Assessment of Two-spotted Spider Mite (Tetranychus urticae) on Potato (Solanum tuberosum L.) in Eastern Hararghe, Ethiopia

Abstract

Potato is an important tuberous vegetable crop in Ethiopia. However, its production is constrained by arthropod pests, nutrient depletion of soil and diseases. Among arthropod pests, two-spotted spider mite (TSSM, Tetranychus urticae) is one of the major arthropod pests affecting potato production and contributing to low yield in eastern Hararghe, Ethiopia. To tackle this problem, the survey was undertaken to assess the distribution, farmers’ management practices and their perception of TSSM on the irrigated potato. The data were collected from ninety-six potato producers during the dry season in Haramaya, Kombolcha, Kersa and Metta districts of Eastern Hararghe Zone by interviewing, observing and recording from October to March in 2018/2019. The meteorological data were obtained from the National meteorological agency, Jijiga station. The number of TSSM/potato plants, prevalence, incidence and severity levels of potato were analyzed using three-stage nested design. Farmers’ perceptions and practices were analyzed by using descriptive statistics, while the relationship of weather factors and altitude with the status of TSSM was analyzed using SPSS software program version 16.0 and determination of Pearson correlation was done using SPSS statistical software. This assessment confirmed that TSSM was found in all the districts with variation in number per potato leaves, incidence and severity levels. The highest incidence (37.88%), severity (3), number of TSSM/potato (39) per plant was scored from Haramaya district and the lowest was recorded from Kombolcha district. Based on the observation and response of the respondents, the TSSM was mostly prevailed in autumn (44.79%) but was the lowest in spring seasons (6.25%). It severely affected the potato production at flowering stages (44.2%). But the lowest damage was at seedling stage (7.4%). Data on farmer’s perception also showed that 60% of them recognized TSSM on potato plants. The linear correlation coefficient indicated that the incidence (r=-0.546, Y=-0.548X+38.7), number of TSSM/potato plant (r=-0.847,Y=-0.06.232X+38.24) and severity level (r=-0.431,Y=-0.0221X+2.805) was decreased as rainfall intensity increased. The studies suggested that provision of resistant variety of potato, chemical pesticides, water supply will help the farmers to increase the production and productivity of potato by decreasing the yield losses due to TSSM. Further research on the seasonal abundance, effect of microclimate, natural enemies and management practices on the population dynamics of TSSM in the major potato growing areas of eastern part of Ethiopia was suggested from the study.