercariae). We found a decrease in snail survival, snail egg mass production, and snail infection prevalence as salinity increases. However, cercarial survival peaked at an intermediate salinity value. Our results suggest that seawater intrusion into freshwaters has the potential to decrease schistosome transmission to humans.
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Affiliation(s)
- Ao Yu
- Purdue University, West Lafayette, Indiana, United States of America
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7
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Born-Torrijos A, Paterson RA, van Beest GS, Vyhlídalová T, Henriksen EH, Knudsen R, Kristoffersen R, Amundsen PA, Soldánová M. Cercarial behaviour alters the consumer functional response of three-spined sticklebacks. J Anim Ecol 2021; 90:978-988. [PMID: 33481253 DOI: 10.1111/1365-2656.13427] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2020] [Accepted: 01/04/2021] [Indexed: 01/16/2023]
Abstract
Free-living parasite life stages may contribute substantially to ecosystem biomass and thus represent a significant source of energy flow when consumed by non-host organisms. However, ambient temperature and the predator's own infection status may modulate consumption rates towards parasite prey. We investigated the combined effects of temperature and predator infection status on the consumer functional response of three-spined sticklebacks towards the free-living cercariae stages of two common freshwater trematode parasites (Plagiorchis spp., Trichobilharzia franki). Our results revealed genera-specific functional responses and consumption rates towards each parasite prey: Type II for Plagiorchis spp. and Type III for T. franki, with an overall higher consumption rate on T. franki. Elevated temperature (13°C) increased the consumption rate on Plagiorchis spp. prey for sticklebacks with mild cestode infections (<5% fish body weight) only. High consumption of cercarial prey by sticklebacks may impact parasite population dynamics by severely reducing or even functionally eliminating free-living parasite life stages from the environment. This supports the potential role of fish as biocontrol agents for cercariae with similar dispersion strategies, in instances where functional response relationships have been established. Our study demonstrates how parasite consumption by non-host organisms may be shaped by traits inherent to parasite transmission and dispersal, and emphasises the need to consider free-living parasite life stages as integral energy resources in aquatic food webs.
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Affiliation(s)
- Ana Born-Torrijos
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
| | - Rachel A Paterson
- School of Biosciences, Cardiff University, Cardiff, UK.,The Norwegian Institute for Nature Research, Trondheim, Norway
| | - Gabrielle S van Beest
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic.,Cavanilles Institute for Biodiversity and Evolutionary Biology, Science Park, University of Valencia, Valencia, Spain
| | - Tereza Vyhlídalová
- Faculty of Science, University of South Bohemia in České Budějovice, České Budějovice, Czech Republic
| | - Eirik H Henriksen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | - Rune Knudsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | - Roar Kristoffersen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | - Per-Arne Amundsen
- Department of Arctic and Marine Biology, Faculty of Biosciences, Fisheries and Economics, UiT The Arctic University of Norway, Tromsø, Norway
| | - Miroslava Soldánová
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, České Budějovice, Czech Republic
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The effects of temperature and salinity on the longevity of Opisthorchis viverrini cercariae: a climate change concern. J Helminthol 2020; 94:e165. [PMID: 32571436 DOI: 10.1017/s0022149x20000498] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Research on the effects of environmental factors influenced by climate change on parasite transmissibility is an area garnering recent attention worldwide. However, there is still a lack of studies on the life cycle of Opisthorchis viverrini, a carcinogenic trematode found in countries of the Lower Mekong subregion of Lao PDR, Cambodia, Myanmar, Vietnam and Thailand. To evaluate the influences of environmental factors water temperature and salinity on the transmissibility of the liver fluke O. viverrini through cercarial stage, longevity of O. viverrini cercaria was examined at different experimental temperatures (22°C, 30°C and 38°C) and salinities (2.5 parts per thousand (PPT), 3.75 PPT and 5 PPT). The results reveal that different temperatures have statistically significant effects on cercarial longevity. The cercariae exhibited a thermostability zone ranging between 22°C and 30°C. Cercarial longevity was significantly shortened when water temperatures reached 38°C. Salinity also plays a key role in cercarial longevity, with cercarial survival significantly shorter at a salinity of 3.75 PPT than at 2.5 PPT and 5 PPT. A combined analysis of salinity and temperature revealed unique trends in cercarial longevity. At all experimental salinities, cercarial longevity was lowest when incubated in 38°C, but statistically significant from cercarial longevity at temperatures of 22°C and 30°C, and salinities of 2.5 PPT and 5 PPT. The results suggest that higher temperatures negatively impact parasite longevity. This reflects that O. viverrini transmission patterns may be impacted by changes in water temperature and salinity resulting from climate change.
