Academic literature on the topic 'Adaptation des ectoparasites'

Currently, disgust is regarded as the main adaptation for defence against pathogens and parasites in humans. Disgust's motivational and behavioural features, including withdrawal, nausea, appetite suppression and the urge to vomit, defend effectively against ingesting or touching sources of pathogens. However, ectoparasites do not attack their hosts via ingestion, but rather actively attach themselves to the body surface. Accordingly, by itself, disgust offers limited defence against ectoparasites. We propose that, like non-human animals, humans have a distinct ectoparasite defence system that includes cutaneous sensory mechanisms, itch-generation mechanisms and grooming behaviours. The existence of adaptations for ectoparasite defence is supported by abundant evidence from non-human animals, as well as more recent evidence concerning human responses to ectoparasite cues. Several clinical disorders may be dysfunctions of the ectoparasite defence system, including some that are pathologies of grooming, such as skin picking and trichotillomania, and others, such as delusory parasitosis and trypophobia, which are pathologies of ectoparasite detection. We conclude that future research should explore both distinctions between, and overlap across, ectoparasite defence systems and pathogen avoidance systems, as doing so will not only illuminate proximate motivational systems, including disgust, but may also reveal important clinical and social consequences. This article is part of the Theo Murphy meeting issue ‘Evolution of pathogen and parasite avoidance behaviours'.

Reciprocal selective pressures can drive coevolutionary changes in parasites and hosts, and result in parasites that are highly specialized to their hosts. Selection and host co-adaptation are better understood in endoparasites than in ectoparasites, whose life cycles may be more loosely linked to that of their hosts. Blood-feeding ectoparasites use salivary proteins to prevent haemostasis in the host, and maximize energy intake. Here we looked for signals of selection in salivary protein genes of ectoparasite species from a single genus ( Cimex ) that associate with a range of hosts including mammals (bats and humans) and birds (swallows). We analysed two genes that code for salivary proteins that inhibit platelet aggregation and vasoconstriction and may directly affect the efficiency of blood feeding in these species. Significant positive selection was detected at five codons in one gene in all bat-associated species groups. Our results suggest association with bats, versus humans or swallows, has posed a selective pressure on the salivary apyrase gene in species of Cimex .

This study aimed to report an interspecific association between brown-nosed coatis (Nasua nasua) and capybaras (Hydrochoerus hydrochaeris) in an urban area of Brazil. We recorded N. nasua feeding on ectoparasites (ticks) attached to H. hydrochaeris, which in turns, did not show any reaction of discomfort with the situation. Thus, we report an unprecedented case of protocooperation between apparently unrelated species. Moreover, the interspecies interaction reveals other interesting scenarios as the inclusion of ticks in the diet of N. Nasua and the possibility of parasite transmission and adaptation to a new host species, a phenomenon known as ‘host switching’. We associate these new records as adaptations of wildlife to urbanization, and their effects should be further investigated from both wildlife conservation and ‘One Health’ approach.

Parasites significantly influence food webs and ecosystems and occur all over the world in almost every animal group. Within crustaceans there are numerous examples of ectoparasites; for example, representatives of the isopod group Cymothoidae. These obligatory parasitic isopods are relatively poorly studied regarding their functional morphology. Here we present new details of the morphological adaptations to parasitism of the cymothoiid ingroupNerocilawith up-to-date imaging methods (macro photography, stereo imaging, fluorescence photography, micro CT, and histology). Central aspects of the study were (1) the morphology of the mouthparts and (2) the attachment on the host, hence the morphology of the thoracopods. The mouthparts (labrum, mandibles, paragnaths, maxillulae, maxillae, maxillipeds) form a distinct mouth cone and are most likely used for true sucking. The mouthparts are tightly “folded” around each other and provide functional rails for the only two moving mouthparts, mandible and maxillula. Both are not moving in an ancestral-type median-lateral movement, but are strongly tilted to move more in a proximal-distal axis. New details concerning the attachment demonstrate that the angular arrangement of the thoracopods is differentiated to impede removal by the host. The increased understanding of morphological adaptation to parasitism of modern forms will be useful in identifying disarticulated (not attached to the host) fossil parasites.

