Bio-chemicals triggering host preference mechanism against tomato fruit borer, Helicoverpa armigera (H�bner)

Abstract

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’. 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). In order to locate the sources for resistance in tomato foliage various macro and micro- nutrients were extracted from these varieties and chemical composition of tomato fruits viz., content of total phenols, titrable acidity, reducing sugars and total sugars were also estimated to compare for varying levels of resistance to Helicoverpa armigera . The content of phenol and sugars in tomato fruits was found to be negatively correlated with fruit infestation with values of correlation coefficient (r = - 0.895) and (r = - 0.650), respectively, indicating that susceptible varieties were low in phenols as well as in sugars. 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 observed resistance can be exploited for developing crop cultivars, which readily produce the inducible response upon mild infestation, and can act as important components of integrated pest management compatible with other approaches like biological control, cultural control as well as chemical control.