Efficacy of Pesticides against Two-Spotted Spider mite (Tetranychus urticae Koch) (Acari: Tetranychidae) and Its Performance on Some Hosts in Greenhouse at Haramaya, Eastern Ethiopia

Abstract

The study was conducted in greenhouse (GH) of Haramaya University under 30±2 oC and 60±5% RH during 2016. The objectives were to evaluate the efficacy of some pesticides against T. urticae; and to evaluate the performance of the pest on six host plants. The efficacy of five pesticides, viz. Amitraz, Profenofos, Chlorantrniliprole +λ-cyhalothrin, and Profenofos"Q"720 g/l, @ manufacturers’ rate and Paraffin oil @ 2.5%, were evaluated alone in addition to rotating Amitraz with the other four pesticides. All the experiments were arranged in completely randomized design and replicated four times. The pesticides were applied for straight three times at weekly interval. In the efficacy study, the results after third spray indicated a highly significant (p≤0.0001) difference between the treatments over the control. A week after third spray, all treatments provided 100% reduction of the mite. In the pest performance study, six plants were studied and replicated thrice. The mite counts were recorded until four weeks beginning two weeks after infestation. There were highly significant (p≤0.0001) differences in the mite population among the hosts. Solanum incanum, Datura stramonium, and Solanum tuberosum had not statistically different population size though the mite population on the hosts vary and were in order of performance. But these plants differed significantly from Solanum lycopersicon, Capsicum spp. and Phaseolus vulgaris. Therefore, the study showed that all the tested pesticides were effective to suppress T.urticae and gave opportunity to use them in rotation to slow or prevent pest resistance development. But, it needs careful research under farmers’ field conditions. The study also revealed that Capsicum spp. was least preferred while S.lycopersicon and P.vulgaris were intermediate in status; however, S. incanum, D.stramonium, and S.tuberosum were the most preferred hosts. To this effect, host plants like S.incanum and D.stramonium should be removed from farm boundaries as these weeds are potential shelters of the pest. Further study is required on other host plants especially on weeds as documented materials are not available on Ethiopian conditions to manage the pest.