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ThesisItem Open Access Estimation of losses and management of maize stem borer, Chilo partellus (Swinhoe) in Kharif maize(Punjab Agricultural University, Ludhiana, 2016) Dhaliwal, Ashwinder Kaur; Gill, R.S.The studies on "Estimation of losses and management of maize stem borer, Chilo partellus (Swinhoe) in Kharif maize" were conducted during 2013, 2014 and 2015 in the Punjab. The key insect pest of Kharif maize was found to be C. partellus, however the insect pests other than C. partellus were of minor importance. The deadhearts incidence of C. partellus was significantly lower in the crop sown on 25th June (6.07, 7.06; and 7.29, 9.11 %) than that in the crop sown during last week of May (9.17, 10.24; and 10.30, 11.99 %) and on 10th of June (8.09, 9.06 & 9.08, 11.06 %) at Ludhiana and Jalandhar during 2013 and 2014, respectively. Accordingly, the maize grain yield was significantly higher in the crop sown on 25th June (54.51, 54.58; and 52.85, 52.02 q/ ha) than that in the crop sown during last week of May (52.69, 51.34; and 49.91, 48.70 q/ ha) and on 10th of June (52.53, 51.01; and 50.88, 50.01 q/ ha) at Ludhiana and Jalandhar during 2013 and 2014, respectively. The mean maize grain yield losses caused by C. partellus ranging from 10.99 to 14.69 per cent, were also lower in the crop sown on 25th June than that sown during last week of May and on 10th June. The laboratory evaluation of different isolates of Beauveria bassiana Balsamo (Vuillemin) against C. partellus revealed that the Local isolate (caused 39.00 % mortality of C. partellus) followed by Bb 4668 (caused 31.75 % mortality of C. partellus) isolate of B. bassiana were most virulent against C. partellus. However, Mycojaal, Bb 7126, Bb 7130 and Bb 4644 isolates of B. bassiana were moderately (caused 19.7522.50 % mortality of C. partellus); and Bb 5412, Bb 5408 isolates of B. bassiana were least virulent (caused 17.50-18.00 % mortality of C. partellus) against C. partellus. The evaluation of Local, Bb 4668 and Mycojaal isolates of B. bassiana against C. partellus under artificial infestation conditions in screen house revealed that the Local isolate was most effective against C. partellus. The field evaluation of different Integrated Pest Management (IPM) strategies against C. partellus revealed that the standard check treatment i.e. deltamethrin was most effective (with deadhearts incidence of 6.256.85 %) against C. partellus. The treatments i.e. Bacillus thuringiensis var. kurstaki, chlorantraniliprole @ 8, 10 and 12 Kg/ ha and maize intercropped with one or two rows of cowpea (with deadhearts incidence of 9.80-11.96 %) being at par with each other were moderately effective against C. partellus. The cowpea fodder yield obtained in maize intercropped with cowpea treatments provided additional benefit. The seed treatment with imidacloprid; water based and talc based formulation of Local isolate of B. bassiana (with deadhearts incidence of 14.11-16.46 %) being at par with each other were least effective against C. partellus. The present studies clearly showed that the effective management of C. partellus involves integration of different management strategies.