Insecticidal and biting deterrent activity of rose-scented geranium (Pelargonium spp.) essential oils and individual compounds against Stephanitis pyrioides and 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 = 13.4ppm) was the most toxic compound against one-day-old Ae. aegypti larvae, followed by geraniol (49.3ppm), citronellol (49.9ppm) and geranyl formate (58.5ppm). Essential oil of cultivar 'Egypt' at 100μg 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.