Temporal modelling of Lymnaea natalensis (Krauss, 1848) in tropical aquatic habitats.

Abstract

Lymnaea natalensisis the only snail intermediate host ofFasciola gigantica, the causative agent of fascioliasis, in Nigeria. The species also serves as intermediate host for many other African trematode species of medical and veterinary importance, and it is found throughout the country. However, there is no detailed information on the factors that influence its distribution and seasonal abundance in the tropical aquatic habitats in Nigeria. This study used the geographic information system and remotely sensed data to develop models for predicting the distribution ofL. natalensisin South-Western Nigeria. Both land surface temperature (LST) and normalised difference vegetation index (NDVI) were extracted from Landsat satellite imagery; other variables (slope and elevation) were extracted from a digital elevation model (DEM) while rainfall data were retrieved from the European Meteorology Research Programme (EMRP). These environmental variables were integrated into a geographic information system (GIS) to predict suitable habitats ofL. natalensisusing exploratory regression. A total of 1410L. natalensissnails were collectedvis-à-vis22 sampling sites. Built-up areas recorded moreL. natalensiscompared with farmlands. There was no significant difference in the abundance of snails with season (p 0.05). The regression models showed that rainfall, NDVI, and slope were predictors ofL. natalensisdistribution. The habitats suitable forL. natalensiswere central areas, while areas to the north and south were not suitable forL. natalensis.Contribution:The predictive risk models ofL. natalensisin the study will be useful in mapping other areas where the snail sampling could not be conducted.