Two powdered spices, turmeric (Curcuma longa L.) and cinnamon (Cinnamomum zeylanicum Ness.) were evaluated for their ability to protect stored wheat grains against infestation by two important stored-product pests. The spices were added separately to 20 g wheat grains as direct admixtures at five different rates 0.5, 0.85, 1.5, 3 and 5% (w/w) to assess for mortality and reduction of F 1 progeny. Twenty adult insects were released in each container. All tested insects were removed after 14 days and the experiments were monitored for the following 36 days in order to count the number of emerged adults. Each of the experiments was performed in four replicates. The results revealed that powders had significant insecticidal effects on the adults of both insects. The toxicities of these powders increased with an increase in dosage as well as an increase in the period of exposure to the plant materials. Powders at 5% (w/w) exhibited a significant toxicity on the adults of both pests, but did not cause complete mortality. Turmeric is more effective than cinnamon against both insects and S. granarius adults were more sensitive than R. dominica. Moreover, they caused complete reduction in F 1 progeny of both insects at the highest dosages.