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9
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Rosenkranz M, Poulin R, Selbach C. Behavioural impacts of trematodes on their snail host: Species-specific effects or generalised response? Ethology 2018. [DOI: 10.1111/eth.12808] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Micha Rosenkranz
- Department of Infectious Diseases; University of Heidelberg; Heidelberg Germany
| | - Robert Poulin
- Department of Zoology; University of Otago; Dunedin New Zealand
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10
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Parasites in space and time: a novel method to assess and illustrate host-searching behaviour of trematode cercariae. Parasitology 2018; 145:1469-1474. [PMID: 29502550 DOI: 10.1017/s0031182018000288] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The transmission from one host to another constitutes a challenging obstacle for parasites and is a key determinant of their fitness. Due to their complex life histories involving several different hosts, the free-living dispersal stages (cercariae) of digenean trematodes show a huge diversity in morphology and behaviour. On a finer scale, we still have an extremely limited understanding of the inter- and intraspecific variation in transmission strategies of many trematode species. Here, we present a novel method to study the movement patterns of cercariae of four New Zealand trematode species (Coitocaecum parvum, Maritrema poulini, Apatemon sp. and Aporocotylid sp. I.) via automated video tracking. This approach allows to quantify parameters otherwise not measurable and clearly illustrates the individual strategies of parasites to search for their respective target hosts. Cercariae that seek out an evasive fish target hosts showed higher swimming speeds (acceleration and velocity) and travelled further distances, compared with species searching for high-density crustacean hosts. Automated video tracking provides a powerful tool for such detailed analyses of parasites' host-searching strategies and can enhance our understanding of complex host-parasite interactions, ranging from parasite community structure to the transmission of potential disease agents.
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11
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Hutson KS, Brazenor AK, Vaughan DB, Trujillo-González A. Monogenean Parasite Cultures: Current Techniques and Recent Advances. ADVANCES IN PARASITOLOGY 2018. [PMID: 29530311 DOI: 10.1016/bs.apar.2018.01.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Global expansion in fish production and trade of aquatic ornamental species requires advances in aquatic animal health management. Aquatic parasite cultures permit diverse research opportunities to understand parasite-host dynamics and are essential to validate the efficacy of treatments that could reduce infections in captive populations. Monogeneans are important pathogenic parasites of captured captive fishes and exhibit a single-host life cycle, which makes them amenable to in vivo culture. Continuous cultures of oviparous monogenean parasites provide a valuable resource of eggs, oncomiracidia (larvae) and adult parasites for use in varied ecological and applied scientific research. For example, the parasite-host dynamics of Entobdella soleae (van Beneden and Hesse, 1864) and its fish host, Solea solea (Linnaeus, 1758), is one of the most well-documented of all monogeneans following meticulous, dedicated study. Polystoma spp. cultures provide an intriguing model for examining evolution in monogeneans because they exhibit two alternative phenotypes depending on the age of infection of amphibians. Furthermore, assessments of the ecological, pathological and immunological effects of fish parasites in aquaculture have been achieved through cultures of Gyrodactylus von Nordmann, 1832 spp., Benedenia seriolae (Yamaguti, 1934), Neobenedenia Yamaguti, 1963 spp. and Zeuxapta seriolae (Meserve, 1938). This review critically examines methods to establish and maintain in vivo monogenean monocultures on finfish, elasmobranchs and amphibians. Four separate approaches to establish cultures are scrutinised including the collection of live infected hosts, cohabiting recipient hosts with infected stock, cohabiting hosts with parasite eggs or oncomiracidia (larvae) and direct transfer of live adult parasites onto new fish hosts. Specific parasite species' biology and behaviour permits predictive collection of parasite life stages to effectively maintain a continuous culture, while environmental parameters can be altered to manipulate parasite generation time. Parasite virulence and biosecurity are vital components of a well-managed culture to ensure appropriate animal welfare and uncontaminated surrounding environments. Contemporary approaches and techniques are reviewed to ensure optimised monogenean cultures, which ultimately can be used to further our understanding of aquatic parasitology and identify mechanisms to limit infestations in public aquaria, ornamental trade and intensive aquaculture.
