Acta Entomologica Sinica ›› 2016, Vol. 59 ›› Issue (11): 1159-1165.doi: 10.16380/j.kcxb.2016.11.002

• RESEARCH PAPERS • Previous Articles     Next Articles

In vivo effects of piperonyl butoxide on the activities of 7-ethoxycoumarin O-deethylase and carboxylesterase in larval Chilo suppressalis (Lepidoptera: Pyralidae)

LI Yang, SHI Xue-Yan*, GAO Xi-Wu*   

  1. (Department of Entomology, College of Plant Protection, China Agricultural University, Beijing 100193, China)
  • Online:2016-11-20 Published:2016-11-20

Abstract: 【Aim】 In order to provide data for efficient management of insecticide resistance of Chilo suppressalis (Walker), we measured the cytochrome P450-mediated 7-ethoxycoumarin-O-deethylase (ECOD) activity in different instars of larval C. suppressalis, and evaluated the time-dependent in vivo effects of piperonyl butoxide (PBO) treatment on the activities of ECOD and carboxylesterase (CarE) in the 4th instar larvae. 【Methods】 By using 7-ethoxycoumarin as the substrate, the ECOD activity in different instar larvae and pupae of C. suppressalis was determined by fluorospectrophotometric analysis. Variations of ECOD and CarE activities in the 4th instar larvae were examined at each hour within 24 hours after treatment topically by PBO (0.69 μg/larva). 【Results】 The ECOD activity in C. suppressalis from the 1st instar larval stage to the pupal stage showed a firstly increasing and then decreasing trend. The ECOD activity increased to the highest level of 14.11±1.01 pmol/mg pro·min in the 4th instar larvae, while decreased to the lowest (1.34±0.11 pmol/mg pro·min) in pupae. PBO exhibited time-dependent effects on the ECOD activity of the 4th instar larvae. As compared with the untreated control, PBO treatment inhibited the ECOD activity during 4-9 h with a maximal inhibition rate of 21% at 6 h, induced its activity during 10-11 h, and then inhibited its activity during 15-17 h. In addition, PBO exposure also affected the CarE activity in the 4th instar larvae, showing inhibition effects during 14-17 h and 20-21 h and induction effects during 10-12 h and 18-20 h after treatment. 【Conclusion】 The ECOD activity varies in different instar larvae and pupae of C. suppressalis. PBO treatment displays time-dependent effects of inhibition or induction on the activities of ECOD and CarE in the 4th instar larvae of C. suppressalis.  

Key words: Chilo supperssalis, piperonyl butoxide, cytochrome P450, 7-ethoxycoumarin-O-deethylase (ECOD), carboxylesterase