The red flour beetle (Tribolium castaneum) is a worldwide pest of stored products, particularly food grains, and food products including flour, cereals, pasta, biscuits, beans, and nuts, causing loss and damage. The toxicity effects of an important medicinal plant, peppermint (Mentha piperita) was studied under controlled conditions (16:8 h L:D at 25 ± 1 C and 65 ± 5% RH). The acetonic, methanolic extracts of peppermint were prepared. Five concentrations (0.625%, 1.25%, 2.5%, 5%, and 10%) were used for toxicity and to evaluate LC50 values with the control, which was treated with acetone, or methanol. Each bioassay was performed with 25 adult of T.castaneum per concentration for all the experiments in three replicates. LC50 values were calculated using probit MsChart software by recording the mortality at 36 h. The LC50 value were 61.777% for methanolic extract and 4.19% for, respectively. These results indicate that this medicinal plant might possess potential secondary metabolites that may be useful for controlling potential insect pests.
