Marcela Lareschi

Arthropod and filarioid parasites associated with wild rodents in the northeast marshes of Buenos Aires, Argentina.

During 1995, 16 species of arthropods and 2 species of filarioids, totaling 1 287 specimens were collected from 64 wild rodents captured in the Hudson Natural Reserve, Buenos Aires, Argentina. Infestation parameters and indexes were analyzed. Host specific richness was S = 6, diversity H = 1.48, and relative density RDI = 40%. High values of parasite species richness and diversity were found on Oligoryzomys delticola (S = 9; H = 1.40), Oxymycterus rufus (S = 9; H = 1.37), and Oligoryzomys flavescens (S = 9; H = 1.28), followed by Scapteromys aquaticus (S = 6; H = 0.17), and Akodon azarae (S = 4; H = 1.20). Deltamys kempi was infested only by Androlaelaps rotundus. O. delticola and O. flavescens showed the highest similarity index (O = 74.19%), followed by O. flavescens with S. aquaticus, as a result of historical processes and shared microhabitats. Considering arthropods-filarioids associations, significant affinity was observed in Litomosoides bonaerensis with Hoplopleura travassosi, Laelaps paulistanensis, and Gigantolaelaps wolffsohni.

A method for testing the host specificity of ectoparasites: give them the opportunity to choose

Host-choice experiments were carried out with rodent and bat ectoparasites on Ilha Grande, state of Rio de Janeiro, Brazil. We constructed experimental chambers that enclosed three different rodent or bat host species, and then introduced a selected set of ectoparasitic arthropods. When given the opportunity to choose among host species, the ectoparasites showed a strong tendency to select their primary hosts, and reject novel host species. These kinds of simple experiments can be valuable tools for assessing the ability of ectoparasites to locate and discern differences between host species, and make choices about which hosts to infest, and which hosts to avoid.

Fleas Associated with Mammals from Northwestern Argentina, with New Distributional Reports

Abstract Northwestern Argentina is an area of a high biodiversity. However, few fleas have been recorded parasitizing mammals. In the present study we report the results of surveys carried out in the provinces of Salta, Jujuy, Tucumán, and Catamarca. The following 9 flea species and subspecies were collected from 17 species of mammals: Craneopsylla minerva minerva (Rothschild, 1903) (Stephanocircidae); Neotyphloceras crassispina hemisus Jordan, 1936 (Ctenophthalmidae); Adoratopsylla (Tritopsylla) intermedia intermedia (Wagner, 1901) (Ctenophthalmidae); Tetrapsyllus (Phylliver) bleptus (Jordan and Rothschild, 1923) (Rhopalopsyllidae); Polygenis (Polygenis) acodontis (Jordan and Rothschild, 1923) (Rhopalopsyllidae); Phthiropsylla agenoris (Rothschild, 1904) (Malacopsyllidae); Malacopsylla grossiventris (Weyenbergh, 1879) (Malacopsyllidae); Pulex irritans Linnaeus, 1758 (Pulicidae); and Hectopsylla gracilis Mahnert, 1982 (Tungidae). Neotyphloceras crassispina hemisus, Ad. (T.) i. intermedia, Ph. agenoris, and H. gracilis are reported for the first time from northwestern Argentina, from specimens collected in the provinces of Jujuy, Salta, and Catamarca. The mammals Micoureus constantiae (Thomas, 1904); Thylamys cf. cinderella (Thomas, 1902); Thylamys sponsorius (Thomas, 1921) (Didelphimorphia); Akodon albiventer Thomas, 1897; Akodon caenosus Thomas, 1918; Calomys lepidus (Thomas, 1884); Eligmodontia hirtipes Thomas, 1902; Eligmodontia puerulus (Philippi, 1896); Phyllotis xanthopygus (Waterhouse, 1837); Tapecomys primus Anderson and Yates, 2000 (Rodentia); and Chaetophractus vellerosus (Gray, 1865) (Cingulata) have an increased number of parasite species known to them. Eighteen new parasite–host associations are also reported.

