author(s)
V Chinna Babu Naik, Prasad NVVSD, Vani Sree K, Upendhar S and Subbireddy KB

abstract
The present investigations on relative incidence of sucking pest complex on different Bt and non Bt hybrids was evaluated by recording the pest incidence viz., aphids, leafhoppers, thrips and whiteflies during kharif, 2007-08 and 2008-09 at Regional Agricultural Research Station, Lam, Guntur on four Bt cotton hybrids viz., RCH 2 Bt, JK Durga Bt, Nath baba Bt and RCH 2 BGII Bt representing Mon 531event, JK Cry 1Ac event, GFM event and Mon 15985 event, respectively and RCH 2 non Bt, JK Durga non Bt and Nath baba non Bt. The lowest initial population of 1.20 aphids/3 leaves/plant was recorded on JK Durga non Bt. The thrips population reached its peak at 55 DAS with maximum of 18.46 thrips/3 leaves/plant on RCH 2 BG II and The leafhopper population reached its peak levels at 85 DAS 16.00 leafhoppers/3 leaves/plant and whitefly reached its maximum number at 100 DAS with 5.53 whiteflies/3 leaves/plant on RCH 2 BG II hybrids during 2007-08. Whereas, during 2008-09 the peak population of aphids was observed 115 DAS with minimum population was noticed on JK Durga non Bt (12.50 aphids/3 leaves/plant). The mean population of thrips was significantly lowest on Nath baba non Bt (6.82). Peak population of leaf hopper was recorded at 85 DAS with 11.33 to 15.07 leafhoppers/3 leaves/plant on different hybrids. Initially the whitefly population was noticed in negligible amounts up to 70 DAS and peak population was observed at 100 DAS with highest 6.36 whiteflies/3 leaves/plant RCH 2 BGII. The incidence of sucking pests in general was slightly high in Bt hybrid events compared to their corresponding non Bt versions.