Akademik Veri Yönetim Sistemi
Journal of Plant Diseases and Protection, cilt.131, sa.2, ss.413-421, 2024 (SCI-Expanded)
In this study, three plant essential oils extracted from thyme (Thymus vulgaris L.), orange (Citrus sinensis L.) and laurel (Laurus nobilis L.), whose major components were carvacrol (93.95%), limonene (96.87%) and 1,8-cineole (57.49%), respectively, according to our GS/MS analysis results, were evaluated singly and in binary (1:1) and tertiary (1:1:1) combinations for their fumigant and contact toxicities against adult Aphis gossypii Glover (Hemiptera: Aphididae), a pest on a wide range of commercially important crops grown both indoor and outdoor, under laboratory conditions. Results showed that all essential oils tested, both alone and in all binary and tertiary combinations, exhibited concentration-depended fumigant and contact toxicities. In fumigant toxicity tests, mortality rates of adult A. gossypii increased with increasing concentration from 2 to 10 µL/L and increasing exposure time from 8 to 48 h. In general, binary and tertiary combinations of the oils were more toxic than either oil alone. For instance, at the highest concentration (10 µL/L air) and exposure time (48 h) used in fumigant tests, all possible binary and tertiary combinations of three essential oils tested caused mortalities ranging from 92.4 to 100%, whereas single treatments of these oils yielded mortalities changing between 72.7 and 97.3%. The highest synergistic action was seen in their tertiary combination (thyme + orange + laurel) by a LC90 value of 5.5 µL/L air after an 8-h-fumigation. In contact toxicity tests, mortality of the aphid species generally increased with increasing concentrations of the oils. For instance, thyme, orange and laurel oils did not produce more than 36% mortality after 24 h of exposure at two lower concentrations (0.5% and 1%), they achieved 98.7, 100 and 97.8% mortalities at the highest concentration (5%), respectively. Although mortalities by the oils alone and their binary and tertiary mixtures at the highest concentration (5%) did not differ significantly from each other, the highest synergistic action was seen in their tertiary combination (thyme + orange + laurel) by 7400 ppm after an exposure period of 24 h. Neither the essential oils alone nor their binary and tertiary combinations had any phytotoxic effect on potted tomato, eggplant, pepper and bean plants at the highest concentration and longest exposure period. Overall results suggest that tested essential oils, especially their binary and combinations each other may be promising candidates for the control of A. gossypii. However, further tests under field conditions are recommended to validate the laboratory results.