Chemical control of Ornithonyssus sylviarum on caged layer hens

Manual application of aqueous solutions of malathion, carbaryl and permethrin controlled northern fowl mite, Ornithonyssus sylviarum Canestrini and Fanzago, on caged layer hens for at least 118 days. Azamethiphos sprayed manually provided acceptable control for a shorter period. Machine application, particularly of azamethiphos, but also malathion, provided lesser control. The addition of surfactant increased the wetting ability of the sprays but interfered with the efficacy of azamethiphos.     

Factors affecting the feeding of northern fowl mites, Ornithonyssus sylvarium, through a membrane

Northern fowl mites, Ornithonyssus sylviarum (Canestrini & Fanzago) (Acari: Macronyssidae), were fed artificially through chick skin membranes to investigate several factors that affected the degree of mite feeding. More mites fed after starving 24 h than unstarved mites or mites starved 48 or 72 h. Protonymphs fed as well as adults. More mites fed on refrigerated blood than on fresh blood and on frozen blood than on refrigated blood. However, mites fed well on newly drawn blood that had been lysed. They fed as well on plasma and serum as on whole blood but less well on washed erythrocytes. They also fed well on citrated blood, but fewer mites fed on oxalated blood or freshly defibrinated blood.

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Résumé O. sylviarum Canestri & Fanzago a été alimenté artificiellement pour étudier plusieurs facteurs qui affectent l'intensité de la prise de nourriture. Le dispositif d'alimentation consistait en un cylindre de verre de 24 mm de long, dont les ouvertures étaient fermées, à une extrémité par une membrane en peau de volaille, et à l'autre extrémité avec du polyéthylène.Après un jeûne de 24 h, le nombre de pucerons qui s'étaient alimentés était plus élevé (87%) qu'après un jeûne de 48 ou 72 h (respectivement 71 et 73%) ou en absence de jeûne (11%). Les protonymphes se sont aussi bien alimentées que les adultes; elles ont été significativement plus nombreuses à le faire aprés 2 h (84%) qu'après 1 h (71%). Le sang refroidi pendant une nuit, ou pendant une ou 2 semaines a été consommé par un plus grand nombre d'acariens (59%, 70% et 78%) que le sang frais (46%); les différences entre durées voisines ne sont pas significatives, mais elles le sont entre une nuit et deux semaines. Le sang congelé pendant 1, 2 ou 4 semaines a été consommé par un plus grand nombre d'acariens (87%, 90% et 82%) que le sang refroid: la consommation était aussi bonne pour les différentes durées de congélation. Puisque les acariens se sont bien alimentés sur sang lysé (75%), les matériaux propres au sang frais devaient être tombés hors d'atteinte des pièces bucales des acariens. Autant se sont alimentés sur plasma (87%), sérum (79%) que sur sang complet (85%), mais ils ont été moins nombreux à le faire sur érythrocytes lavés (69%); ils ont été nombreux à le faire sur sang citraté (87%), mais en plus faible nombre sur sang oxalaté (66%) ou défibriné depuis peu (32%). Le taux de mortalité des acariens qui avaient consommé du sang oxalaté était élevée (25%), à l'opposé de celui observé après alimentation sur sang citraté (6%) ou sang héparinisé (9%). Le sang défibriné n'était pas lysé, et ales érythrocytes étaient probablement hors d'atteinte, et ainsi, non ingérés par les acariens.

     

Description of a new species of Haemogamasus (Mesostigmata, Laelapidae, Haemogamasinae) from Chubut, Río Negro and Neuquén Provinces, Argentina

A new species of Haemogamasus mites is described from Chubut, Neuquén and Río Negro Provinces, Argentina. It was collected primarily from rodents of the genus Abrothrix (65 of 77 collections): Abrothrix longipilis (63), Abrothrix olivaceus olivaceus (1) and Abrothrix olivaceus xanthorhinus (1). Additional collections were made from Geoxus valdivianus (5) and Loxdomtomys micropus (5). Possibly incidental or contaminate collections were recorded from Oligoryzomys longicaudatus (1) and Dromiciops gliroides (1). Most collections came from Río Negro Province (36), with 22 from Neuquén and 19 from Chubut. An identification key is provided to distinguish ♀s of this new species from ♀s of species from the western hemisphere, based on morphological characters.     

