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Functional and sex-specific dynamics of ectoparasite size evolution in marine isopod-fish interactions: Harrison's rule and increasing variance. Oecologia 2023; 201:213-225. [PMID: 36522603 DOI: 10.1007/s00442-022-05302-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022]
Abstract
Harrison's rule, a pattern predicting that the body size of parasites correlates positively with the size of their hosts, is well-supported. However, its interaction with highly distinct "guilds" of closely related parasites warrants further exploration. The increasing variance hypothesis predicts that the variance in parasite size should also increase with the size of their hosts. Though untested, in parasite taxa with differential sex-dependent pressures on body size, this relationship should also be divergent across sexes due to differential size-fecundity relationships. We compiled global data on sequentially hermaphroditic isopods (Isopoda: Cymothoidae) parasitic on fish from published literature. With a data set comprising of 204 marine cymothoid species and their hosts, we used Bayesian hierarchical models to primarily test (1) Harrison's rule and its scaling across three functionally distinct guilds (mouth, gill, external); (2) the increasing variance hypothesis and sex-specific patterns. Our results revealed a strong positive association between parasite and host body sizes, but with uniform scaling across guilds. Host size exerted divergent, sex-specific effects on the relative intraspecific variation in parasite size, where this association was positive in males and absent in females. Here, we show that Harrison's rule is independent of guild, suggesting body size evolution across all cymothoids is equally underpinned by the size of their hosts. The sex-specificity of the increasing variance hypothesis can be explained by female fecundity being tightly bound to body size, whereas the dependency of reproductive success on size is inherently more relaxed in males.
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2
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De Vivo M, Huang J. Modeling the geographical distributions of
Chordodes formosanus
and its mantis hosts in Taiwan, with considerations for their niche overlaps. Ecol Evol 2022; 12:e9546. [PMCID: PMC9702995 DOI: 10.1002/ece3.9546] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Revised: 10/28/2022] [Accepted: 11/08/2022] [Indexed: 11/29/2022] Open
Affiliation(s)
- Mattia De Vivo
- Biodiversity Research Center Academia Sinica Taipei Taiwan
- Department of Life Science National Taiwan Normal University Taipei Taiwan
- Biodiversity Program, Taiwan International Graduate Program Academia Sinica and National Taiwan Normal University Taipei Taiwan
| | - Jen‐Pan Huang
- Biodiversity Research Center Academia Sinica Taipei Taiwan
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3
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Poulin R, Presswell B. Is parasite taxonomy really in trouble? A quantitative analysis. Int J Parasitol 2022; 52:469-474. [DOI: 10.1016/j.ijpara.2022.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2022] [Revised: 03/14/2022] [Accepted: 03/16/2022] [Indexed: 11/25/2022]
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4
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Doherty JF, Poulin R. The return to land: association between hairworm infection and aquatic insect development. Parasitol Res 2022; 121:667-673. [PMID: 35067741 DOI: 10.1007/s00436-021-07410-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Accepted: 12/14/2021] [Indexed: 11/30/2022]
Abstract
Host manipulation by parasites can shape host behaviour, community structure, and the flow of energy through food webs. A well-known example of host manipulation comes from hairworms (phylum Nematomorpha), which somehow cause their terrestrial insect definitive hosts to enter water, a phenomenon that has received lots of attention in recent years. However, little focus has been directed towards the interactions between hairworms and their aquatic insect hosts and the return of dormant hairworms from water to land. Here, we ask whether hairworm cyst infections impact, either directly or indirectly, the life history of their aquatic transport hosts. By observing the development of last-instar Olinga jeanae (Trichoptera: Conoesucidae) caddisfly larvae naturally infected with Gordius-type hairworm cysts under controlled conditions, we found that higher numbers of cysts per infected caddisfly correlated with a decrease in time to pupation. These new observations suggest that, apart from the striking host manipulation that brings the parasite from land to water, the presence of dormant hairworms is associated with changes in the development of their aquatic hosts, either through direct or indirect mechanisms, which may accelerate their transition from water to land.
