2. Materials and methods
The experiments were conducted in the laboratory,
green house and fields at the Proagro Research Station,
Gurgaon from the year 1997–2000.
2.1. Insects
Helicoverpa armigera was reared in the laboratory on
an artificial diet (Nagarkatti and Prakash, 1974). The
initial colony of the fruit borer was obtained from a
farmer’s field in 1997. Larvae were reared individually
on the diet by the method described by Raulston and
Lingren (1972). Adults were maintained in a nylon net
cage (40 cm20 cm diameter) for mating and oviposition.
Eggs deposited on the nylon mesh ofthe cage were
removed by washing in 0.2% sodium hypochlorite
solution in a small plastic bucket, and filtered with a
fine brass mesh screen. Eggs were then spread on a
20 cm20 cm filter paper, air-dried and then stored in a
plastic box (30 cm long, 14 cm broad, 12 cm high) at
2871C and 40–50% r.h. for hatching.