Development and Evaluation of Microencapsulated Formulations for Enhanced Stability and Efficacy of Helicoverpa armigera Nucleopolyhedrovirus (HaNPV)
Aakanksha Bhosale
Department of Agricultural Entomology, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
N. S. Satpute *
Department of Agricultural Entomology, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
B. D. Ghodake
Biotechnology Centre, Department of Agricultural Botany, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
M. P. Moharil
Biotechnology Centre, Department of Agricultural Botany, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
D. B. Undirwade
Department of Agricultural Entomology, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
A. K. Sadawarte
Department of Agricultural Entomology, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
Harshada Atkar
Department of Agricultural Entomology, Dr Panjabrao Deshmukh Krishi Vidyapeeth, Akola, Maharashtra, India.
*Author to whom correspondence should be addressed.
Abstract
Helicoverpa armigera nucleopolyhedrovirus (HaNPV) is a species-specific baculovirus used as a biological control agent against Helicoverpa armigera. This study developed and evaluated microencapsulated HaNPV formulations using three biodegradable polymer systems: gelatin-carboxymethyl cellulose (gelatin-CMC), starch, and sodium alginate-chitosan. The formulations were prepared using polymer-based encapsulation procedures and assessed under laboratory conditions for ultraviolet-C (UV-C) protection, polyhedral occlusion body (POB) retention, larvicidal activity, and lethal-time parameters. UV-C exposure was evaluated at 10, 20, and 30 min, while larval mortality was recorded at 24 h intervals for seven days. After 10, 20, and 30 min of UV-C exposure, gelatin-CMC retained 75.0%, 50.0%, and 25.0% of POBs, respectively. The corresponding values were 40.0%, 20.0%, and 0% for starch; 70.0%, 40.0%, and 20.0% for sodium alginate-chitosan (5 mL); and 62.5%, 46.9%, and 31.3% for sodium alginate-chitosan (10 mL). Larval mortality increased progressively with exposure time. The sodium alginate-chitosan (5 mL) formulation produced 88.5% observed mortality and 87.18% corrected mortality at 168 h. The sodium alginate-chitosan (10 mL) formulation showed the shortest LT₅₀ (83.6 h) and LT₉₀ (183.6 h), followed by the 5 mL formulation. These findings indicate formulation-dependent performance: gelatin-CMC provided the greatest POB retention during UV-C exposure, whereas sodium alginate-chitosan formulations produced faster and greater larvicidal activity. Microencapsulation therefore improved the laboratory stability and biological performance of HaNPV under the tested conditions.
Keywords: HaNPV, Helicoverpa armigera, microencapsulation, gelatin-CMC, starch, sodium alginate-chitosan, UV-C protection, polyhedral occlusion bodies, larvicidal activity, biological control