Amphibian Infection Risk Changes with Host Life Stage and across a Landscape Gradient

2020 ◽  
Vol 54 (3) ◽  
Author(s):  
Samantha L. Rumschlag ◽  
Michelle D. Boone
Keyword(s):  
Life Stage ◽  
Infection Risk ◽  
Host Life ◽  
Landscape Gradient

scholarly journals Life-stage and sex influence Philornis ectoparasitism in a Neotropical woodpecker (Melanerpes striatus) with essential male parental care

2021 ◽  
Author(s):  
Joshua Burke LaPergola
Keyword(s):  
Parental Care ◽  
Recent Work ◽  
Life Stage ◽  
Bird Species ◽  
Adult Males ◽  
Sex Influence ◽  
Adult Females ◽  
Overnight Incubation ◽  
Per Se ◽  
Host Life

The nestlings of many Neotropical bird species suffer from Philornis (Diptera: Muscidae) ectoparasitism. While nestlings are typically considered the intended targets, recent work indicates that Philornis infest adult birds more frequently than previously appreciated, yet few studies have concurrently surveyed nestlings and adults for Philornis in the same population. Over six field seasons (2012 to 2017), I documented the presence of current or recent subcutaneous Philornis infestations on adult and nestling Hispaniolan Woodpeckers (Melanerpes striatus) from the same population. I tested the following three non-mutually exclusive hypotheses regarding occurrence of Philornis on adult birds: (1) nestlings are more vulnerable to Philornis parasitism than adults, (2) nesting is associated with Philornis parasitism in adults, and (3) Philornis parasitism is associated with incubation and brooding investment. While nestling and adult woodpeckers exhibited similar prevalence of parasitism, parasitized nestlings hosted on average 3.5 times more Philornis wounds (larvae plus scars) than parasitized adults. Nesting per se was not significantly associated with parasitism among adults, as breeding and non-breeding adults showed similar prevalence and intensity. However, adult males, which perform overnight incubation and brooding, were significantly more likely to be parasitized than adult females. This last result supports the hypothesis that incubation and brooding investment increase the risk of Philornis parasitism for adults, but this conclusion is complicated by the lack of an association between parasitism and nesting status. Together, these results raise questions about the degree of host life-stage specialization and whether adult parasitism is incidental or part of an alternative parasitic strategy for Philornis.

scholarly journals The expression of virulence for a mixed-mode transmitted parasite in a diapausing host

Parasitology ◽  
2014 ◽  
Vol 141 (8) ◽  
pp. 1097-1107 ◽  
Author(s):  
ELHAM SHEIKH-JABBARI ◽  
MATTHEW D. HALL ◽  
FRIDA BEN-AMI ◽  
DIETER EBERT
Keyword(s):  
Hatching Success ◽  
Life Stage ◽  
Horizontal Transmission ◽  
Resting Eggs ◽  
Life Stages ◽  
Infected Female ◽  
Population Prevalence ◽  
High Virulence ◽  
Host Life ◽  
Adaptive Nature

SUMMARYMany parasites survive harsh periods together with their hosts. Without the possibility of horizontal transmission during host diapause, parasite persistence depends entirely on host survival. We therefore hypothesize that a parasite should be avirulent during its host's diapausing stage. In contrast, the parasite may express higher virulence, i.e. parasite-induced fitness reduction of the host, during host life stages with good opportunities for horizontal transmission. Here we study the effects of a vertically and horizontally transmitted microsporidium parasite, Hamiltosporidium tvaerminnensis, on the quantity and survival of resting eggs of its host Daphnia magna. We find that the parasite did not affect egg volume, hatching success and time to hatching of the Daphnia's resting eggs, although it did strongly reduce the number of resting eggs produced by infected females, revealing high virulence during the non-diapause phase of the host's life cycle. These results also explain another aspect of this system – namely the strong decline in natural population prevalence across diapause. This decline is not caused by mortality in infected resting stages, as was previously hypothesized, but because infected female hosts produce lower rates of resting eggs. Together, these results help explain the epidemiological dynamics of a microsporidian disease and highlight the adaptive nature of life stage-dependent parasite virulence.

scholarly journals A link between mitochondrial gene expression and life stage morphologies in Trypanosoma cruzi

2019 ◽  
Author(s):  
Roger Ramirez-Barrios ◽  
Emily K. Susa ◽  
Sean P. Faacks ◽  
Charles K. Liggett ◽  
Sara L. Zimmer
Keyword(s):  
Gene Expression ◽  
Trypanosoma Cruzi ◽  
Mitochondrial Gene ◽  
Life Stage ◽  
Mitochondrial Rna ◽  
Mitochondrial Gene Expression ◽  
Signaling Mechanism ◽  
Transport Chain ◽  
Host Life ◽  
Induced Changes

