BIOACTIVITY OF EUGENOL, A MAJOR COMPONENT OF ESSENTIAL OIL OF OCIMUM-SUAVE (WILD) AGAINST 4 SPECIES OF STORED-PRODUCT COLEOPTERA

Toxicity and protectant potential of eugenol against Sitophilus granar ius, Sitophilus zeamais, Tribolium castaneum and Prostephanus truncatu s was investigated in the laboratory using contact toxicity, grain tre atment and repellency assays. Eugenol applied topically, impregnated o n filter papers, whole grains or glass pebbles was highly toxic to all the four species. Beetle mortality was dosage-dependent. Eugenol was more effective on grain than on filter paper discs since the lowest do sage of 1 mu l/kg of grain killed all the beetles within 24 h. The eff ectiveness of eugenol was significantly reduced by the length of stora ge after application. For grains bioassayed after 10 days of storage f ollowing treatment mortality decresed to less than 30% even with the h ighest dose of 10 mu l/kg. Eugenol was also highly repellent to the fo ur beetle species tested with overall repellency in the range of 80 - 100%. Development of eggs and immature stages inside grain kernels was completely inhibited by eugenol treatment.