Chemical Composition and Insecticidal Effects of Essential Oils Extracted from Four Cumin ‎Ecotypes on the Larvae of Pink Stem Borer

Pink stem borer, Sesamia creticaLed, is one of the most important pests of sugarcane and maize in Iran. Insecticidal properties of essential oils of four cumin ecotypes, namely Fars-Sivand (FS), North Khorasan-Shirvan (KS), Kerman-Kuhbanan (KK), and Kerman-Rafsanjan (KR), has been evaluated against 4th instar-larvae of S. cretica in a completely randomized design with four replications. Larval mortality at 27±2 °C, relative humidity of 65±5%, and 16:8 hours light: darkness period is recorded after 72 hours. Results show that all cumin ecotypes have been toxic to the pest, with the lowest LC50 value, obtained from the essential oil of KR ecotype (2725 ppm) followed by KK, FS, and KS ecotypes (2777, 3099, and 8390 ppm, respectively). The chemical analysis of essential oils tested by GC-MS shows that m-cymene in the KR ecotype has been higher than other cumin ecotypes. Therefore, the high toxicity of KS ecotype compared to other cumin ecotypes can be related to the presence of such compounds. According to the present study’s results, the essential oils of cumin ecotypes are potentially a great substitute for chemical insecticides in the integrated management of S. cretica.