Ectoparasites such as louse flies (Diptera: Hippoboscidae) have tendency for host specialization, which is driven by adaptation to host biology as well as competition avoidance between parasites of the same host. However, some louse fly species, especially in genera attacking birds, show wide range of suitable hosts. In the presented study, we have surveyed the current status of bird specific louse flies in Finland to provide comprehensive host association data to analyse the ecological requirements of the generalist species. A thorough sampling of 9342 birds, representing 134 species, recovered 576 specimens of louse flies, belonging to six species: Crataerina hirundinis, C. pallida, Ornithomya avicularia, O. chloropus, O. fringillina and Ornithophila metallica. Despite some overlapping hosts, the three Ornithomya species showed a notable pattern in their host preference, which was influenced not only by the host size but also by the habitat and host breeding strategy. We also provide DNA barcodes for ten Finnish species of Hippoboscidae, which can be used as a resource for species identification as well as metabarcoding studies in the future.

We test the hypothesis that living on larger fish may impose constraints, i.e. the need to develop large attachment organs, related to the necessity to remain attached on large gills. For this, we compiled data on body size and morphometric measurements of attachment organs of 44 Dactylogyrus species (ectoparasites with direct life-cycle) from 19 cyprinid species. Nineteen dactylogyrid species were considered as specialists (infecting only 1 host species) and 25 as generalists (infecting more than 1 species). The lack of phylogenetic information lead us to perform comparative analyses using raw values and independent contrasts obtained by random phylogenies. Our results show that rich parasite communities are formed by specialists and generalists whereas poor communities are composed mainly of generalist parasites. Moreover, specialists are found on larger hosts, which may reflect a specialization on a predictable resource, as larger fish live longer and offer large gills for parasite colonization. Parasite specialization is shown to be linked with adaptation of attachment organs to their fish hosts. Two morphometric variables of the attachment organ, the total length of anchor and length of base of anchor, were positively correlated with host length for specialists.

Carassius gibelio is an extraordinary cyprinid species exhibiting both sexual and asexual reproduction. We hypothesized that parasitism selection is one of the potential mechanisms contributing to the coexistence of the two reproductive forms of C. gibelio living in the same habitat. We performed a four-year study to investigate the dynamics of parasite infection in C. gibelio. According to the Red Queen prediction, the asexual form is a target of parasite adaptation due to its low genetic variability. Both sexual and gynogenetic forms of C. gibelio exhibited similar levels of prevalence, with monogeneans being the most frequently observed parasite group. We observed the temporal dynamics of parasite infection in the last year of investigation, when both forms were more strongly parasitized. The sexual form was more parasitized by ectoparasites in the first and last years and less parasitized by nematodes in the last year when compared to the gynogenetic form. We found no trend of high parasite infection in gynogenetic mtDNA haplotypes. We conclude that Red Queen dynamics is not the mechanism driving parasite infection in sexual-gynogenetic C. gibelio over a long time scale. Alternatively, we suggest that the dynamics of parasite infection in this complex may be generated by multiple mechanisms.

Ectoparasite host specificity can be influenced by factors such as the degree of host isolation and ectoparasite mobility. Host-site specificity can result from factors such as proximity to mates, competition, and host grooming behaviour. Ectoparasitic bat flies on bats from the Lamanai area of Belize were collected from hosts captured in mist nets to determine host specificity and host-site specificity. Bat grooming behaviour was also recorded and quantified. From 455 bats (25 species in five families), 773 bat flies (32 species in two families) were collected. Of 32 bat fly species, 25 were only found on 1 bat species, 6 were found on 2 species of the same genus, and 1 was found on 2 species of different genera (the latter appearing to be an accidental association). Specificity of the bat flies tended to follow the taxonomy of the bat hosts, not the ecological isolation of the host species, since bat species that often roost in polyspecific groups did not share bat fly species. Mobility of the bat flies was not related to host specificity. Host-site specificity of bat flies occurred for either fur or membrane on the host, and long hind legs and ctenidia appear to be morphological adaptations for living in fur. Bat grooming behaviour was consistent with the assumptions of a simulation model, which suggested that host grooming could be responsible for host-site segregation of bat flies.

