Effect of Site Location and Collecting Period on the Chemical Composition of Hyptis SpicigeraLam. an Insecticidal Essential Oil from North-Cameroon

AbstractHyptis spicigeraessential oils from seven localities in the North-Cameroon (Ngaoundere, Guirvidig, Kodeck, Lara, Toloum, Kaele, Tchecal-baila) were investigated by GC and GC/MS. Results showed differences within harvesting sites and between the different sites of collection but did not revealed clear tendencies in the evolution of the oil composition with regard to the sampling period. The main group of compounds in all the analyzed samples were: α-pinene (11.9%-42.1%), β-pinene + sabinene (6.0%-39.8%) and β-phellandrene + 1,8-cineole (8.8%-27.4%) except in one oil where β-caryophyllene (23.4%) was the principal component. The insecticidal activity of H. spicigeraand its principal terpenic components was evaluated against the cowpea weevil Callosobruchus maculatusF., the major cause of damages of cowpea (Vigna unguiculata(L.) Walp) in North Cameroon.