Bio-active principles in Commiphora africana resin dichloromethane extract and their insecticidal activity against bedbugs

Abstract

Bedbugs (Cimex lecturalius Linnaeus) are ecto-parasite pests that wholly feed on human and domestic animals’ blood causing anemia to the host on excessive feeding. Bedbug control has proved futile due to various challenges including; development of insecticide resistance, high associated cost and environmental pollution. Natural herbal-based phytochemicals remain unexploited and we focused on Comiphora africana (A. Rich.) Engl. resin traditsionally used bedbug control. We previously showed that dichloromethane extract of C. africana resin is highly repellent and toxic against bedbugs. In this study, we isolated compounds from the dichloromethane extract using column chromatographic techniques. The isolated compounds were evaluated for repellency and toxicity against bedbugs; and characterized using conventional spectroscopic techniques. Five compounds (taraxasterol, pseudo-taraxasterol, beta-sitosterol, fungisterol and guggusterol) were isolated and characterized for the first time in this plant. Fungisterol had the highest repellency (75%) against bedbugs which was not significantly different (P > .05) to the positive control (neocidol) (74%) after > one-hour exposure. Fungisterol also elicited highest toxicity against bedbugs with LC50 of 25.73 mg/L after 24 h exposure. Blending fungisterol with other identified active terpenes did not synergize the overall repellent/toxic responses. This study identifies active compounds in C. africana resin and therefore lays a solid background in bedbug control using isolated compounds.