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Affiliation(s)
| | - Robert Poulin
- Department of Zoology, University of Otago, Dunedin, New Zealand
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5
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Anaya C, Bolek MG. Is there life after parasitism? Survival, longevity, and oogenesis in Acheta domesticus (Orthoptera: Gryllidae) infected with the hairworm, Paragordius varius (Phylum: Nematomorpha). Parasitol Res 2021; 120:2333-2342. [PMID: 33956214 DOI: 10.1007/s00436-021-07173-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2020] [Accepted: 04/26/2021] [Indexed: 11/30/2022]
Abstract
The costs parasites impose on hosts can lead to reductions in survival and fecundity, but few studies have evaluated the impacts after infection. Hairworms are parasites of terrestrial arthropods that are free-living in aquatic systems as adults. As parasitic juveniles, hairworms acquire nutrients from their definitive hosts, shifting resources away from host development to parasite growth. However, until now, only one study has examined survivorship of naturally infected hosts with hairworms. Using a different hairworm and host system, we conducted experimental infections to examine growth, survivorship, and egg production in virgin female Acheta domesticus infected with the hairworm, Paragordius varius. We found that infected crickets grew significantly less during hairworm development compared to sham-infected control crickets. After releasing their worms, infected crickets survived for 73 ± 32 days but had significantly shorter life spans by an average of 13 days compared to sham-infected control crickets. However, we found that 50% of previously infected crickets produced eggs after releasing their worms. Taken together, these observations suggest that female crickets infected with hairworms may experience less mortality than previous anecdotal evidence suggests. Finally, we discuss the definition of parasitoid and how it relates to nematomorphs, and we suggest that more field and laboratory research is required before suggesting hairworms are parasitoids.
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Affiliation(s)
- Christina Anaya
- Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078, USA. .,School of Biological Sciences, University of Nebraska Lincoln, Lincoln, NE, 68588, USA.
| | - Matthew G Bolek
- Department of Integrative Biology, Oklahoma State University, 501 Life Sciences West, Stillwater, OK, 74078, USA
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6
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Chiu MC, Huang CG, Wu WJ, Lin ZH, Chen HW, Shiao SF. A new millipede-parasitizing horsehair worm, Gordius chiashanus sp. nov., at medium altitudes in Taiwan (Nematomorpha, Gordiida). Zookeys 2020; 941:25-48. [PMID: 32595406 PMCID: PMC7311483 DOI: 10.3897/zookeys.941.49100] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 04/08/2020] [Indexed: 11/24/2022] Open
Abstract
Gordius chiashanus sp. nov., a newly described horsehair worm that parasitizes the Spirobolus millipede, is one of the three described horsehair worm species in Taiwan. It is morphologically similar to G. helveticus Schmidt-Rhaesa, 2010 because of the progressively broadening distribution of bristles concentrated on the male tail lobes, but it is distinguishable from G. helveticus because of the stout bristles on the mid-body. In addition, a vertical white stripe on the anterior ventral side and areoles on the inside wall of the cloacal opening are rarely mentioned in other Gordius species. Free-living adults emerged and mated on wet soil under the forest canopy in the winter (late November to early February) at medium altitudes (1100-1700 m). Mucus-like structure covering on the body surface, which creates a rainbow-like reflection, might endow the worm with high tolerance to dehydration. Although Gordius chiashanus sp. nov. seems to be more adaptive to the terrestrial environment than other horsehair worm species, cysts putatively identified as belonging to this hairworm species found in the aquatic paratenic host, Ephemera orientalis McLachlan, 1875, suggest the life cycle of Gordius chiashanus sp. nov. could involve water and land. The free-living adults emerged from the definitive hosts might reproduce in the terrestrial environment or enter an aquatic habitat by moving or being washed away by heavy rain instead of manipulating the behavior of their terrestrial definitive hosts.