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12
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Gordy MA, Kish L, Tarrabain M, Hanington PC. A comprehensive survey of larval digenean trematodes and their snail hosts in central Alberta, Canada. Parasitol Res 2016; 115:3867-80. [DOI: 10.1007/s00436-016-5152-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2015] [Accepted: 05/23/2016] [Indexed: 10/21/2022]
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13
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Théron A. Chronobiology of trematode cercarial emergence: from data recovery to epidemiological, ecological and evolutionary implications. ADVANCES IN PARASITOLOGY 2015; 88:123-64. [PMID: 25911367 DOI: 10.1016/bs.apar.2015.02.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
One major challenge for parasites with complex cycles consists to succeed in the transmission from one host to the next host. To maximize the probability of encountering the right host, numerous trematode species have selected various emergence rhythms occurring during the escape of the short-lived cercariae from the mollusc host. Cercarial shedding patterns are beautiful examples of adaptation of the parasite for a successful rendezvous with its subsequent host. In this review, after an analysis of the technical and statistical aspects specific to such studies, we compile the knowledge and unresolved issues we have about the synchronization of these rhythms, their genetic support and the role of the host physiology or activity. We are also interested on how cercarial rhythmicity influences cercarial densities in waters of transmission sites and then the risk of host infection in case of schistosomiasis. Ecological significance of the inter- and intra-specific diversity of these rhythms is emphasized as well as the evolutionary implication of new chronotypes resulting from the capture of new host species and promoting reproductive isolation and alloxenic speciation. Currently, genome sequence data now available for some trematodes such as the schistosomes provide an unprecedented resource for new research approaches that should contribute identification of the genes and mechanisms involved in determining the cercarial shedding rhythms observed.
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Affiliation(s)
- André Théron
- CNRS, UMR 5244, Ecologie et Evolution des Interactions (2EI), Université de Perpignan Via Domitia, Université, Perpignan, France.
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14
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Parasites in a man-made landscape: contrasting patterns of trematode flow in a fishpond area in Central Europe. Parasitology 2014; 138:789-807. [PMID: 24650935 DOI: 10.1017/s0031182011000291] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We have explored a large body of novel data focusing on small-scale temporal and spatial patterns in the composition and structure of larval trematode communities in Lymnaea stagnalis (L.) from a typical Central European agricultural landscape. The 5 eutrophic fishponds studied provide excellent environments for the development of species-rich and abundant trematode communities. Nine prevalent species were consistently present in component communities, but had differential contribution to the parasite flow in the 5 ponds resulting in significant contrasting patterns of community similarity and the prevalence of the 3 major transmission guilds driving this similarity. Component communities split into 2 groups: (i) those from the large pond dominated by anatid and larid generalists with active miracidial transmission; and (ii) those from the smaller ponds dominated by 2 plagiorchioideans infecting snails via egg ingestion. We put forward 3 hypotheses for the remarkable differences in larval trematode flow in the similar and closely located eutrophic ponds: (i) species-specific differences in parasite colonization potential displayed by an 'active-passive' dichotomy in miracidial transmission strategies of the species; (ii) top-down effects of pond context on transmission pathways of the trematodes; and (iii) competition as an important mechanism in eutrophic environments with a bottom-up effect on component community structure.
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Sears BF, Rohr JR. Loss of Trematode Parthenitae inPlanorbella trivolvis(Mollusca: Gastropoda). J Parasitol 2013; 99:738-9. [DOI: 10.1645/12-111.1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Abstract
SUMMARY Temperature is an important factor influencing the biology of ectothermic organisms and is intrinsically linked to climate change. Trematodes are potentially susceptible to temperature changes and in order to develop predictive frameworks of their responses to climate change large-scale analyses are needed. The present study, using the Q 10 value, analyses experimental data from the scientific literature on the effects of temperature on cercarial development and emergence across a wide range of temperature in low (⩽35°) and mid-latitude (36-60°) species. Temperature appears to have no significant effect on the rate of development of cercariae within molluscan hosts. Data on cercarial emergence, corrected to incorporate the minimum emergence temperature threshold (METT) and acclimation status, was found to be largely unaffected by temperature over optimum ranges of ≈20 °C (15-25 °C) for mid-latitude species and ≈25 °C (20-30 °C) for low-latitude species. In addition, a decline in emergence rates was shown at higher temperatures. These results are contrary to a previous study on the meta-analysis of cercarial emergence. Some evidence of strain-specific differences and thermostability over a wide temperature range for both cercarial development and emergence was apparent. The significance of these results in furthering our understanding of cercarial biology under natural conditions is discussed.
