Variation and covariation in infectivity, virulence and immunodepression in the host–parasite association
            Gammarus pulex
            –
            Pomphorhynchus laevis

Parasites often manipulate host immunity for their own benefit, either by exacerbating or suppressing the immune response and this may directly affect the expression of parasite virulence. However, genetic variation in immunodepression, which is a prerequisite to its evolution, and the relationship between immunodepression and virulence, have rarely been studied. Here, we investigated the variation among sibships of the acanthocephalan parasite, Pomphorhynchus laevis , in infecting and in immunodepressing its amphipod host, Gammarus pulex . We also assessed the covariation between infectivity, parasite-induced immune depression and host mortality (parasite virulence). We found that infectivity, the intensity of immunodepression and virulence were variable among parasite sibships. Infectivity and the level of immunodepression were not correlated across parasite sibships. Whereas infectivity was unrelated to host mortality, we found that gammarids that were exposed to the parasite sibships that immunodepressed their hosts the most survived better. This positive covariation between host survival and immunodepression suggests that gammarids exposed to the less immunodepressive parasites could suffer from damage imposed by a higher activity of the phenoloxidase.

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The effect of the acanthocephalan Pomphorhynchus laevis upon the respiration of its intermediate host, Gammarus pulex

Parasitology ◽

10.1017/s0031182000045789 ◽

1974 ◽

Vol 68 (2) ◽

pp. 271-284 ◽

Cited By ~ 39

Author(s):

A. E. Rumpus ◽

C. R. Kennedy

Keyword(s):

Oxygen Consumption ◽

Oxygen Uptake ◽

Host Population ◽

Gammarus Pulex ◽

Multiple Infections ◽

Pomphorhynchus Laevis ◽

Respiration Rates ◽

Physiological Processes ◽

Stage Of Development ◽

Host Parasite

The respiration rates of individual Gammarus pulex infected by larval Pomphorhynchus laevis were investigated with particular reference to the stage of development of the host and parasite and to the water temperature. At 20°C the oxygen consumption of Gammarus of all sizes was reduced by an average of 19·3 % by the presence of cystacanths of the parasite, but was unaffected by the presence of acanthellae. It is considered that the small size of this larval stage, in relation to that of its host, is responsible for the failure to detect an effect. Multiple infections did not exert any greater effect upon host respiration than single cystacanths, nor did it appear that the parasite had different effects upon hosts of different sexes. At 10°C no significant differences were observed between the respiration rates of infected and uninfected gammarids. The parasite was probably still depressing the host respiration rate at this temperature, but the oxygen uptake of G. pulex is so low that the differences between infected and uninfected individuals were too small to be detected. The parasite has a direct effect upon the physiological processes of the host, but neither the mechanism of this nor the reasons for the different effects found in different host-parasite systems are yet understood. Despite the pronounced effect of P. laevis on respiration of individual hosts, its effect upon the oxygen consumption of a natural host population is small since only a small proportion of the population carries infections and water temperatures remain below 10°C for over half the year.

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Phylogeny affects host's weight, immune response and parasitism in damselflies and dragonflies

Royal Society Open Science ◽

10.1098/rsos.160421 ◽

2016 ◽

Vol 3 (11) ◽

pp. 160421 ◽

Cited By ~ 9

Author(s):

Jaakko J. Ilvonen ◽

Jukka Suhonen

Keyword(s):

Immune Response ◽

Body Mass ◽

Large Scale ◽

Phylogenetic Signal ◽

Strong Association ◽

Immune Defence ◽

Water Mite ◽

Host Parasite ◽

The Relationship ◽

Dragonfly Species

Host–parasite interactions are an intriguing part of ecology, and understanding how hosts are able to withstand parasitic attacks, e.g. by allocating resources to immune defence, is important. Damselflies and dragonflies show a variety of parasitism patterns, but large-scale comparative immune defence studies are rare, and it is difficult to say what the interplay is between their immune defence and parasitism. The aim of this study was to find whether there are differences in immune response between different damselfly and dragonfly species and whether these could explain their levels of gregarine and water mite parasitism. Using an artificial pathogen, a piece of nylon filament, we measured the encapsulation response of 22 different damselfly and dragonfly species and found that (i) there are significant encapsulation differences between species, (ii) body mass has a strong association with encapsulation and parasite prevalences, (iii) body mass shows a strong phylogenetic signal, whereas encapsulation response and gregarine and water mite prevalences show weak signals, and (iv) associations between the traits are affected by phylogeny. We do not know what the relationship is between these four traits, but it seems clear that phylogeny plays a role in determining parasitism levels of damselflies and dragonflies.

