African Journal of Agricultural Research Vol. 2(4), pp. 173-177, April, 2007

ISSN 1991- 637X­© 2007 Academic Journals

Full Length Research Paper

Persistence of insecticidal activities of crude essential oils of three aromatic plants towards four major stored product insect pests

Ngamo T. S. L¹, Ngatanko I¹*, Ngassoum M. B. ¹, Mapongmestsem P. M. ¹, Hance T. ²

¹University of Ngaoundéré BP 454, Cameroon,

²Laboratory of Ecology and Biogeography, Research Center on the Biodiversty, 4-5 Place Croix du Sud, 1348, Louvain-la-Neuve, Belgium.

Corresponding author. E-mail: iliassangatanko2000@yahoo.fr 

Accepted 16 February, 2007

Essential oils of aromatic plants with insecticidal properties are more and more considered as alternative insecticides to protect stored products. Many banned insecticides have high persistence which allow them to occur at several levels of trophic chains. The aim of the present work is to analyse the persistence of insecticidal activity of crude essential oil of three most used local aromatic plants : Annona senegalensis Pers. (Annonaceae), Hyptis spicigera L. (Lamiaceae) and Lippia rugosa L. (Verbenaceae) towards the four majors stored product insect pests: Sitophilus zeamais Motsch., Sitophilus oryzae L., Callosobruchus maculatus Fab. and Tribolium castaneum Herbst. This research revealed that H. spicigera essential oil was the most active towards S. oryzae with a LD50 = 20.18ppm. T. castaneum was the less sensitive insect to the three essential oils tested. During a period of 24 hours L. rugosa essential oil was the most persistent, showing mortalities for S. zeamais of 80%, S. oryzae more than 60%, C. maculatus 100% and T. castaneum 50%. The two other oils tested were not as persistent as L. rugosa. This important persistence of the essential oil of L. rugosa could be explained by its high content of oxygenated compounds compared to that of the other oils. This most interesting essential oil is therefore a suitable one for popularisation in strategies of pest management in storage.

Key words: essential oils, aromatic plants, stored products, insect pests, persistence.