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Studer A, Poulin R. Cercarial survival in an intertidal trematode: a multifactorial experiment with temperature, salinity and ultraviolet radiation. Parasitol Res 2012; 112:243-9. [DOI: 10.1007/s00436-012-3131-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 09/18/2012] [Indexed: 11/30/2022]
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Mitchell-Foster K, Ma BO, Warsame-Ali S, Logan C, Rau ME, Lowenberger C. The influence of larval density, food stress, and parasitism on the bionomics of the dengue vector Aedes aegypti (Diptera: Culicidae): implications for integrated vector management. JOURNAL OF VECTOR ECOLOGY : JOURNAL OF THE SOCIETY FOR VECTOR ECOLOGY 2012; 37:221-229. [PMID: 22548557 DOI: 10.1111/j.1948-7134.2012.00220.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
New larval control strategies for integrated vector management of Aedes aegypti are in high demand, including the use of biological control agents. Exposure of Aedes aegypti to parasites, starvation, and overcrowded conditions during larval development reduces the probability of survival to eclosion, can directly affect fitness parameters such as adult size and fecundity, and can affect the size, provisioning, and viability of eggs produced by females. We compared these parameters after exposing larvae to 1) abundant food at low larval densities, 2) food deprivation and high larval density, and 2) infection with the endoparasite Plagiorchis elegans, an entomopathogenic digenean trematode. Female mosquitoes that eclosed from larval conditions of starvation and overcrowding were smaller and laid fewer and smaller eggs than controls. The proportion of females to complete an oviposition cycle was reduced in the P. elegans-infected treatment group. Parasite load was negatively correlated with wing length and egg size. Infection of Ae. aegypti with P. elegans has sublethal effects and may reduce population-level reproductive output, but one-time low-density P. elegans exposure does not have sufficient effect on Ae. aegypti fitness parameters to be considered a viable biocontrol option.
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Affiliation(s)
- K Mitchell-Foster
- Department of Biological Sciences, Simon Fraser University, 8888 University Dr., Burnaby, BC, Canada.
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Daoust SP, Mader BJ, Maure F, McLaughlin JD, Thomas F, Rau ME. Experimental evidence of size/age-biased infection of Biomphalaria glabrata (Pulmonata: Planorbidae) by an incompatible parasite species: consequences for biological control. INFECTION, GENETICS AND EVOLUTION : JOURNAL OF MOLECULAR EPIDEMIOLOGY AND EVOLUTIONARY GENETICS IN INFECTIOUS DISEASES 2010; 10:1008-1012. [PMID: 20601177 DOI: 10.1016/j.meegid.2010.06.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2010] [Revised: 06/09/2010] [Accepted: 06/15/2010] [Indexed: 05/29/2023]
Abstract
Because the digenetic trematode Plagiorchis elegans can elicit a rapid, severe and permanent suppression of the reproductive output in the snail Biomphalaria glabrata, it is considered as a potential biological control agent of human schistosomiasis. This assumption however is derived from laboratory experiments that are poor approximations of what occurs in a natural ecosystem. In order to recreate conditions that resemble those found in nature, we exposed B. glabrata as individual populations composed of a young, juvenile and adult snails to various concentrations of P. elegans eggs to assess the probability of encountering the parasite eggs by the different snail sizes/age groups. We demonstrated that within populations composed of different size/age classes, larger/older snails displayed the negative effects typical of exposure to P. elegans, whereas smaller individuals appeared relatively unaffected, particularly at lower levels of exposure. These findings coupled with the difficulty of producing large quantities of parasite eggs suggest that P. elegans has limited efficiency as a biological control agent of human schistosomiasis.
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Affiliation(s)
- Simon P Daoust
- Department of Natural Resource Sciences, McGill University (Macdonald Campus), 21111 Lakeshore Road, Ste-Anne-de-Bellevue, QC, Canada, H9X 3V9.
