Chemical composition and repellent effects of powders and essential oils from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae)

The present study evaluated the chemical composition and the potential repellent effect of powders and essential oils (EOs) from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against T. castaneum adults. The EOs were extracted by the hydrodistillation method, and their chemical composition was analyzed using gas chromatography-mass spectrometry (GC-MS) analysis. The repellent effect of powders and EOs was assessed using the area preference method. GC-MS revealed that the major components of the studied EOs were alpha-pinene (28.27%) and cubenol (10.75%) for J. phoenicea, beta-Eudesmol (23.74%), hedycaryol (12.54%), and olopanone (10.04%) for J. oxycedrus, and oplopanone (26.84%) and alpha-Santanol acetate (17.28%) for J. thurifera. The powders of three Juniperus species had a repellent effect (class IV) against T. castaneum adults. Among the powders tested, J. phoenicea had the highest average repellency rate of 75.40%, followed by J. oxycedrus with 62.30%, and J. thurifera had the lowest average repellency rate of 60.30%. Moreover, J. phoenicea EO had the highest average repellency rate of 72.50%, followed by J. oxycedrus with 67.40%, while J. thurifera had the lowest average repellency rate of 61.80%. The potential of Juniperus species can be used as biopesticides to control T. castaneum infestations as an alternative to synthetic pesticides.