In India, Helicoverpa armigera is of major importance damaging a wide variety of food, fibre, oilseed, fodder and horticultural crops. The nuclear polyhedrosis virus of H. armigera (HaNPV) is currently used for the management of H. armigera on chickpea, cotton, pigeon pea, tomato and sunflower. Mass production of Nuclear Polyhedrosis Virus (NPV) on commercial scale is restricted to in vivo procedures in host larvae which are obtained by

• Field collection from cotton, pigeon pea and chickpea – H. armigera
• Mass culturing in the laboratory in semisynthetic diet – H. armiger

Some small scale producers use field – collected larvae for mass production of NPV in spite of the following constraints.

• Collection of a large number of larvae in optimum stage (late IV / early V instars) is time-consuming and can be expensive in terms of labour and transportation costs.
• Wild populations of insects may carry disease causing organisms like microsporidians, cytoplasmic polyhedrosis virus, stunt virus and fungal pathogens which will affect both virus production and quality.
• Introduction of wild strains of NPV resulting in quality control problems.
• Transportation of a large number of larvae with cannibalistic behaviour will be a difficult task.
• Parasitized larvae collected from the field will die prematurely yielding little virus.

Rearing of larvae in the natural host plant will involve frequent change of food at least once a day during the incubation period of 5-9 days increasing the handling time and hence the cost. In order to reduce the cost, field collected larvae are released into semi synthetic diet treated with virus inoculum. Mass culturing of insects in semi synthetic diet involves high level of expertise, hygiene and cleanliness.