Proteinase inhibitors (PIs) from a variety of plant and animal source reduce the growth and survival of a range of insects when added to their diet. The current investigation focused on the effect of trypsin inhibitor from Dimorphandra mollis seeds -DMTI- incorporated into insect artificial diets, on the growth and metabolism of Corcyra cephalonica larvae. In addition, the effects on gut proteinases were determined by analyzing the digestive enzymes properties of larvae fed on artificial diet containing DMTI. C. cephalonica is a major pest of stored grains of pearl milled and sorghum. To examine the effect of DMTI on larval development C. cephalonica, the moths were maintained in plastic boxes, with perforated plastic covers at a relative humidity of 65-75% and temperature of 28 ºC. Artificial diets were prepared by mixing integral wheat, flour with 0.5% up to 1.0% of DMTI. Control meal without proteins was also prepared. Each treatment was repeated ten times with five larvae (n=50). DMTI didn't have effect on the survival and weight larvae fed on DMTI-diet. Midguts from the larvae were centrifuged at 10.000g for 10 min at 4 ºC. Supernatants were used as enzymes sources. Trypsin-like and chymotrypsin-like activity present in the midguts was determined using BapNA and SspFpNA as substrate, respectively. No alteration was verified either in midgut chymotrypsin and trypsin activities or in the feces of larvae, when compared with the control. In conclusion, the adaptation of C. cephalonica larvae to DMTI may involve DMTI-insensitive trypsin-like and chymotrypsin-like proteinases production.

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