Identification and characterization of new mutations in mitochondrial cytochrome b that confer resistance to bifenazate and acequinocyl in the spider mite Tetranychus urticae

Abstract

BACKGROUND In spider mites, mutations in the mitochondrial cytochrome b Qo pocket have been reported to confer resistance to the Qo inhibitors bifenazate and acequinocyl. In this study, we surveyed populations of the two‐spotted spider mite Tetranychus urticae for mutations in cytochrome b, linked newly discovered mutations with resistance and assessed potential pleiotropic fitness costs. RESULTS We identified two novel mutations in the Qo site: G132A (equivalent to G143A in fungi resistant to strobilurins) and G126S + A133T (previously reported to cause bifenazate and acequinocyl resistance in Panonychus citri). Two T. urticae strains carrying G132A were highly resistant to bifenazate but not acequinocyl, whereas a strain with G126S + A133T displayed high levels of acequinocyl resistance, but only moderate levels of bifenazate resistance. Bifenazate and acequinocyl resistance were inherited maternally, providing strong evidence for the involvement of these mutations in the resistance phenotype. Near isogenic lines carrying G132A revealed several fitness penalties in T. urticae; a lower net reproductive rate (R0), intrinsic rate of increase (rm) and finite rate of increase (LM); a higher doubling time (DT); and a more male‐biased sex ratio. CONCLUSIONS Several lines of evidence were provided to support the causal role of newly discovered cytochrome b mutations in bifenazate and acequinocyl resistance. Because of the fitness costs associated with the G132A mutation, resistant T. urticae populations might be less competitive in a bifenazate‐free environment, offering opportunities for resistance management. © 2019 Society of Chemical Industry

Resistance risk assessment of the novel complex II inhibitor pyflubumide in the polyphagous pest Tetranychus urticae

“…However, the fast development of resistance in the species, in part due to biological characteristics such as a short life cycle, high reproductive potential, arrhenotokous reproduction, together with a broad host plant range, reduces the efficacy of the application of acaricides (Dermauw et al 2013;Van Leeuwen et al 2010;Wybouw et al 2019). It is therefore important to continue to develop acaricides with new modes of action and limited cross-resistance to other commercially available compounds to secure proper resistance management in T. urticae (Nauen et al 2012;Van Leeuwen, Thomas et al 2015;Fotoukkiaii et al 2019). The carboxanilide pyflubumide is a recently developed acaricide by Nihon Nohyaku Co. Ltd with excellent activity against phytophagous mites of the genus Tetranychus and Panonychus (both belong to the Tetranychidae family) .…”

Identification and characterization of striking multiple‐insecticide resistance in a Tetranychus urticae field population from Greece

“…Several studies have reported T. urticae strains with high levels of resistance against certain active ingredients, 22–25 including some cases of cross‐ or multiple resistance 18,26–28 . Several mechanisms have been associated with these phenotypes, with the most studied being target‐site mutations, 9,27,29–32 and over‐expression of detoxification enzymes 33–39 …”

Target-Site Mutations and Glutathione S-Transferases Are Associated with Acequinocyl and Pyridaben Resistance in the Two-Spotted Spider Mite Tetranychus urticae (Acari: Tetranychidae)

“…L1024V, A1215D, and F1538I mutations of voltage-gated chloride channel genes and a I1017F mutation of chitin synthase I have been reported [30,31]. Van Leeuwen et al [32] reported G126S, I136T, S141T, P262T and A133T, G132A [18] mutations in cytb of acequinocyl-and bifenazate-resistant T. urticae. In addition, I256V and N321S mutations were reported in cytb of acequinocyl-resistant T. urticae in a recent study [19].…”

“…Arthropods have developed two main mechanisms of acaricide resistance: decreasing exposure due to quantitative or qualitative changes in major detoxification enzymes and decreasing sensitivity due to changes in target-site sensitivity caused by point mutations [15][16][17]. Fotoukkiaii et al [18] demonstrated that amino acid residue substitutions (G126S + A133T) in cytochrome b of T. urticae are associated with acequinocyl resistance. Kim et al [19] also observed the I256V + N321S point mutations in an acequinocyl-resistant strain.…”