The effect of some plant essential oils on the biology of the storage pest tenebrio molitor (Coleoptera: tenebrionidae), their use as insecticide and evaluation of their effects on the environment

This study was carried out to investigate the use of herbal essential oils as insecticides to replace synthetic pesticides on storage pests. In the study, contact and repellent effects of Tyhmus vulgaris (Thyme), Hypericum perforatum (St John's wort), Pogostemon cablin (Patchouli) and Azadirachta indica (Chinaberry tree) essential oils were investigated on the developmental stages of the important storage pest Tenebrio molitor. Contact and repellent trials were carried out with %10 solutions of essential oils and mortality rates were investigated after 24 hours. The trials for both methods were carried out in five replicates and 10 larvae, pupae and adults were used for each replicate. It was observed that larvae, pupae and adults were affected by plant essential oils at the same rate. According to the results of the contact effect trial, %100,0  0,0 mortality rate was observed in larvae, pupae and adults in the treatment of plant essential oils. In the repellent effect trials, %90,0  0,1 mortality occurred in the larval trials of thyme essential oil and %100,0  0,0 mortality occurred in other life stages of T. molitor. In the adult trials of Chinaberry tree, %95,0  0,6 mortality occurred, %100,0  0,0 mortality occurred in other life stages of T. molitor. St John's wort and patchouli essential oils caused %100,0  0,0 mortality in all life stages of T. molitor. The plant essential oils used in the study showed highly toxic effects on larvae, pupae and adults of T. molitor. According to the results of the study, promising results were obtained and it was shown that plant essential oils can be used as insecticides.