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Keywords:

  • rose-scented geranium;
  • citronellol;
  • geranic acid;
  • geraniol;
  • nerolidol;
  • Stephanitis pyrioides;
  • Aedes aegypti

Abstract

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. © 2013 Society of Chemical Industry