Host-parasite interactions under extreme climatic conditions

Abstract The effect that climatic changes can exert on parasitic interactions represents a multifactor problem whose results are difficult to predict. The actual impact of changes will depend on their magnitude and the physiological tolerance of affected organisms. When the change is considered extreme (i.e. unusual weather events that are at the extremes of the historical distribution for a given area), the probability of an alteration in an organisms’ homeostasis increases dramatically. However, factors determining the altered dynamics of host-parasite interactions due to an extreme change are the same as those acting in response to changes of lower magnitude. Only a deep knowledge of these factors will help to produce more accurate predictive models for the effects of extreme changes on parasitic interactions. Extreme environmental conditions may affect pathogens directly when they include free-living stages in their life-cycles and indirectly through reduced resource availability for hosts and thus reduced ability to produce efficient anti-parasite defenses, or by effects on host density affecting transmission dynamics of diseases or the frequency of intraspecific contact. What are the consequences for host-parasite interactions? Here we summarize the present knowledge on three principal factors in determining host-parasite associations; biodiversity, population density and immunocompetence. In addition, we analyzed examples of the effects of environmental alteration of anthropogenic origin on parasitic systems because the effects are analogous to that exerted by an extreme climatic change.

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EFFECT OF DENSITY ON HOST–PARASITE INTERACTIONS BETWEEN HYPERA POSTICA (COLEOPTERA: CURCULIONIDAE) AND BATHYPLECTES ANURUS (HYMENOPTERA: ICHNEUMONIDAE)

The Canadian Entomologist ◽

10.4039/ent1091057-8 ◽

1977 ◽

Vol 109 (8) ◽

pp. 1057-1062 ◽

Cited By ~ 5

Author(s):

M. A. Latheef ◽

K. V. Yeargan ◽

B. C. Pass

Keyword(s):

Poisson Distribution ◽

Frequency Distribution ◽

Parasite Density ◽

Significant Relationship ◽

Host Density ◽

Mutual Interference ◽

Hypera Postica ◽

Host Parasite Interactions ◽

Quadratic Relationship ◽

Host Parasite

AbstractThe effect of density on host–parasite interactions between Hypera postica (Gyllenhal) and Bathyplectes anurus (Thomson) was studied in a caged system in the laboratory. There was no significant relationship between proportion of hosts parasitized and host density. The frequency distribution of the parasite’s eggs approximated the Poisson distribution in 83% of the cases. There was a quadratic relationship between number of superparasitized hosts and parasite density. However, no significant correlation between proportion superparasitized and host density was detected. The Nicholsonian area of discovery was inversely related to parasite density with a strong mutual interference constant of −.467.

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Culture of Protozoan Parasites

Clinical Microbiology Reviews ◽

10.1128/cmr.15.3.327-328.2002 ◽

2002 ◽

Vol 15 (3) ◽

pp. 327-328 ◽

Cited By ~ 25

Author(s):

Govinda S. Visvesvara ◽

Lynne S. Garcia

Keyword(s):

Strain Differences ◽

Life Cycle Stage ◽

Life Cycles ◽

In Vitro Cultivation ◽

Protozoan Parasites ◽

Complex Life Cycles ◽

Host Parasite Interactions ◽

Host Parasite

SUMMARY The in vitro culture of protozoan parasites involves highly complex procedures, which are subject to many variables. These parasites have very complex life cycles and, depending on the life cycle stage, may require different culture parameters. However, in vitro cultivation is important for many reasons, some of which include: diagnosis, antigen and antibody production, assessment of parasite immune modulating capabilities, drug screening, improvements in chemotherapy, differentiation of clinical isolates, determination of strain differences, vaccine production, development of attenuated strains, and the continued supply of viable organisms for studying host-parasite interactions.

