Third or fourth instars, or pupae were collected
from each sampling site. Adults that emerged from the collections
were fed on 10% diluted sugar solution (10% weight-to-volume solution)
in cotton wool and mated at random in cages (about 100 males
and 100 females). Potted radish seedlings were placed in the cages for
oviposition. Third instars of the next generation, which represent the
progeny of field collected insects, were used for the resistance studies.
The insectaries were maintained at 25 ± 1 °C and RH of 60%-70% with
a photoperiod of 16:8 h L:D.