Abstract
BackgroundCulex pipiens pallens poses a serious threat to human health because of its widespread distribution, high carrier capacity for several arboviruses, frequent human-biting, and growth in urban environments. Pyrethroid insecticides have been mainly used to control adult Cx. pipiens pallens during outbreaks of mosquito-borne diseases. Unfortunately, mosquitoes have developed resistance, rendering the insecticides ineffective. Cuticular resistance is the primary mechanism of pyrethroid resistance. Previously, we revealed that cuticular protein of low complexity CPLCG5 is a major cuticular protein associated with deltamethrin resistance in Cx. pipiens pallens, which is enriched in the cuticle of mosquitoes’ legs and participates in pyrethroid resistance by forming a rigid matrix. However, the regulatory mechanisms of its transcription remain unknown.ResultsFirst, qRT-PCR analysis revealed that the expression of FTZ-F1 (encoding Fushi tarazu-Factor 1) was ~ 1.8-fold higher in the deltamethrin-resistant (DR) than deltamethrin-susceptible (DS) strains at 24 h post-eclosion (PE) and ~ 2.2-fold higher in the DR strain than in the DS strain at 48 h PE. CPLCG5 and FTZ-F1 were co-expressed in the legs, indicating that they might play an essential role in the legs. Dual luciferase reporter assays and EMSA (electrophoretic mobility shift experiments) revealed that FTZ-F1 regulates the transcription of CPLCG5 by binding to the FTZ-F1 response element (− 870/− 864). Lastly, knockdown of FTZ-F1 not only affected CPLCG5 expression but also altered the cuticle thickness and structure of the legs, increasing the susceptibility of the mosquitoes to deltamethrin in vivo.ConclusionsThe results revealed that FTZ-F1 regulates the expression of CPLCG5 by binding to the CPLCG5 promoter region, altering cuticle thickness and structure, and increasing the susceptibility of mosquitoes to deltamethrin in vivo. This study revealed part of the mechanism of cuticular resistance, providing a deeper understanding of insecticide resistance.
Highlights
Culex pipiens pallens poses a serious threat to human health because of its widespread distribution, high carrier capacity for several arboviruses, frequent human-biting, and growth in urban environments
Does Fushi tarazuFactor 1 (FTZ-F1) regulate the expression of CPLCG5 by binding to the promoter region of CPLCG5, causing altered cuticle thickness and structure, and affecting insecticide resistance in mosquitoes (Fig. 1)? The present study aimed to explore the regulatory role of FTZ-F1 in deltamethrin resistance by regulating the expression of CPLCG5
The results suggested that FTZ-F1 might be related to insecticide resistance
Summary
Culex pipiens pallens poses a serious threat to human health because of its widespread distribution, high carrier capacity for several arboviruses, frequent human-biting, and growth in urban environments. Pyrethroid insecticides have been mainly used to control adult Cx. pipiens pallens during outbreaks of mosquito-borne diseases. Mosquitoes have developed resistance, rendering the insecticides ineffective. We revealed that cuticular protein of low complexity CPLCG5 is a major cuticular protein associated with deltamethrin resistance in Cx. pipiens pallens, which is enriched in the cuticle of mosquitoes’ legs and participates in pyrethroid resistance by forming a rigid matrix. Culex pipiens pallens is the primary vector of the filamentous nematode, Wuchereria bancrofti, which is widely prevalent in Asia and sub-Saharan Africa. Insecticides, especially pyrethroids, remain the mainstay to control these. Resistance to insecticides is widespread and is increasing rapidly in intensity in Culex mosquitoes across China, which have threatened the effectiveness of insecticides and become the major obstacle for mosquito control [8]. A key challenge is to maintain the efficacy of current interventions under the threat of growing insecticide resistance
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