author(s)
Arun Debbarma, KI Singh, MK Gupta and P Sobitadevi

abstract
A field trial was carried out in randomized block design with thirteen treatments including control during Rabi, 2010-11 at vegetables Research Farm, College of Agriculture, Central Agricultural University, Imphal to evaluate the efficacy of certain bio-rational insecticides against Plutella xylostella and Pieris brassicae on a crop variety “Pride of India” under Manipur valley. The studied revealed that due to the Diamondback moth pre-treatment mean extent of leaf damage reached 90.67 percent and whereas it reached 91.11 percent due to the cabbage butterfly, Pieris brassicae. Spinosad (Saccharopolyspora spinosa)2.5 SC @ 500 ml ha^-1 was found most effective to control both these pests registering lower extent of mean leaf damage by 14.22 percent and 24.30 percent respectively. It was followed by myco-jaal (Beauveria bassiana) 10 SC @ 500 ml ha^-1 with 15.11 percent and 26.59 percent and differs significantly from untreated control 69.18 percent. The yield harvested in the bio-rational treatment were spinosad 2.5 SC 24.77 t ha^-1, myco-jaal 10 SC 23.70 t ha^-1, malathion 50 EC 22.97 t ha^-1, racer (Beauveria bassiana) 22.85 t ha^-1, achook (Azadirachtin 1500 ppm) 22.73 t ha^-1, lipel (Bacillus thuringiensis var. kurstaki) 22.60 t ha^-1, shakti (Azadirachtin 300 ppm) 20.13 t ha^-1, margosom(300 ppm) 20.10 t ha^-1, multineem (Azadirachtin 1500 ppm) 20.03 t ha^-1, Cow–urine + Melia azedarach19.97 t ha^-1, pestoneem (Azadirachtin 1500 ppm) 19.90 t ha^-1, pacer (Metarhizium anisopliae) 19.27 t ha^-1 and untreated control 15.40 t ha^-1respectively.