Method For Efficacy Testing of Rodent Bait Stations Under Laboratory Conditions
  Key Words  
  Rattus norvegicus, Mus musculus, rodenticides, risk mitigation
  Erik Schmolz, Agnes Kalle and Melanie Könecke
  The use of bait in a bait station may significantly alter bait acceptance, and consequently its efficacy for rodent control. Here, we describe a method for efficacy testing of rodent bait stations under laboratory conditions. Bait stations are tested in an experimental setup of three test chambers (A, B, and C, each 5 m˛) which are connected with passage holes. Nest boxes are placed in chamber A, an open tray with food as well as a water supply are placed in chamber C. The bait stations to be tested are placed in chamber B between A and C. Non-poisonous food is offered in the bait stations and an open tray to equal amounts for 10 days. Each day, the amount of consumed food is determined and food and water are replenished. Exemplary results are presented for absolute and relative efficacy of rodent bait stations: for evaluation of absolute efficacy, 3 bait station products for use against mice were tested with groups of 20 to 22 wild strain house mice (Mus musculus) in each experiment. In the first experiment (product I), the mice did prefer food from the open tray (62% of total food consumption), in the experiment with product II the amount taken up from the open tray was about equal to the amount taken up in bait stations (52% from open tray) and in a test with product III, the mice preferred food from bait stations (58% from bait stations). In all cases, more than 25% of all food consumed by the mice was taken up from the bait stations. The relative efficacy of two products with same design but with material of different optical properties (translucent vs. opaque) was tested with house mice and brown rats. From all food taken up in the bait stations in an experiment with a group of 8 wild strain brown rats (Rattus norvegicus) only 26% were consumed in translucent bait stations, clearly indicating that opaque bait stations are preferred. Similar results were achieved in a test with a group of 24 wild strain house mice, although the preference for opaque bait stations was less pronounced: 38% of all food consumed in bait stations was taken up in translucent bait stations.