Study of the bio-insecticidal potential of certain essential oil components: Investigation of the structure/activity relationships of aromatic components

A wide variety of essential oils are known for their insecticidal and insect repellent properties. In most cases, this activity is due to the presence of active constituents, mainly monoterpenes, sesquiterpenes, and alcohols. In this context, the aim of this study is to evaluate the insecticidal activity of certain essential oil components belonging to two different chemical groups, namely a monoterpene (limonene) and three cyclic aromatic alcohols (eugenol, iso-eugenol, and carvacrol) and their combinations on the stored product pest Tribolium castaneum (Herbst). The toxic and repellent effects of the different components are evaluated in the laboratory through fumigation and repellency tests. The study of co-repellency and co-toxicity between the different components shows the presence of three effects: synergism, indifference, and antagonism. This was confirmed by principal component analysis. Obviously, the chemical structure and interactions between the components of essential oils influence their biological activities.