scholarly journals 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

2010 ◽  
Vol 39 (5) ◽  
pp. 818-822 ◽  
Author(s):  
Marcela Lareschi
Keyword(s):  
Wild Rodents ◽  
Males And Females ◽  
Akodon Azarae ◽  
Oligoryzomys Flavescens

Ixodes spp. (Acari: Ixodidae) ticks in Rio Grande do Sul state, Brazil

2017 ◽  
Vol 22 (12) ◽  
pp. 2057 ◽  
Author(s):  
Thais Michel ◽  
Ugo Souza ◽  
Bruno DallAgnol ◽  
Anelise Webster ◽  
Felipe Peters ◽  
...  
Keyword(s):  
Rio Grande ◽  
Molecular Techniques ◽  
Rio Grande Do Sul ◽  
Small Rodents ◽  
Wild Rodents ◽  
Pampa Biome ◽  
Potential Impact ◽  
Akodon Azarae ◽  
Oligoryzomys Flavescens ◽  
Cavia Aperea

Among the 251 described species of ticks from the genus Ixodes, only eight were previously reported in Brazil, Ixodes amarali, Ixodes aragaoi, Ixodes auritulus, Ixodes fuscipes, Ixodes loricatus, Ixodes luciae, Ixodes paranaensis and Ixodes schulzei. Of those species, I. loricatus is considered commonly found, whereas I. auritulus and I. aragaoi were registered just one time in Rio Grande do Sul (RS) state, Southern Brazil. This paper aims to update the Ixodes species occurring in RS through the investigation of the ixodofauna of small rodents. Data from 314 wild rodents were analyzed from nine municipalities of Pampa biome and five from the Atlantic Rainforest in RS. Rodents belonging to the following species were infested by Ixodes spp. ticks: Akodon azarae, Akodon montensis, Akodon paranaensis, Akodon reigi, Calomys laucha, Delomys dorsalis, Deltamys kempi, Holochilus brasiliensis, Oligoryzomys flavescens, Oligoryzomys nigripes, Oxymycterus nasutus, Scapteromys tumidus (Cricetidae) and Cavia aperea (Caviidae). The tick identification was performed based on morphological dichotomous keys, their updates and by molecular techniques. Considering the ticks from the rodents and those collected directly from the environment, 34 specimens of Ixodes spp. were collected. Our results improved to five the list of Ixodes species that occur in RS: I. loricatus, I. auritulus, I. aragaoi, I. fuscipes and I. longiscutatus. Moreover, the finding of I. longiscutatus increases to nine the number of Ixodes species in Brazil. The occurrence of two species of the Ixodes ricinus complex (I. aragaoi and I. fuscipes) highlights the potential impact of Ixodes spp. ticks on public health.

Mating strategies of Pampean mouse males

2012 ◽  
Vol 62 (4) ◽  
pp. 381-396 ◽  
Author(s):  
Florencia Bonatto ◽  
Daniela Gomez ◽  
Andrea Steinmann ◽  
José Priotto
Keyword(s):  
Body Size ◽  
Sexual Dimorphism ◽  
Home Range ◽  
Space Use ◽  
Home Range Size ◽  
Mating Strategies ◽  
Range Size ◽  
Home Ranges ◽  
Males And Females ◽  
Akodon Azarae

Patterns of space use and sexual dimorphism are frequently used to infer mating systems. We examined body size and home range size and intra- and intersexual overlap degree in order to elucidate mating strategy of Akodon azarae males. We studied spacing patterns using 113 and 129 home ranges established by males and females, respectively, in four 0.25 ha enclosures during the breeding season. Significant differences between sexes in home range size and overlap degree were found. Male home ranges were always larger than those of females. We observed exclusive space use among males and among females. Considering only those males that shared their home ranges with females, average intersexual overlap value was about 50%. Males mainly overlap their home ranges with home ranges of two or three females. Significant differences in body size were found between males and females, with males being larger. We concluded that space use and sexual dimorphism in this species is consistent with patterns characteristic of polygynous rodents, and we propose a polygynous system in A. azarae.

scholarly journals Ticks infesting wild small rodents in three areas of the state of São Paulo, Brazil