Made available in DSpace on 2015-04-17T14:55:28Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 1250638 bytes, checksum: d83f38db8255b998ec13aaf8ad13c20b (MD5) Previous issue date: 2013-04-30
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Parasite is an organism that lives inside (endo) or in surface (ectoparasites) from another organism, the host, feeding, showing some degree of adaptation and causing some damage to it. In Brazil one of the most commonly found lizard is the Cnemidophorus ocellifer, active forager, with wide national distribution except Amazon, and diurnal heliotherms, which mainly inhabits open areas. Therefore, this study aims to characterize the patterns of infestation by parasites in populations of C. ocellifer in four ecoregions of northeastern Brazil, the abundance, composition, diversity and body distribution. We examined 399 specimens of C. ocellifer. Eutrombicula alfreddugesi was the only ectoparasite species found in all populations studied. The Sete Cidades population was the most parasitized with 9,819 mites found, and the population of Barra Cunhaú was less parasitized, with only 445 individuals and 66 mites free from ectoparasites. We found six types of endoparasites: Platyhelminths Cestoda (n=49) and Nemathelminths Pharyngodon sp. (n=1633) in stomachs and intestines, Nemathelminths Piratuba sp. (n=6), Oswaldofilaria sp. (n=17) and Physaloptera spp. (n=1), only in coelomic cavities in Sete Cidades, and Pentastomid Raillietiella mottae (n=5) in the lungs only in Barra do Cunhaú. For ectoparasites males are significantly more infested than females and this is probably linked to the inverse relationship that exists between testosterone levels in the blood and immune system efficiency. The sites of infestation were instrumental in the infestation by ectoparasites in all populations studied, indicating mainly post-inguinal regions as significantly more infested sites in all populations. These results are not only related to the presence of dermal folds in these regions, since there are folds in other parts of the body of these lizards and they showed no such significant results. The infestation was also partially influenced by the environment, but it may be that this is influenced by secondary factors and not necessarily environmental. Body condition, another fitness parameter, was also partially influenced by parasitic infestation, but not as expected, where most infected individuals have better body condition, refuting the hypothesis (individuals with greater intensity would be less parasitic body condition score). An overview of all these results suggests that the infestation by ectoparasites can be associated with characteristics of fitness and sexual selection, corroborating the Handicap Theory. If not this way, a parasite can present with its host, a neutral relationship (comensal) or even positive, even at low level (mutual). Endoparasites may be acting illegitimate way, without the hosts in no way benefit from this interaction, but can at least present a pattern of species diversity known for other taxa.
Parasita é um organismo que vive dentro (endoparasitas) ou na superfície (ectoparasitas) de outro organismo, o hospedeiro, se alimentando, apresentando certo grau de adaptação e causando algum dano ao mesmo. No Brasil um dos lagartos mais comumente encontradas é Cnemidophorus ocellifer, forrageador ativo, de ampla distribuição nacional exceto Amazônia, heliófilo e diurno, que habita principalmente áreas abertas. Sendo assim, o presente estudo tem como objetivo caracterizar e testar hipóteses sobre os padrões de infestação por parasitas em populações de C. ocellifer de quatro ecorregiões do Nordeste Brasileiro, quanto à abundância, composição, diversidade e distribuição corporal, bem como sobre os efeitos da intensidade parasitária sobre a aptidão dos hospedeiros. Foram examinados 399 exemplares de C. ocellifer de quatro populações: Barra do Cunhaú/RN, Cabaceiras/PB, PARNA Sete Cidades/PI e REBIO Guaribas/PB. Eutrombicula alfreddugesi foi a única espécie de ectoparasita encontrada em todas as populações estudadas. A população de Sete Cidades/PI foi a mais parasitada, com 9.819 ácaros encontrados, e a população de Barra do Cunhaú/RN foi a menos parasitada, com apenas 445 ácaros e 66 indivíduos livres de ectoparasitas. Foram encontrados seis tipos de endoparasitas: Platelmintos Cestoda (n=49) e Nematelmintos Pharyngodon sp. (n=1.633), em estômagos e intestinos; Nematelmintos Piratuba sp. (n=6), Oswaldofilaria sp. (n=17) e Physaloptera sp. (n=1), em cavidades celomáticas (apenas em Sete Cidades); e o Pentastomídeo Raillietiella mottae (n=5) nos pulmões dos indivíduos de Barra do Cunhaú. Para ectoparasitas os machos são significativamente mais infestados que fêmeas e isso provavelmente está ligado à relação inversamente proporcional que existe entre as taxas de testosterona no sangue e a eficiência do sistema imune. Os sítios de infestação foram determinantes para a infestação por ectoparasitas em todas as populações estudadas, indicando principalmente as regiões pósinguinais como os sítios significativamente mais infestado em todas as populações. Esses resultados não estão relacionados apenas a presença de dobras dérmicas nessas regiões, já que existem dobras em outras partes do corpo desses lagartos e elas não apresentaram, significativamente, altas infestações. A infestação também foi parcialmente influenciada pelo ambiente, mas pode ser que essa influência seja por fatores secundários e não necessariamente ambientais. A condição corporal, outro parâmetro de aptidão, também foi parcialmente influenciada pela infestação parasitária, mas não como esperado, onde indivíduos mais parasitados apresentaram melhor condição corporal, refutando a hipótese mencionada na introdução (indivíduos com maior intensidade parasitária teriam menor índice de condição corporal). Um apanhado geral de todos esses resultados sugere que a infestação por ectoparasitas pode estar associada a características de aptidão e seleção sexual, corroborando a Teoria da Desvantagem. Se não dessa forma, um parasita pode apresentar, com seu hospedeiro, uma relação neutra (comensalista) ou até mesmo positiva, mesmo que em baixo nível (mutualista). Os endoparasitas podem estar atuando de forma espúria, sem que os hospedeiros em nada se beneficiem com essa interação, mas podem ao menos apresentar um padrão de diversidade de espécies conhecido para outros táxons.

