Host Plant Resistance to Insects: Modern Approaches and Limitations*

Large scale application of pesticides to reduce the losses due to insect pests has not only led to serious environmental hazards, but has also has resulted in development of resistance in pest populations. It is in this context that varieties capable of resisting pest damage would play a vital role in pest management in future. Considerable progress has been made in identification of sources of resistance to the insect pests in different crops. However, there is a need to transfer the resistant genes into high-yielding cultivars with adaptation to different agro-ecosystems. Resistance to insects should form one of the criteria to release varieties and hybrids. Genes from the wild relatives of crops, and novel genes from un-related species such as Bacillus thuringiensis, protease inhibitors, and lectin genes can also be inserted into crop plants to make plant resistance an effective weapon in pest management. In addition, molecular techniques such as marker assisted selection, changing of metabolic pathways, and gene switches can also be used for accelerating the pace of developing crop cultivars with resistance to insect pests. Development of insect-resistant varieties will not only cause a major reduction in pesticide use, but also lead to increased activity of beneficial organisms, and a safer environment to live.