Crop damage, rodent abundance and stone bund density in Tigray highlands, Ethiopia

Farmers in Tigray highlands have ranked rodents as the number one pre- and post-harvest crop pests. We investigated temporal dynamics of rodent populations in rainfed crop fields with low stone bund density (LSBD) and high stone bund density (HSBD) grids near the town of Hagere Selam, and relate this with the level of pre-harvest damage to mixed barley and wheat crop. Rodent population changes were also compared with changes in crop developmental stages, density of stone bunds, and meteorological information (rainfall and temperature). We report that the multimammate mouse Mastomys awashensis and the African grass rat Arvicantis dembeensis were the two dominant pest species (accounting for 86.6% of the capture) in the crop fields. Monthly paired abundance estimates of the two grids revealed that indeed the abundance of rodents in HSBD grid was significantly higher than in LSBD grid. The generalized mixed model fitted to the data clearly showed correlation between the proportion of crop damage and abundance of rodents. We found significantly higher proportion of damage in HSBD grid, at both milky and maturation stages, than in LSBD grids. More significant damage was particularly observed at milky stage, where about 50% more damage difference was estimated in HSBD grid at a density of 40 animals ha-1. We could not find correlation between rodent abundance and weather data. However, seasonality and interannual variations in abundance were evident. Our findings show more damage at the reproductive stages of the crops. This implies obvious pest control significance