Deltamethrin interacts with Culex quinquefasciatus odorant-binding protein: a novel potential resistance mechanism

Abstract

Background Odorant-binding proteins (OBPs) play important roles in many physiological processes of mosquitoes. Previous high-throughput sequencing studies have revealed that some OBPs of Culex quinquefasciatus might be involved in the development of resistance to insecticides. Methods Based on the results of sequencing analyses, the OBP28 gene was selected for evaluation in this study. Three laboratory strains of Cx. quinquefasciatus [susceptible strain (SS), deltamethrin-resistant strain 1 (HN) and deltamethrin-resistant strain 2 (RR)] were first examined by using the Centers for Disease Control and Prevention bottle bioassay, after which the expression level of the OBP28 gene in the susceptible and deltamethrin-resistant strains was determined by real-time quantitative polymerase chain reaction. The OBP28 gene in deltamethrin-resistant strain RR was silenced using RNA interference technology. The expression level of OBP28 and the resistance level were tested in the silenced strain and control strain after microinjection of double-stranded RNA for a 48-h interference period. Four field-collected strains (henceforth ‘field strains’) of Cx. quinquefasciatus were also examined for their resistance to deltamethrin and levels of OBP28 expression. Finally, a correlation analysis between deltamethrin resistance and gene expression was carried out for all seven strains, i.e. the four field strains and the three laboratory strains. Results In the bioassay, the mortality of SS, HN and RR was 100%, 21.33% and 1.67%, respectively. The relative expression levels of OBP28 in strains HN and RR were 6.30- and 6.86-fold higher, respectively, than that of strain SS. After silencing of the OBP28 gene, the mortality of strain RR was 72.20% and that of the control strain 26.32%. The mortality of strain RR increased significantly after interference compared to that of the control strain. There was a negative correlation between OBP28 gene expression and mortality in adult mosquitoes after exposure to deltamethrin. Conclusions To our knowledge, this study shows for the first time a correlation between the expression of a gene coding for OBP and insecticide resistance in mosquitoes. The potential resistance mechanism that was elucidated provides a new target gene for the surveillance of resistance in mosquitoes. Graphical abstract

Odorant Binding Protein Expressed in Legs Enhances Malathion Tolerance in Bactrocera dorsalis (Hendel)

“…11 A study shows a correlation between OBP28 and insecticide resistance in Culex quinquefasciatus. 12 A similar study has also been reported in coleoptera, OBPs of Tribolium castaneum are involved in essential oils' metabolic detoxification. 13 A sensory appendage protein (SAP2, a type of CSP), is enriched in the legs, making significant contribution to insecticide resistance to Anopheles gambiae.…”

“…For example, OBPs and CSPs of Spodoptera litura are involved in resistance to chlorpyrifos, emamectin benzoate, and fipronil . A study shows a correlation between OBP28 and insecticide resistance in Culex quinquefasciatus . A similar study has also been reported in coleoptera, OBPs of Tribolium castaneum are involved in essential oils’ metabolic detoxification .…”

Fumigant activity and transcriptomic analysis of two plant essential oils against the tea green leafhopper, Empoasca onukii Matsuda

“…Recent studies have shown that the high expression of these genes is related to the drug resistance of various insects such as Diaphorina citri , N. lugens , Culex quinquefasciatus , and T . castaneum ( Liu et al, 2020 ; Gao et al, 2021 ; Shen et al, 2022 ; Zhang et al, 2022 ). Expressions of nine OBPs were upregulated in this study, and we theorized that this increased the tolerance of E. onukii to essential oil.…”

Neuroanatomical basis of sexual dimorphism in the mosquito brain

“…C x. quinquefasciatus mosquitoes used in this study were collected from Haikou city, Hainan province in 2013 and have been maintained in the laboratory until use ( Shen et al., 2022 ). A total of 200 adult mosquitoes were collected in a 30 × 30 × 30 cm fabric box provisioned with cotton balls saturated with 10% sucrose (w/v) solution.…”