2016 ◽  
Vol 46 (5) ◽  
pp. 871-875 ◽  
Author(s):  
Thiago Fernandes Martins ◽  
Marina Gea Peres ◽  
Francisco Borges Costa ◽  
Thais Silva Bacchiega ◽  
Camila Michele Appolinario ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Species Level ◽  
São Paulo ◽  
Small Rodents ◽  
Wild Rodents ◽  
Morphological Examination ◽  
Paulo State ◽  
The Mean ◽  
Oligoryzomys Flavescens ◽  
Mitochondrial Rdna

ABSTRACT: From May to September 2011, a total of 138 wild rodents of the Cricetidae family were collected in the cities of Anhembi, Bofete and Torre de Pedra, in São Paulo State. All animals were examined for the presence of ticks, which were collected and identified at species level in the laboratory by morphological examination (for adults, nymphs and larvae) and molecular biology, by sequencing of a fragment of the 16S mitochondrial rDNA (for larvae). A total of 47 ticks (21 larvae and 26 nymphs) were collected from rodents, identified as 21 larvae and 23 nymphs of Amblyomma ovale (collected on Oligoryzomys nigripes , Oligoryzomys flavescens , Sooretamys agouya and Nectomys squamipes ), two nymphs of Ixodes schulzei (O. nigripes and O. flavescens ) and an Amblyomma sculptum nymph in S. agouya . The overall prevalence of parasitism by A. ovale was 4.3% for larvae, and 10.1% for nymphs. The mean intensity of parasitism was 3.5 larvae/parasitized animal, and 1.6 nymphs/parasitized animal. One O. nigripes was found parasitized by both larva and nymph of A. ovale , and another O. nigripes was parasitized simultaneously by an I. schulzei nymph and five A. ovale nymphs. This research reports the following unpublished records: A. ovale on O. flavescens , O. nigripes and S. agouya ; A. sculptum on S. agouya ; and I. schulzei on O. flavescens and O. nigripes .

scholarly journals Ontogenetic allometry in the foot size of Oligoryzomys flavescens (Waterhouse, 1837) (Rodentia, Sigmodontinae)

2015 ◽  
Vol 75 (2) ◽  
pp. 435-441 ◽  
Author(s):  
R. Maestri ◽  
R. Fornel ◽  
TRO. Freitas ◽  
JR. Marinho
Keyword(s):  
Sexual Selection ◽  
Natural Selection ◽  
Sexual Dimorphism ◽  
Encounter Rate ◽  
Allometric Growth ◽  
Positive Allometry ◽  
Rate Of Growth ◽  
Ontogenetic Allometry ◽  
Males And Females ◽  
Oligoryzomys Flavescens

Ontogenetic allometry is the study of how the size or shape of certain structures changes over the course of an animal’s development. In this study, using Huxley's formula of allometric growth (1932), we assessed the changes in the rate of growth of the feet size of the sigmodontine rodent Oligoryzomys flavescens during its ontogeny and compared differences between males and females. We find evidence of a change of polarity during the ontogenetic development of the species, with the presence of positive allometry during pregnancy and negative allometry in adulthood. Moreover, we note the presence of sexual dimorphism in the size of the feet, in which males of the species have a higher rate of growth than females. This growth pattern is positively related to escape from predators in childhood in both sexes and, in adulthood, provides a higher encounter rate of females by males, due to the larger displacement of the latter. We suggest that both the forces of natural selection and sexual selection have acted to shape the evolution of foot size in this species.

scholarly journals Evidence of hantavirus infection in wild rodents captured in a rural area of the state of São Paulo, Brazil

2004 ◽  
Vol 24 (2) ◽  
pp. 71-73 ◽  
Author(s):  
Elba Regina S. de Lemos ◽  
Paulo S. D'Andrea ◽  
Cibele R. Bonvicino ◽  
Kátia M. Famadas ◽  
Paula Padula ◽  
...  
Keyword(s):  
Sao Paulo ◽  
Hantavirus Infection ◽  
São Paulo ◽  
Wild Rodents ◽  
Myocastor Coypus ◽  
Suburban Areas ◽  
Andes Virus ◽  
Etiological Agents ◽  
Antigen Antibody ◽  
Oligoryzomys Flavescens

Hantaviruses are the etiological agents of the Hantavirus Cardio-Pulmonary Syndrome, a serious rodent-borne disease in Brazil. In order to investigate the occurrence of hantavirus infection in wild rodents, a survey was conducted in three different suburban areas of the municipality of Pedreira, State of São Paulo, Brazil. Of the 145 wild animals captured belonging to 12 different species identified by morphology and karyological analysis, 107 were rodents of the following species: Akodon montensis, Bolomys lasiurus, Calomys tener, Oligoryzomys nigripes, Oligoryzomys flavescens, and Myocastor coypus. Blood samples from these rodents were assayed for the presence of antibodies against hantavirus by IgG ELISA using Andes recombinant nucleocapsid antigen. Antibody reactive to Andes virus was found in two different species, O. nigripes and O. flavescens. These results indicate a potential risk for hantavirus transmission to humans in this area, where reservoir rodents are present in peridomestic settings.