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Parasite communities of a fish assemblage from the intertidal rocky zone of central Chile: similarity and host specificity between temporal and resident fish. Parasitology 2009; 136:1291-303. [PMID: 19646306 DOI: 10.1017/s0031182009990758] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The different species of a fish assemblage can, to some extent, be similar in terms of their parasite communities, which can be associated with certain ecological host traits. This study compared the parasite community descriptors between temporal and resident fish species composing an intertidal assemblage from central Chile. Host specificity and similarity indices of parasite communities among the fish species were also considered. A total of 1097 fish representing 14 species were collected during spring and summer of 2 consecutive years. A total spectrum of 40 parasite species was found, of which copepods and trematodes were the commonest. Congeneric fish species had the highest similarities in their parasite communities. Based on a cluster analysis, using only some fish species, no group was distinguished using abundance or prevalence of parasites, because 50% of parasite species had high host specificity and only few of them were shared among fish species. Adult parasites showed high host specificity and were found mainly in resident intertidal fish, whereas the temporal fish had parasites with different degrees of specificity. Consequently, resident intertidal fish were characterized by their own parasite species, meaning that their transmissions might be restricted to the intertidal zone.
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Abstract
AbstractThe tail chamber's role in the survival and infectivity of Proterometra macrostoma (Digenea: Azygiidae) was investigated. Intact cercariae and cercarial bodies dissected from tails were incubated for 14 h in artificial pond water (APW) and cercarial infectivity was assessed in laboratory infections of the bluegill sunfish, Lepomis macrochirus. Although most cercariae stopped swimming and settled to the bottom after 14 h, survival and infectivity of bodies from intact cercariae did not decrease significantly during this period. All isolated bodies survived in APW, but they were 54% less infective. By contrast, infectivity of isolated bodies did not decrease significantly in an artificial snail saline. The results indicate that maximum infectivity in P. macrostoma is sustained throughout the swimming phase because of the tail chamber which protects the body from the effects of osmotic stress.
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Effect of temperature on survival and infectivity of Echinostoma trivolvis cercariae: a test of the energy limitation hypothesis. Parasitology 2009. [DOI: 10.1017/s0031182000081920] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
SUMMARYTrematode cercariae typically become unable to successfully infect a host many hours before they die. We examined the hypothesis that both time to 50% mortality and time to loss of infective capacity are controlled to the same degree by rates of energy expenditure, by determining the relative effects of temperature on both parameters. Infective capacity was assessed by exposing Echinostoma trivolvis cercariae of different ages to a suitable second intermediate host (the gastropod Biomphalaria glabrata) and counting 1–2 days later the number of metacercarial cysts formed. Temperature had a remarkably similar effect on time to 50% mortality and loss of infective capacity, supporting the hypothesis that both absolute and functional cercarial life-spans are limited by the rates at which energy stores are utilized.
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Phototactic responses of the cercaria of Echinoparyphium recurvatum during phases of sub-maximal and maximal infectivity. J Helminthol 2007. [DOI: 10.1017/s0022149x99000086] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Phototactic responses of cercariae of the echinostome Echinoparyphium recurvatum (Digenea: Echinostomatidae) were investigated during phases of sub-maximal and maximal infectivity using a simple light/dark choice chamber. The phototactic responses of a total of 400 cercariae were examined in 20 replicate experiments during their sub-maxinal infectivity dispersal phase (0.5 h post-emergence from the first intermediate host Lymnaea peregra) and during their maximal infectivity phase (2.5 h post-emergence). Cercariae in the sub-maximal infectivity dispersal phase were found to be positively phototactic, significantly larger numbers of them occurring on the light side of a light/dark choice chamber P < 0.001. Cercariae in the maximal infectivity phase were found to be negatively phototactic, significantly larger numbers of them being found on the dark side of the choice chamber, P < 0.001. This report of ‘phototactic switching’ demonstrated by the cercariae of E. recurvatum from a positively phototactic dispersal phase to a negatively phototactic infection phase constitutes the first record of such behaviour in the cercaria of an echinostome.
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Survival and infectivity of Hypoderaeum conoideum and Euparyphium albuferensis cercariae under laboratory conditions. J Helminthol 2007. [DOI: 10.1017/s0022149x9900027x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The survival characteristics of the cercariae of Hypoderaeumconoideum and Euparyphiumalbuferensis (Trematoda: Echinostomatidae) at 20°C and 30°C are described, and the age dependency of their infectivity at 20°C is studied to determine their respective transmission efficiencies. Cercarial survival was found to be age-dependent and was higher at 20°C. For both cercariae, the maximum life-span was 26 h at 20°C and 16 h at 30°C, and their respective times to 50% mortality were similar at each temperature. Both cercariae seem to be well adapted to transmission in their natural habitat, though cercarial infectivity of H. conoideum was higher than that of E. albuferensis, this being correlated with their prevalences in nature. The age-dependency of cercarial survival may be related to steadily diminishing endogenous energy levels, though the delay in attaining maximum infectivity suggests that other factors not related to energy considerations are involved in the delimitation of the cercarial infective period. However, this latter observation may constitute an adaptative mechanism allowing cercarial dissemination.
