Propoxur resistance associated with insensitivity of acetylcholinesterase (AChE) in the housefly, Musca domestica (Diptera: Muscidae)

Chunmei You,Jing Li,Chao Shan,Xiaopeng Zeng,Xiwu Gao,Zhuo Ma,Yi Zhang,Juanjuan Xin

doi:10.1038/s41598-020-65242-3

Abstract

Two unique housefly strains, PSS and N-PRS (near-isogenic line with the PSS), were used to clarify the mechanisms associated with propoxur resistance in the housefly, Musca domestica. The propoxur-selected resistant (N-PRS) strain exhibited >1035-fold resistance to propoxur and 1.70-, 12.06-, 4.28-, 57.76-, and 57.54-fold cross-resistance to beta-cypermethrin, deltamethrin, bifenthrin, phoxim, and azamethiphos, respectively, compared to the susceptible (PSS) strain. We purified acetylcholinesterase (AChE) from the N-PRS and PSS strains using a procainamide affinity column and characterized the AChE. The sensitivity of AChE to propoxur based on the bimolecular rate constant (Ki) was approximately 100-fold higher in the PSS strain compared to the N-PRS strain. The cDNA encoding Mdace from both the N-PRS strain and the PSS strain were cloned and sequenced using RT-PCR. The cDNA was 2073 nucleotides long and encoded a protein of 691 amino acids. A total of four single nucleotide polymorphisms (SNPs), I162M, V260L, G342A, and F407Y, were present in the region of the active site of AChE from the N-PRS strain. The transcription level and DNA copy number of Mdace were significantly higher in the resistant strain than in the susceptible strain. These results indicated that mutations combined with the up-regulation of Mdace might be essential in the housefly resistance to propoxur.

Highlights

The housefly, Musca domestica, is found in the vicinity of human habitations throughout the world
We noticed that the N-PRS strain possessed the cross-resistance to organophosphate compounds (OPs), which target the same site as CBs
The insects with Pattern I are more resistant to CBs than OPs or alternatively the insects with Pattern II are not significantly different in resistance to OPs and CBs and may be especially resistant to OPs32.The case of M. domestica is identified as Pattern II resistance based on about the same Ki values for OPs and CBs14,32

Summary

Introduction

The housefly, Musca domestica, is found in the vicinity of human habitations throughout the world. G342A I162M ATA → ATG V260L GTC → CTC GGC → GCC To determine whether Mdace gene expression may be related to propoxur resistance, the relative mRNA expression level and DNA copy number in the N-PRS strain and PSS strain were determined by qRT-PCR (Fig. 1).

Results

Conclusion