Bioactivity of fenchone and Plectranthus glandulosus oil against Prostephanus truncatus and two strains of Sitophilus zeamais

Abstract

The toxic, repellent and reproduction inhibitory effects of Plectranthus glandulosus essential oil and one of its major compounds, fenchone, were evaluated against adult Prostephanus truncatus (Horn) and for two strains of Sitophilus zeamais Motschulsky from Cameroon and Germany. Maize grains were coated with the oil at 0, 10, 20, 40 and 80 μl/40 g grain and fenchone at 0, 20, 40, 80 and 120 μl/40 g grain. Mortality was assessed over a 7‐day period, followed by the determination of F1 progeny production. The repellence of the two products was evaluated at five rates (0.5, 1, 3, 5, 10 μl/half disc) in a choice bioassay on filter paper. The oil and fenchone caused significant dose‐dependent mortality to the three insects, with the oil achieving 100% and 90% mortality for the two S. zeamais strains and P. truncatus, respectively, within 1 day of exposure at the dosage of 80 μl/40 g grain. The insects were less susceptible to fenchone compared with the crude oil. The German strain of S. zeamais was susceptible to the oil than the Cameroonian strain. At the dosage of 20 μl/40 g grain, S. zeamais F1 progeny emergency was completely inhibited by the oil, while 80 μl/40 g grain treatment with fenchone prevented also insect emergence. Plectranthus glandulosus oil generally evoked a maximum per cent repellency of 100% for the three insects, but fenchone caused 55–60% to S. zeamais and 80% to P. truncatus. These results suggest that fenchone, though a major constituent of P. glandulosus oil, may only be a minor component of its bioactivity.

Steam sauna and mother roasting in Lao PDR: practices and chemical constituents of essential oils of plant species used in postpartum recovery

“…Fenchone is also effective as pesticide [50-52] through inhibition of acetylcholinesterase activity [53]. …”

Excess molar enthalpies of R-fenchone+propan-1-ol or +propan-2-ol. Modeling with COSMO-RS and UNIFAC

“…But it has also potential uses in a variety of different fields. For example, R-fenchone shows activity as toxic repellent and inhibitor of reproduction for insects [2]. It has been also tested as a drug in medical therapy for ureterolithiasis [3].…”

Biotransformation of (+)-Fenchone by Salmonella typhimurium OY1002/2A6 Expressing Human CYP2A6 and NADPH-P450 Reductase

“…In this study, compound 3 was preferentially produced by a mechanism similar to human microsomal metabolism. There have been reports that fenchone shows strong species-specific toxicity 25 . However, detailed investigations about hydroxyfenchone toxicity have not been reported.…”