Co‐occurrence of subunit B and C mutations in respiratory complex II confers high resistance levels to pyflubumide and cyenopyrafen in the two‐spotted spider mite Tetranychus urticae (Acari: Tetranychidae)

Abstract

BACKGROUND Pyflubumide and cyenopyrafen are respiratory complex II (complex II) inhibitors. Previous quantitative trait locus analyses suggested associations of I260V and S56L in complex II subunit B (B‐I260V) and subunit C (C‐S56L) with pyflubumide and cyenopyrafen resistance, respectively, in Tetranychus urticae. However, although resistant strains had been selected separately by these acaricides, all strains were homozygous for both B‐I260V and C‐S56L. Hence, the effects of each mutation on resistance development remain unclear. RESULTS We established strains homozygous for B‐I260V with C‐S56 (B‐I260V_I260V/C‐S56_S56) and for C‐S56L with B‐I260 (B‐I260_I260/C‐S56L_S56L). High resistance levels (LC50 > 1000 mg L−1) to pyflubumide and cyenopyrafen was not conferred by B‐I260V or C‐S56L alone. Next, we prepared intermixed strains by crossing B‐I260V_I260V/C‐S56_S56 and B‐I260_I260/C‐S56L_S56L. Selection of the intermixed strains by either acaricide caused very high resistance levels (LC50 ≥ 10 000 mg L−1) to both acaricides and fixed both mutations. Allele‐selected recoupling of the mutations without acaricide selection also conferred very high resistance levels to both acaricides in the intermixed strains. Unlike these, B‐I260V or C‐S56L alone conferred very high and high resistance levels to cyflumetofen, respectively. CONCLUSION We conclude that the effect of individual mutations characteristically varies among complex II inhibitors. Moreover, very high resistance levels to pyflubumide and cyenopyrafen is conferred by the co‐occurrence of B‐I260V and C‐S56L mutations, which alone have limited effects on resistance level.

Selectivity and molecular stress responses to classical and botanical acaricides in the predatory mite Phytoseiulus persimilisAthias‐Henriot (Acari: Phytoseiidae)

“…In contrast, cyenopyrafen resistance was mapped to SdhC carrying S56L substitution. 15,106 We have identified the substitution of I260 (I260M) in SdhB of P. persimilis, which may explain the high selectivity of cyflumetofen seen in this study (Figs 2 and 3, and File S6). The same substitution has been found in sequences of A. swirskii available via the NCBI (Table 1).…”

“…The genetic basis of METI II resistance in T. urticae was clarified using quantitative trait locus (QTL) analysis, revealing that cyflumetofen and pyflumubide resistance was associated with I260T and I260V in SdhB, respectively. In contrast, cyenopyrafen resistance was mapped to SdhC carrying S56L substitution 15,106 . We have identified the substitution of I260 (I260M) in SdhB of P. persimilis , which may explain the high selectivity of cyflumetofen seen in this study (Figs 2 and 3, and File S6).…”

The G126S substitution in mitochondrially encoded cytochrome b does not confer bifenazate resistance in the spider mite Tetranychus urticae

“…After the role of candidate target-site mutations in pesticide resistance is functionally validated, these genetic variants can be incorporated in diagnostic field kits (Van Leeuwen et al 2020). In T. urticae, more than 15 mutations in eight target genes have been determined and associated with pesticide resistance (reviewed in Van Leeuwen et al 2020;Maeoka and Osakabe, 2021;Sugimoto et al, 2020).…”

A high‐throughput KASP assay provides insights into the evolution of multiple resistant mutations in populations of the two‐spotted spider mite Tetranychus urticae across China

“…1,2 Although many agricultural, physical, and biological control methods have been developed to control this pest, [3][4][5][6][7] the usage of synthetic acaricides remains the most frequent method to reduce the damage of TSSMs in the field. [8][9][10][11] Due to the misuse and overuse of acaricides and the rapid evolutionary response of the TSSM to acaricide selection, field populations have developed resistance to most of the acaricides used to control them. [12][13][14][15][16] Currently, at least 877 cases of resistance to 97 active ingredients have been reported in the TSSM.…”