Origin and Evolution of Feather Mites (Astigmata)

Feather mites are highly specialized plumage and skin ectoparasites that are variously adapted for inhabiting certain microhabitats on a bird's body. Different feather mite taxa of higher (familial) rank adapted to the same microhabitats display similar main morphological adaptations even if they are rather distantly related to one another. Hypotheses on the evolution of general adaptations in morphology of feather mites during colonization and establishment in different microhabitats are presented. According to recent data, feather mites are a paraphyletic group consisting of three superfamilies: Analgoidea, Pterolichoidea and Freyanoidea. We present our view on the general feather mite phylogeny course at the familial rank for the Analgoidea by means of cladistic analysis. Co-speciation of parasites with their hosts is postulated as a main factor driving feather mite evolution. Examples are given of non-coevolutionary events, for example recolonization from one host species onto another, extinction and multiple speciation.     

MHC haplotype involvement in avian resistance to an ectoparasite

Research on immune function in evolutionary ecology has frequently focused on avian ectoparasites (e.g., mites and lice). However, host immunogenetics involved with bird resistance to ectoparasites has not been determined. The critical role of the major histocompatibility complex (MHC) in adaptive immunity and high genetic variation found within the MHC make this gene complex useful for exploring the immunogenetic basis for bird resistance to ectoparasites. The objective of this study was to determine if the avian MHC influenced resistance to a blood-feeding ectoparasite. Four congenic lines of chickens, differing only at the MHC, were comparatively infested with a cosmopolitan ectoparasite of birds-northern fowl mite (NFM)-which is also a serious pest species of poultry. Mite infestations were monitored over time and mite densities (weekly and maximum) were compared among lines. Chickens with the MHC haplotype B21 were relatively resistant to NFM, compared with birds in the B15 congenic line (P < 0.02). To test for similar effects in an outbred genetic background, a separate experiment was performed with 107 commercial chickens (white leghorn, W-36 strain) infested with NFM. Hens were genotyped using a MHC microsatellite marker (LEI0258) and associations between MHC haplotype and NFM density were tested. The highest peak NFM populations occurred more often on hens with the B15 haplotype versus the B21 haplotype (P = 0.012), which supported the results of the congenic study. These data indicate the avian MHC influences ectoparasite resistance, which is relevant to disease ecology and avian-ectoparasite interaction.     

Condition‐dependent immune defence in the Magpie: how important is ectoparasitism?

The immune system has high costs of maintenance and production and expression of immune function should be dependent on the condition of the individual. The fitness cost that parasites impose on hosts may then be reflected in the investment that hosts make in immunity. Little is known about sources and consequences of intra- and interspecific variation in the presence and size of organs of the immune system in relation to ectoparasitism. Variation in the presence and size of the bursa of Fabricius and spleen size was measured to assess potential relationships between immune defence, nutritional condition and ectoparasites in the Magpie Pica pica. We found three species of lice (Mallophaga), two species of louse flies (Hippoboscidae), and the larvae of a tick (Ixodidae) infecting magpies. Age explained a significant proportion of variation in prevalence and number of parasite species, first-year birds being more parasitized than adults. Spleen size increased with nutritional condition, and the level of ectoparasitism negatively affected nutritional condition. Only one species of lice (Philopterus picae) was involved; the negative effect of this species on nutritional condition was more pronounced in males than females. These results are consistent with the hypotheses of condition-dependent investment in the immune system and sexual differences in susceptibility to parasite effects. Ectoparasites may thus play a role in modulating the relationship between condition and immune defence. We also found evidence for an interaction between the bursa and the spleen. Magpies with bursa had larger spleens than those where it had atrophied. This interaction did not affect ectoparasitism or nutritional condition.     

Parasites differentially increase the degree of fluctuating asymmetry in secondary sexual characters

