Transcriptome analysis of Spodoptera litura reveals the molecular mechanism to pyrethroids resistance

Abstract Background Spodoptera litura is a destructive agricultural pest and has evolved resistance to multiple insecticides, especially pyrethroids. At present, the resistance mechanism to pyrethroids remains unclear.Results Four field-collected populations, namely CZ, LF, NJ and JD, were identified to have high resistance to pyrethroids comparing to pyrethroid-susceptible population (GX), with increased resistant ratio ranging from 40.8 to 1764.0-fold. To characterize pyrethroid resistance mechanism, the transcriptomes between pyrethroid-resistant (LF and NJ) and pyrethroid-susceptible (GX) populations were compared by RNA-sequencing. Results showed that multiple differentially expressed genes were enriched in metabolism-related GO terms and KEGG pathways. 35 up-regulated metabolism-related genes were screened to verify by qRT-PCR. Consistent up-regulation of 13 unigenes, including 3 P450s, 4 GSTs, 1 UGT, 4 COEs and 1ABC, were verified in the additional pyrethroid resistant populations CZ and JD. The expression levels of CYP3 and GST3 , which were homologous to CYP321A8 and GST1 , respectively, showed positive correlation with their pyrethroid resistance levels within CZ, LF, NJ and JD populations. While the expression levels of CYP12 , CYP14 , COE4 and ABC5 showed good correlation with their pyrethroid resistance levels in at least three populations. UGT5 had the highest expression level among the tested UGT genes in the four pyrethroid resistant populations.Conclusion CYP3 , CYP12 , CYP14 , GST3 , COE4 , UGT5 and ABC5 play important roles in pyrethroid resistance among the four field-collected populations. Our work provides a valuable clue for further study of pyrethroid resistance mechanisms in S. litura .