Broadcast application of a placebo rodenticide bait in a native Hawaiian forest

This study consisted of three replicates of controlled field trials using a pelletized placebo (Ramik® Green formulated without diphacinone) bait treated with a biological marker and broadcast at three application rates — 11.25, 22.5 and 33.75 kg/ha. We determined that Polynesian (Rattus exulans) and roof rats (Rattus rattus) consumed this bait when broadcast on the ground and assessed the optimal sowage rate to result in maximum exposure of bait to the rats while minimizing bait usage. All Polynesian rats captured in all application rates had eaten the bait. The percentage of roof rats that had eaten the bait increased with application rate, however, 22.5 kg/ha was clearly the optimal application rate. Bait degradation and invertebrate activity was documented and assessed.