Evaluation of Relative Abundance Techniques (RATs) for Monitoring Rodent Abundance and Predicting Rodent Damage in Rice Agroecosystems.

Relative abundance techniques (RATs) are simple and low-cost tools that researchers, agricultural technicians, pest management personnel, and farmers can use to monitor relative abundance of rodent populations in rice agroecosystems. These tools have been developed to monitor rodent abundance in heterogenous habitats but have not yet been evaluated for forecasting rodent damage to rice crops. This study aimed to evaluate the effectiveness of RATs, including giving-up density (GUD) trays, chew cards, wax blocks, and active burrow counts in monitoring rodent abundance and predicting damage in rice fields in the Philippines. The effectiveness of these indices for monitoring rodent abundance and predicting damage were evaluated in rice fields over two consecutive cropping seasons. Relative abundance data were collected at early tillering (ET), maximum tillering (MT), and post-harvest stages of the rice crop. Tiller damage was assessed at maximum tillering (MT), booting (BT), and ripening (RP) stages. The optimum number of GUD stations for estimating rodent abundance and predicting damage was determined using different GUD arrays over three consecutive cropping seasons. Among the different RATs, GUDs measured during ET and MT showed the strongest associations with cumulative tiller damage, while burrow counts performed best at post-harvest. The use of eight-array grids of GUD stations per field resulted in the highest correlation with cumulative damage. To improve the efficiency of forecasting rodent damage in a current rice crop, we recommend the use of GUDs during the early stages of growth. To predict damage in the following cropping season, burrow counts at post-harvest should be used to monitor rodent abundance.