Evaluate the Susceptibility of Helicoverpa armigera against Helicoverpa armigera Nuclear Polyhedrosis Virus under Laboratory Conditions
Vijay Kumar *
School of Agriculture, Tulas University, Dehradun, Uttarakhand, India.
Rajneesh Pal
School of Agricultural Science, Babu Banarasi Das University, Lucknow, Uttar Pradesh, India.
Suraj Kumar
School of Agriculture, ITM University, Gwalior, Madhya Pradesh, India.
Moutushi Das
School of Agriculture, Uttaranchal University, Dehradun, Uttarakhand, India.
Hari Krishna
School of Agriculture, ITM University, Gwalior, Madhya Pradesh, India.
Ram Ajeet Chaudhary
Department of Entomology, Chandra Shekhar Azad University of Agriculture and Technology, Kanpur, Uttar Pradesh, India.
*Author to whom correspondence should be addressed.
Abstract
Helicoverpa armigera is a major polyphagous pest that can cause substantial crop losses. This laboratory study evaluated the susceptibility of H. armigera larvae to Helicoverpa armigera nuclear polyhedrosis virus (Ha-NPV) and examined the effects of host food and virus concentration on larval mortality and polyhedral inclusion body (PIB) yield. Third-instar larvae were maintained at 25 ± 2°C, 75 ± 5% RH, and a 14:10 h (L:D) photoperiod. For host-food evaluation, larvae received Ha-NPV at 1.66 × 10⁶ PIBs/larva through chickpea leaves, soaked chickpea grains, chickpea flour, or wheat flour. In 2019–20, mortality was highest with wheat flour (90.00%), followed by chickpea leaves (88.00%) and chickpea seed (86.00%), and lowest with chickpea flour (72.0%). Corresponding values in 2020–21 were 92.00%, 90.00%, 86.00%, and 72.0%, respectively. The highest PIB yields were recorded with wheat flour, reaching 2.21 × 10⁹ PIBs/larva in 2019–20 and 2.15 × 10⁹ PIBs/larva in 2020–21. Across virus doses from 1.66 × 10⁶ to 1.00 × 10⁷ PIBs/larva, cumulative mortality increased with concentration. Mortality ranged from 60.83% to 92.33% in 2019–20 and from 60.50% to 92.50% in 2020–21. The findings indicate that Ha-NPV pathogenicity under laboratory conditions varies with host food and dose, supporting further evaluation of this biocontrol agent for integrated management of H. armigera.
Keywords: Helicoverpa armigera, Ha-NPV, nucleopolyhedrovirus, polyhedral inclusion bodies, biological control, larval mortality, host food, susceptibility, dose-mortality response, integrated pest management