Resistance monitoring in field populations of Chilo suppressalis (Lepidoptera: Crambidae) in Hubei Province to four insecticides in 2019-2022

Chilo suppressalis is a highly destructive insect pest of rice crops. Chemical insecticides have been used as an effective method for controlling this pest. In this study, we evaluated the susceptibility of seven field populations of C. suppressalis from three regions in Hubei Province, China, to four different insecticides over a period of 4 years (2019-2022). Our results showed that the populations of C. suppressalis in these areas have evolved low to high levels of resistance to abamectin (Resistant Ratio, RR = 8.5-413.4). Furthermore, the field populations were susceptible to high levels of resistance to chlorantraniliprole (RR = 2.0-401.6) and showed moderate levels of resistance to triazophos (RR = 56.9-78.7) and chlorpyrifos (RR = 10.6-54.5). Correlation analysis indicated significant positive correlations between the susceptibility of abamectin and chlorantraniliprole and chlorpyrifos, as well as chlorpyrifos and chlorantraniliprole, and triazophos. This study provides valuable information on the current resistance status of field populations of C. suppressalis, which can aid in the judicious use of these insecticides and serve as an important reference for effective resistance management strategies.