Potential of essential oils from four Cameroonian aromatic plants used in integrated protection of stored products programs

Vortrag

Abstract

The efficacy of essential oils extracted from fruits of Piper capense and Xylopia parviflora, and roots of Echinops giganteus and Mondia whitei were evaluated against Acanthoscelides obtectus and fungi isolated from bean seeds in laboratory conditions in Cameroon. The essential oils were extracted by water-distillation and their chemical composition identified by Gas Chromatography-Flame Ionization Detection (GC-FID) and Gas Chromatography- Mass Spectrometry (GC-MS). Toxicity assays of essential oils against A. obtectus were carried out by fumigation in which insect pests were exposed fumes of the essential oils, and mortality recorded after 6, 12, and 24 hours. Additionally, the toxicity by contact of the essential oils was evaluated through coating grains with essential oils or impregnating the essential oils onto the filter paper, allowing the insects to physically get in contact with the essential oil, and assessing weevil mortality recorded after 1, 2, 3, and 4 days. The essential oils from P. capense and X. parviflora consisted mainly of hydrocarbon monoterpenes (56.5% and 50.0% respectively), whereas the essential oils from E. giganteus was mostly constituted of sesquiterpenes (94.3%) in which the tricyclic compounds are more abundant. A major compound identified in the essential oil from M. whitei was 2-hydroxy- 4-methoxy-benzaldehyde (81%). The essential oil from X. parviflora was the most effective as contact and fumigant against A. obtectus, causing 100% mortality within 1 day at low lethal concentrations. On the other hand, the essential oil from M. whitei exhibited the best anti-fungal activity. These essential oils could play an important role in pest protection of stored beans and reduce the risks associated with use of synthetic insecticides especially in low income small holder farming systems.