Search results for "Crustacea"
showing 10 items of 244 documents
Experimental evidence for a hierarchy of mate- and host-induced cues in a fish ectoparasite, Argulus coregoni (Crustacea: Branchiura)
2007
Argulus coregoni is an ectoparasite primarily infesting freshwater salmonids. Sexually reproducing parasites such as A. coregoni are confronted with a dilemma between finding a mate and the costs involved in doing so; if mating partners are unavailable on a host, by leaving to search for a mate on a new host, the parasite is exposed to risks such as predation and energy loss. The utilization of chemical cues could enhance the probability of finding a host and/or a suitable mating partner and thus decrease the level of costs associated with detachment from the host. In this study we constructed a Y-maze arena to determine if adult A. coregoni respond to mate- and host-related chemical cues. …
Genetic evidence confirms polygamous mating system in a crustacean parasite with multiple hosts.
2014
Mating systems are diverse in animals, notably in crustaceans, but can be inferred from a limited set of parameters. Baeza and Thiel (2007) proposed a model predicting mating systems of symbiotic crustaceans with three host characteristics and the risk of predation. These authors proposed five mating systems, ranging from monogamy to polygynandry (where multiple mating occurs for both genders). Using microsatellite loci, we tested the putatively mating system of the ectoparasite crab Dissodactylus primitivus. We determined the mating frequencies of males and females, parentage assignment (COLONY & GERUD software) as well as the contents of female spermathecae. Our results are globally consi…
The effect of the acanthocephalan parasite Pomphorhynchus laevis on the lipid and glycogen content of its intermediate host Gammarus pulex
2001
Besides conspicuous changes in behaviour, manipulative parasites may also induce subtle physiological effects in the host that may also be favourable to the parasite. In particular, parasites may be able to influence the re-allocation of resources in their own favour. We studied the association between the presence of the acanthocephalan parasite, Pomphorhynchus laevis, and inter-individual variation in the lipid and glycogen content of its crustacean host, Gammarus pulex (Amphipoda). Infected gravid females had significantly lower lipid contents than uninfected females, but there was no difference in the lipid contents of non-gravid females and males that were infected with P. laevis. In c…
Carbonic anhydrase activity in a calcium-mobilizing epithelium of the crustacean Orchestia cavimana during molting
1987
We investigated the involvement of the enzyme, carbonic anhydrase, in the calcification-decalcification processes occurring in the posterior caeca of the midgut of the terrestrial crustacean, Orchestia cavimana, before and after exuviation. This enzyme was ultrahistochemically localized throughout the membranes of the caecal epithelium as well as extracellularly, i.e., within pre-exuvial calcareous concretions and postexuvial calcified spherules. During the molt cycle, the pattern of carbonic anhydrase activity in the posterior caeca was correlated with the calcium content at this level. Acetazolamide treatment in vivo inhibited about 50% of the calcium uptake during both pre-exuvial secret…
ISOPOD (ASELLUS AQUATICUS) SIZE AND ACANTHOCEPHALAN (ACANTHOCEPHALUS LUCII) INFECTIONS
2007
We examined the effect of isopod size and age on the success of an acanthocephalan infection and on the effects of that infection on the growth and survival of the isopods. Groups of isopods (Asellus aquaticus) belonging to 4 size classes (juveniles, maturing adults, young adults, and older adults) were exposed to infective acanthors of Acanthocephalus lucii. At the end of the experiment, survival of the isopods, lengths of male and female isopods, and numbers of different developmental stages of A. lucii larvae in infected isopods were assessed. Acanthocephalus lucii prevalence was significantly lower in juvenile isopods than in adults. Intensity of infection increased with the size of iso…
Coexistence of three microsporidia parasites in populations of the freshwater amphipod Gammarus roeseli: evidence for vertical transmission and posit…
2004
We investigated the prevalence, transmission mode and fitness effects of infections by obligatory intracellular, microsporidian parasites in the freshwater amphipod Gammarus roeseli. We found three different microsporidia species in this host, all using transovarial (vertical) transmission. All three coexist at different prevalences in two host populations, but bi-infected individuals were rarely found, suggesting no (or very little) horizontal transmission. It is predicted that vertically-transmitted parasites may exhibit sex-specific virulence in their hosts, or they may have either positive or neutral effects on host fitness. All three species differed in their transmission efficiency an…
Differential phenoloxidase activity between native and invasive gammarids infected by local acanthocephalans: differential immunosuppression?
2003
Manipulative endoparasites can alter the behaviour and the physiology of their intermediate hosts in ways that increase the probability of successful transmission to the final host. This requires that the parasite is able to circumvent its host's immune defence. Successful immune evasion may depend on host-parasite coevolutionary history and the appearance of new hosts invading the local host population may promote local parasite maladaptation. To test this hypothesis, we examined the effect of 2 acanthocephalan parasites, Pomphorhynchus laevis and Polymorphus minutus, on the immunity of their local and new invasive gammarid intermediate hosts, respectively Gammarus pulex and Gammarus roese…
Exceptional cryptic diversity and multiple origins of parthenogenesis in a freshwater ostracod.
2009
The persistence of asexual reproduction in many taxa depends on a balance between the origin of new asexual lineages and the extinction of old ones. This turnover determines the diversity of extant asexual populations and so influences the interaction between sexual and asexual modes of reproduction. Species with mixed reproduction, like the freshwater ostracod (Crustacea) morphospecies Eucypris virens, are a good model to examine these dynamics. This species is also a geographic parthenogen, in which sexual females and males co-exist with asexual females in the circum-Mediterranean area only, whereas asexual females occur all over Europe. A molecular phylogeny of E. virens based on the mit…
EFFECT OF TRIAENOPHORUS CRASSUS (CESTODA) INFECTION ON BEHAVIOR AND SUSCEPTIBILITY TO PREDATION OF THE FIRST INTERMEDIATE HOST CYCLOPS STRENUUS (COPE…
2000
Some parasites have been shown to manipulate host behavior so that parasite transmission to the next host is enhanced. Infection with Triaenophorus crassus Forel (Cestoda) caused alterations in the activity and microhabitat selection of the first intermediate host Cyclops strenuus Fischer (Copepoda) in the laboratory. Infected copepods made more starts to swim but spent less time swimming than uninfected copepods. These changes were independent of the intensity of infection. In a water column illuminated from above, infected copepods approached the surface, whereas uninfected ones remained close to the bottom. In the dark both infected and uninfected copepods stayed near the bottom. Finally…
PARASITIC INFECTION AND DEVELOPMENTAL STABILITY: FLUCTUATING ASYMMETRY IN GAMMARUS PULEX INFECTED WITH TWO ACANTHOCEPHALAN SPECIES
2002
Several studies have reported a negative association between developmental stability and parasitic infection. However, the host-parasite associations examined so far consist only of a limited number of parasite taxa, and developmental stability was appraised on definitive hosts. The present study examines the association between infection by 2 acanthocephalan parasites. Pomphorhynchus laevis and Polymorphus minutus, and the developmental stability of their common intermediate host Gammarus pulex. Developmental stability was estimated from the fluctuating asymmetry (FA) levels of 6 morphological traits. A positive association was found between FA and infection. Infected gammarids tended to b…