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Poulin R. Global warming and temperature-mediated increases in cercarial emergence in trematode parasites. Parasitology 2005; 132:143-51. [PMID: 16393363 DOI: 10.1017/s0031182005008693] [Citation(s) in RCA: 215] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2005] [Revised: 06/28/2005] [Accepted: 06/28/2005] [Indexed: 11/06/2022]
Abstract
Global warming can affect the world's biota and the functioning of ecosystems in many indirect ways. Recent evidence indicates that climate change can alter the geographical distribution of parasitic diseases, with potentially drastic consequences for their hosts. It is also possible that warmer conditions could promote the transmission of parasites and raise their local abundance. Here I have compiled experimental data on the effect of temperature on the emergence of infective stages (cercariae) of trematode parasites from their snail intermediate hosts. Temperature-mediated changes in cercarial output varied widely among trematode species, from small reductions to 200-fold increases in response to a 10 °C rise in temperature, with a geometric mean suggesting an almost 8-fold increase. Overall, the observed temperature-mediated increases in cercarial output are much more substantial than those expected from basic physiological processes, for which 2- to 3-fold increases are normally seen. Some of the most extreme increases in cercarial output may be artefacts of the methods used in the original studies; however, exclusion of these extreme values has little impact on the preceding conclusion. Across both species values and phylogenetically independent contrasts, neither the magnitude of the initial cercarial output nor the shell size of the snail host correlated with the relative increase in cercarial production mediated by rising temperature. In contrast, the latitude from which the snail-trematode association originated correlated negatively with temperature-mediated increases in cercarial production: within the 20 ° to 55 ° latitude range, trematodes from lower latitudes showed more pronounced temperature-driven increases in cercarial output than those from higher latitudes. These results suggest that the small increases in air and water temperature forecast by many climate models will not only influence the geographical distribution of some diseases, but may also promote the proliferation of their infective stages in many ecosystems.
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Affiliation(s)
- R Poulin
- Department of Zoology, University of Otago, P.O. Box 56, Dunedin, New Zealand.
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Zbikowska E. Do larvae of Trichobilharzia szidati and Echinostoma revolutum generate behavioral fever in Lymnaea stagnalis individuals? Parasitol Res 2005; 97:68-72. [PMID: 15952039 DOI: 10.1007/s00436-005-1394-7] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2005] [Accepted: 04/26/2005] [Indexed: 10/25/2022]
Abstract
The objective of this study was to determine whether individuals of Lymnaea stagnalis naturally parasitized with Trichobilharzia szidati and Echinostoma revolutum can generate the behavioral fever against larvae of those parasites. Thermal preferences of each snail were examined in an oblong thermal gradient during 48 h observation. Uninfected animals under study chose higher temperatures than those releasing cercariae of parasites. Infected snails kept in constant temperature lived shorter than uninfected ones. At high temperature, they released more cercariae per day than at low temperature. Temperature had a great influence on the longevity of emerged cercariae. The thermal behavior of infected snails is not a symptom of behavioral fever but probably can play a therapeutic role in the host.
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Affiliation(s)
- Elzbieta Zbikowska
- Department of Invertebrate Zoology, Institute of General and Molecular Biology, Nicholas Copernicus University, Gagarina 9, 87-100 Toruń, Poland.
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Mouritsen KN. The Hydrobia ulvae-Maritrema subdolum association: influence of temperature, salinity, light, water-pressure and secondary host exudates on cercarial emergence and longevity. J Helminthol 2002; 76:341-7. [PMID: 12498640 DOI: 10.1079/joh2002136] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The effects of environmental factors and exudates from the amphipod Corophium volutator on the emergence of Maritrema subdolum cercariae (Digenea: Microphallidae) from the snail Hydrobia ulvae were investigated in the laboratory. Increasing the temperature (15 to 25 degrees C) caused an overall 11-fold increase in emergence rate under varying salinities (24 to 36 per thousand). The effect of salinity depended on the experimental temperature. Emergence increased with increasing salinity at higher temperatures, but decreased with increasing salinity at 15 degrees C. Whereas the different levels of salinity had no effect, increasing the temperature significantly reduced the life span of cercariae. In comparison with complete darkness, light caused a two-fold increase in emergence, whereas an increment of the water pressure from 1.0 to 1.3 ATM (corresponding to 0 and 3 m of depth) left the shedding rate unaffected. Unidentified exudates from the second intermediate host, C. volutator, significantly depressed the cercarial emergence rate. The main transmission window of M. subdolum seems to occur during low water in tidal pools where light levels are high and solar radiation rapidly elevates the water temperature, as well as salinity through evaporation. The consequence of such a transmission strategy is discussed in relation to the impact of M. subdolum on the population dynamics of the second intermediate host.
