AN EXPERIMENTAL FIELD-STUDY TO EVALUATE A TRAP-BARRIER SYSTEM AND FUMIGATION FOR CONTROLLING THE RICE FIELD RAT, RATTUS ARGENTIVENTER, IN RICE CROPS IN WEST JAVA

The effectiveness of a trap-barrier system (TBS), which enclosed a cro p planted 2-3 weeks early (trap-crop), and fumigation (sulfur dioxide) was assessed for managing pre-harvest damage by the rice field rat. R attus argentiventer, to rice crops in West Java, Indonesia. The TBS wa s a 50 x 50 m plastic fence with live-multiple-capture traps inserted intermittently at its base. Damage to tillers and yield loss were asse ssed within the trap-crop and at 5, 50, 100, 150 and 200 m from the TB S. Two crops were monitored: dry season crop when rat densities were h igh and 20-55% of rice tillers were cut by rats; wet season crop when rat densities were low and 0-4% of rice tillers were cut. Over the two crops, rats caused a 20% annual loss in potential rice production. Th e benefit-cost ratios for using a TBS were in the range of 20:1 to 7:1 for the dry season and 7:1 to 2:1 for the wet season. Fumigation was not effective in reducing rat losses. Damage assessment provided a phe nology of rat damage for the two crops but, unlike the yield data, dif ferences were not significant between treatments. The benefits of the TBS need to be weighed against high labour input, initial cost, logist ics of growing a trap-crop, and whether the technology can be transfer red to growers. Research on how rats respond to a TBS-plus-trap-crop i s required before it can be recommended to manage rats. (C) 1998 Elsev ier Science Ltd. All rights reserved.