Molecular Approaches for the Control of Fruit Borer in Tomato

Abstract

Tomato (Solanum lycopersicum L.) is one of the most popular and high valued vegetable crops grown throughout the world for fresh market purposes and processing. Tomato fruit borer, Helicoverpa armigera (Hübner), is a notorious pest hampering the production and productivity of tomatoes to a massive extent, besides having a large host range including vegetables, agronomic crops, even trees, and many weeds. The approximate loss of crop due to this pest has been reported to as high as 55% by various workers. Chemical control is most common due to convenience of obtaining them and usage, but their excessive and non-judicious use has led to resurgence of minor insect pests, development of insecticidal resistance in insects, devastation of population of natural enemies and non-target species, besides high levels of pesticide residue in harvested produce resulting in different health hazards as well as environmental pollution. Naturally occurring insecticidal proteins and molecules may be a safer alternative. Spray formulations of Bacillus thuringiensis (Bt) that producing an array of insecticidal crystal proteins (ICP) toxic to lepidopteran insects have been used for killing Helicoverpa. The ICP genes of Bt (viz., Cry1Ac, Cry1Ab, Cry2A, Cry2Ax1) have been successfully engineered into tomato for resistance against tomato fruit borer. However, large scale cultivation of Bt crop brings with it the terror of resistant strain of the insect, hence, other strategies should also be in hand. Proteinase inhibitors in many plant species also offer a good source of resistance to insect pests, and a combination of such proteinase inhibitors has been suggested by researchers for control of tomato fruit borer. RNA interference (RNAi) technology may be used for silencing the β-actin gene of the Helicoverpa armigera leading to hampered development and death in larvae. Besides, discovery of novel insecticidal proteins differing in mechanism of action of toxicity has enabled creation of strategy to control the pest without development of resistance in insect. The insect control through transgenic may be durable through incorporation of integrated pest management strategies during cultivation.