To delay once or twice: the effect of hypobiosis and free-living stages on the stability of host–parasite interactions

The life cycle of many endoparasites can be delayed by free-living infective stages and a developmental arrestment in the host referred to as hypobiosis. We investigated the effects of hypobiosis and its interaction with delay in the free-living stages on host–parasite population dynamics by expanding a previous attempt by Dobson & Hudson. When the parasite life cycle does not include free-living stages, hypobiosis destabilizes the host–parasite interactions, irrespective of the assumptions about the regulation of the host population dynamics. Interestingly, the destabilizing effect varies in a nonlinear way with the duration of hypobiosis, the maximal effect being expected for three to five months delay. When the parasite life cycle involves free-living stages, hypobiosis of short or intermediate duration increases the destabilizing effect of the first time delay. However, hypobiosis of a duration of five months or more can stabilize interactions, irrespective of the regulation of the host population dynamics. Overall, we confirmed that hypobiosis is an unusual time delay as it can stabilize a two-way interaction. Contrary to the previous conclusions, such an atypical effect does not require self-regulation of the host population, but instead depends on the existence of free-living stages.

Download Full-text

Does host socio-spatial behavior lead to a fine-scale spatial genetic structure in its associated parasites?

Parasite ◽

10.1051/parasite/2019062 ◽

2019 ◽

Vol 26 ◽

pp. 64

Author(s):

Elodie Portanier ◽

Mathieu Garel ◽

Sébastien Devillard ◽

Jeanne Duhayer ◽

Marie-Thérèse Poirel ◽

...

Keyword(s):

Life Cycle ◽

Genetic Structure ◽

Spatial Genetic Structure ◽

Small Ruminants ◽

Spatial Behavior ◽

Biological Factors ◽

Parasite Life Cycle ◽

Host Parasite Interactions ◽

Host Genetic ◽

Host Parasite

Gastro-intestinal nematodes, especially Haemonchus contortus, are widespread pathogenic parasites of small ruminants. Studying their spatial genetic structure is as important as studying host genetic structure to fully understand host-parasite interactions and transmission patterns. For parasites having a simple life cycle (e.g., monoxenous parasites), gene flow and spatial genetic structure are expected to strongly rely on the socio-spatial behavior of their hosts. Based on five microsatellite loci, we tested this hypothesis for H. contortus sampled in a wild Mediterranean mouflon population (Ovis gmelini musimon × Ovis sp.) in which species- and environment-related characteristics have been found to generate socio-spatial units. We nevertheless found that their parasites had no spatial genetic structure, suggesting that mouflon behavior was not enough to limit parasite dispersal in this study area and/or that other ecological and biological factors were involved in this process, for example other hosts, the parasite life cycle, or the study area history.

Download Full-text

Global stability and Hopf bifurcation of a host–parasite system

International Journal of Biomathematics ◽

10.1142/s1793524517500474 ◽

2017 ◽

Vol 10 (04) ◽

pp. 1750047

Author(s):

Xuerui Wei ◽

Zhipeng Qiu

Keyword(s):

Hopf Bifurcation ◽

Time Scale ◽

Sufficient Conditions ◽

Host Population ◽

Complete Analysis ◽

Logistic Growth ◽

Free Living ◽

Dynamical Mechanism ◽

Host Parasite Interactions ◽

Host Parasite

Understanding the dynamical mechanism of the host–parasite interactions is one of important issues on host–parasite association. In this paper, we formulate a three-dimensional host–macroparasite system to describe the host–parasite interactions, which includes the logistic growth rate of host population, the important free-living stage and the host fecundity reduction due to parasite infection. The purpose of the paper is to investigate the asymptotical behavior of the system. By using the properties of the solution to non-autonomous linear system, the basic production number [Formula: see text] is proved to be a threshold which determines the outcome of the parasites. If [Formula: see text], the parasite will eventually die out, and if [Formula: see text] the parasite will be uniformly persistent. Hopf bifurcation of the system is further studied, and sufficient conditions for the Hopf bifurcation are obtained. By using the singular perturbation techniques, the system is separated into two time scales with a faster time scale for the free-living infective particles and a slower time scale for the population dynamics of host and parasite, and then a complete analysis of the dynamics on the slow manifold is conducted. The theoretical results show that the level of aggregation of parasites within host may influence the persistence and stability of the system.

