In Silico and in Vivo Investigations of Bioagent Helicoverpa Nucleopolyhedrovirus against Helicoverpa armigera in Chickpea

Abstract

During investigations; homology model of 3D-structure was built for sequence of polyhedrin protein of Helicoverpa armigera nucleopolyhedrovirus, containing 246 amino acids (Accession: ACI05106.1 GI: 205946055), and evaluated through multiple tools/ applications to judge extent of accuracy in light of existing crystal structure. Further, in vivo experiments were conducted and determined response of different adjuvants with HaNPV and their efficacy. The pooled mean mortality of larvae exposed to virus mixed with 5% green tea and 5% rice bran filtrates (8.3 larvae per 25 plants) was differ significantly from control (15.8 larvae per 25 plants), suggesting that UV protectants & diet enhancer (mannitol) has ability to protect stability of virulence of the virus, under field conditions. The minimum percent pod damage of 8.6% and maximum yield of 1604.8 Kg ha-1 at harvesting was recorded with formulation of indigenous BHA virus isolate @ 2.2 x 105 POBs mL-1 mixed with Roket @50 ppm; followed by formulation with mannitol (@ 1% + green tea 5% + 5% rice bran filtrates) with percent pod damage of 16.8 % and yield of 1045.8 Kg ha-1 of chickpea. Furthermore, in vitro toxicity of fresh virus suspension @ 250 mL ha-1 was recorded more toxic in terms of percent mortality and LT50 (5.65 days). However, three months stored HaNPV formulations [(A) mannitol @ 1%+ green tea@ 5% and (B) mannitol @ 1% + green tea 5% + 5% rice bran filtrates] were more effective in larval reduction with LT50 of 7.89 and 6.00 days, respectively. Virus mixed with 5% green tea and 5% rice bran filtrates gave stability to formulation up-to one year with LT50 of 7.64 days. Findings showed that HaNPV formulations with mannitol (B) have potential that can be used in integrated manner with other IPM practices, to reduce the use of toxic synthetic pesticides in chickpea.