Abstract: The insect-resistance genetic engineering of plants provides a new way of controlling crop pests. Genes that have so far been found resistant to homopteran insects come from three origins : (1) resistance genes from plants such as plant lectins genes and the root-knot nematode resistance gene Mi of tomato ; (2) resistance genes from microorganisms such as the isopentenyl-transferase gene ; and (3) resistance genes from animals such as certain proteinase-inhibitor genes from some insects. Some of these genes have been successfully incorporated into plants. The insect-resistant transgenic plants inhibit development and decrease fecundity of homopteran insects , demonstrating practical potential of these insect-resistant genes in the control of this group of pests. Snowdrop lectin (GNA) delivered via rtificial diet or transgenic plants to the homopteran insects can be transferred through trophic levels , and has direct and indirect effects on natural enemies.