The degree of fluctuating asymmetry has been demonstrated to reflect the ability of individuals to cope with different kinds of environmental stress (Parsons 1990). Parasites and diseases are one kind of environmental stress which most individuals encounter during their lifetime. Parasites have also been suggested to play an important role in sexual selection and the development of ornaments, since the full expression of ornaments may reflect the ability of hosts to cope with the debilitating effects of parasites. Here I report for the first time that a parasite, the haematophagous tropical fowl mite Ornithonyssus bursa (Macronyssidae, Gamasida), directly affects the degree of fluctuating asymmetry in a secondary sexual character of its host, the elongated tail of the swallow Hirundo rustica (Aves: Hirundinidae). I experimentally manipulated the mite load of swallow nests during one season by either increasing or reducing the number of mites, or keeping nests as controls. The degree of fluctuating asymmetry was measured in the subsequent year after the swallows had grown new tail ornaments under the altered parasite regime. The degree of fluctuating asymmetry was larger at increasing levels of parasites for male tail length, but not for the length of the shortest tail feather or wing length or for tail and wing length in females. These results suggest that the degree of fluctuating asymmetry in tail ornaments, but not in other feather traits, reliably reveals the level of parasite infestation. This has important implications for the ability of conspecifics to use the size and the expression of ornaments in assessment of phenotypic quality and thus in sexual selection.     

Dampness,mites and respiratory allergy

Summary This paper reviews the relationships between humidity, house-dust mites and respiratory allergy. In vitro relationship between relative humidity and house-dust mite growth are quite clear cut. In real conditions also, there is a significant association between relative humidity and the presence of live mites. The relevance of house-dust mites for respiratory allergy lies on clinical, physiopathological and mostly on epidemiological data. The latter demonstrate a correlation between exposure to mites and risk of sensitization and development of overt allergic diseases. Lastly, humidity of dwellings is linked to respiratory allergy. These results should lead to building safer dwellings for allergic subjects, or modifying existing dwellings. In this respect, emphasis should be put on a proper ventilation rate and also a proper behaviour of inhabitants in order to minimize humidity production.     

Survival and reproductive rate of mites in relation to resistance of their barn swallow hosts

Parasite resistance may act via a number of different mechanisms that regulate or control the survival and the reproductive rate of parasites. Observations and experiments were used to test for effects of host resistance on parasite survival and rate of reproduction. Natural levels of infestation of barn swallow Hirundo rustica nests by the tropical fowl mite Ornithonyssus bursa were positively related to brood size, inversely related to the length of the outermost tail feathers of male nest owners (a secondary sexual character) and affected by time of reproduction by the host. A mite inoculation experiment, in which 50 adult mites were introduced into nests during the laying period of the host, was used to test for differential survival and reproduction of mites as a function of host resistance. The relationship between survival and reproduction of parasites, male tail length and host resistance was investigated. There was a negative relationship between mite numbers per nest after fledging of nestlings and male tail length. This relationship was mainly caused by a reduction in the number of mites in the first and second nymph stage with increasing tail length of male hosts, implying a reduction in rate of reproduction of mites. The proportion of mites that had recently fed was inversely related to tail length of male hosts. The proportion of nymph stages was positively related to the proportion of mites that had recently had a blood meal. Parasite resistance of barn swallows to the tropical fowl mite thus appeared to act through increased mortality rate of adult and nymph stages of mites, and through reduced reproductive rates of mites on resistant hosts. This is the first study demonstating a direct relationship between fitness components of a parasite and the expression of a secondary sexual character of a host. Received: 11 January 2000 / Accepted: 22 March 2000     

Comprehensive investigation of ectoparasite community and abundance across life history stages of avian host

Fitness consequences of ectoparasitism are expressed over the lifetime of their hosts in relation to variation in composition and abundance of the entire ectoparasite community and across all host life history stages. However, most empirical studies have focused on parasite species-specific effects and only during some life history stages. We conducted a systematic, year-long survey of an ectoparasite community in a wild population of house finches Carpodacus mexicanus Müller in south-western Arizona, with a specific focus on ecological and behavioral correlates of ectoparasite prevalence and abundance. We investigated five ectoparasite species: two feather mite genera – both novel for house finches – Strelkoviacarus (Analgidae) and Dermoglyphus (Dermoglyphidae), the nest mite Pellonyssus reedi (Macronyssidae), and the lice Menacanthus alaudae (Menoponidae) and Ricinus microcephalus (Ricinidae). Mite P. reedi and louse Menacanthus alaudae abundance peaked during host breeding season, especially in older birds, whereas feather mite abundance peaked during molt. Overall, breeding birds had more P. reedi than non-breeders, molting males had greater abundance of feather mites than molting females and non-molting males, and young males had more feather mites than older males. We discuss these results in relation to natural history of ectoparasites under study and suggest that ectoparasites might synchronize their life cycles to those of their hosts. Pronounced differences in relative abundance of ectoparasite species among host's life history stages have important implications for evolution of parasite-specific host defenses.