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The effect of the acanthocephalan parasite Pomphorhynchus laevis on the lipid and glycogen content of its intermediate host Gammarus pulex

International Journal for Parasitology ◽

10.1016/s0020-7519(01)00115-1 ◽

2001 ◽

Vol 31 (4) ◽

pp. 346-351 ◽

Cited By ~ 68

Author(s):

Stewart J Plaistow ◽

Jean-Phillipe Troussard ◽

Frank Cézilly

Keyword(s):

Intermediate Host ◽

Glycogen Content ◽

Gammarus Pulex ◽

Pomphorhynchus Laevis ◽

Acanthocephalan Parasite

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Carbohydrate titres in the haemolymph and midgut glands of Gammarus pulex infected with the acanthocephalan Pomphorhynchus laevis

Journal of Helminthology ◽

10.1017/s0022149x00015236 ◽

1996 ◽

Vol 70 (2) ◽

pp. 103-107 ◽

Cited By ~ 11

Author(s):

C.R. Bentley ◽

H. Hurd

Keyword(s):

Linear Relationship ◽

Intermediate Host ◽

Gammarus Pulex ◽

Midgut Gland ◽

Pomphorhynchus Laevis ◽

Chow Test ◽

Wet Weight ◽

The Relationship

AbstractAn examination of the effects of Pomphorhynchus laevis cystacanths on the haemolymph and midgut gland carbohydrate titres of its intermediate host, Gammarus pulex (Crustacea) was undertaken. In the haemolymph, infection with cystacanths did not alter the relationship between haemolymph carbohydrate titres and body wet weight. However, in the midgut glands, infection did alter the relationship between gammarid wet weight and titres of glucose and trehalose (P<0.05, Chow test). The linear relationship between gammarid size and midgut glycogen titre was also significantly altered by infection. Thus circulating carbohydrate titres are unaltered in infected gammarids but storage ones are. The changes in carbohydrate titres and the relationship between individual titres and body wet weight are discussed, especially regarding parasite index.

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Stage-dependent behavioural changes but early castration induced by the acanthocephalan parasite Polymorphus minutus in its Gammarus pulex intermediate host

Parasitology ◽

10.1017/s0031182017001457 ◽

2017 ◽

Vol 145 (3) ◽

pp. 260-268 ◽

Cited By ~ 6

Author(s):

YANN BAILLY ◽

FRANK CÉZILLY ◽

THIERRY RIGAUD

Keyword(s):

Significant Variation ◽

Developmental Stages ◽

Life Cycles ◽

Gammarus Pulex ◽

Complex Life Cycles ◽

Behavioural Changes ◽

Single Mechanism ◽

Behavioural Alteration ◽

Host Parasite ◽

Acanthocephalan Parasite

SUMMARYMultidimensionality in parasite-induced phenotypic alterations (PIPA) has been observed in a large number of host–parasite associations, particularly in parasites with complex life cycles. However, it is still unclear whether such a syndrome is due to the successive activation of independent PIPAs, or results from the synchronous disruption of a single mechanism. The aim of the present study was to investigate the onset and progression of two PIPAs (a behavioural alteration: reversion of geotaxis, and castration) occurring in the crustacean amphipod Gammarus pulex infected with the acanthocephalan Polymorphus minutus, at different parasite developmental stages. Modifications of geotaxis in hosts differed according to the parasite developmental stage. Whereas the cystacanth stage induced a negative geotaxis (exposing the gammarid to predation by birds, the definitive hosts), the acanthella stage, not yet infective for the definitive host, induced a stronger positive geotaxis (presumably protecting gammarids from bird predation). In contrast, castration was almost total at the acanthella stage, with no significant variation in the intensity according to parasite maturation. Finally, no significant correlation was found between the intensity of behavioural changes and the intensity of castration. We discuss our results in relation with current views on the evolution of multidimensionality in PIPA.

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The influence of Hymenolepis diminuta on the survival and fecundity of the intermediate host, Tribolium confusum

Parasitology ◽

10.1017/s0031182000056134 ◽

1980 ◽

Vol 81 (2) ◽

pp. 405-421 ◽

Cited By ~ 47

Author(s):

Anne E. Keymer

Keyword(s):

Experimental Study ◽

Intermediate Host ◽

Parasite Burden ◽

Tribolium Confusum ◽

Hymenolepis Diminuta ◽

Density Dependent ◽

Host Mortality ◽

Host Parasite ◽

The Relationship ◽

High Parasite

SUMMARYAn experimental study of the effects of parasitism by H. diminuta on the intermediate host, Tribolium confusum, is described. No density- dependent constraints on parasite establishment within individual hosts are evident, although a reduction in cysticercoid size at high parasite burdens is demonstrated. The relationship between parasite burden, host mortality and host fecundity is investigated. Host mortality is linearly related to parasite burden, whereas the relationship between parasite burden and host fecundity is non-linear. There is no difference in viability between eggs from infected and uninfected females. The generative causes of these effects are not investigated experimentally, although it is postulated that survival is related to the degree of damage to the midgut wall caused by parasite penetration, and fecundity to the biomass of parasites harboured by the host. The significance of these effects is discussed in relation to the overall dynamics of the host-parasite association.

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