The parasitism of immature stages of Ixodes loricatus (Acari: Ixodidae) on wild rodents in Argentina.

Ixodes loricatus has long been considered with strict-total specificity to New World Marsupials. However, frequent findings of its immature stages on rodents suggest that these vertebrates play an important role in the tick’s life cycle. Aspects dealing with the ecology of Sigmodontinae rodents infestation by I. loricatus are unknown. To contribute to the knowledge of the ecology of this tick species, environmental factors, as well as host species, sex and age, were evaluated to find associations of immature I. loricatus infestation of the most abundant wild rodent species from riparian locations of Buenos Aires province (Argentina). A total of 290 hosts belonging to the subfamily Sigmodontinae were captured and examined for ticks at six locations. The data analysis showed that there was a preference of I. loricatus towards Akodon azarae, but only for those hosts captured in lands not prone to flooding. The results suggest that the host preference of I. loricatus is mainly related to factors such as habitat type and host density.

LAELAPINE MITES (ACARI: LAELAPIDAE) ASSOCIATED WITH SMALL MAMMALS FROM AMAZONAS, BRAZIL , INCLUDING A NEW SPECIES FROM MARSUPIALS

An intensive survey of ectoparasitic arthropods associated with small mammals in upland forests near Manaus, Brazil, provides information on the taxonomy and host distribution of laelapine mites in the Amazonian Region. We identified 5 genera and 21 species of these mites by comparison with representative museum specimens, the taxonomic literature, and, when possible, the original type specimens. These mites are host specific, with associations ranging from strict monoxeny (18 species) to oligoxeny (1 species) and pleioxeny (2 species). Marsupials were infested with species of Androlaelaps, echimyid rodents with Tur, and sigmodontine rodents with Gigantolaelaps, Laelaps, and Mysolaelaps. Androlaelaps bergalloi, a new species of Laelapinae, is described from the pelage of the marsupial Monodelphis brevicaudata.

Parasite community (Arthropods and Filarioids) associated with wild rodents from the marshes of La Plata River, Argentina

Abstract We investigated the parasite community (arthropods and filarioids) associated with wild rodents from a marshy area in Buenos Aires province, Argentina. During 1995 and 1996, 105 sigmodontine rodents were trapped in The Reserva Selva Marginal de Punta Lara and in La Balandra (Argentina). Six sigmodontine species with a relative density (RDI) of 11.1% were trapped. A total of 3,371 specimens from 16 species of arthropods and 2 species of filarioids were collected. The values of parasite species richness (S) and prevalence (P) were as follows: from Scapteromys aquaticus S = 9; P = 96%, from Oligoryzomys spp. S = 8; P = 100%, from Oxymycterus rufus S = 8; P = 93%, and from Akodon azarae S = 6; P = 93%. The single Deltamys kempi captured was not parasitized. Parasite communities of S. aquaticus and Ox. rufus showed the highest similarity resulting from their overlapped microhabitats, not only when presence/absence of species was considered (Sorensons index; Css = 82%), but also when the proportion of every species was taken into account (Piankas index; O = 26.67). The 2 species of filarioids collected were restricted to Oligoryzomys spp. and Ox. rufus. The absence of lice and filarioids from Ox. rufus from La Balandra suggests an isolation of this host population from the northern localities. Considering arthropod–filarioid associations, a significant affinity was observed from Ox. rufus from Punta Lara, between Litomosoides oxymycteri and the mite Ornithonyssus bacoti. Scapteromys aquaticus and Ak. azarae may not be susceptible to filarioids; although Or. bacoti were recovered from both.

