Two-spotted spider mite (TSSM), Tetranychus urticae, is a key pest devastating 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 from October to March in Haramaya, Kombolcha, Kersa and Metta districts of Eastern Hararghe Zone by interviewing, observing and recording in 2018/2019. The meteorology data were obtained from the National Meteorological Agency, Jijiga station. The survey data analysis was made by descriptive statistics using Microsoft excel 2013. This assessment confirmed that TSSM was found in all the districts with variation in number per potato leaves, incidence and damage levels. Data on farmer’s perception showed that 60% of the producers recognized TSSM on the potato plant. Its damage to potato plants mostly prevailed during the flowering stage (44.2%) in the autumn season. Investigation of management of TSSM by application of botanicals and synthetic pesticides was conducted in the laboratory and greenhouse. The experiment was arranged in CRD which was replicated five times in the greenhouse and four times in the laboratory. In laboratory Azadirachta indica seed oil, Tagetus minuta leaf oil, A. indica and T. minuta leaf aqueous extracts, Amitraz, Profenofos and Emamectin benzoate at three dose levels and their LC50 by leaf disk spraying and dipping bioassays were evaluated. Similarly, in greenhouse Azadirachta indica seed oil, Amitraz, Profenofos and Emamectin benzoate (EB) in their combinations and alone were evaluated. The data was recorded at 24, 48, and 72 hours in the laboratory after the application of the treatments. But the applications of the treatments were conducted at weekly intervals for three weeks and data were collected before and after the spray. The laboratory results indicated that the highest percentage of TSSM adult mortality was recorded with EB at 80µL (74-97%), followed by profenofos35µL (71-90%), while Amitraz 80µL caused the lowest (58-83% mortality). From the evaluated botanicals A. indica seed oil at 5% caused the highest percentage of TSSM adult mortality (72-100%), followed by T. minuta leaf oil at 5% (74- 92% mortality) in a laboratory bioassay. Amitraz caused the highest percentage mortality of TSSM eggs (72.5-92.5%) and it required 24.35µL to kill 50% of eggs, which was lower than EB (54.146 µL) and profenofos (12.737µL). Among the botanicals, A. indica seed oil had the highest toxicity against TSSM adults (2.14%), followed by A. indica leaf oil (2.31%). Furthermore, T. minuta leaf oil had higher toxic effects on TSSM eggs (0.239%) than A. indica seed oil (1.162%). The greenhouse results indicated that the combination of half doses of Amitraz and EB, one-third doses of Amitraz, EB and profenofos, and half doses of profenofos and EB resulted in better reduction (100%) of TSSM adults, immature and eggs than their sole application. It is hoped that this research would create a scientific knowledge base for sustainable management of TSSM in potato cultivation. Further research is suggested for future work on farms, under multiple locations to manage TSSM.
Keywords: Assessment, Botanicals, Chemical pesticide, Median lethal concentrations, LC50, Management, Potato, TSSM