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Affiliation(s)
- K N Mouritsen
- Department of Marine Ecology, Institute of Biological Sciences, University of Aarhus, Finlandsgade 14, 8200 Aarhus N, Denmark.
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Miller AA, Poulin R. Parasitism, movement, and distribution of the snail Diloma subrostrata (Trochidae) in a soft-sediment intertidal zone. CAN J ZOOL 2001. [DOI: 10.1139/z01-167] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Despite reports of their effects on host reproduction, growth, survival, and habitat use, the role of parasites in determining community structure is still poorly understood. Trematode infections in snails are a ubiquitous feature of intertidal systems worldwide. In this study, the influence of a trematode parasite on the movement and dispersal of the trochid snail Diloma subrostrata on a soft-sediment shore is examined using markrecapture experiments. The natural densities and shell widths of the snail peak between the upper and lower portions of the intertidal zone; marked snails were released within this area. Parasitized snails tended to have larger shells than nonparasitized conspecifics, and larger snails tended to move a greater linear distance than smaller snails in the 24 h following their marking and release. After shell width was corrected for, parasitized snails were found to move a significantly shorter distance than nonparasitized snails. In addition, the mean direction chosen by parasitized snails was almost parallel to the water's edge, whereas that taken by nonparasitized snails was almost directly toward the upper portion of the intertidal zone. Although the mean directions taken by the two types of snails were statistically different, the considerable scatter in the distributions of directions taken by individual snails casts a doubt over the biological significance of the result. Without detailed knowledge of the parasite's full life cycle it is difficult to determine whether this small bias in the direction of dispersal is an adaptive manipulation of snail behaviour by the parasitic trematode. Nevertheless, these results show that the trematode limits the range of movement, and possibly the direction of movement, of parasitized D. subrostrata, and can therefore contribute to the spatial structuring of the snail population.
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Wallage HR, Niven DF, Rau ME. Effects of Plagiorchis elegans (Trematoda: Plagiorchiidae) infection on the carbohydrate metabolism of fourth instar Aedes aegypti (Diptera: Culicidae). JOURNAL OF MEDICAL ENTOMOLOGY 2001; 38:312-317. [PMID: 11296841 DOI: 10.1603/0022-2585-38.2.312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Infection of fourth-instar Aedes aegypti (L.) with the entomopathogenic digenean Plagiorchis elegans (Rudolphi) alters the carbohydrate metabolism of the insect. Within 24 h of cercarial penetration, total body extracts of infected fourth instars exhibited decreased trehalase activity, increased trehalose-6-phosphatase activity, and a concomitant accumulation of trehalose when compared with uninfected larvae. The amounts of glucose, glycogen and lipids, and the activity of glycogen phosphorylase a were similar in extracts of infected and control larvae. The predominant fatty acids, in both control and infected larvae, were C 18:0, C 18:1, and C 18:3. There were no significant differences in the types or proportions of fatty acids found in control and infected larvae. Parasitic infection is discussed in terms of impaired trehalose metabolism.
