Thumbtack bioassay: a quick method for measuring plant resistance to twospotted spider mites (Acari: Tetranychidae)

In a novel bioassay for measuring plant resistance to Tetranychus urticae, 10 mites are placed on a thumbtack which is inserted through a test leaf, the number of mites that remain on the tack, as well as the distances mites moved onto the leaf, are recorded at designated time intervals. A sampling time of 2 h maximized the ability to detect differences in numbers of mites per thumbtack among 3 tomato Lycopersicon spp. and allowed detection of differences in distances travelled. -from Authors