The Fleas (Insecta: Siphonaptera), Parasites of Sigmodontine Rodents (Cricetidae) from Northern Patagonia, Argentina

The flea fauna of Patagonia in Argentina comprises about 50% of the total species and subspecies known for Argentina. Given the high diversity of environments and the rich assemblage of sigmodontine rodents of the Patagonian region, flea richness is probably underestimated. In the present study, 16 species and subspecies of fleas parasitizing sigmodontines from Northern Patagonia are reported. Fifteen new parasite–host associations and new records of geographical distribution are reported. The results suggest the coexistence of an endemic flea fauna (Tetrapsyllus (Tetrapsyllus) tantillus; Tetrapsyllus (Tetrapsyllus) rhombus; Ectinorus (Ectinorus) spiculatus; Agastopsylla boxi boxi; and Sphinctopsylla ares) with other species and genera that occur mainly at lower latitudes than those of Patagonia (Tetrapsyllus (Phylliver) bleptus; Ectinorus (Ectinorus) hapalus and Polygenis (Polygenis) rimatus). Considering that the same situation occurs with some species and genera of their sigmodontine hosts, future studies will allow us to determine the distributional limits of each flea taxon and analyze the influence of host geographical distribution.

A review of the fleas (Insecta: Siphonaptera) from Argentina.

The Order Siphonaptera comprises cosmopolitan haematophagous ectoparasites of birds and mammals. More than ten years have past since the last list of species known for Argentina. Herein we provide a review of the fleas from the country, which includes an updated list, host species and geographical distribution for each taxa, as well as some comments. We report 127 species and subspecies belonging to eleven different families; 42 of these species are endemic. Four genera (Adoratopsylla, Cleopsylla, Ctenidiosomus, and Nonnapsylla) and six species and subspecies (Adoratopsylla (Adoratopsylla) antiquorum antiquorum, Agastopsylla pearsoni, Polygenis (Polygenis) roberti beebei, Plocopsylla (Plocopsylla) silewi, Plocopsylla (Plocopsylla) wilesi and Tunga terasma) are added to the list for Argentina. Nine species new to science are included, described on the bases of specimens collected from Argentina (Ctenidiosomus austrinus, Ectinorus (Ectinorus) lareschiae, Ectinorus (Ectinorus) spiculatus, Ectinorus (Ectinorus) morenoi, Hectopsylla narium, Plocopsylla (Plocopsylla) linardii, Neotyphloceras crackensis, Neotyphloceras pardinasii and Tunga perforans). Information provided herein contributes to the knowledge of the fleas from Argentina, necessary to a better understanding of their role as parasites themselves and vectors of zoonotic importance.

Mites (Acari: Laelapidae) associated with sigmodontinae rodents in Entre Ríos Province, Argentina

The richness, diversity, abundance and prevalence of mite species associated with sigmodontine rodents of different species in Entre Ríos province, Argentina are studied. Five of the six species of mites were reported for the first time in the study area. The richness and diversity of mites was higher on Oligoryzomys flavescens and O. delticola than on Akodon azarae. Androlaelaps rotundus was dominant and exhibited higher values of mean abundance and prevalence on A. azarae, Mysolaelaps microspinosus on O. flavescens and Gigantolaelaps mattogrossensis on O. delticola.

Ectoparasite occurrence associated with males and females of wild rodents Oligoryzomys flavescens (Waterhouse) and Akodon azarae (Fischer) (Rodentia: Cricetidae: Sigmodontinae) in the Punta Lara wetlands, Argentina

The objective of this research was to study infestation parameters and indexes of ectoparasites associated with each sex of the wild rodents Oligoryzomys flavescens (Waterhouse) andAkodon azarae (Fischer) in the Punta Lara wetlands, Argentina. A trend towards higher mean abundance (MA) and ectoparasite specific richness was observed in males of O. flavescens whereas those values were similar for both A. azarae sexes. The prevalence of the following ectoparasites was significantly higher on males (P<0.05): Mysolaelaps microspinosus Fonseca (65.2%) and Hoplopleura travassosi Werneck (73.9%) on O. flavescens, and Ixodes loricatus Neumann (71.4%) on A. azarae. Only H. travassosi mean abundance was significantly higher on males (MA=44.1). Since I. loricatus and Hoplopleura spp. are involved in the transmission of pathogens that cause diseases in animals and humans, and whose reservoirs are rodent hosts, these results are epidemiologically important.