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Affiliation(s)
- Ming-Chung Chiu
- Department of Biology, Kobe University, Kobe 657-8501, JapanKobe UniversityKobeJapan
- Current address: Department of Biology, National Changhua University of Education, Changhua City 55007, TaiwanNational Changhua University of EducationChanghuaTaiwan
| | - Chin-Gi Huang
- National Mosquito-Borne Diseases Control Research Center, National Health Research Institutes, Tainan City 704, TaiwanNational Health Research InstitutesTainanTaiwan
- Department of Earth and Life Science, University of Taipei, Taipei 100, TaiwanUniversity of TaipeiTaipeiTaiwan
| | - Wen-Jer Wu
- Department of Entomology, National Taiwan University, Taipei 106, TaiwanNational Taiwan UniversityTaipeiTaiwan
| | - Zhao-Hui Lin
- Department of Biological Resources, National Chiayi University, Chiayi 300, TaiwanNational Chiayi UniversityChiayiTaiwan
| | - Hsuan-Wien Chen
- Department of Biological Resources, National Chiayi University, Chiayi 300, TaiwanNational Chiayi UniversityChiayiTaiwan
| | - Shiuh-Feng Shiao
- Department of Entomology, National Taiwan University, Taipei 106, TaiwanNational Taiwan UniversityTaipeiTaiwan
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7
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Seoane-Scheitermaier E, Dang S, Barry M, Shea JF. Observations on the Occurrence of Knotting Behavior in the Horsehair Worm, Paragordius varius. COMP PARASITOL 2019. [DOI: 10.1654/1525-2647-87.1.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Erik Seoane-Scheitermaier
- Department of Biology, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, U.S.A. (e-mail: )
| | - Sydney Dang
- Department of Biology, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, U.S.A. (e-mail: )
| | - Michael Barry
- Department of Biology, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, U.S.A. (e-mail: )
| | - John F. Shea
- Department of Biology, Creighton University, 2500 California Plaza, Omaha, Nebraska 68178, U.S.A. (e-mail: )
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8
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Aznar FJ, Hernández-Orts JS, Vélez-Rubio G, Fernández LM, Muriel NT, Raga JA. Reproductive inequalities in the acanthocephalan Corynosoma cetaceum: looking beyond 'crowding' effects. Parasit Vectors 2018; 11:203. [PMID: 29562941 PMCID: PMC5863374 DOI: 10.1186/s13071-018-2723-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/15/2018] [Indexed: 11/26/2022] Open
Abstract
Background At present, much research effort has been devoted to investigate overall (“average”) responses of parasite populations to specific factors, e.g. density-dependence in fecundity or mortality. However, studies on parasite populations usually pay little attention to individual variation (“inequality”) in reproductive success. A previous study on the acanthocephalan Corynosoma cetaceum in franciscana dolphins, Pontoporia blainvillei, revealed no overall intensity-dependent, or microhabitat effects, on mass and fecundity of worms. In this study, we investigated whether the same factors could influence mass inequalities for this species of acanthocephalan. Methods A total of 10,138 specimens of C. cetaceum were collected from 10 franciscanas accidentally caught in Buenos Aires Province between 1988 and 1990. To investigate mass inequalities, all the specimens were sexed, and females were classified according to their developmental stage and weighed. Additionally, the relationship between biomass and fecundity (estimated as the number of acanthors) was investigated for some females. Inequalities in fecundity and biomass were assessed using standard methods, i.e. the Lorenz curve and the Gini coefficient (G). Results We found a modest, but highly significant linear relationship between mass and fecundity. The G was very low (0.314) compared with that from other helminth species. G values were significantly lower in gravid females, which presumably exhibit a slow rate of growth. Also, G values significantly increased with total intensity, but only for gravid females, and the effect was more predictable considering only the intensity of gravid females. Conclusions Apparently, high intensity infections increase inequality of reproducing females without producing “crowding” effects. Although several processes could generate this pattern, gravid females, at higher intensities, expanded their distribution and occupied gut chambers with contrasting environmental conditions, which might result in greater variability in body size. The observed inequalities are not expected to strongly influence the population genetics of C. cetaceum, but they reveal subtle individual effects beyond an overall population impact. Electronic supplementary material The online version of this article (10.1186/s13071-018-2723-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Francisco Javier Aznar
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Parque Científico, Universidad de Valencia, Paterna, Valencia, España.
