Chlorantraniliprole was very effective against P.
xylostella in most tested populations except those from Taihe and Wuxi. Approximately 61% of tested populations displayed moderate resistance
to spinosad, while other field populations showed minor changes (3-fold) in their susceptibility to this insecticide. Obvious variation
(93-fold) of susceptibility to chlorfenapyr existed in field populations of which 32% displayed low level resistance, and 36% exhibited moderate
resistance. Only one field population (Wuxi) showed very high resistance to chlorfenapyr (RR = 260.1). Diafenthiuron and chlorfluazuron
were highly effective against all of the tested populations with resistance ratios (RR) ranging from 0.4 to 8.7 – fold. Decreased susceptibility
ranging to moderate resistance to Btk was observed (RR = 3.8 – 35.3).