1

Fig. 1. Dog A performs the final indication on the bark beetle target container. Bark beetles are visible for illustrative purposes.

2

Fig. 2. During the bark beetle detection testing phase, the glass containers were placed into opaque containers to eliminate any visual clues for the dog or the handler.

Fig. 3. Dog B indicating on a bark beetle target placed into a spruce tree during the field tests on area C.

4

Fig. 4. Area A field-type test site, urban area, Area B forested test site, Area C forested test site, and Area D forested test site. Terrain information and Creative Commons Licence CC BY-SA 4.0, © Maanmittauslaitos, 1/2025.

Table 1. Schedule and results of the scent detection dog testing phase of spruce bark beetle detection in laboratory conditions. Dogs were tested on a blind trial, ten-option line-up setting. Dog A participated in nine testing days, dog B in 11 testing days.
Date Correct positives/
total positives (Dog A) 		Correct negatives /
total negatives (Dog A) 		Correct positives/
total positives (Dog B) 		Correct negatives/
total negatives (Dog B)
27.7.2022 - - 5/5 45/45
29.7.2022 - - 5/5 45/45
1.8.2022 5/5 45/45 5/5 45/45
3.8.2022 5/5 45/45 5/5 45/45
9.8.2022 5/5 45/45 5/5 45/45
13.8.2022 5/5 45/45 5/5 45/45
15.8.2022 4/5 44/45 5/5 45/45
19.8.2022 4/5 44/45 5/5 45/45
20.8.2022 5/5 45/45 5/5 45/45
29.8.2022 5/5 45/45 5/5 45/45
2.9.2022 5/5 45/45 5/5 45/45
Overall 43/45 403/405 55/55 495/495
Table 2. Spruce bark beetle detection sensitivity, specificity and accuracy (n = 100) in the scent detection dog laboratory testing phase.
Spruce bark beetle detection n Sensitivity Specificity Accuracy
Mean S.D. Mean Correct 1 Mean Correct 2
Dog A 45 95.6% ±8.31% 99.5% 403/405 99.1% (43+403)/450
Dog B 55 100% ±0,00% 100% 495/495 100% (55+495)/550
Overall 100 98.0% ±3.86% 99.8% 898/900 99.6% (98+898)/1000
1 correct negatives/all negatives × 100
2 correct positives+correct negatives/all samples × 100
Table 3. Results of field tests where the abilities of laboratory trained dogs to detect spruce bark beetles in natural conditions were evaluated. Dogs were tested on 12 days, on four different field sites. Each day consisted of two or three test runs; 1–3 targets were hidden for each run. One dog was tested per day.
Date Field site, location, area Total number of targets per day Finds
(correct positives) 		Dog
5.6.2023 A, Sastamala; 5519 m2 2 2 A
3.7.2023 A, Sastamala; 5519 m2 3 3 B
15.7.2023 A, Sastamala; 5519 m2 5 4 A
28.7.2023 B, Urjala; 6724 m2 6 6 B
29.7.2023 B, Urjala; 6724 m2 8 7 B
5.8.2023 A, Sastamala; 5519 m2 4 3 A
12.8.2023 C, Huittinen; 8390 m2 4 4 B
14.8.2023 B, Urjala; 6724 m2 5 4 B
16.8.2023 A, Sastamala; 5519 m2 3 3 A
4.9.2023 D, Sastamala; 10050 m2 4 2 B
5.9.2023 D, Sastamala; 10050 m2 4 3 B
11.9.2023 B, Urjala; 6724 m2 6 5 B
Total sum 54 46
Overall sensitivity 1 85.2%
1 Correct positives/all positives × 100