Olfactory threshold of dogs (Canis lupus familiaris) to cold-killed spotted lantern fly eggs

The Spotted Lantern fly (Lycorma delicatula) is an invasive foreign species that is affecting US forestry and agriculture for which dogs have been deployed to detect and eradicate. However, dogs' olfactory threshold or limits of detection for this target is unknown. Thus, the aim of this study was to evaluate dogs' olfactory threshold to SLF eggs. Using an automated air dilution olfactometer and an adaptive staircase procedure, we evaluated dogs' (N = 10) olfactory threshold in two experiments. Experiment 1 evaluated the highest air dilution at which dogs were able to accurately discriminate between a vial containing cold-killed SLF eggs and a blank vial. In Experiment 2 we added tree bark as background noise to the vials and evaluated the highest air dilution at which dogs were able to discriminate a vial with cold-killed SLF eggs + bark from a vial containing egg free bark only. Overall, dogs were able to accurately discriminate cold-killed SLF eggs from a blank vial at a 0.09 (v/ v) air dilution. Adding tree bark as background noise increased dogs' discrimination threshold to 0.041 (v/v) air dilution. Nonetheless, for most of the dogs, their olfactory threshold in Experiment 2 was ten-fold or higher than in Experiment 1. Our study further confirms that detection dogs are efficient detecting dead SLF eggs and highlights the negative effects background noise can have on olfactory discrimination threshold.