Repellent and Toxicant Effects of Eight Essential Oils against the Red Flour Beetle, Tribolium castaneum Herbst (Coleoptera: Tenebrionidae)

SIMPLE SUMMARY: There is a growing need to preserve stored products and cereal grains from loss of weight and quality during storage. Tribolium castaneum Herbst is known as a serious pest of stored products. Several studies have estimated the efficacy of essential oils (EOs) against T. castaneum but still not enough information on the comparison between repellency and toxicity effects for the EOs. So, this study was to compare the repellency and toxicity effects of eight EOs against the adults of T. castaneum. The results indicated that the 5, 10, and 15% concentrations of Syzygium aromaticum EO had a higher repellent effect against T. castaneum than A. sativum, E. camaldulensis, L. officinalis, S. chinensis, M. chamomilla, C. limon, and P. dulcis after 30 min of exposure. Moreover, the use of Prunus dulcis and Matricaria chamomilla EOs caused a significantly higher mortality percentage than Syzygium aromaticum, Allium sativum, Eucalyptus camaldulensis, Lavandula officinalis, and Simmondsia chinensis at 15% concentration. ABSTRACT: This study was conducted to compare the repellent effect and contact toxicity of eight essential oils (EOs), including Syzygium aromaticum, Allium sativum, Eucalyptus camaldulensis, Lavandula officinalis, Simmondsia chinensis, Matricaria chamomilla, Citrus limon, and Prunus dulcis, against adults of Tribolium castaneum Herbst. Four concentrations (1, 5, 10, and 15% in acetone solvent) of each EO were tested. The 5, 10, and 15% concentrations of S. aromaticum EO had a high repellency effect against T. castaneum compared with A. sativum, E. camaldulensis, L. officinalis, S. chinensis, M. chamomilla, C. limon, and P. dulcis after 30 min of exposure. The repellency test of the S. aromaticum, E. camaldulensis, L. officinalis, M. chamomilla, C. limon, and P. dulcis EOs on T. castaneum has shown that the mortality percentages enhanced with the increase in the EOs concentration and also with the exposure time. The 15% concentration of P. dulcis and M. chamomilla EOs have a significant impact on the mortality rate of T. castaneum compared with S. aromaticum, A. sativum, E. camaldulensis, L. officinalis, and S. chinensis after the 24 h of contact test. Moreover, the 15% concentration of the C. limon EO caused a greater mortality percentage compared with S. aromaticum, A. sativum, E. camaldulensis, and L. officinalis. It could be concluded that using the S. aromaticum EO as a repellent oil and using P. dulcis, M. chamomilla, and C. limon for contact toxicity to treat the flour infested by T. castaneum can play an important role in protecting stored grains and their products.