• Korean journal of applied entomology
• /
• v.57 no.1
• /
• pp.43-50
• /
• 2018

The present study evaluated the susceptibility of field populations of Plutella xylostella and Spodoptera exigua larvae to four diamide insecticides-chlorantraniliprole, cyantraniliprole, cyclaniliprole, and flubendiamide. All the four diamide insecticides induced 100% mortality in the populations from Seongju (SJ) and Geochang (GC) when treated at a concentration recommended for P. xylostella. However, a very low insecticidal activity was observed in the population from Pyeongchang (PC) with 42.3% 3 d after treatment with chlorantraniliprole. The relative resistance ratio of P. xylostella to cyclaniliprole was similar or low (0.1-6.3 folds) in all the four areas. However, the population from PC exhibited a high resistance ratio to chlorantraniliprole (1,196.3 folds), cyantraniliprole (105.6 folds), and flubendiamide (191.6 folds) compared with that of the susceptible strain P. xylostella. Further, the populations of S. exigua from Cheongju (CJ), Jindo (JD), and Yeonggwang (YG) were not completely controlled by the 4 diamide insecticides. These populations also showed high relative resistance ratio when compared with that of the susceptible strain S. exigua. In particular, the populations from CJ and JD showed 100,000-fold higher resistance ratio to flubendiamide. A comparison of susceptibility of S. exigua larvae to chlorantraniliprole between 2014 and 2017 showed that chlorantraniliprole induced 100% mortality in all populations in 2014, whereas a very low insecticidal activity was observed among the populations in 2017. The results of the present study indicate that the insect pests rapidly develop resistance to diamide insecticides. Therefore, alternative insecticides with a different mechanism of action and comprehensive control strategy are needed. This study can serve as a basis to control pests effectively using diamide insecticides.