Interspecific Social Relationships in Three Murid Rodent Species of Central Argentina, After Fasting and Unlimited Food

Behaviour ◽  
1995 ◽  
Vol 132 (11-12) ◽  
pp. 811-820 ◽  
Author(s):  
David N. Bilenca ◽  
Fernando O. Kravetz ◽  
Gerardo R. Cueto
Keyword(s):  
The Other ◽  
Food Sources ◽  
Feeding Time ◽  
Murid Rodent ◽  
Food Treatment ◽  
Aggressive Interactions ◽  
The Social ◽  
Akodon Azarae ◽  
Access To Food ◽  
Oligoryzomys Flavescens

AbstractWe studied the social interactions between Akodon azarae and Calomys laucha, and between A. azarae and Oligoryzomys flavescens, by means of experimental confrontations under laboratory conditions. Trials were carried out after two treatments: in the first one ('food' treatment), the animals were offered food ad libitum permanently, whereas in the other ('fast' treatment), the animals were previously submitted to fasting for 30 hours. The largest species- A. azarae - dominated the other two species, being dominant in 69.6% of the aggressive interactions in which a clear dominant/subordinate relationship was detected (N = 79). During the 'fast' treatment, A. azarae fed longer than C. laucha and O. flavescens, and it was the only species which significantly increased its feeding time with respect to 'food' treatment. There were higher frequencies of aggressive interactions in A. azarae - C. laucha trials than in A. azarae - O. flavescens trials. Comparisons of the behavioural variables between C. laucha and O. flavescens during their respective confrontations with A. azarae showed that C. laucha had significantly higher median values of freezing and walking behaviours, whereas O. flavescens showed a higher frequency of alertness. Species differences found in the laboratory support the interpretation that A. azarae is usually dominant over C. laucha and O. flavescens, and that A. azarae has the priority of access to food sources in situations of food shortage (winter) by means of its social dominance over the other two species. We suggest that the differences in the behavioural reactions of the subordinate species when meeting the dominant one may help to explain the different scales of spatial segregation that C. laucha and O. flavescens maintain with A. azarae in the field.

scholarly journals Small mammals (Didelphimorphia, Rodentia and Chiroptera) from Pampean Region, Argentina

Check List ◽  
2012 ◽  
Vol 8 (1) ◽  
pp. 130 ◽  
Author(s):  
Fernando J. Fernández ◽  
Fabricio Idoeta ◽  
César García-Esponda ◽  
Joaquín D. Carrera ◽  
Germán J. Moreira ◽  
...  
Keyword(s):  
Small Mammals ◽  
Buenos Aires ◽  
First Record ◽  
Buenos Aires Province ◽  
Pampean Region ◽  
Akodon Azarae ◽  
Mammal Assemblages ◽  
Oligoryzomys Flavescens ◽  
Cavia Aperea ◽  
Owl Pellets

We studied small mammal assemblages recovered from owl pellets collected at 11 locations throughout the Argentina’s Pampean Region. We identified 21 species, including two marsupials, one bat, and 18 rodents. From the analysis of this dataset, we could distinguish three main groups of small mammals that currently inhabit the Pampean Region: 1) a group of taxa related to Pampean agroecosystems (Calomys spp., Akodon azarae, and Oligoryzomys flavescens); 2) a group of Brazilian species (Cavia aperea, Oxymycterus rufus, Necromys lasiurus, Necromys obscurus, Holochilus brasiliensis, and Monodelphis dimidiata); and 3) a group including species from Patagonia, Espinal and Monte phytogeographic provinces (Microcavia australis, Oligoryzomys longicaudatus, Eligmodontia typus, Graomys griseoflavus, and Akodon molinae). In addition, we documented the first record of a species of the large-bodied group of Calomys in Buenos Aires province, expanding its distribution ca. 420 km southward.

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