L’évolution divergente est un processus clef générant de la biodiversité. Elle peut avoir lieu entre localités, via la réduction des flux de gènes, et au sein des localités via la spécialisation écologique. Dans le cas des systèmes parasitaires multi-hôtes, l’adaptation dépend des taux relatifs de flux de gènes des hôtes et des parasites entre différentes localités, ainsi que des échanges locaux de parasites entre différents types d’hôtes. En combinant génétique des populations et expérimentations sur le système composé de la puce Ceratophyllus gallinae et deux de ses hôtes, la mésange charbonnière Parus major et le gobe-mouche à collier Ficedula albicollis dans un habitat fragmenté, nous avons examiné comment l’adaptation et l’isolation génétique façonnent l’évolution des parasites. Nous avons aussi testé comment les choix d’habitat des hôtes pouvaient influencer la rencontre avec des populations de parasites spécialisées. Les analyses de microsatellites révèlent que les populations de puce sont différenciées à une échelle spatiale fine, et fréquemment entre espèces hôtes. De plus, des populations de parasites semblent adaptées à chaque type d’hôte. Cependant, aucune variation dans les choix d’habitats par rapport aux parasites n’a été observée chez les hôtes. Enfin, la réponse des hôtes aux parasites variait entre nos deux zones réplica ; l’histoire des populations d’hôtes pourrait donc influer sur la coevolution avec leurs parasites. Ce système semble donc localement façonné à la fois par une isolation génétique et une sélection par différents hôtes. L’étude de nouveaux sites permettraient d’évaluer si cette évolution divergente peut être génératrice de biodiversité
Divergent evolution is a key process generating biodiversity. This can occur between localities, through reduced gene flow followed by local adaptation or genetic drift, and within localities through ecological specialization. In the case of multi-host parasite systems, adaptation can be driven by the relative rate of host-parasite gene flow among spatially isolated populations, and the amount of parasite exchange among local host types. Combining population genetics and field experiments, we examined how adaptation and genetic isolation shape parasite evolution. Focusing on the hen flea Ceratophyllus gallinae, a presumed host generalist, and two of its hosts, the great tit Parus major and the collared flycatcher Ficedula albicollis, we investigated parasite population structure and adaptation within a fragmented landscape. Additionally, we tested how hosts can influence encounter rates with specialized flea populations through their habitat choice. Neutral markers analyses show that flea populations are genetically differentiated at fine spatial scales, and frequently between the two host species. Evidence for parasite adaptation to each host type were also observed. Host specialization may therefore be ongoing in hen fleas. However, birds did not show specific habitat choice strategies regarding flea-infested nests. Host responses differed between two replicate sites, indicating that local population history may impact parasite evolution. Both isolation and host-based selection are therefore acting on hen flea populations at a local scale. Investigations in new localities will help to assess to what extend this divergent evolution may generate biodiversity

