The two-spotted spider mite, Tetranychus urticae Koch (Acari: Tetranychidae), is one of the most important pest species, because it devastates many horticultural and ornamental crops and fruit trees. The resistance ratios calculated for the LC50 value in acequinocyl- and pyridaben-resistant strain was 4,237- and 5,555-fold higher than that of the susceptible strain, respectively. The objective of this study was to evaluate the cross-resistance to several acaricides and to identify the mechanisms associated with acequinocyl- and pyridaben-resistant strain of T. urticae.

The two-spotted spider mite, Tetranychus urticae, is a worldwide agricultural pest that invades a wide range of host crops and rapidly develops resistance to pesticides. T. urticae can be resistant to one acaricide or exhibit multiple resistances or cross resistance to various other acaricides. Acequinocyl inhibits respiration in mitochondria at the ubiquinol oxidation site (Q0) of Complex III of the electron transfer chain. Pyridaben is a METI acaricide that inhibits mitochondrial electron transport at complex I. In this study, we investigated the cross resistance to seven acaricides in acequinocyl- and pyridaben-resistant strain. Furthermore, the frequencies of the I256V and N321S mutations in mitochondrial cytochrome b (cytb) of pyridaben-resistant and fieldcollected strain was analyzed.

Gene expression is regulated by DNA and histone methylation by DNA and histone methyltransferases, respectively. In animal system, DNA methyltransferase with CG methylation activity is modified by SUMO conjugation and then its activity was increased, which means that the activity of DNA methyltransferase is modulated by posttranslational modification. so Chromatin remodeling is a new concept for expression of controlling of gene function. We thus analyzed the effect of E3 SUMO ligase AtSIZ1 in CMT3 (chromometnylase 3)-mediated genome methylation by next-generation sequencing (NGS), methyl binding domain MeDIP-sequencing and gene analysis using siz1-2 and cmt3 mutants. we carried out CG-enrich analysis by MeDIP sequencing revealed that the methylation level of the genome including transposons was significantly low in siz1-2 mutants compared to wild-type. Result showed the genes regulated by methylation, that genes related of embryo and root development, cellulose metabolism, and post-translational modifications. All of our data indicate that the methyltransfearse activity of CMT3 may be able to be regulated by AtSIZ1 and thereby CMT3-mediated gene expression and plant development also can be controlled by E3 SUMO ligase activity. Besides, our data also suggest that ammonium (NH4+) can stimulate AtSIZ1- and CMT3- mediated DNA methylation.