Download Full-text

Simulation of host—parasite interactions within a resource management framework: impact of brucellosis on bison population dynamics

Ecological Modelling ◽

10.1016/0304-3800(91)90081-b ◽

1991 ◽

Vol 54 (3-4) ◽

pp. 299-320 ◽

Cited By ~ 12

Author(s):

M.J. Peterson ◽

W.E. Grant ◽

D.S. Davis

Keyword(s):

Population Dynamics ◽

Resource Management ◽

Management Framework ◽

Host Parasite Interactions ◽

Host Parasite

Download Full-text

Host-Parasite Interactions and Population Dynamics of Rock Ptarmigan

PLoS ONE ◽

10.1371/journal.pone.0165293 ◽

2016 ◽

Vol 11 (11) ◽

pp. e0165293 ◽

Cited By ~ 15

Author(s):

Ute Stenkewitz ◽

Ólafur K. Nielsen ◽

Karl Skírnisson ◽

Gunnar Stefánsson

Keyword(s):

Population Dynamics ◽

Rock Ptarmigan ◽

Host Parasite Interactions ◽

Host Parasite

Download Full-text

From Metabolite to Metabolome: Metabolomics Applications in Plasmodium Research

Frontiers in Microbiology ◽

10.3389/fmicb.2020.626183 ◽

2021 ◽

Vol 11 ◽

Author(s):

Xinyu Yu ◽

Gaoqian Feng ◽

Qingfeng Zhang ◽

Jun Cao

Keyword(s):

Life Cycle ◽

Life Stages ◽

Disease Etiology ◽

Malaria Research ◽

Metabolic Mapping ◽

The Past ◽

Host Parasite Interactions ◽

Life Cycle Stages ◽

Parasite Biology ◽

Host Parasite

Advances in research over the past few decades have greatly improved metabolomics-based approaches in studying parasite biology and disease etiology. This improves the investigation of varied metabolic requirements during life stages or when following transmission to their hosts, and fulfills the demand for improved diagnostics and precise therapeutics. Therefore, this review highlights the progress of metabolomics in malaria research, including metabolic mapping of Plasmodium vertebrate life cycle stages to investigate antimalarials mode of actions and underlying complex host-parasite interactions. Also, we discuss current limitations as well as make several practical suggestions for methodological improvements which could drive metabolomics progress for malaria from a comprehensive perspective.

Download Full-text

Hidden paths to endless forms most wonderful: Parasite-blind diversification of host quality

10.1101/2020.12.23.424158 ◽

2020 ◽

Author(s):

Lisa Freund ◽

Marie Vasse ◽

Gregory J. Velicer

Keyword(s):

Growth Suppression ◽

Host Population ◽

Host Quality ◽

Evolution Theory ◽

Evolutionary Diversification ◽

Adaptive Landscapes ◽

Host Parasite Interactions ◽

Parasite Evolution ◽

Host Parasite ◽

Selective Environment

Evolutionary diversification can occur in allopatry or sympatry, can be unselected or driven by selection, and can be phenotypically manifested immediately or remain phenotypically latent until later manifestation in a newly encountered environment. Diversification of host-parasite interactions is frequently studied in the context of intrinsically selective coevolution, but the potential for host-parasite interaction phenotypes to diversify latently during parasite-blind evolution is rarely considered. Here we use a social bacterium experimentally adapted to several environments in the absence of phage to analyse allopatric diversification of latent host quality - the degree to which a host population supports a viral epidemic. Phage-blind evolution reduced host quality overall, with some bacteria becoming completely resistant to growth suppression by phage. Selective-environment differences generated only mild divergence in host-quality. However, selective environments nonetheless played a major role in shaping evolution by determining the degree of stochastic diversification among replicate populations within treatments. Ancestral motility genotype was also found to strongly shape patterns of latent hostquality evolution and diversification. These outcomes show that adaptive landscapes can differ in how they constrain stochastic diversification of a latent phenotype and that major effects of selection on biological diversification can be missed by focusing on trait means. Collectively, our findings suggest that latent-phenotype evolution (LPE) should inform host-parasite evolution theory and that diversification should be conceived broadly to include latent phenotypes.

Download Full-text

The population dynamics of competition between parasites

Parasitology ◽

10.1017/s0031182000057401 ◽

1985 ◽

Vol 91 (2) ◽

pp. 317-347 ◽

Cited By ~ 124

Author(s):

A. P. Dobson

Keyword(s):

