Appearance and Chemical Control of White Mango Scale (Aulacaspis tubercularis) in Central Rift Valley

Occurrence of White Mango Scale (WMS), Diaspididae), in Ethiopia was known in 2010. It had remained confined to western Ethiopia where local mango trees of old age found until recently. Leaf samples infested by the pest were brought to Melkassa Agricultural Research Center (MARC) for diagnosis in June 2014. Hence, a survey to determine occurrence and distribution of the pest on mango orchards in the Central Rift Valley was conducted in August 2014. Four out of seventeen fields surveyed were infested by the pest. Of these infestation in two orchards was 100%. These orchards are located around Batu Degaga and Melkawoba about 10 Km east of MARC. Infestation in the other two orchards was very slight. Leaf infestation in the highly affected orchards ranged no single insecticide has been registered for use against the pest in Ethiopia, a new systemic insecticide spirotetramat (Movento) obtained from Bayer chemical company in Addis Ababa was tested for its efficacy to control the pest a insecticide for the control of Red scale, Aonidiella aurantii and untreated control. The study was conducted at Melkawoba located close to MARC using Randomized complete Block Design (RCBD) with three replications. Treatments were applied using motorized knapsack sprayer. Movento 150 OD and Methidathion 400 EC were applied at 1.7 and 5 ml mixed with three liters of water, respectively biweekly for a total of five times. Number of WMS per ten leaves randomly picked per treatment prior to treatment application was used to assess efficacy of the test insecticide. Number of WMS was similar after the first spray in all the treatments. After the second to fourth spray, WMS number in t was consistently higher than the insecticide treatments without significant difference between treatments. After the fifth spray population in the untreated control was significantly higher and nearly ten-fold over the insecticide treatme Methidathion. Percent corrected mortality showed a progressive increase from 36 to 90% and 49 to 74 % in Movento and Methidathion treatments respectively after the second to fifth spray. The results reported in this study are preliminaries aimed at confirming presence of WMS in the CRV and to test efficacy of Movento against the pest. A study towards integrated management of the pest based on understanding the ecology of the pest need to be conducted. Insecticide screening program should focus on systemic insecticides that are less harmful to the pest's natural enemies similar to Movento considered in this study.