A new methodology for small-scale studies on twospotted spider mites, Tetranychus urticae Koch: Rearing, sorting life-history stages, and quantifying

The twospotted spider mite, Tetranychus urticae Koch, is an important pest that causes economic damage to cultivated plants in greenhouse and field conditions throughout the world. Research efforts into spider mites and their interactions with plants, particularly in regards to host plant resistance, would benefit from methodologies that rear, sort, and quantify mites with minimal effort and high efficiency. In this study, we provide a new methodology for small-scale research on spider mites. Mites were reared on excised bean leaves that were rooted in a cotton-substrate and kept in small plastic containers. Overall, the rearing method is cheap, easy to maintain, requires little space, allows for rearing of even-aged cohorts, and keeps infestations isolated to help reduce susceptibility of the colony as a whole. To assess population parameters, we developed a small-scale method that strains mites from water suspension and sorts them according to life-history stage (eggs, larvae and adult males, and adult females). Finally, mites were photographed and digitally quantified using Image J. We demonstrate this technique by examination of mite-populations from individual cotton plants to assess host-plant resistance. Results will be included when available.