To broaden the scope of potential target insects that utilize serine proteases for digestion, we cloned sugar beet root genes that are associated with root defense responses.  One of the genes, BvSTI, codes for a serine proteinase inhibitor which we cloned and reconstructed for over-expression in a heterologous plant system.  This figure shows tobacco hornworm (M. sexta) larvae (left) and pupae (right) after feeding on N. benthamiana transformed with the BvSTI gene or on normal, untransformed control plants.  Our results revealed a substantial reduction in larval and pupal sizes that is mediated by the production of the BvSTI gene product in tobacco.