Exploitation of wild relatives of pigeonpea and chickpea for resistance to Helicoverpa armigera

Wild relatives continue to evolve in nature, and live by a different rule than the crop plants – which is survival of the fittest. Wild species have evolved to survive droughts, floods, extremes of heat and cold, and have the capability to withstand damage by insect pests and diseases that cause heavy damage to cultivated species. Many improved cultivars of crops are vulnerable to insect pests as they lack defense mechanism of their wild progenitors. The natural defense mechanisms in crop plants have been lost during intense selection for high yield, wider adaptability and improved nutritional quality. Helicoverpa armigera, commonly known as cotton bollworm, tomato fruitworm, or legume pod borer, is a major pest of several crops including chickpea (Cicer arietinum) and pigeonpea (Cajanus cajan). Annual yield losses due to this pest have been estimated to be US$ 400 million per annum in India, and over US$ 1 billion in the semi-arid tropics. Chemical control of H. armigera has become increasingly difficult due to the development of resistance to commonly used insecticides. Widespread and injudicious use of insecticides to control H. armigera has not only led to the development of insecticideresistant insects, but also has detrimental effects on the environment.