Knockdown Resistance (kdr) Mutations I1532T and F1534S Were Identified in Aedes albopictus Field Populations in Zhejiang Province, Central China.

Yuyan Wu,Yunpeng Qi,Jimin Sun,Tianqi Li,Jinna Wang,Mingyu Luo,Qinmei Liu,Qinxiang Ni,Zhenyu Gong,Weihua Chen,Yinping Wu,Juan Hou

doi:10.3389/fcimb.2021.702081

Abstract

Aedes albopictus is the only vector that can transmit the dengue virus in Zhejiang Province, central China, and it can develop insecticide resistance due to long-term exposure to pyrethroids. The presence of knockdown resistance (kdr) mutations is one of the mechanisms responsible for pyrethroid resistance, and has been reported in some Ae. albopictus populations in southern China. However, little is known about the DNA diversity of the voltage-gated sodium channel (VGSC) gene in Ae. albopictus populations in central China. Four Ae. albopictus field populations were collected, in Yiwu (YW), Quzhou (QZ), Wenzhou (WZ), and Jiaxing (JX) from Zhejiang Province, central China. The susceptibility of Ae. albopictus adults to three pyrethroids (beta-cypermethrin, deltamethrin, and permethrin) was tested using the WHO tube assay, and Kdr mutations were identified via PCR and sequencing. The relationship between kdr mutations and pyrethroid phenotypes was also analyzed. Of the four populations, none was sensitive to any pyrethroid tested, and the YW population showed the strongest pyrethroid resistance. Non-synonymous kdr mutations were detected in codons 1532 and 1534, domain III. At codon 1534, one mutant allele, TCC(S), was detected in the four populations with a frequency of 42.08%, while at codon 1532, one mutant allele, ACC(T), was detected in the JX and QZ populations, with frequencies of 4.22 and 3.03%, respectively. The F1534S mutant allele was positively correlated with both beta-cypermethrin and deltamethrin resistance phenotypes (OR > 1, P < 0.05), whereas the I1532T mutant allele was possibly negatively correlated with beta-cypermethrin, deltamethrin, and permethrin resistance phenotypes (OR < 1, P > 0.05). In conclusion, resistance and resistance mutations regarding to three pyrethroids are already present in the Ae. Albopictus populations from Zhejiang, central China, which prompts the need to use non-insecticide-based methods of insect control.

Highlights

Ae. albopictus, known as the Asian tiger mosquito, is widely distributed in southern and central China (Robertson and Hu, 1988)
We investigated the insecticide resistance of Ae. albopictus populations collected from the north, south, east, and west of Zhejiang Province to three pyrethroids, and the corresponding kdr mutations in these four populations were examined
One hundred fifty-three specimens were sequenced for domains II and IV of the voltage-gated sodium channel (VGSC) gene, and we found synonymous mutations in both domains, they were not recorded in this study

Summary

Introduction

Ae. albopictus, known as the Asian tiger mosquito, is widely distributed in southern and central China (Robertson and Hu, 1988). It is perhaps the most dangerous mosquito vector species in Zhejiang Province because of its high density and primary role in transmitting Zika, chikungunya, and dengue viruses (Robertson and Hu, 1988; Yang and Fu, 2006). Ae. albopictus is the only vector species responsible for chikungunya and dengue fever in Zhejiang Province and its surrounding areas, which needs to be controlled (Guo et al, 2016). The long-term and heavy utilization of pyrethroids has resulted in the resistance of many populations of Ae. albopictus, which poses a significant challenge for its control when it triggers an outbreak of dengue fever (Hou et al, 2017)

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