ORIGINAL RESEARCH ARTICLE Cyclic and acyclic alcohols: a structure-activity relationship study correlation between insecticidal activity and chemical structure Amel Ben Hamouda 1 & Enis Ben Bnina 2 & Ikbal Chaieb 1,3 & Asma Laarif 1 & Hichem Ben Jannet 2 Received: 17 January 2020 /Accepted: 18 September 2020 # African Association of Insect Scientists 2020 Abstract The efficiency of essential oil depends upon the chemical nature, composition, and the relative proportion of its functional groups. In some case, individual compounds can exhibit a pertinent effect than do the essential oils. To underline their efficiency according to their chemical structure, five cyclic and acyclic alcohols were tested in vitro for their potential insecticidal and repellent activities against Tribolium castaneum (Herbst). The ability to repel more than 95% was observed in all tested compounds from 15 min to 10 h, except for eugenol that exhibited the weakest effect. Fumigant bioassay showed that the five alcohols applied separately caused significant insect mortality that exceeds 60% at 400 μL/L air. The lowest median lethal dose, LC 50 = 18.24 μL/L was observed with citronellol. PCA analysis revealed that the acyclic alcohols showed stronger toxicity compared to the cyclic ones. Moreover, the combined effect of these alcohols was lower than individual ones in all tested combinations. According to the outcome of this study, acyclic alcohols might be more effective in reducing stored grain Tribolium infestation than cyclic ones as a single compound. The knowledge of the degree of efficiency of each chemical group gives the possibility to create artificial combinations of different constituents for the development of more effective eco-friendly control agents. Keywords Alcohols . Chemical structure . Fumigant . Repellency . Tribolium castaneum Introduction As many insects affect food production storage, synthetic in- secticides have often been used to control them. However, in- appropriate use of these chemicals is associated to the occur- rence of resistance in pests and contamination of the food and environment (Helps et al. 2020; Lardeux et al. 2010; Michaelakis et al. 2009; Tabashnik et al. 2014; Toloza et al. 2010; Tunaz et al. 2009). Moreover, pests exhibited tolerance toward insecticides, occurring following the use of many appli- cation rates (Stoll 2000). In current storage technologies, man- agement of insect pests is controlled by chemical insecticides, including both fumigants and contact insecticides, which dis- play severe hazard to human health and environment, leave residues and intensify insect resistance (Benhalima et al. 2004; Nayak et al. 2003; Opit et al. 2012). Additionally, the high cost of pest control requires recent alternatives (Yildirim et al. 2001). Fumigation is considered among the most effica- cious and widespread mode for the control of the stored product (Marriott et al. 2018). Methyl bromide and phosphine are the most common and widely used fumigants (Annis 2016; Fields and White 2002; Iturralde-García et al. 2016). Likewise, carbon dioxide and sulfuryl fluoride are used for fumigation of stored grains instead of phosphine (United Nations Environment Programme (UNEP) 2019; Van Someren Graven 2004). Nevertheless, the current fumigants present some concerns since methyl bromide has been phased out in many countries including Tunisia because it has been found to cause strato- spheric ozone layer depletion (Fields and White 2002). Subsequently, the effect of natural products as insecticide and * Amel Ben Hamouda ben.hamouda@yahoo.fr 1 UR13AGR09-Intergrated Horticultural Production in the Tunisian Centre-East, Regional Research Centre in Horticulture and Organic Agriculture, Chott-Mariem, 4042 Sousse, Tunisia 2 Laboratory of Heterocyclic Chemistry, Natural Products and Reactivity, Team: Chemistry Medicinal and Natural Products, Department of Chemistry, Faculty of Sciences of Monastir, University of Monastir, Monastir, Tunisia 3 Plant Protection Laboratory, National Institute of Agricultural Research of Tunisia, University of Carthage, Tunis, Tunisia International Journal of Tropical Insect Science https://doi.org/10.1007/s42690-020-00277-7