Studies on field life-tables and key mortality factors of cotton bollworm Helicoverpa armigera (Hubner) on deshi cotton

Abstract

The non-replicated field experiment on field-life tables of bollworm infesting deshi cotton was conducted at the Experimental Farm of College of Agriculture, Latur (MS) India, during kharif 2016. On deshi cotton, early instar larvae of Helicoverpa armigera were died to the extent of 11.66, 4.76 and 8.19 per cent due to Campoletis chlorideae during first, second and third generation, respectively. While unknown reasons caused the mortality of early instar larvae of H. armigera to the tune of 7.54, 8.44 and 8.95 per cent in first, second and third generation, respectively. The entomopathogenic fungi caused the mortality of early instar larvae of H. armigera to the tune of 4, 3.33 and 1.78 per cent in first, second and third generation, respectively. HaNPV caused the mortality of early instar larvae of H. armigera to the tune of 3.07 per cent in second generation, respectively. Late instar larvae of H. armigera were died to the extent of 6.3, 3.44 and 5.7 per cent due to unknown reason during first, second and third generation, respectively. While C. chlorideae caused the mortality of late instar larvae of H. armigera to the tune of 4.5, 1.78 and 3.63 per cent in first, second and third generation, respectively. Entomopathogenic fungi caused the mortality of late instar larvae of H. armigera to the tune of 1.81 and 1.78 per cent in second and third generation. While unknown reason caused the pupal mortality of H. armigera to the extent of 4.7 and 1.85 per cent in first and second generation, respectively. The maximum contribution towards generation mortality of H. armigera came from early instar larvae in all three generations (k = 0.1061, 0.0878 and 0.0857). The total K for first, second and third generation was 0.1761, 0.127 and 0.1359, respectively.