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Elevational Patterns of Blowfly Parasitism in Two Hole Nesting Avian Species

Diversity ◽

10.3390/d13110591 ◽

2021 ◽

Vol 13 (11) ◽

pp. 591

Author(s):

Gregorio Moreno-Rueda

Keyword(s):

Sierra Nevada ◽

Negative Impact ◽

Parus Major ◽

Climatic Conditions ◽

Life Cycles ◽

Parasite Abundance ◽

Coal Tit ◽

Elevational Variation ◽

Host Parasite ◽

High Elevations

Climate change is predicted to cause shifts in parasite distributions, leading to encounters with new hosts. Mountains offer a natural experimental background to study how parasite distributions vary across climatic gradients. Parasite abundance is generally assumed to decrease with ascending elevation, as colder climates may preclude several parasites to complete their life cycles. The present study analyses the elevational variation in the prevalence and intensity of the blowfly Protocalliphora azurea found in the nests of two hosts—the coal tit (Periparus ater) and great tit (Parus major)—in Sierra Nevada (SE Spain). Protocalliphora azurea adults are free-living flies, while their larvae are nest-dwelling parasites that feed on nestling blood. In contrast to initial predictions, P. azurea larvae were less prevalent at lower elevations. In Mediterranean environments, the colder and damper climate of medium and high elevations might favour this parasite. Alternatively, greater anthropogenic perturbation in lowland environments may have a negative impact on the parasite. The findings also show that the two host species had similar parasite loads. As coal tits are half the size of great tits, this suggests that the coal tits were more severely parasitised. In conclusion, the generalised assumption that parasite abundance decreases with elevation does not hold true for the present case and elevational parasite patterns probably depend on specific host–parasite systems and climatic conditions in the mountains.

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Temperature during the free-living phase of an ectoparasite influences the emergence pattern of the infective phase

Parasitology ◽

10.1017/s0031182013000929 ◽

2013 ◽

Vol 140 (11) ◽

pp. 1357-1367 ◽

Cited By ~ 8

Author(s):

M. AMAT-VALERO ◽

M. A. CALERO-TORRALBO ◽

F. VALERA

Keyword(s):

Environmental Influence ◽

Abiotic Factors ◽

Life Cycles ◽

Detailed Knowledge ◽

Free Living ◽

Emergence Period ◽

Host Parasite Interactions ◽

Emergence Rate ◽

Emergence Date ◽

Host Parasite

SUMMARYUnderstanding the population dynamics and co-evolution of host–parasite systems requires detailed knowledge of their phenology which, in turn, requires a deep knowledge of the effect of abiotic factors on the life cycles of organisms. Temperature is known to be a key environmental influence that participates in the regulation of diapause. Yet, not much is known about the effect of temperature on the free-living stages of true parasites and how it may influence host–parasite interactions. Here we experimentally study the effect of ambient temperature on overwintering pupae ofCarnus hemapterus(Diptera, Carnidae), an ectoparasitic fly of various bird species. We also test whether chilling is a prerequisite for completion of diapause in this species. In the course of three winter seasons we experimentally exposed carnid pupae from nests of various host species to spring temperatures with and without chilling and recorded the emergence patterns in experimental and control groups. Experimental groups showed an advanced emergence date, a lower emergence rate and, consequently, a protracted emergence period. Chilling had no obvious effect on the start of emergence but it did advance the mean emergence date, shortened the length of the emergence period when compared with the control treatment and increased the emergence rate when compared with the spring treatment. This study identifies an environmental cue, namely temperature during the free-living stage, affecting the emergence of a widespread parasite and demonstrates the plasticity of diapause in this parasite. Our findings are of potential significance in understanding host–parasite interactions.

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THE IMPORTANCE OF COINCIDENCE IN THE FUNCTIONAL AND NUMERICAL RESPONSES OF TWO PARASITES OF THE EUROPEAN PINE SAWFLY, NEODIPRION SERTIFER

The Canadian Entomologist ◽

10.4039/ent101673-7 ◽

1969 ◽

Vol 101 (7) ◽

pp. 673-713 ◽

Cited By ~ 40

Author(s):

K. J. Griffiths

Keyword(s):