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Affiliation(s)
- H R Wallage
- Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, QC, Canada
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Ferrell DL, Negovetich NJ, Wetzel EJ. Effect of temperature on the infectivity of metacercariae of Zygocotyle lunata (Digenea: Paramphistomidae). J Parasitol 2001; 87:10-3. [PMID: 11227871 DOI: 10.1645/0022-3395(2001)087[0010:eototi]2.0.co;2] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
As a test of the energy limitation hypothesis (ELH), we predicted that temperature would have a significant influence on the infectivity of metacercariae of the digenetic trematode Zygocotyle lunata. Snails infected with Z. lunata were collected from ponds near Crawfordsville, Indiana, isolated at room temperature, and examined for the release of cercariae. Newly encysted metacercariae were collected and incubated 1-30 days at 1 of 5 temperatures (0, 3, 25, 31, 37 C). Twenty-five cysts were fed to each of 5 or 10 mice per treatment group (temperature). At 17 days postinfection, mice were killed and worms were recovered; data were collected on levels of infection in each group and the total body area of each worm. No worms were found in mice fed cysts that had been held at 0 C or 37 C (after 30 days). There were no differences in prevalence, infectivity, or mean intensity among the 3, 25, and 31 C treatments. Infectivity of metacercariae incubated at 37 C for 1 day was significantly greater than in all other treatments, while infectivity of metacercariae in the 37 C/15-day treatment was significantly lower than in all others. Mean body area of worms at 37 C/15 days was significantly greater than at other temperatures, suggesting density-dependent increases in growth. These results, particularly those from the 37 C treatments, are consistent with the ELH; infectivity was lower at high temperatures or when incubated for more time at 1 temperature (fewer energy reserves). It is suggested that microhabitat conditions experienced by metacercariae of Z. lunata could contribute to longer larval life, thus influencing this parasite's temporal dispersal.
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Affiliation(s)
- D L Ferrell
- Department of Biology, Wabash College, Crawfordsville, Indiana 47933, USA
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Abstract
New scientific paradigms often generate an early wave of enthusiasm among researchers and a barrage of studies seeking to validate or refute the newly proposed idea. All else being equal, the strength and direction of the empirical evidence being published should not change over time, allowing one to assess the generality of the paradigm based on the gradual accumulation of evidence. Here, I examine the relationship between the magnitude of published quantitative estimates of parasite-induced changes in host behaviour and year of publication from the time the adaptive host manipulation hypothesis was first proposed. Two independent data sets were used, both originally gathered for other purposes. First, across 137 comparisons between the behaviour of infected and uninfected hosts, the estimated relative influence of parasites correlated negatively with year of publication. This effect was contingent upon the transmission mode of the parasites studied. The negative relationship was very strong among studies of parasites which benefit from host manipulation (transmission to the next host occurs by predation on an infected intermediate host), i.e. among studies which were explicit tests of the adaptive manipulation hypothesis. There was no correlation with year of publication among studies on other types of parasites which do not seem to receive benefits from host manipulation. Second, among 14 estimates of the relative, parasite-mediated increase in transmission rate (i.e. increases in predation rates by definitive hosts on intermediate hosts), the estimated influence of parasites again correlated negatively with year of publication. These results have several possible explanations, but tend to suggest biases with regard to what results are published through time as accepted paradigms changed.
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Affiliation(s)
- R Poulin
- Department of Zoology, University of Otago, Dunedin, New Zealand.
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Abstract
The diversity of ways in which parasites can modify the host genotypic signal has been documented in recent years. For example, parasites can shift the mean value and increase the variance of phenotypic traits in host populations, or alter the phenotypic sex ratio of host populations, with several evolutionary implications. Here, Robert Poulin and Frederic Thomas review the types of host traits that are modified by parasites, then explore some of the evolutionary consequences of parasite-induced alterations in host phenotypes and suggest some avenues for future research.
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Affiliation(s)
- R Poulin
- Department of Zoology, University of Otago, PO Box 56, Dunedin, New Zealand.
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Abstract
Changes in host behaviour following infection with parasites are frequently reported in the literature, and are often hypothesized to be adaptive for either host or parasite. However, investigators of such phenomena often use the "adaptation" label for host behavioural changes based on their intuition and not on rigorous criteria. Alterations in host behaviour following infection can only be considered adaptive if they satisfy certain conditions: (1) they must be complex; (2) they must show signs of a purposive design; (3) they are more likely to be adaptations if they have arisen independently in several lineages of hosts or parasites; and (4) they must be shown to increase the fitness of either the host or the parasite. A survey of published examples of host behavioural changes indicates that while some are spectacularly complex and are extremely well-fitted to their presumed function, most are simple increases or decreases in an activity performed prior to infection. There are some suggestions of convergent evolution in behavioural change in distantly related host or parasite groups but more evidence is needed. Finally, most known behavioural changes have not been demonstrated to lead to fitness gains in either hosts or parasites. Few known examples satisfy more than two of the above criteria, and, in general, the adaptive function of changes in host behaviour following infection is in need of more solid proof.
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Affiliation(s)
- R Poulin
- Department of Zoology, University of Otago, Dunedin, New Zealand. robert
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