| | - Jesús Servando Hernández-Orts
- Centro de Investigación Aplicada y Transferencia Tecnológica en Recursos Marinos Almirante Storni (CIMAS - CCT CONICET - CENPAT), San Antonio Oeste, Río Negro, Argentina
| | - Gabriela Vélez-Rubio
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Parque Científico, Universidad de Valencia, Paterna, Valencia, España.,Karumbe NGO, Av. Rivera 3245, CP 11400, Montevideo, Uruguay.,Centro Universitario Regional del Este (CURE), Universidad de la República, Sede Rocha, Intersección Ruta 9 y Ruta 15, Rocha, Uruguay
| | - Luis M Fernández
- Ceiba Foundation for Tropical Conservation, 301 S. Bedford Street, Suite 7A, Madison, WI, 53703, USA
| | - Nadia T Muriel
- Padre Lozano 329, Barrio Alto Alberdi, Córdoba, Argentina
| | - Juan Antonio Raga
- Instituto Cavanilles de Biodiversidad y Biología Evolutiva, Parque Científico, Universidad de Valencia, Paterna, Valencia, España
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9
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Strona G. Why do nematomorphs leave their hosts? INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2017; 6:226-228. [PMID: 28831378 PMCID: PMC5554920 DOI: 10.1016/j.ijppaw.2017.07.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 07/17/2017] [Accepted: 07/19/2017] [Indexed: 11/25/2022]
Abstract
Nematomorphs induce their arthropod host to jump into water. The drowning host is often eaten by aquatic predators. This creates an opportunity for nematomorphs to increase life-cycle complexity. I speculate on why nematomorphs have always dropped this opportunity.
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Affiliation(s)
- Giovanni Strona
- European Commission, Joint Research Centre, Directorate D - Sustainable Resources, Via Enrico Fermi 2749, 21027 Ispra, Italy
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10
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Chiu MC, Huang CG, Wu WJ, Shiao SF. A new orthopteran-parasitizing horsehair worm, Acutogordius taiwanensis sp. n., with a redescription of Chordodes formosanus and novel host records from Taiwan (Nematomorpha, Gordiida). Zookeys 2017; 683:1-23. [PMID: 28824281 PMCID: PMC5523353 DOI: 10.3897/zookeys.683.12673] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/19/2017] [Indexed: 11/20/2022] Open
Abstract
A description of a new species of horsehair worm, Acutogordius taiwanensissp. n., a redescription of Chordodes formosanus, and novel host records for the latter are provided. Acutogordius taiwanensissp. n. is morphologically similar to A. protectus with moderately flat areoles on its tail tips, but is distinguishable by small mid-body ornamentations. Despite the distinct differences in the post-cloacal crescents between 14 male samples, their conspecific status, along with that of nine female samples, was upheld by a phylogenetic comparison of partial cytochrome oxidase subunit I (COI) sequences. Chordodes formosanus is another common horsehair worm species in Taiwan, which was previously believed to specifically parasitize Hierodula mantids. However, in this study, five C. formosanus were observed emerging from an Acromantis mantid, and two long-horned grasshopper hosts (Leptoteratura sp. and Holochlora japonica). These five worms showed high degrees of similarity in COI sequences and morphology, but one of these individuals bore abnormal crowned areoles, which has never been observed in C. formosanus, and may be attributed to the incomplete development of this particular individual.
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Affiliation(s)
- Ming-Chung Chiu
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
| | - Chin-Gi Huang
- Department of Earth and Life Science, University of Taipei, Taipei 100, Taiwan
| | - Wen-Jer Wu
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
| | - Shiuh-Feng Shiao
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
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11
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Maure F, Poulin R. Inequalities in body size among mermithid nematodes parasitizing earwigs. Parasitol Res 2016; 115:4471-4475. [PMID: 27545022 DOI: 10.1007/s00436-016-5233-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Accepted: 08/12/2016] [Indexed: 11/29/2022]
Abstract
Variation among body sizes of adult parasitic worms determines the relative genetic contribution of individuals to the next generation as it affects the effective parasite population size. Here, we investigate inequalities in body size and how they are affected by intensity of infection in Mermis nigrescens (Mermithidae: Nematoda) parasitizing the European earwig Forficula auricularia in New Zealand. Among a population of pre-adult worms prior to their emergence from the host, we observed only modest inequalities in body length; however, among worms sharing the same individual host, inequalities in body sizes decreased with increasing intensity of infection. Thus, the more worms occurred in a host, the more the second-longest, third-longest and even fourth-longest worms approached the longest worm in body length. This pattern, also known from another mermithid species, suggests that worms sharing the same host may have infected it roughly simultaneously, when the host encountered a clump of eggs in the environment. Thus, the life history and mode of infection of the parasite may explain the modest inequalities in the sizes achieved by pre-adult worms, which are lower than those reported for endoparasitic helminths of vertebrates.
