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Li J, Fu N, Ge S, Ren L, Luo Y. Physiological Measurements and Transcriptomics Reveal the Fitness Costs of Monochamus saltuarius to Bursaphelenchus xylophilus. Int J Mol Sci 2024; 25:4906. [PMID: 38732123 PMCID: PMC11084816 DOI: 10.3390/ijms25094906] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Revised: 04/27/2024] [Accepted: 04/28/2024] [Indexed: 05/13/2024] Open
Abstract
The pine wood nematode (PWN) uses several Monochamus species as vehicles, through a temporary hitchhiking process known as phoresy, enabling it to access new host plant resources. Monochamus saltuarius acts as a new and major vector of the PWN in Northeastern China, showing lower PWN carrying capacity and a shorter transmission cycle compared to established vectors. The apparently altered symbiotic relationship offers an interesting area for researching the costs and adaptions involved in nematode-beetle, a specialized phoresy. We analyzed the response and fitness costs of M. saltuarius through physiological measurements and transcriptomics. The PWN exerted adverse repercussions on the growth and development of M. saltuarius. The PWN accelerated larval development into pupae, while beetle adults carrying the PWN exhibited an elevated abnormality rate and mortality, and reduced starvation resistance. During the pupal stage, the expression of growth-related genes, including ecdysone-inducible genes (E74EA), cuticle proteins, and chitin genes (CHTs), markedly increased. Meanwhile, the induced immune response, mainly by the IMD and Toll signaling pathways, could be a contributing factor to adult abnormality and mortality. Adult gonads and trachea exhibited enrichment in pathways related to fatty acid elongation, biosynthesis, and metabolism. FASN, ELOVL, and SCD possibly contributed to resistance against PWN. Our research indicated that phoretic interactions between vector beetles and PWN vary throughout the vector's lifespan, particularly before and after entry into the trachea. This study highlighted the fitness costs of immunity and metabolism on the vector beetle, indicating the adaptation mechanisms and evolutionary trade-offs to PWN.
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Affiliation(s)
- Jiaxing Li
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China; (J.L.); (S.G.)
| | - Ningning Fu
- Department of Forest Protection, College of Forestry, Hebei Agricultural University, Baoding 071033, China;
| | - Sixun Ge
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China; (J.L.); (S.G.)
| | - Lili Ren
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China; (J.L.); (S.G.)
| | - Youqing Luo
- Beijing Key Laboratory for Forest Pest Control, Beijing Forestry University, Beijing 100083, China; (J.L.); (S.G.)
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Wałach K, Blagden B. Tardigrade stowaways: literature review of Propyxidium tardigradum and its first record in Scotland. Eur J Protistol 2023; 89:125974. [PMID: 37084697 DOI: 10.1016/j.ejop.2023.125974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2022] [Revised: 02/27/2023] [Accepted: 03/16/2023] [Indexed: 04/07/2023]
Abstract
Tardigrades are a phylum of microscopic invertebrates with a global distribution. Although our understanding of their systematic position and taxonomy has increased and continues to grow, their relationship with the other organisms that share their habitat remains poorly studied. One such organism is Propyxidium tardigradum, a peritrich ciliate which uses tardigrades for dispersion and as a substrate for reproduction. Here, we present the first Scottish record and tenth global occurrence of Propyxidium tardigradum, thereby expanding our knowledge of its poorly understood zoogeographic distribution. We also summarise the literature concerning P. tardigradum biology, proffer hypotheses regarding the Propyxidium-tardigrade relationship, and the apparent lack of heterotardigrade ciliate infestation. Additionally, we indicate a number of recommendations for the direction of future studies regarding the ciliate. Finally, we add a further three species, Milnesium variefidum, Hypsibius cf. scabropygus and Macrobiotus scoticus to the list of Propyxidium host species.
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Van Goor J, Herre EA, Gómez A, Nason JD. Extraordinarily precise nematode sex ratios: adaptive responses to vanishingly rare mating opportunities. Proc Biol Sci 2022; 289:20211572. [PMID: 35042409 PMCID: PMC8767218 DOI: 10.1098/rspb.2021.1572] [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: 07/09/2021] [Accepted: 12/10/2021] [Indexed: 01/28/2023] Open
Abstract
Sex ratio theory predicts both mean sex ratio and variance under a range of population structures. Here, we compare two genera of phoretic nematodes (Parasitodiplogaster and Ficophagus spp.) associated with 12 fig pollinating wasp species in Panama. The host wasps exhibit classic local mate competition: only inseminated females disperse from natal figs, and their offspring form mating pools that consist of scores of the adult offspring contributed by one or a few foundress mothers. By contrast, in both nematode genera, only sexually undifferentiated juveniles disperse and their mating pools routinely consist of 10 or fewer adults. Across all mating pool sizes, the sex ratios observed in both nematode genera are consistently female-biased (approx. 0.34 males), but markedly less female-biased than is often observed in the host wasps (approx. 0.10 males). In further contrast with their hosts, variances in nematode sex ratios are also consistently precise (significantly less than binomial). The constraints associated with predictably small mating pools within highly subdivided populations appear to select for precise sex ratios that contribute both to the reproductive success of individual nematodes, and to the evolutionary persistence of nematode species. We suggest that some form of environmental sex determination underlies these precise sex ratios.
