THE OIL OF GARLIC, ALLIUM-SATIVUM L (AMARYLLIDACEAE), AS A POTENTIAL GRAIN PROTECTANT AGAINST TRIBOLIUM-CASTANEUM (HERBST) AND SITOPHILUS-ZEAMAIS MOTSCH

Fresh garlic cloves were steam-distilled to obtain the essential oil. The garlic oil was tested for toxicity against the eggs, larvae and ad ults of Tribolium castaneum and adults of Sitophilus zeamais. T. casta neum egg mortality increased with garlic oil concentration, complete k ill of eggs being achieved at 4.4 mg/cm(2), using the filter paper imp regnation bioassay. The eggs were the most susceptible stage, followed by adults, 10-day old larvae and older larvae. T. castaneum adults we re more susceptible to garlic oil than S. zeamais adults, with KD50 va lues of 1.32 mg/cm(2) and 7.65 mg/cm(2), respectively. When rice and w heat were treated with garlic oil, eggs that were laid in the media fa iled to produce Fl progeny at concentrations of >2000 ppm in rice for T. castaneum and 5000 ppm in wheat for S. zeamais. The weights of Fl a dults of T. castaneum and S. zeamais in treated media were not signifi cantly different (P > 0.05) from those of the controls. The potential of garlic oil, and the bioactive compounds therein, as an effective gr ain protectant is discussed.