Antifeedant activity of plant extracts from Mentha piperita L. and Mentha pulegium L. were tested against the Indian meal moth, Plodia interpunctella (Hübner). The nutritional indices: relative growth rate (RGR), relative consumption rate (RCR), efficiency of conversion of ingested food (ECI) and feeding deterrence index (FDI) were measured for first-instar larvae (15-d old). Treatments were evaluated using a flour disk bioassay in the dark, at 25±1°C and 60±5% R.H. Concentrations of 0, 0.1, 0.5, 0.75, 1, 1.5 and 2 mL/disk were prepared from each essential oil. After 72 h, nutritional indices were calculated. M. piperita oils were more effective than M. pulegium oils, by significantly decreasing the RGR, RCR and FDI. At the highest concentration tested (2 mL/disk), the ECI (9%) was significantly reduced.
essential oil, nutritional indices, Plodia interpunctella.