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Affiliation(s)
- Justin Van Goor
- Department of Biology, University of Maryland College Park, College Park, MD 20742, USA
- Smithsonian Tropical Research Institute, Unit 9100, Box 0948, DPO AA 34002-9998, Miami, FL 34002, USA
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50010, USA
| | - Edward Allen Herre
- Smithsonian Tropical Research Institute, Unit 9100, Box 0948, DPO AA 34002-9998, Miami, FL 34002, USA
| | - Adalberto Gómez
- Smithsonian Tropical Research Institute, Unit 9100, Box 0948, DPO AA 34002-9998, Miami, FL 34002, USA
| | - John D. Nason
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA 50010, USA
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Van Goor J, Piatscheck F, Houston DD, Nason JD. Differential effects of nematode infection on pollinating and non-pollinating fig wasps: Can shared antagonism provide net benefits to a mutualism? J Anim Ecol 2021; 90:1764-1775. [PMID: 33934356 DOI: 10.1111/1365-2656.13495] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Accepted: 04/01/2021] [Indexed: 01/12/2023]
Abstract
Species pairs that form mutualistic associations are also components of broader organismal community networks. These interaction networks have shaped the evolution of individual mutualisms through interspecific interactions ranging from secondarily mutualistic to intensely antagonistic. Our understanding of this complex context remains limited because characterizing the impacts of species interacting with focal mutualists is often difficult. How is the fitness of mutualists impacted by the co-occurring interactive network of community associates? We investigated this context using a model interaction network comprised of a fig and fig wasp mutualist, eight non-pollinating fig wasp (NPFW) antagonists/commensals and a nematode previously believed to be associated only with the pollinator wasp mutualist. Through repeated sampling and field observations, we characterized the ecological roles of these mutualist-associated organisms to identify key antagonists. We then investigated how potential nematode infection of NPFWs could impact wasp survival across key life stages and, in turn, inferred how this influences the fitness of the fig-pollinator mutualists. Unexpectedly, we found all Ficus petiolaris-associated NPFWs to be the targets for nematode infection, with infection levels sometimes exceeding that of pollinators. Experimental data collected for the most abundant NPFW species suggest that nematode infection significantly reduces their longevity. Further, comparisons of nematode loads for emerging and successfully arriving NPFWs suggest that infection severely limits their dispersal ability. Through these observations, we conclude that this infection could impact NPFWs more severely than either mutualistic partner, suggesting a novel role of density-dependent facultative mutualism between figs, pollinator wasps and the nematode. This antagonist-mediated suppression of other network antagonists may present an ecologically common mechanism through which antagonists can present net benefits for mutualists' fitness.
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Affiliation(s)
- Justin Van Goor
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Department of Biology, University of Maryland College Park, College Park, MD, USA
| | - Finn Piatscheck
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Smithsonian Tropical Research Institute, Panamá, República de Panamá
| | - Derek D Houston
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA.,Department of Natural and Environmental Sciences, Western Colorado University, Gunnison, CO, USA
| | - John D Nason
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, IA, USA
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Gupta S, Kumble ALK, Dey K, Bessière JM, Borges RM. The Scent of Life: Phoretic Nematodes Use Wasp Volatiles and Carbon Dioxide to Choose Functional Vehicles for Dispersal. J Chem Ecol 2021; 47:139-152. [PMID: 33475939 DOI: 10.1007/s10886-021-01242-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Revised: 12/18/2020] [Accepted: 01/04/2021] [Indexed: 10/22/2022]
Abstract
Hitchhikers (phoretic organisms) need vehicles to disperse out of unsuitable habitats. Therefore, finding vehicles with the right functional attributes is essential for phoretic organisms. To locate these vehicles, phoretic organisms employ cues within modalities, ranging from visual to chemical senses. However, how hitchhikers discriminate between individual vehicles has rarely been investigated. Using a phoretic nematode community associated with an obligate fig-fig wasp pollination mutualism, we had earlier established that hitchhiking nematodes make decisions based on vehicle species identity and number of conspecific hitchhikers already present on the vehicle. Here we investigate if hitchhikers can differentiate between physiological states of vehicles. We asked whether phoretic nematodes choose between live or dead vehicles present in a chemically crowded environment and we investigated the basis for any discrimination. We conducted two-choice and single-choice behavioral assays using single nematodes and found that plant- and animal-parasitic nematodes preferred live over dead vehicles and used volatiles as a sensory cue to make this decision. However, in single-choice assays, animal-parasitic nematodes were also attracted towards naturally dead or freeze-killed wasps. The volatile profile of the wasps was dominated by terpenes and spiroketals. We examined the volatile blend emitted by the different wasp physiological states and determined a set of volatiles that the phoretic nematodes might use to discriminate between these states which is likely coupled with respired CO2. We determined that CO2 levels emitted by single wasps are sufficient to attract nematodes, demonstrating the high sensitivity of nematodes to this metabolic product.
