Efficacy of microencapsulated repellents based on Psiadia punctulata exudate and Daphne essential oils

Abstract

This paper presents the results of testing the efficacy of microencapsulated repellents isolated from P. punctulata leaves, and the Daphne repellents. The active compound of Daphne is a mixture of more than twenty natural and synthetic volatile compounds, contributing to smell- and taste-based repellent effects against deer. P. punctulata, a plant species from Eastern Africa, is known to be avoided by browsing herbivores, even during severe drought. Its extract, obtained by ethyl acetate extraction of a resinous surface leaf exudate, was tested as a taste-based repellent. A modified in situ polymerization method of aminoaldehyde resins with styrene-maleic acid anhydride modifier was used for the microencapsulation. The product was mixed with polyvinyl alcohol and acrylate binders into a suspension formulation. The efficacy of the repellent on roe deer (Capreolus capreolus) in winter was tested with baits, containing one-year-old apple branches, on agricultural surfaces sown with wheat. The damage caused by browsing was evaluated at different time intervals. The results of testing showed a prolonged activity and improved efficacy of microencapsulated repellent formulations in comparison with the standard non-encapsulated Daphne repellent. P. punctulata leaf exudate exhibited stronger repelling effect than Daphne essential oils.