Use of computer simulation models to encourage farmers to adopt best rodent management practices in lowland irrigated rice systems in An Giang Province, the Mekong Delta, Vietnam

Rice field rats are an important pre-harvest pest of lowland irrigated rice farming systems in Vietnam. Farmers often apply traditional control measures too late for economic benefits to be achieved, due to the progressive inability of rice plants to compensate for damage. The use of computer simulation modelling was examined as a potential alternative approach to the management of rodents in lowland rice crop ecosystems. It was projected that 16 farmers who are involved in action learning cycles using crop simulation models to look at the relationship between timing and effectiveness of different control methods, would change their behaviour about rodent management, so that management is preventative rather than reactionary to pest damage. The study was conducted in three villages (2 treatment villages and 1 reference village) during the autumn–winter cropping season (July–November) in 2009, in An Giang Province in the Mekong Delta of Vietnam. Effects of alternative rodent management practices were explored using APSIM modelling in a farmer participatory approach. The changes in rodent control practices of farmers before and after the involvement in the APSIM modelling approach are also discussed.The study showed that APSIM modelling adequately simulated actual yields at different rodent damage intensities, for the different growth stages of the rice crop. Pre-season yield predictions in response to rat management were the same for farmers’ actual rice yields at the treatment and reference sites. The use of the modelling was an integral component of the learning cycle for farmers and extension workers in achieving a clear understanding of the rationale for changing their traditional rodent control strategies. Farmers subsequently changed the timing of rodent management to the tillering stage of crop development instead of later in crop growth after most damage has been done. It is believed that the model has the potential for application in other provinces of Vietnam with similar rice farming systems to those in the Mekong Delta.

► APSIM modelling could simulate actual yields at different rodent damage intensities.
► Pre-yield predictions in response to rat management were the same for farmers’ rice yields.
► Exploring the optimum time and best rodent management options using the model were feasible.
► Farmers conducted rodent management early instead of later in rice crop growth stage.