author(s)
VV Neethu and N Muthukrishnan

abstract
We conducted an experiment on field evaluation of ecological engineering based designer seeds on the biocontrol services of predatory coccinellids on Aphis craccivora (Koch) in black gram (cv. VBN 6). Experiment was laid out randomized block design with 11 treatments and three replications. Ecologically engineered seed is an integrated seed treatment that involves addition of the nutrients, plant protectents and bio inoculants for improved emergence and establishment. Out of these 11 treatments coccinellids population determined range from 2.3 to 5.9 coccinellids/ plant. Beauveria bassiana with rhizobium treated black gram plot significantly recorded maximum coccinellids along with highest pest defender ratio (PDR) of 1: 3.91, occurrence ratio (OR) of coccinellids (2.6), minimum A. craccivora (1.5 numbers/terminal shoot) and preference ratio (PR) of A. craccivora (0.2). The treatment with other ecological engineering seeds also exerted a good impact against aphids compared to control. Ecologically engineered black gram seeds showed good impact in enhancing the population of natural enemies and pest suppression. Olfactometer studies revealed the preference of coccinellids towards leaves of B. bassiana with rhizobium treated black gram plot followed by B. bassiana treated black gram plot. Therefore, we conclude that farmers should use ecological engineering seeds instead of toxic chemical insecticides for controlling pests in the black gram field.