Identification of insecticidal constituents of the essential oils of Dahlia pinnata Cav. against Sitophilus zeamais and Sitophilus oryzae
2015
Wang, Da-Cheng | Qiu, Da-Ren | Shi, Li-Na | Pan, Hong-Yu | Li, Ya-Wei | Sun, Jin-Zhu | Xue, Ying-Jie | Wei, Dong-Sheng | Li, Xiang | Zhang, Ya-Mei | Qin, Jian-Chun
The aim of this research was to determine the chemical composition of the essential oils of Dahlia pinnata , their insecticidal activity against Sitophilus zeamais and Sitophilus oryzae and to isolate insecticidal constituents. Based on bioactivity-guided fractionation, active constituents were isolated and identified as d -limonene, 4-terpineol and α-terpineol. Essential oils and active compounds tested exhibited contact toxicity, with LD ₅₀ values ranging from 132.48 to 828.79 μg/cm ² against S . zeamais and S . oryzae . Essential oils possessed fumigant toxicity against S . zeamais and S . oryzae with LC ₅₀ from 14.10 to 73.46 mg/L. d -Limonene (LC ₅₀ = 4.55 and 7.92 mg/L) showed stronger fumigant toxicity against target insects. 4-Terpineol (88 ± 8%) and d -limonene (87 ± 5%) showed the strongest repellency against S . zeamais and S . oryzae , respectively. The results indicate that essential oils and insecticidal constituents have potential for development into natural fumigants, insecticides or repellents for control of the stored-product insect pests.
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