Chemical composition and repellent effects of powders and essential oils from Juniperus oxycedrus, Juniperus phoenicea, and Juniperus thurifera against Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae) Imane Naimi * , Hafida Bouamama , Touria Ba M’hamed Laboratory of Sustainable Development and Health Research, Faculty of Sciences and Techniques, Cadi Ayyad University, Marrakech, 40000, Morocco ARTICLE INFO Handling Editor: Dr Christos Athanassiou Keywords: Juniperus species Powders Essential oils (EOs) Repellency rate T. castaneum ABSTRACT 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 α-pinene (28.27%) and cubenol (10.75%) for J. phoenicea, β-Eudesmol (23.74%), hedycaryol (12.54%), and olopanone (10.04%) for J. oxycedrus, and oplopanone (26.84%) and α-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. 1. Introduction The red flour beetle, Tribolium castaneum (Herbst) (Coleoptera: Tenebrionidae), is one of the most damaging secondary pests against a wide range of stored products (Sadiq et al., 2021; Nenaah, 2014). This insect results in significant economic losses amounting to billions of dollars each year (Memon et al., 2024). The conditions of elevated temperature and moisture can lead to an accelerated insect growth rate of 85% (Atta et al., 2020; Boukraa et al., 2022). Moreover, when T. castaneum is abundant, it secretes carcinogenic chemicals known as quinones (Abouelatta et al., 2022). Phosphine is widely utilized as a fumigant for the control of this insect pest (Sakka et al., 2020). However, the repeated use of phosphine presented the most serious drawback: the development of resistance in major stored product insects worldwide, including T. castaneum (Machuca-Mesa et al., 2023). Additionally, the chemical pesticides cause ecosystem dysfunction, lethal effects on non-target organisms, and direct toxicity to consumers (Sileem et al., 2019). The genus Juniperus belongs to the family Cupressaceae, which comprises about 67 species and 28 varieties (Zeraib et al., 2014; Vall`es et al., 2015). In Morocco, they are found in several locations, including the Ourika basin, where the three species J. oxycedrus,J. phoenicea, and J. thurifera can be found (Elmalki et al., 2022). Many studies have shown that Juniperus species are characterized by a high amount of EO in the berries, needles, wood, and seed (Sela et al., 2015). Many components are reported to possess several biological properties (Majewska et al., 2017; Fotiadou et al., 2023). The search for sustainable and effective methods to control pest insects constitutes a crucial global challenge in the context of food security and public health. In this context, the use of natural compounds, such as plant powders and EOs, emerges as a promising strategy to replace synthetic pesticides that are potentially toxic and harmful to the environment (Boukraa et al., 2022; Rad et al., 2022). Our objective was to determine the chemical composition and examine the repellent effect of J. oxycedrus, J. phoenicea, and J. thurifera applied as powders and EOs against T. castaneum adults. However, to the best of our knowledge, there is still no published study on this topic. * Corresponding author. E-mail address: imane.naimi94@gmail.com (I. Naimi). Contents lists available at ScienceDirect Journal of Stored Products Research journal homepage: www.elsevier.com/locate/jspr https://doi.org/10.1016/j.jspr.2024.102435 Received 13 February 2024; Received in revised form 15 August 2024; Accepted 27 September 2024 Journal of Stored Products Research 109 (2024) 102435 Available online 24 October 2024 0022-474X/© 2024 Elsevier Ltd. All rights are reserved, including those for text and data mining, AI training, and similar technologies.