Plant Bio-chemicals against Helicoverpa armigera (Hubner): A Study in Tomato

The Mechanism of host plant resistance in tomato varieties was evaluated and compared against tomato fruit borer, Helicoverpa armigera (Hubner) attack in the Solan district known to be ‘Tomato bowl of Himachal Pradesh’. By understanding the mechanisms of induced resistance, we can predict the pests that are likely to be affected by induced responses. The elicitors of induced responses can be sprayed on crop plants to build up the natural defense system against damage caused by herbivores. Eight varieties utilized for the experiment included three self pollinating indeterminate varieties developed by selection (Solan Lalima, Solan Vajar, Palam Pink) and four hybrids (Naveen 2000+, Heem Sohna, Red Gold, Rakshita, Yash Tomato). To find the sources of resistance in tomato foliage, researchers extracted various macro and micronutrients from these varieties, as well as estimating the chemical composition of tomato fruits, such as total phenols, titrable acidity, reducing sugars and total sugars, to compare for varying levels of resistance to Helicoverpa armigera. Fruit infestation was found to be inversely connected with phenol and sugar content in tomato fruits, as measured by correlation coefficient values (r= -0.895) and (r= -0.650), respectively, indicating that less susceptible varieties were high in phenols as well as in sugars which protected them from the attack of the pest. Nitrogen (r= 0.660), potassium (r=0.679), magnesium (r= 0.698), iron (r= 0.547) and manganese (r=0.546) content were found to be optimistically correlated with per cent fruit infestation while, phosphorous (r= -0.857) and zinc (r= -0.801) content did not favor the fruit borer attack. This resistance can be used to develop crop cultivars that rapidly produce the inducible response upon mild infestation and can be used as significant components of integrated pest management alongside other techniques such as biological, cultural, and chemical control.