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    Chemical compositions and larvicidal effectiveness on nerium oleander flower essential oil on hyphantria cunea larvae
    (Gheorghe Asachi Technical University of Iasi, Romania, 2024) Göktürk, Temel; Dumbadze, Guguli; Jgenti, Lali
    In this research, the chemical composition of oleander (Nerium oleander L) (Apocynaceae) flower essential oil was analyzed using GC-MS (Gas Chromatography-Mass Spectrometer), and its larvicidal effectiveness on five Fall webworm (Hyphantria cunea Drury) larval stages was investigated. The essential oil was extracted from the flowers of N. oleander by the hydrodistillation method using the Clevenger apparatus. A total of 48 chemical constituents present in oleander essential oil were identified using Gas Chromatography-Mass Spectrometry analysis. Camphore (10.3%), Digitoxigenine (10.21%), Eugenol (8.61%), Thymol (6.15%), and 1.8-Cineole (5.05%) were found as the primary components of oil. It is observed that the applications of N. oleander essential oil at doses of 10, 15, and 20 μL/Petri and the controls at 24, 48, 72, and 96 hours induced fatalities at varied rates (40.4-100%) on five H. cunea larval stages (L1-L5). The highest toxicity was identified at L1 (0.56 μL/larva), and the lowest toxicity was determined at L5 (12.64 μL/larva) according to LD50 and LD90 values. The research was conducted in laboratory settings during 2021-22. In conclusion, N. oleander essential oil showed high toxicity against L1 and L2 larval stages of H. cunea.
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    Natural insecticides: Effectiveness of essential oils against Orasanga Japonica in nymphal and adult stages
    (Springer Nature, 2025) Göktürk, Temel; Dumbadze, Guguli; Jgenti, Lali
    Orosanga japonica Melichar (Hemiptera: Ricaniidae) is an invasive polyphagous pest in the eastern Black Sea coastal zone of Turkey. Synthetic broad-spectrum insecticides are often used to control O. japonica. The increased risk of chemical contamination when using synthetic insecticides to control insect pests has led to a growing interest in essential oils. In this study, the insecticidal effect of the essential oils of Artemisia absinthium, Cuminum cyminum, Mentha pulegium, Rhododendron ponticum and Rhododendron luteum on the nymphal and adult stages of O. japonica was tested under laboratory conditions. 10, 15 and 20 µL/Petri essential oils were sprayed on adults and nymphs of O. japonica. It was observed that mortality rates increased with increasing dose and exposure time in all experiments. The oils caused a mortality rate of 6.7–80.8% in the nymphs and 0.8–55.8% in the adults at 20 µL/Petri after 96 h of exposure. It was found that the essential oils of R. ponticum and R. luteum had the strongest insecticidal effect on the nymphal and adult stages of O. japonica. The highest mortality occurred at a dose of 20 µL/Petri of the oils after 96 h of exposure. The positive control had the highest mortality rate for nymphs and adults (100%). R. ponticum and R. luteum proved to be the most toxic essential plant oils in the second part of the study. C. cyminum, on the other hand, had the least toxic effect, based on LD50 and LD90.