Evaluation of Resistance in Seven Populations of the Two - Spotted Spider Mite (Tetranychus urticae Kosh) for Abamectin on Cucumber under Plastic Houses Conditions in Jordan

Laboratory bioassays were conducted during the period from June 2009 till August 2010 to evaluate the toxicities of abamectin against adult females of seven populations of the two- spotted spider mite, Tetranychus urticae (Kosh). Six out of the seven tested populations were collected from Al-Ramtha, Baqa, Zyzya, Krimeh, Deir-Alla and Karamah covering the main regions devoted to cucumber cultivation in Jordan. The seventh populations, was brought from Syria and considered as a susceptible strain (SSS). All the seven populations except the Syrian susceptible strain were resistant to abamectin. The Karamah population was moderately resistant to abamectin (RF=11.6), while Al-Ramtha population was the least resistant one (RF= 4.05). These results indicated that most of the local T. urticae populations displayed different level, of resistance to abamectin. The study results recommend using registered acaricides in Jordan alternatively with abamectin to keep these pesticides effective to avoid or decrease the resistance of the two- spotted spider mite for these acaricides.