Fumigant and repellent potentials of Mentha pulegium L. and Citrus limon L. (Burm) essential oils against Tribolium confusum Duval. (Coleoptera: Tenebrionidae)

This study aims to investigate the chemical composition of essential oils (EOs) extracted from the aerial parts of pennyroyal (Mentha pulegium L.) and lemon peels (Citrus limon L.) and evaluate the fumigant toxicity and repellency against the most important and destructive stored product beetle in Algeria (T. confusum). Chemical analysis of the essential oil of M. pulegium showed that pulegone (62.24%), sabinene (5.51%) and menthol (16.5%) were the main essential components, while C. limon essential oil had limonene (66.93%) as the main compound, followed by β-pinene (4.52%), citral (3.09%) and β-Bisabolen (2.67%). The results show that the fumigant toxicity varies according to the concentration of essential oils, the median lethal concentration (LC₅₀) values of Mentha pulegium and Citrus limon were 92.89 and 818.5 μl/L_air on T. confusum respectively. In addition, significant pest repellent activity was demonstrated with pennyroyal where repellent effects reached 80 and 90% (Class V) after 60 min exposure against the beetle at all concentrations (0.126, 0.314, 0.628 and 0.942 μL/cm²). The data obtained indicate that pennyroyal EOs show a higher toxicity and repellent activity against adults of T. confusum comparing to those of C. limon.