Made available in DSpace on 2016-06-02T19:22:04Z (GMT). No. of bitstreams: 1 2037.pdf: 7513733 bytes, checksum: ae85e56e3e497054d13c4189f0a93d84 (MD5) Previous issue date: 2006-12-21
The freshwater fish louse Dolops carvalhoi is an ectoparasite of pacu, Piaractus mesopotamicus capable of causing substantial damage to its hosts. The aim of this study was to investigate some aspects of the host-parasite interaction between these two species. For this purpose the physiological and morphological responses and the participation of the non-adaptive immune system of pacu to the experimental infestation with D. carvalhoi were analyzed. Three different experimental protocols were designed in order to find out the effects of the parasites on their hosts, the host responses that may interfere with parasite establishment and the influence of chronic exposure of hosts with juvenile D. carvalhoi to a second acute stressor of confinement. The results showed that even low level of adult parasite infestation is capable to induce a stress response in the hosts. No changes were observed regarding the plasma osmoregulatory parameters, while an increased number of gill chloride cells and enhanced N+/K+-ATPase activity suggested that gill adaptive adjustments may be responsible for the maintenance of hydromineral homeostasis in P. mesopotamicus during the stressful situation imposed by parasites. The infestation also induced changes in the frequency of circulating blood defense cells and in the epidermis morphology of the hosts. These responses were considered to be adaptive and they points out to the activation and participation of the non-specific immune system during the time course of infestation. Hosts which have experienced a previous D. carvalhoi infestation displayed a lower infestation density and different patterns of physiological, morphological and immunological responses when they were submitted to a re-infestation. Macrophages were activated in both infested and previously infested fish. The increased density of mucous cells in the epidermis of previously infested fish suggests the participation of mucus in the defense mechanisms and possibly in the parasite detachment. Chronic infestation with juvenile parasites did not induce a stress response in the hosts. On the other hand, they were capable of modulating the stress response of fish to a second acute stressor. In conclusion, infestation with D. carvalhoi induced physiological and morphological responses in P. mesopotamicus, which were considered to be adaptive, and activated the non-adaptive immune mechanisms of the hosts in order to cope with the stress and damages imposed by parasites.
O piolho-de-peixe branquiúro Dolops carvalhoi é um ectoparasito normalmente encontrado infestando pacus, Piaractus mesopotamicus, sendo capaz de causar-lhes danos substanciais. O objetivo do presente estudo foi investigar alguns aspectos da relação parasito-hospedeiro entre estas duas espécies. Para tal propósito, as respostas fisiológicas e morfológicas e a participação do sistema imune não-adaptativo de pacus experimentalmente infestados com D. carvalhoi foram analisadas. Três protocolos experimentais diferentes foram desenhados com o intuito de se investigar os efeitos dos parasitos sobre seus hospedeiros, as respostas dos hospedeiros que possam interferir no estabelecimento dos parasitos e a influência da exposição crônica dos hospedeiros às formas jovens de D. carvalhoi sobre as respostas ao estresse agudo de confinamento. Os resultados mostraram que mesmo baixos níveis de infestação com parasitos adultos são capazes de induzir uma resposta ao estresse nos hospedeiros. Nenhuma alteração foi verificada com relação aos parâmetros plasmáticos osmorregulatórios, enquanto que um aumento no número de células cloreto nas brânquias e na atividade específica da enzima Na+/K+-ATPase sugeriram que ajustes branquiais adaptativos podem ter sido responsáveis pela manutenção do equilíbrio hidroeletrolítico em P. mesopotamicus durante a situação de estresse imposta pelos parasitos. A infestação induziu também mudanças na freqüência de células sanguíneas de defesa circulantes e na morfologia da epiderme dos hospedeiros. Estas respostas foram consideradas adaptativas e elas apontam para a participação do sistema imune não-adaptativo durante o período de infestação. Hospedeiros que experimentaram uma infestação prévia com D. carvalhoi apresentaram uma menor densidade de infestação e diferentes padrões de respostas fisiológicas, morfológicas e imunológicas quando foram submetidos a uma reinfestação. Os macrófagos foram ativados tanto em animais infestados quanto em previamente infestados. O aumento na densidade de células mucosas na epiderme de peixes previamente infestados sugere a participação do muco nos mecanismos de defesa e, possivelmente, na rejeição dos parasitos por parte dos hospedeiros. Infestações crônicas com as formas jovens dos parasitos não induziram respostas ao estresse nos hospedeiros. Por outro lado, elas foram capazes de modular as respostas ao estresse em peixes submetidos a um estressor agudo. Em conclusão, a infestação com D. carvalhoi induziu respostas fisiológicas e morfológicas em P. mesopotamcius, que foram consideradas adaptativas, e ativou os mecanismos de imunidade inata dos hospedeiros, permitindo que estes sobrevivessem ao estresse e outros danos impostos pelos parasitos.