Population Dynamics ◽

Parasite Species ◽

Interference Competition ◽

Population Level ◽

Experimental Tests ◽

Theoretical Models ◽

Control Agent ◽

Host Population ◽

Free Living ◽

The Impact

A number of published studies of competition between parasite species are examined and compared. It is suggested that two general levels of interaction are discernible: these correspond to the two levels of competition recognized by workers studying free-living animals and plants: ‘exploitation’ and ‘interference’ competition. The former may be defined as the joint utilization of a host species by two or more parasite species, while the latter occurs when antagonistic mechanisms are utilized by one species either to reduce the survival or fecundity of a second species or to displace it from a preferred site of attachment. Data illustrating both levels of interaction are collated from a survey of the published literature and these suggest that interference competition invariably operates asymmetrically. The data are also used to estimate a number of population parameters which are important in determining the impact of competition at the population level. Theoretical models of host-parasite associations for both classes of competition are used to examine the expected patterns of population dynamics that will be exhibited by simple two-species communities of parasites that utilize the same host population. The analysis suggests that the most important factor allowing competing species of parasites to coexist is the statistical distribution of the parasites within the host population. A joint stable equilibrium should be possible if both species are aggregated in their distribution. The size of the parasite burdens at equilibrium is then determined by other life-history parameters such as pathogenicity, rates of resource utilization and antagonistic ability. Comparison of these theoretical expectations with a variety of sets of empirical data forms the basis for a discussion about the importance of competition in natural parasite populations. The models are used to assess quantitatively the potential for using competing parasite species as biological control agents for pathogens of economic or medical importance. The most important criterion for identifying a successful control agent is an ability to infect a high proportion of the host population. If such a parasite species also exhibits an intermediate level of pathology or an efficient ability to utilize shared common resources, antagonistic interactions between the parasite species contribute only secondarily to the success of the control. Competition in parasites is compared with competition in free-living animals and plants. The comparison suggests further experimental tests which may help to assess the importance of competition in determining the structure of more complex parasite-host communities.

Download Full-text

Effect of environmental variables and their interaction on gordiid hairworm larvae (Nematomorpha)

Journal of Helminthology ◽

10.1017/s0022149x21000420 ◽

2021 ◽

Vol 95 ◽

Author(s):

C.L. Achiorno ◽

G. Minardi ◽

L. Ferrari

Keyword(s):

Freshwater Ecosystems ◽

Effect Of Temperature ◽

Extreme Temperatures ◽

Free Living ◽

Temperature Variations ◽

Host Parasite Interactions ◽

Effects Of Ph ◽

Chordodes Nobilii ◽

Increasing Temperature ◽

Host Parasite

Abstract The different stages of the life cycle of parasites are important components of ecosystems. Changes in environmental conditions may affect free-living stages, host–parasite interactions and ecosystem functioning. The larvae of Chordodes nobilii, which belongs to the parasitic phylum Nematomorpha, are susceptible to extreme temperatures and different pollutants, but the effects of pH and moderate temperature variations have not been evaluated yet. Our objective was to assess the effect of temperature, pH and their interaction on the infectivity of C. nobilii larvae to Aedes aegypti larvae over time. Larvae were treated with factorial combinations of temperature (18, 23 and 28°C), pH (7, 8 and 9) and time periods (24 and 48 h). Results show a highly significant interaction among all variables. The highest infectivity was recorded at 18°C and pH 7 at 24 and 48 h, and the lowest one at 28°C and pH 8 at 24 and 48 h. Infectivity differed significantly among the three temperatures only at pH 8 and 48 h, decreasing with increasing temperature. Our study is the first report of the effect of pH on a Nematomorpha species and suggests that the infectivity of C. nobilii larvae may be affected negatively by an increase in temperature and its interaction with pH and time. Since parasites must be considered for a better understanding of the effects of stressors on freshwater ecosystems, our results may help in the design and analysis of studies of anthropogenic impact.

Download Full-text

Population interactions between a parasitic castrator, Probopyrus pandalicola (Isopoda: Bopyridae), and one of its freshwater shrimp hosts, Palaemonetes paludosus (Decapoda: Caridea)

Parasitology ◽

10.1017/s003118200005383x ◽

1979 ◽

Vol 79 (3) ◽

pp. 431-449 ◽

Cited By ~ 20

Author(s):

J. T. Beck

Keyword(s):

Host Population ◽

Acartia Tonsa ◽

Parasite Control ◽

Freshwater Shrimp ◽

Free Swimming ◽

Host Parasite Interactions ◽

Population Interactions ◽

Parasitic Castrator ◽

Host Parasite ◽

And Control

SUMMARYFreshwater shrimp, Palaemonetes paludosus, infected by the bopyrid isopod, Probopyrus pandalicola, occurred as far as 33 km upstream in many coastal rivers and canals throughout Florida. Free-swimming isopod larvae and the intermediate copepod host, Acartia tonsa, were collected in the plankton of the Wakulla River, and it appeared that cryptoniscus larvae swam at least as far as 13 km upstream to infect the definitive shrimp host after leaving the copepod in brackish water. In the Wakulla River infection levels ranged from 87·5 to 100%. In contrast, at McBride's Slough infection levels fluctuated from 0·9 to 93·2%. In the St Marks River the frequency of infected shrimp gradually increased from 0% upstream to 96%, 6 km further downstream. A significantly greater percentage of female than male hosts were infected, but only females of size classes less than 31 mm long had a greater frequency of infection. Female P. pandalicola were greatly under-dispersed (coefficient of dispersion (s2/x¯) less than 1) throughout the host population; 99·6% of the infected hosts carried only 1 female parasite. Control of P. pandalicola at the infrapopulation level is probably accomplished by some mode of intraspecific competition, and control at the suprapopulation level occurs through an upstream limitation of the transmission range of the cryptoniscus larval stage. Host–parasite interactions appear to be unstable.

Download Full-text