Evaluation of acaricide resistance on two spotted spider mite (tetranychus urticae, coch) in the central rift valley of Ethiopia

Abstract

Spider mite has been one of the major constraints of tomato production in the central rift valley of Ethiopia. The main obstacle in spider mite control in the area is associated with failure of control of tomato spider mite using the available pesticides from time to time. The objective of this study was to evaluate the level of resistance of two spotted spider mite for different acaricides in the central rift valley of Ethiopia. To determine the level of resistance, spider mite populations were collected from four major locations of tomato production areas in central rift valley of Ethiopia such as “Zewai”, “Meki”, “Adama”, and “upper Awash”, leaf dipping assay was performed for different concentrations of dicofol, profenos, endosulfan, abamectin, lambda-cyhalothrin, amitraz. Probit analysis was used to determine the LC_50.  RF was calculated to asses the development of resistance in the test populations using the “Hawassa” population for they have not been exposed for pesticedes as a control. The RF ranged from 1.79 to 3.11for dicofol, 0.92 to 2.26 for profenose, 1.37 to 1.67 for abamectine, 1.34 to 1.71 for endosulfan, 0.88 to  2.01 for lambda-cyhalothrin  1.99 to  4.47 for amitraz  (p<5). The highest RF was observed in “Upper Awash” population of T. urticea. In the T. urticae population of Upper Awash showed resistance to dicofol, profenos, lambda-cyhalothrins and amitraz whereas in Adama and Meki, there is resistance to dicofol, profenos and amitraz. On the other hand, T. urticae population from Zewai is susceptible to all acaricides except amitraz. All the studied populations were susceptible to abamectin and endosulfan. In  general,  the  result  suggests  that  the  emergence  of  resistance  in  the  T.  urticae populations for most of the acaricides in the rift valley of Ethiopia and should be reduced through finding appropriate resistance management mechanism.