Geographic susceptibility of Chilo suppressalis Walker (Lepidoptera: Crambidae), to chlorantraniliprole in China.

Background: Chilo suppressalis Walker, the rice striped stem borer (RSSB) is one of the most serious lepidopteron insect pests of rice in Asia. The registration of chlorantraniliprole added an option for the chemical control of RSSBs.

Results: In this study, the geographic variability of susceptibility of field-collected RSSBs to chlorantraniliprole was assessed to establish a baseline for future comparisons of field population responses to the increased use of chlorantraniliprole products. Thirty-one RSSB colonies were established from 22 geographic areas in seven provinces of China, and were evaluated for chlorantraniliprole susceptibility. The range of mean lethal concentration (LC50 ) values in response to this chemical was between 0.821 and 17.720 mg (AI)/L across the populations. Susceptibility was significantly different (21.7-fold for LC50 and 55.6-fold for LC90 ) across the various geographic populations. No significant correlations were detected between the LC50 values of chlorantraniliprole and four conventional insecticides (monosultap, triazophos, chlorpyrifos and abamectin).

Conclusion: These results revealed great geographical variations in chlorantraniliprole susceptibilities among different geographic populations of RSSBs, which might indicate the potential for RSSBs to develop resistance to chlorantraniliprole. The effective execution of insecticide resistance monitoring programs and management strategies is urgently needed in China to sustain RSSB susceptibility to chlorantraniliprole.