The field populations of P. xylostella used for the resistancemonitoring
in this studywere collected fromcabbage fields in four different geographical
regions of Central China during 2013–2014 (Fig. 1, Table 1).
More than 200 larvae or pupae were collected each year at each site.
The collected insects were reared on cruciferous vegetables in controlled
environmental conditions with a temperature of 25 ± 1 °C and
a photoperiod of 16-h light/8-h dark.