SummaryThe protozoan Trypanosoma cruzi has a complicated dual-host life cycle, and starvation can trigger transition from the replicating insect stage to the mammalian-infectious nonreplicating insect stage (epimastigote to trypomastigote differentiation). Abundance of some mature RNAs derived from its mitochondrial genome increase during culture starvation of T. cruzi for unknown reasons. Here we examine T. cruzi mitochondrial gene expression in the mammalian intracellular replicating life stage (amastigote), and uncover implications of starvation-induced changes in gene expression in insect-stage cells. Mitochondrial RNA levels in general were found to be lowest in actively replicating amastigotes. We discovered that mitochondrial respiration decreases during starvation, despite the previously-observed increases in mitochondrial mRNAs encoding electron transport chain components. Surprisingly, T. cruzi epimastigotes in replete medium grow at normal rates when we genetically compromised their ability to perform insertion/deletion editing and thereby generate mature forms of some mitochondrial mRNAs. However, these cells, when starved, were impeded in the epimastigote to trypomastigote transition. Further, they experience a short-flagella phenotype that may also be linked to differentiation. We hypothesize a scenario where levels of mature RNA species or editing in the single T. cruzi mitochondrion are linked to differentiation by a yet-unknown signaling mechanism.

scholarly journals The Influence of Pesticide Use on Amphibian Chytrid Fungal Infections Varies with Host Life Stage

2017 ◽  
Author(s):  
Samantha L. Rumschlag ◽  
Jason R. Rohr
Keyword(s):  
Disease Risk ◽  
Fungal Infections ◽  
Spatial Scales ◽  
Life Stage ◽  
Infection Risk ◽  
Disease Spread ◽  
Infection Prevalence ◽  
Pesticide Use ◽  
Amphibian Species ◽  
The Impact

ABSTRACTAimPesticides are widespread and may alter host-pathogen interactions, ultimately influencing pathogen distributions across landscapes. Previous laboratory research supports two hypotheses regarding the effects of pesticides on interactions between amphibians and the predominately aquatic fungal pathogen Batrachochytrium dendrobatidis (Bd): 1) pesticides can be directly toxic to Bd reducing infection risk of aquatic larval amphibians, and 2) exposure to pesticides at formative stages of amphibian development can have long-term consequences on defenses, increasing disease risk after metamorphosis. It remains equivocal whether these laboratory patterns are consistent across amphibian species and occur in the field across broad spatial scales. The aim of this research is to address this research gap on the impact of pesticides on Bd distributions.LocationContiguous United States.Time Period1998-2009.Major Taxa StudiedAmphibian hosts and Bd.MethodsOur data included 3,946 individuals evaluated for Bd infection across 49 amphibian species, at 126 locations, which resulted in 199 estimates of Bd prevalence in populations. We used species distribution models and multimodel inference to assess the influence of 1) total pesticide use, 2) pesticide use by type (herbicide, insecticide, fungicide), and 3) the most commonly used pesticide compounds on Bd infection prevalence in amphibian populations across life stages, controlling for several factors previously documented to affect Bd's distribution.ResultsConsistent with laboratory findings, our results indicate 36 that exposure to multiple herbicide compounds is associated with lowered infection risk in the aquatic larval stage but higher risk in the terrestrial post-metamorphic stage.Main ConclusionsOur study highlights the complex nature of the effects that pesticides can have on disease distributions and suggests that pesticides should be strongly considered at broad scales and across host species, especially in environments in which exposure is widespread. Accurate predictions of disease distributions may lead to more effective management strategies to limit disease spread.

scholarly journals A meta-analysis reveals temperature, dose, life stage, and taxonomy influence host susceptibility to a fungal parasite

2019 ◽  
Author(s):  
Erin L. Sauer ◽  
Jeremy M. Cohen ◽  
Marc J. Lajeunesse ◽  
Taegan A. McMahon ◽  
David J. Civitello ◽  
...  
Keyword(s):  
Host Species ◽  
Species Interactions ◽  
Pathogenic Fungus ◽  
Meta Analysis ◽  
Life Stage ◽  
Host Susceptibility ◽  
Average Dose ◽  
Infection Dose ◽  
Host Mortality ◽  
Host Life

AbstractComplex ecological relationships, such as host-parasite interactions, are often modeled with laboratory experiments. However, some experimental laboratory conditions, such as temperature or infection dose, are regularly chosen based on convenience or convention and it is unclear how these decisions systematically affect experimental outcomes. Here, we conducted a meta-analysis of 58 laboratory studies that exposed amphibians to the pathogenic fungus Batrachochytrium dendrobatidis (Bd) to better understand how laboratory temperature, host life stage, infection dose, and host species affect host mortality. We found that host mortality was driven by thermal mismatches: hosts native to cooler environments experienced greater Bd-induced mortality at relatively warm experimental temperatures and vice versa. We also found that Bd dose positively predicted Bd-induced host mortality and that the superfamilies Bufonoidea and Hyloidea were especially susceptible to Bd. Finally, the effect of Bd on host mortality varied across host life stages, with larval amphibians experiencing lower risk of Bd-induced mortality than adults or metamorphs. Metamorphs were especially susceptible and experienced mortality when inoculated with much smaller Bd doses than the average dose used by researchers. Our results suggest that when designing experiments on species interactions, researchers should carefully consider the experimental temperature, and inoculum dose, and life stage and taxonomy of the host species.

