Eco-epidemiología de ácaros del género Ornithonyssus (Acari: Mesostigmata: Mactonyssidae) en aves silvestres y gallinas ponedoras de la provincia de Santa Fe

Thesis

Summary

Mites of the Ornithonyssus genus are found parasitizing both wild birds and laying hens. A variety of factors are linked to its prevalence and intensity, both related to its hosts and the environment. Due to the fact that these mites are hemathophagous, they may have a negative impact on its hosts, producing for example weight loss, nest abandonment, stress, and mortality, among others. In productive systems such as poultry industry, they may produce reductions in egg production and thus produce important economic losses. Wild birds have been pointed out as a probable sources of infestation. In the present study, the drivers of parasitism of mites of the Ornithonsyssus genus were determined on both wild birds and laying hens, besides establishing possible impacts of this mite on wild bird nestlings. In addition, mites found on wild birds of commercial poultry farms were compared to the mites found on laying hens. On one hand, a longitudinal study was carried out on a community of birds on two natural areas for two years, which was added to previous data obtained for over four years, where counts of O. bursa abundance on nestlings was conducted. Data on its hosts, microhabitat and environment were taken. Subsequently, an analysis on different levels of biological organization was carried out to determine different factors associated to the prevalence and intensity of O. bursa. At the microhabitat level, the host species was more important than the nest material or type of nest at affecting mite levels of parasitism. Age was also involved, varying between the different host species, and the brood size, where fledglings of larger broods had lower infestation. At a higher level, factors associated were minimum and maximum temperature before mite data was obtained, and also abundance of nests of Sicalis flaveola in the area. At the interannual level, the preliminary analysis found an association between abundance of nests of S. flaveola and prevalence and intensity of O. bursa. About the effect of the mites on the nestlings, only higher mortality on three of the species under study was found, P. sulphuratus, S. flaveola and P. sibilatrix with no impact on the development or on weight gain of the hosts. On the other hand, a two year study in laying hens farms was carried out, where the mite intensity and prevalence on hens' vent was estimated and data on the epidemiology of mesostigmatid mites on wild birds was obtained. According to this study, lower prevalence and intensity was found on hens that were parasitised by lice and on the ones that had less density of feathers around the vent. Feathers are the microhabitat of mites and the substrate where they lay their eggs, and also what lice feed on. Prevalence was also associated to the number of hens in each cage and to their age. Mites found on hens and on adult wild birds and their nests were collected and later identified. Ornithonyssus sylviarum was present on both hens and adult wild birds, and in less abundance, on wild bird nestlings. Utilizing molecular and morphometrical techniques, both classical morphometrics and geometric morphometrics, no differences were found between specimens of O. sylviarum collected from laying hens and adult wild birds, which would indicate a possible cross transmission between these hosts.

Download or request the full text:

http://hdl.handle.net/11336/223971