Insecticidal and biting deterrent activity of rose-scented geranium (Pelargonium spp.) essential oils and individual compounds against Stephanitis pyrioides and Aedes aegypti

Abstract

BackgroundRose-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. ResultsAll 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 100g 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). ConclusionEssential 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