scholarly journals Whole gut microbiome composition of damselfish and cardinalfish before and after reef settlement

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e2412 ◽  
Author(s):  
Darren J. Parris ◽  
Rohan M. Brooker ◽  
Michael A. Morgan ◽  
Danielle L. Dixson ◽  
Frank J. Stewart
Keyword(s):  
Life Stage ◽  
Benthic Habitat ◽  
Rrna Gene ◽  
Microbial Composition ◽  
Surrounding Water ◽  
Core Microbiome ◽  
Microbiome Composition ◽  
Pelagic Larvae ◽  
Before And After ◽  
Host Life

The Pomacentridae (damselfish) and Apogonidae (cardinalfish) are among the most common fish families on coral reefs and in the aquarium trade. Members of both families undergo a pelagic larvae phase prior to settlement on the reef, where adults play key roles in benthic habitat structuring and trophic interactions. Fish-associated microbial communities (microbiomes) significantly influence fish health and ecology, yet little is known of how microbiomes change with life stage. We quantified the taxonomic (16S rRNA gene) composition of whole gut microbiomes from ten species of damselfish and two species of cardinalfish from Lizard Island, Australia, focusing specifically on comparisons between pelagic larvae prior to settlement on the reef versus post-settlement juvenile and adult individuals. On average, microbiome phylogenetic diversity increased from pre- to post-settlement, and was unrelated to the microbial composition in the surrounding water column. However, this trend varied among species, suggesting stochasticity in fish microbiome assembly. Pre-settlement fish were enriched with bacteria of the Endozoicomonaceae, Shewanellaceae, and Fusobacteriaceae, whereas settled fish harbored higher abundances of Vibrionaceae and Pasteurellaceae. Several individual operational taxonomic units, including ones related toVibrio harveyi,Shewanella sp., and unculturedEndozoicomonasbacteria, were shared between both pre and post-settlement stages and may be of central importance in the intestinal niche across development. Richness of the core microbiome shared among pre-settlement fish was comparable to that of settled individuals, suggesting that changes in diversity with adulthood are due to the acquisition or loss of host-specific microbes. These results identify a key transition in microbiome structure across host life stage, suggesting changes in the functional contribution of microbiomes over development in two ecologically dominant reef fish families.

Effect of Temperature and Host Life Stage on Efficacy of Soil Entomopathogens Against the Swede Midge (Diptera: Cecidomyiidae)

2015 ◽  
Vol 108 (2) ◽  
pp. 473-483 ◽  
Author(s):  
B. G. Evans ◽  
K. S. Jordan ◽  
M. Brownbridge ◽  
R. H. Hallett
Keyword(s):  
Life Stage ◽  
Effect Of Temperature ◽  
Swede Midge ◽  
Host Life

scholarly journals Abundance, placement and sexual identity of the epizoic barnacle Chelonibia testudinaria relative to the size and species of host turtles in Mabul Island, Malaysia

2020 ◽  
Vol 100 (8) ◽  
pp. 1299-1309
Author(s):  
Kah Kheng Lim ◽  
Muhammad Ali Syed Hussein ◽  
Pushpa Palaniappan
Keyword(s):  
Sea Turtles ◽  
Life Stage ◽  
Chelonia Mydas ◽  
Life Stages ◽  
Adult Males ◽  
Shell Size ◽  
Marine Fauna ◽  
Eretmochelys Imbricata ◽  
Acorn Barnacle ◽  
Host Life

AbstractSea turtles are partners in commensal relationships with a variety of epibionts, including barnacles. The acorn barnacle Chelonibia testudinaria is one species commonly found associated with sea turtles and other marine fauna throughout temperate to tropical waters including the Indo-Pacific. We conducted a study to assess the occurrence of this barnacle, relative to host life stage and species in a mixed foraging population of green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles (juvenile, sub-adult, adults (female and male)) in Mabul Island, Sabah, Malaysia (Celebes Sea). Expecting similar relative abundance by life stage, we found instead a significant effect between the combined dependent variables (abundance and size of barnacles) and the life stages of sea turtles in Mabul after controlling for the covariates of size and species of sea turtles (F(8, 428) = 5.77, P < 0.001, Pillai = 0.19). Among green turtles with barnacles, though adult males had larger barnacles compared with the female turtles, the mean barnacle abundance on adult females (43.4 individuals ± 5.19 SD) was higher than all other life stages. Most of the barnacles (85.6%; N = 1931) were found on the plastron of the sea turtles. The highest number of barnacle reacquisition was found among the juvenile turtles. In assessing the complemental males of the barnacles, we found they were consistently attached to the shells of the larger of the hermaphrodites from each region of the host's body despite average shell-size differences with each region.

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