Potential use of essential oils from Cameroon applied as fumigant or contact insecticides against Sitophilus zeamais Motsch. (Coleoptera: Curculionidae).

Essential oils from seven plants species currently found in Cameroon were extracted by steam distillation and tested for their insecticidal activities against Sitophilus zeamats Motsch. Responses varied with the test applied and the plant species. For the contact toxicity, the acetone was used in order to dilute the pure essential oil. Formulations of 1% of essential oils of Xylopia aethiopica and Ocimum gratissimum were the most toxic and led to 96 and 98% of mortality respectively after 24 h. There was no death in control (0% of mortality). Fumigation test were done by applying 300 microl of pure essential oils in the bottom of closed 800 ml glass containers. In that case, the essential oil of Hyptis spicigera was the most toxic (fumigant) after 48 hours of fumigation followed by Annona seregalensis and Xylopia aethiopica 96 and 95% of mortality respectively. Some of the essential oils of plant species tested are promising for pest control in farmer granaries. However, further investigations are to be done on formulation and side effects.