Changes in the abundance of Oligoryzomys longicaudatus, host of Andes Virus, in Cholila (Chubut, Argentina)

FRANCISCO POLOP; VERÓNICA ANDREO; CECILIA PROVENSAL; JOSÉ PRIOTTO; NOEMI PINI; SILVANA LEVIS; GLADYS CALDERÓN; MARCELO SCAVUZZO; MARIO LAMFRI; DELIA ENRÍA; JAIME POLOP

Buenos Aires

Conferencia; VII International Conference on HRFS, HPS, and Hantaviruses; 2007

Fundación Mundo Sano

Seasonal censuses have been carried out since September 2003 and bimonthly censuses since September 2005 in Cholila (Chubut province, Argentina) to study the spatio-temporal dynamics of Oligoryzomys longicaudatus, host of Andes virus, and its relationship with environmental variables. Small mammals were trapped in four types of habitats: forest, shrubland, grassland and peridomestic settings in the four valleys of the sampling area: El Rincón; El Cajón; El Blanco y Villa Lago Rivadavia. Traplines and grids were geo-referenced to the latitude-longitude coordinate system and relative density indexes (RDI) were estimated for every small mammal species. Southern Oscillation Index (SOI), monthly rainfall and Normalized Difference Vegetation Index (NDVI) were the environmental variables recorded. We captured a total of 2445 animals that corresponded to 13 rodent species, of which O. longicaudatus represented 63 %, Abrothrix longipilis 14% and Abrothrix olivaceus 14% of the whole community. Relative density of O. longicaudatus presented seasonal fluctuations and differences between habitats and valleys. The highest abundances in forests were observed in summer and autumn, while in shrublands the highest abundances were found in winter and the lowest in summer. Pregnancy prevalence in forests was high in spring-summer, while in shrublands it presented high values in summer-autumn. In the latter habitat, pregnant females were captured most of the year. Relative density showed a high correlation with rainfall. These results allow us to conclude partially about the dynamics of the host, suggesting that temporal and spatial differences in abundance are related to local or regional environmental variables. This project was made possible by grant from the Fundación Mundo Sano.