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Affiliation(s)
- Fanny Maure
- Department of Zoology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand
| | - Robert Poulin
- Department of Zoology, University of Otago, PO Box 56, Dunedin, 9054, New Zealand.
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12
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Chiu MC, Huang CG, Wu WJ, Shiao SF. Annual Survey of Horsehair Worm Cysts in Northern Taiwan, with Notes on a Single Seasonal Infection Peak in Chironomid Larvae (Diptera: Chironomidae). J Parasitol 2016; 102:319-26. [PMID: 26885875 DOI: 10.1645/15-907] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The life cycle of the freshwater horsehair worm typically includes a free-living phase (adult, egg, larva) and a multiple-host parasitic phase (aquatic paratenic host, terrestrial definitive host). Such a life cycle involving water and land can improve energy flow in riparian ecosystems; however, its temporal dynamics in nature have rarely been investigated. This study examined seasonal infection with cysts in larval Chironominae (Diptera: Chironomidae) in northern Taiwan. In the larval chironomids, cysts of 3 horsehair worm species were identified. The cysts of the dominant species were morphologically similar to those of Chordodes formosanus. Infection with these cysts increased suddenly and peaked 2 mo after the reproductive season of the adult horsehair worms. Although adult C. formosanus emerged several times in a year, only 1 distinct infection peak was detected in September in the chironomid larvae. Compared with the subfamily Chironominae, samples from the subfamilies Tanypodinae and Orthocladiinae were less parasitized. This indicates that the feeding behavior of the chironomid host likely affects horsehair worm cyst infections; however, bioconcentration in predatory chironomids was not detected.
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Affiliation(s)
- Ming-Chung Chiu
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
| | - Chin-Gi Huang
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
| | - Wen-Jer Wu
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
| | - Shiuh-Feng Shiao
- Department of Entomology, National Taiwan University, Taipei 106, Taiwan
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13
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Bolek MG, Rogers E, Szmygiel C, Shannon RP, Doerfert-Schrader WE, Schmidt-Rhaesa A, Hanelt B. Survival of larval and cyst stages of gordiids (Nematomorpha) after exposure to freezing. J Parasitol 2012; 99:397-402. [PMID: 23252693 DOI: 10.1645/12-62.1] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
Hairworms infect terrestrial arthropods and are 1 of the most understudied groups of parasites. Recently, life cycles of 2 gordiids (Paragordius varius and Paragordius obamai) have been domesticated in the laboratory. We tested the viability of laboratory reared and post-frozen larval and cyst stages of the North American gordiid, P. varius , frozen at -80 C for 7 mo, and the viability of field collected and post-frozen cysts of the African (P. obamai) and North American ( P. varius ) gordiid frozen at -20 C for 2 mo. All snails exposed to post-frozen or control P. varius larvae became infected with cysts, and there was no significant difference in prevalence or mean intensity of cysts among control or experimental snail groups. As with larvae, no significant differences were observed in prevalence or mean intensity of emerging worms from crickets infected with post-frozen or control P. obamai or P. varius cysts. All female P. obamai and P. varius worms from control and post-frozen cyst infections laid eggs and larvae hatched from some of these eggs. Survival and cyst formation of P. varius larvae exposed to different combinations of drying and/or freezing temperatures indicated that gordiid larvae have the ability to survive drying and freezing, but survival significantly increases during freezing at lower temperatures. The major contribution of our study is the demonstration that gordiid larval and cyst stages can survive freezing temperatures to infect and develop in the next host.
