Background: Spider mites are important crop pests that rapidly develop resistance to acaricides. To investigate whether acaricide resistance is a threat to greenhouse rose culture in the Netherlands, the susceptibility of 15 strains of Tetranychus urticae was tested to several currently used acaricides, and resistance mechanisms were investigated.
Results: Although the observed levels of susceptibility differed between strains and acaricides, resistance was detected in most strains.
In recent years, grape growers in California reported failures of acaricides against Tetranychus pacificus McGregor. We collected T. pacificus populations from four vineyards and tested them for resistance to bifenazate, propargite and pyridaben.
View Article and Find Full Text PDFBackground: Resistance of Tetranychus urticae Koch to bifenazate was recently linked with mutations in the mitochondrial cytochrome b Q(o) pocket, suggesting that bifenazate acts as a Q(o) inhibitor (Q(o)I). Since these mutations might cause cross-resistance to the known acaricidal Q(o)I acequinocyl and fluacrypyrim, resistance levels and inheritance patterns were investigated in several bifenazate-susceptible and bifenazate-resistant strains with different mutations in the cd1 and ef helices aligning the Q(o) pocket.
Results: Cross-resistance to acequinocyl in two bifenazate-resistant strains was shown to be maternally inherited and caused by the combination of two specific mutations in the cytochrome b Q(o) pocket.
Genes encoded by mitochondrial DNA (mtDNA) exist in large numbers per cell but can be selected very rapidly as a result of unequal partitioning of mtDNA between germ cells during embryogenesis. However, empirical studies of this "bottlenecking" effect are rare because of the apparent scarcity of heteroplasmic individuals possessing more than one mtDNA haplotype. Here, we report an example of insecticide resistance in an arthropod pest (Tetranychus urticae) being controlled by mtDNA and on its inheritance in a heteroplasmic mite strain.
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