Preference of Escaped Mice for Live Capture or Glue Traps and Relevance to Pest Control Programs

Abstract

Insects are potential disease vectors for research animals. Therefore, implementing an effective pest control program is an essential component of any animal care and use program. The Guide for the Care and Use of Laboratory Animals emphasizes the humane use of traps; however, insect traps commonly use glue that can entrap escaped research mice, leading to their potential distress and injury. This situation is challenging for research facilities attempting to identify insect populations. In an effort to improve pest control in animal facilities, we sought to characterize the behavioral interactions of mice with common vermin traps. Three experiments using different combinations of traps (glue trap, live mouse trap with a clear viewing window, and live mouse trap with a red-tinted viewing window) were used in multiple behavioral testing arenas to address these questions. Experiments 1 and 2 were performed in a small arena, and Experiment 3 was performed in a simulated mouse housing room. Dependent measures included exploration of the test environment, grooming behavior, time spent near each trap, and latency to capture. Results indicate that mice were captured significantly more quickly by live traps than by glue traps, and were far more likely to enter a live trap as compared with a glue trap. Mice did not appear to differentiate between clear or red-tinted window live traps. Taken together, the results indicate that deploying both a live trap and a glue trap will allow humane capture of escaped mice yet will also capture insects in the same environment.

Figure 1.

Description of parameters and behaviors assessed in Experiments 1 and 2 of this study.

Figure 2.

Traps tested in experiments. (A) the glue trap, (B) the live trap with a clear viewing window, and (C) the live trap with a red-tinted viewing window. All 3 trap types s were assessed in Experiments 1 and 2, and only A and B in Experiment 3.

Figure 3.

Images of experimental arena used in Experiments 1 and 2. (A) A view from the testing room with the camera over one end of the enclosure, reflecting conditions in Experiment 1 in which a single trap was placed on the floor in the target box. Individual mice were placed in the start box. (B) A representative frame of the camera’s field of view for Experiment 2 of a mouse exploring the enclosure. Two traps were used, one placed at each end of the arena within target zones indicated by lines. In Experiment 2, mice were released in the middle of the arena, against a wall equidistant from each trap.

Figure 4.

Image of the test room in Experiment 3. (A) A Glue trap and a Live trap can be seen against the far wall (red arrow). The 4 ft high-density polyethylene (HDPE) wall is visible on the right of the image. (B) A representative frame of the camera (main camera, located above red arrow) field of view for Experiment 3 of a mouse exploring the enclosure.

Figure 5.

Percentage of mice captured per group for Experiments 1 (A), 2 (B), and 3 (C). Mice in Experiment 1 were placed into an arena for a maximum of 3 h with either a Clear, Glue or Red trap. Mice in Experiment 2 were given the same maximum time and chose between 2 traps in the same arena (pairing of 2 traps that were either Clear, Glue, or Red). In Experiment 3 mice chose between Clear and Glue traps while in a mouse housing room for a maximum time of 6 h. Groups that had a live trap type (Clear or Red) available had fewer mice that never become captured compared with groups with only a Glue trap.

Figure 6.

Box plot of the range and median log values for total time until capture in Experiment 1 for each trap type. The plot ignores censoring and assumes the maximum time for mice that were not trapped by 180 min (underestimates true time to being trapped). ‡ = P < 0.001, * = P < 0.05, all other pairwise comparisons did not have a significant difference.

Figure 7.

Dot plot of individual mice for the latency to approach each trap type in minutes for Experiment 1.

Figure 8.

Box plot of the range and median log values for time until capture for Experiment 2 for each trap group. The plot ignores censoring and assumes the maximum time for mice that were not trapped by 180 min (underestimates true time to being trapped). ‡ = P < 0.001, * = P < 0.05, all other pairwise comparisons did not have a significant difference.

Figure 9.

Trap preferences of lab mice in Experiments 2 and 3. (A) Percentage of mice captured per trap in the Clear+Red group from Experiment 2 (P > 0.05 by Fisher exact test). Mice from the Clear+Glue and the Glue+Red group were combined and collectively called “Live+Glue,” because we found no difference in capture time between the Clear and Red group from Experiment 1, and no difference between the Clear+Glue and the Glue+Red group in Experiment 2. (B) Percentage of mice captured per trap in the Live+Glue for Experiment 2 (P < 0.05 by Fisher exact test). (C) Of the 23 mice in the Live+Glue group, 17 investigated both traps in the arena. (D) Average total time allocation of mouse activity in regions of the arena in Experiment 2 Live+Glue. (E) Percentage of mice captured per trap of all mice captured in Experiment 3 (P < 0.05 by Fisher exact test).