Susceptible population
The nucleus culture of susceptible BPH populations
was procured from Rice Entomology Section, ZonalAgricultural Research Station, V. C. Farm, Mandya,Karnataka, India where the population had beenmaintained for more than 10 years (approximately 60generations) without exposure to any insecticides.This culture was maintained on rice seedlings byadopting the mass-rearing technique as described
above.