Comparison of Seasonal incidence and integrated pest management of helicoverpa armigera (Noctuidae; Lepidoptera) on Bt and non Bt cotton in Punjab, Pakistan

Abstract

Cotton is an important commodity in the economy of Pakistan. Different types of insect pest attack on cotton crop. Among all insect pests, Helicoverpa armigera (Noctuidae; Lepidoptera) is one of the most harmful and broad-based pest causing major economic loss in quality and production of cotton and some other crops. A survey was conducted to know the oviposition response, larval incidence and adult population of H. armigera in three districts of Punjab viz Multan, Khanewal and Vehari during 2014/15. Survey results shows that there was non-significant difference in oviposition found in all three districts But number of eggs varies significantly with at each date of observation. Overall mean maximum number of eggs (0.44/plant) were observed at F5 compared to other weeks. In case of larvae there was non-significant difference in H. armigera larval population found in Multan, Khanewal and Vehari district. Overall maximum larval population 0.07/plant was found in Vehari followed by 0.05/plant in Multan and Khanewal. Maximum adult population (3.22/trap) was observed in Vehari followed by (2.47/trap) in Khanewal and Multan (1.83/trap). Different Bt and non Bt cotton cultivars were evaluated in Faisalabad regarding incidence and population fluctuation of H. armigera. Results shows that there was no significant difference in eggs density among Bt and non-Bt cotton cultivars. No of larvae was significantly higher in non-Bt as compared to Bt cultivars. Among Bt cultivars highest overall mean larval population (0.07/plant) was found on VH-259 followed by (0.05) in FH-Lalazar, (0.04) in BH-178 and (0.02) in CIM-602. In non Bt cultivars highest larval population (0.13) was found on CIM-573 and lowest (0.09) in BH-67. Bio-efficacy of different parts of different cotton cultivars against 1st, 2nd and 3rd instar of H. armigera was determined under laboratory condition. All first instar larvae were found dead after feeding on leaves, squares, flowers and tender bolls of all Bt cultivars. While in case of non Bt (CIM-608) mean percent mortality was observed in the range of (8.13), (5.83), (5.00) and (11.25) against 1st instar after feeding on leaves squares flowers and bolls respectively. 2nd instar larvae after feeding on leaves on Bt cotton cultivar FH-142 and CIM-602 showed highest overall mean mortality (100.00%) followed by BH-178 (98.75%), FH-Lalazar (95.63%) and VH-259 (93.75%) compared to non-Bt CIM-608 in which only (3.75%) percent mortality was recorded. Amongst, the Bt cotton cultivar CIM-602 showed highest overall mean mortality of 2nd instar (97.50%) followed by BH-178 (95.83%), FH-Lalazar (92.50%) and VH-259 (90.00%) compared to non-Bt CIM-608 in which only (0.00%) percent mortality was recorded. Second instar after feeding on flowers shows highest mean mortality was (95.00%) in FH-142 and lowest was observed in VH-259 (89.00%) as compared to other Bt cultivars. Bioassay results of 2nd instar after feeding on bolls showed highest overall mean mortality (96.25%) in FH-142 followed by CIM-602 (93.75%), FH-Lalazar (90.00%) and VH-259 (86.25%), as compared to non-Bt CIM-608 (2.50%). 3rd instar of H. armigera showed lower mortality as compared to 1st and 2nd instar after feeding on plants parts. Different components of four modules were designed to suppress the insect pests of cotton including bollworms. Results showed that sucking pest such as whitefly and thrips and bollworms population was below ETL in all the four modules except Jassid shows above ETL population.