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Affiliation(s)
- Satyajeet Gupta
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Anusha L K Kumble
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India
| | - Kaveri Dey
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India
| | | | - Renee M Borges
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, 560012, India.
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Gupta S, Borges RM. Hopping on: Conspecific traveller density within a vehicle regulates parasitic hitchhiking between ephemeral microcosms. J Anim Ecol 2021; 90:899-908. [PMID: 33368398 DOI: 10.1111/1365-2656.13418] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2020] [Accepted: 12/01/2020] [Indexed: 11/27/2022]
Abstract
Hitchhikers (phoretic organisms) identify their vehicles using species-specific visual, chemical and vibrational cues. However, what factors influence their choice between vehicles of the same species has rarely been investigated. Hitchhikers must not only avoid overcrowded vehicles but may also need to travel with conspecifics to ensure mates at their destination. Hence, a trade-off between overcrowding and presence of conspecifics likely determines the choice of a vehicle especially when destination sites are distant, ephemeral and unique. Here, we investigate whether a trade-off between the presence of conspecifics versus overcrowding by conspecifics or heterospecifics on a vehicle affects hitchhiker choice. We also investigate the sensory modality responsible for this choice. We experimentally examine these questions using a phoretic nematode community (containing plant- and animal-parasitic taxa) obligately associated with a brood-site pollination mutualism. In this model system, nematodes co-travel with conspecifics and heterospecifics on pollinators as vehicles, between ephemeral plant brood sites to complete their developmental life cycle. In this system, hitchhiker overcrowding has proven negative impacts on vehicle and plant fitness. We expected nematodes to respond to conspecifics and heterospecific density on offered vehicles when making their choice. We found that animal-parasitic nematodes preferred vehicles containing some conspecifics within a certain density range. However, plant-parasitic nematodes preferentially boarded vehicles that were devoid of conspecifics or had few conspecifics. Plant parasites that preferred empty vehicles likely hitchhiked in pairs. Both nematode types employed volatile cues to discriminate between vehicles with different conspecific nematode densities. Our results suggest that vehicle overcrowding by conspecifics, most likely, guaranteed access to mates at the destination determined hitchhiker choice. Surprisingly, and contrary to our expectations, plant- and animal-parasitic nematodes did not respond to heterospecific crowding on vehicles and did not discriminate between vehicles with different heterospecific nematode densities. The reason for this lack of response to heterospecific presence is unknown. This study not only shows that phoretic organisms use different strategies while choosing a vehicle but also confirms that density-dependent effects can ensure the stability and persistence of phoretic interactions in a mutualism by balancing overcrowding against reproductive assurance.
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Affiliation(s)
- Satyajeet Gupta
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
| | - Renee M Borges
- Centre for Ecological Sciences, Indian Institute of Science, Bangalore, India
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Bartlow AW, Agosta SJ. Phoresy in animals: review and synthesis of a common but understudied mode of dispersal. Biol Rev Camb Philos Soc 2020; 96:223-246. [PMID: 32924275 DOI: 10.1111/brv.12654] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 08/27/2020] [Accepted: 08/28/2020] [Indexed: 12/30/2022]
Abstract
Phoresy is a type of interaction in which one species, the phoront, uses another species, the dispersal host, for transportation to new habitats or resources. Despite being a widespread behaviour, little is known about the ecology and evolution of phoresy. Our goal is to provide a comprehensive review of phoretic dispersal in animals and to bring renewed attention to this subject. We surveyed literature published between 1900 and 2020 to understand the extent of known higher-level taxonomic diversity (phyla, classes, and orders) and functional aspects of animals that use phoretic dispersal. Species dispersing phoretically have been observed in at least 13 animal phyla, 25 classes, and 60 orders. The majority of known phoronts are arthropods (Phylum Euarthropoda) in terrestrial habitats, but phoronts also occur in freshwater and marine environments. Marine phoronts may be severely under-represented in the literature due to the relative difficulty of studying these systems. Phoronts are generally small with low mobility and use habitats or resources that are ephemeral and/or widely dispersed. Many phoronts are also parasites. In general, animals that engage in phoresy use a wide variety of morphological and behavioural traits for locating, attaching to, and detaching from dispersal hosts, but the exact mechanisms behind these activities are largely unknown. In addition to diversity, we discuss the evolution of phoresy including the long-standing idea that it can be a precursor to parasitism and other forms of symbioses. Finally, we suggest several areas of future research to improve our understanding of phoresy and its ecological and evolutionary significance.
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Affiliation(s)
- Andrew W Bartlow
- Biosecurity and Public Health, Los Alamos National Laboratory, Mailstop M888, Los Alamos, NM, 87545, U.S.A
| | - Salvatore J Agosta
- Center for Environmental Studies, VCU Life Sciences, Virginia Commonwealth University, 1000 W. Cary St., Richmond, VA, 23284, U.S.A
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