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Published on: December 30, 2014
Insecticidal and biting deterrent activity of rose-scented geranium (Pelargonium spp.) essential oils and individual
Abbas Ali1, Christine C Murphy, Betul Demirci
1National Center for Natural Products Research, University of Mississippi, University, MS, USA.
Background:
Rose-scented geranium, Pelargonium spp., essential oils from the cultivars 'Bourbon', 'China', 'Egypt', 'Rober's Lemon Rose' and 'Frensham' were analyzed by GC-FID and GC-MS. A total of 136 compounds were identified from five essential oils, constituting 85.5-99.7% of the oils. Essential oils and pure compounds were evaluated for their insecticidal activity against Stephanitis pyrioides and larvicidal and biting deterrent activity against Aedes aegypti.
Results:
All five geranium oils were toxic to S. pyrioides, and four of these five were more potent than malathion and neem. Trans-nerolidol (LD50 = 13.4 ppm) was the most toxic compound against one-day-old Ae. aegypti larvae, followed by geraniol (49.3 ppm), citronellol (49.9 ppm) and geranyl formate (58.5 ppm). Essential oil of cultivar 'Egypt' at 100 μg cm(-2) [biting deterrent index (BDI) = 0.8] showed the highest biting deterrent activity, followed by cultivars 'Frensham' (BDI = 0.76), 'China' (BDI = 0.72), 'Rober's Lemon Rose' (BDI = 0.63) and 'Bourbon' (BDI = 0.45) essential oils. Among the pure compounds, the biting deterrent activity of geranic acid (BDI = 0.99) was not significantly different from that of N,N-diethyl-m-toluamide (DEET).
Conclusion:
Essential oils and pure compounds showed insecticidal activity against S. pyrioides and Ae. aegypti. The high biting deterrent activity of geranic acid points to the need for further research.