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Affiliation(s)
- Matthew G Bolek
- Department of Zoology, Oklahoma State University, Stillwater, Oklahoma 74078, USA
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14
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Hanelt B, Bolek MG, Schmidt-Rhaesa A. Going solo: discovery of the first parthenogenetic gordiid (Nematomorpha: Gordiida). PLoS One 2012; 7:e34472. [PMID: 22529916 PMCID: PMC3329510 DOI: 10.1371/journal.pone.0034472] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 03/02/2012] [Indexed: 11/18/2022] Open
Abstract
Despite the severe fitness costs associated with sexual reproduction, its persistence and pervasiveness among multicellular organisms testifies to its intrinsic, short-term advantages. However, the reproductive assurance hypothesis predicts selection favoring asexual reproduction in sparse populations and when mate finding is difficult. Difficulties in finding mates is especially common in parasites, whose life cycles involve multiple hosts, or being released from the host into the external environment where the parasite can find itself trapped without a sexual partner. To solve this problem and guarantee reproduction, parasites in numerous phyla have evolved reproductive strategies, as predicted by the reproductive assurance hypothesis, such as hermaphroditism or parthenogenesis. However, this type of strategy has not been reported from species in the phylum Nematomorpha, whose populations have often been described as sparse. A new Nematomorpha species, Paragordius obamai n. sp., was discovered from Kenya, Africa, and appears to have solved the problem of being trapped without a mate by eliminating the need for males. Paragordius obamai n. sp. represents the first and only known species within this phylum to reproduce asexually. To determine the mechanism of this mating strategy, we ruled out the involvement of reproduction manipulating endosymbionts by use of next generation sequencing data, thus suggesting that parthenogenesis is determined genetically and may have evolved as a means to assure reproduction. Since this new parthenogenetic species and a closely related gonochoristic North American congener, P. varius, are easy to propagate in the laboratory, these gordiids can be used as model systems to test hypotheses on the genetic advantages and disadvantages of asexual reproduction and the genetic determinants of reproductive strategies in parasites.
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Affiliation(s)
- Ben Hanelt
- Center for Evolutionary and Theoretical Immunology, Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America.
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15
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Is a vertebrate a better host for a parasite than an invertebrate host? Fecundity of Proctoeces cf lintoni (Digenea: Fellodistomidae), a parasite of fish and gastropods in northern Chile. Parasitol Res 2011; 109:1731-4. [PMID: 21681629 DOI: 10.1007/s00436-011-2489-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2011] [Accepted: 06/07/2011] [Indexed: 10/18/2022]
Abstract
The fecundity, the relationship between fecundity and worm size, as well as abundance of the adult worm Proctoeces cf. lintoni (Digenea: Fellodistomidae) in four gastropod hosts (keyhole limpets of the genus Fissurella) and one vertebrate host, the clingfish Sicyases sanguineus from northern Chile, were compared. Worms obtained from Fissurella latimarginata were smaller than those from Fissurella maxima, Fissurella limbata, and S. sanguineus. The mean fecundity of parasites from Fissurella crassa was significantly lower than those from F. limbata, F. maxima and S. sanguineus. For all invertebrate hosts, there were significant, positive relationships between worm size and fecundity, and the slopes of the regression did not differ significantly for the invertebrate hosts. Parasites of the keyhole limpet F. limbata and the clingfish showed the highest intensity, prevalence, and mean fecundity, and these species must be considered to be the hosts in which P. cf lintoni shows the best fitness.
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16
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Sexual size dimorphism, sex ratio and the relationship between seasonality and water quality in four species of Gordiida (Nematomorpha) from Catamarca, Argentina. J Helminthol 2010; 85:319-24. [PMID: 20932355 DOI: 10.1017/s0022149x1000057x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
A total of 687 adult nematomorphs of four species of Gordiida: Chordodes brasiliensis (393 specimens), Noteochorododes cymatium (47 specimens), N. talensis (162 specimens) and Pseudochordodes dugesi (85 specimens) were collected during a period of 1 year from El Simbolar stream, Argentina. Free-living worms were abundant during autumn and spring, but their number decreased during winter and summer. Males were shorter and significantly more abundant than females. The presence of N. cymatium, N. talensis and P. dugesi was correlated with water temperature and these species were most abundant in winter and spring. The presence of C. brasiliensis was correlated with flow rate and pH; this species was more abundant in autumn and winter. These four species are sympatric.
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Walker M, Hall A, Basáñez MG. Trickle or clumped infection process? An analysis of aggregation in the weights of the parasitic roundworm of humans, Ascaris lumbricoides. Int J Parasitol 2010; 40:1373-80. [DOI: 10.1016/j.ijpara.2010.03.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2009] [Revised: 03/10/2010] [Accepted: 03/11/2010] [Indexed: 10/19/2022]
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