RESUMO
Megalurothrips usitatus (Bagnall), the main pest on legume vegetables, is controlled by pyrethroids in the field. Field strains of M. usitatus resistant to pyrethroids were collected from three areas in Hainan Province (Haikou, Ledong, and Sanya City), and two mutations, T929I and K1774N, were detected in the voltage-gated sodium channel. In this study, the sodium channel in M. usitatus was first subcloned and successfully expressed in Xenopus oocytes. The single mutation (T929I or K1774N) and double mutation (T929I/K1774N) shifted the voltage dependence of activation in the hyperpolarization direction. The three mutants all reduced the amplitude of tail currents induced by type I (permethrin and bifenthrin) and type II (deltamethrin and λ-cyhalothrin) pyrethroids. Homology modeling analysis of these two mutations shows that they may change the local hydrophobicity and positive charge of the sodium channel. Our data can be used to reveal the causes of the resistance of M. usitatus to pyrethroids and provide guidance for the comprehensive control of M. usitatus in the future.
Assuntos
Proteínas de Insetos , Resistência a Inseticidas , Inseticidas , Mutação , Piretrinas , Canais de Sódio Disparados por Voltagem , Piretrinas/farmacologia , Animais , Canais de Sódio Disparados por Voltagem/genética , Canais de Sódio Disparados por Voltagem/química , Canais de Sódio Disparados por Voltagem/metabolismo , Inseticidas/farmacologia , Inseticidas/química , Resistência a Inseticidas/genética , Proteínas de Insetos/genética , Proteínas de Insetos/metabolismo , Proteínas de Insetos/química , Mariposas/genética , Mariposas/efeitos dos fármacosRESUMO
BACKGROUND: The larvae of Drosophila suzukii Matsumura feed directly inside the fruit, causing catastrophic damage to orchards. The misuse of pyrethroid insecticides during the control period has led to increasing resistance of D. suzukii to pyrethroids acting on the voltage-gated sodium channel (VGSC). RESULTS: In this study, the sodium channel of D. suzukii was cloned (DsNav 5 GenBank number: OQ871532). The results of multiple-sequence alignment showed that the homology of sodium channel between D. suzukii and Drosophila melanogaster was as high as 95.3%. Analysis of transcripts from 62 variants of D. suzukii VGSC revealed a total of six alternative splicing sites (exons u, j, a, b, e, and h) and 33 RNA editing. Exons j, a, b, e, and h are conserved in D. melanogaster and other insects, whereas exon u has never been reported before. The number of A-to-I was distinctly more than that of U-to-C for RNA editing. All D. suzukii VGSC variants were expressed in Xenopus oocytes, but only one (type 5) was able to produce robust currents and nine produce weak currents. DsNav 5 with TipE of D. melanogaster co-expresses current better than its own TipE. Subsequently, tetrodotoxin was verified to be a blocker of VGSC, and the gating properties of DsNav 5 were investigated. CONCLUSION: These findings proved that the VGSC of D. suzukii has not only the basic gating properties, but also the diversity of gating properties. This study also laid a foundation for the study of pyrethroid resistance mechanism of VGSC in D. suzukii. © 2023 Society of Chemical Industry.
