BIOLOGICAL-ACTIVITY OF 1,8 CINEOLE, A MAJOR COMPONENT OF ESSENTIAL OIL OF OCIMUM-KENYENSE (AYOBANGIRA) AGAINST STORED-PRODUCT BEETLES

The efficacy of 1,8 cineole as repellent, toxicant and grain protectan t against Sitophilus granarius, S. zeamais, Tribolium castaneum and Pr ostephanus truncatus was investiaged in the laboratory using contact t oxicity, grain treatment and repellency assays. 1,8 cineole applied to pically or imprenated on filter paper, whole wheat as well as maize gr ains was highly toxic to all the four beetle species. Beetle mortality was dose-dependent with the highest dose of 10 mu l/insect evoking 10 0% mortalities in the beetles after 24 h exposure. 1,8 cineole was mor e toxic in grain than on filter paper since the lowest dosage of 0.5 m u l/kg controlled all beetles exposed. There was, however, a highly si gnificant loss of toxicity after only 24 h following treatment, irresp ective of dosage applied. Development of eggs amd immature stages with in grain kernels as well as progeny emergence were completely inhibite d in treated grain. 1,8 cineole evoked strong repellent action against S. granarius and S. zeamais but was moderately repellent to T. castan um and P. truncatus. The protectant potential of products derived from O. kenyense against insect damage in traditional grain storage in Afr ica is discussed.