Functional Response ◽

First Generation ◽

Initial Conditions ◽

Host Density ◽

Parasite Development ◽

Neodiprion Sertifer ◽

Pine Sawfly ◽

Host Parasite Interactions ◽

European Pine Sawfly ◽

Host Parasite

AbstractThe possibility of imperfect coincidence between the appropriate stages of Neodiprion sertifer (Geoff.) and two of its important parasites was demonstrated. One of the parasites, the indigenous ichneumonid Exenterus canadensis Prov., which attacks late-stage larvae, has good spatial coincidence; but some members of each generation suffer from imperfect temporal coincidence, or asynchrony, caused by the interaction of temperature influence on parasite development rate and temperature variability between development sites in the litter. The second parasite, Pleolophus basizonus (Grav.), is an introduced, multivoltine ichneumonid cocoon parasite. It may be imperfectly synchronized in its first generation each year and may show imperfect spatial coincidence in all generations through its inability to attack host cocoons beneath approximately 1 in. or more of litter.The intricate relations between parasite and host density, time, attack, and coincidence were investigated using the basic functional response submodel developed by Holling, a submodel that describes changes in oviposition behaviour with time, and a submodel that predicts the number of hosts attacked, given the number of eggs laid and data on the distribution of eggs among hosts. In the two species studied, the effect of asynchrony in one generation cannot be considered without considering the influence of superparasitism. At low host densities, superparasitism largely buffers the effects of decreased synchrony. This buffering effect decreases as host density increases until when each parasite is attacking all the hosts it can, it is almost eliminated. Imperfect spatial coincidence in one generation merely lowers the usable host density. Thus its effect can be seen in the functional response of the parasite to host density. When host–parasite interactions over 25 to 35 host generations were simulated, using initial conditions resembling those ensuing when small numbers of both host and parasite invade a previously unattacked stand, populations became stable after passing through one or more oscillations. Decreasing temporal or spatial coincidence increased host and parasite densities at the peaks of oscillations and increased the ultimate steady density of host and parasite, until coincidence was reduced to nearly half. At this level, the host escaped the regulating ability of both species of parasites.

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Relationship between bronchopulmonary nematode larvae and relative abundances of Spanish ibex (Capra pyrenaica hispanica) from Castilla-La Mancha, Spain

Journal of Helminthology ◽

10.1079/joh2005285 ◽

2005 ◽

Vol 79 (2) ◽

pp. 113-118 ◽

Cited By ~ 15

Author(s):

P. Acevedo ◽

J. Vicente ◽

V. Alzaga ◽

C. Gortazar

Keyword(s):

Host Density ◽

Population Level ◽

Life Cycles ◽

Capra Pyrenaica ◽

Mean Intensity ◽

South Central ◽

La Mancha ◽

Step Procedure ◽

Positive Correlations ◽

Host Parasite

AbstractThe excretion of bronchopulmonary nematode infective larvae was evaluated in 160 faecal samples of Spanish ibex (Capra pyrenaica hispanica) collected from 13 populations in Castilla-La Mancha, south-central Spain in September 2003. Intensities and prevalences were compared with pasture availability, abundances of wild and domestic ungulates at both levels, i.e. for populations and for faeces in a two-step procedure. Protostrongylid larvae showed similar infection rates (mean intensity: 1.56±0.12, n=94; mean prevalence: 25.62±6.86%, n=160) to Dictyocaulus spp. (mean intensity: 1.03±0.11, n=48; mean prevalence: 30.00±7.11%, n=160). At the population level, positive correlations were found between the prevalences of both bronchopulmonary taxa. The prevalence in both groups, but not intensity, also correlated positively with Spanish ibex abundance indexes both for the populations and individual faeces. These findings suggest that: (i) parasite spreading across Spanish ibex populations in Castilla-La Mancha could respond to host density-dependent processes; and (ii) these populations may have similar exposition and/or susceptibility to both bronchopulmonary taxa resulting in similar host–parasite patterns, despite their different life cycles. Bronchopulmonary outputs in the Spanish ibex from Castilla-La Mancha seems not to represent a health risk for this endemic wild ungulate but may be useful in any health surveillance scheme for the increasing populations of Spanish ibex.

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