Acaricide resistance and resistance mechanisms in Tetranychus urticae populations from rose greenhouses in the Netherlands.

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. The activity of detoxifying enzymes was significantly increased in most field-collected strains, and a number of amino acid substitutions known to be involved in resistance were detected.

Conclusions: Resistance levels to traditional acaricides such as bifenthrin and abamectin were prominent, and might result in control failure under field conditions. Resistance to more recently registered compounds was detected in several populations. Resistance levels were generally unstable in the laboratory without selection pressure. The toxicological, biochemical and genetic data in this study will be essential in devising an efficient resistant management for Dutch rose culture.