An evaluation of repellents to suppress browsing by possums.

The efficacy in feeding suppression trials with possums (Trichosorus vulpecula Kerr) of six synthetic odorous chemicals uniquely associated with various of the Mustelidae species and of the red fox (Vulpes vulpes) has been evaluated with respect to several proprietary repellents. The predator odors, two proprietary repellents, and two other repellent formulations (olive oil in petroleum jelly and a synthetic fermented egg odor cocktail) were applied as 5% w/v solutions in paraffin to the foliage ofPinus radiata seedlings and the extent of browse compared with that on seedlings treated with Treepel, an effective egg-based repellent already available commercially. All four of the mustelid predator odors [(∓)-2-n-propylthietane, (∓)-3-n-propyl-1,2-dithiolane, 2,2-dimethylthietane, and 3,3-dimethyl-1,2-dithiolane] and the volatile compound from fox urine (Δ(3)-isopentenyl methyl sulfide) were shown to be more or at least equally effective compared to Treepel. This was true also of one commercial repellent Gori, which contained bitrex and the synthetic fermented egg formulation. The most effective compounds will be evaluated when administered with adhesives and surfactants in the further development of possum repellents with longer field lives.