Determination of insecticidal and behavioral activity of some plant essential oils against three stored product pests

In this study, the efficacy of plant essential oils as an alternative to the negative effects of chemical insecticides in the control of stored product pests was investigated. Mentha longifolia (flower and flower+stem), Mentha piperita and Lavandula angustifolia cvs. Hemus, Raya and Yubileina were used in the study. In biological efficacy trials conducted at Sivas Science and Technology University Plant Pest Laboratory, contact toxicity, repellent effect and F1 generation yield of these essential oils on three important storage pests, Sitophilus oryzae, Tribolium castaneum and Rhyzopertha dominica, were investigated. In addition, the effects of essential oils on germination vigor of wheat were also evaluated. According to the results of the study, M. longifolia flower essential oil showed the highest contact effect on S. oryzae with 86.8% after 72 hours and exhibited strong toxicity with the lowest LD₅₀ (0.070 µl insect-1) and LD₉₀ (0.109 µl insect-1) values. The effect on T. castaneum was more limited, while R. dominica was the most resistant species. The results of the study showed that the effectiveness of essential oils may vary depending on the vegetative organ of the plant and genotype differences. In repellent effect trials, it was determined that all essential oils exhibited strong repellent effect with increasing doses, especially L. angustifolia cvs. Raya and Yubileina and M. longifolia flower essential oil. In F1 generation yield evaluations, essential oil treatments significantly suppressed the new generation population of pests; in some combinations, inhibition of nearly 80% was achieved. In the biological efficacy studies, the most effective essential oil was M. longifolia flower essential oil and it was determined that it had no significant negative effect on the germination rate of wheat seeds. In conclusion, it was determined that the essential oils examined stand out with their contact and repellent effects as well as population suppression capacities in the control of storage pests. The findings indicate that Mentha and Lavandula species can provide an environmentally friendly and sustainable alternative to chemical insecticides in agricultural pest control.