Seasonal Population Dynamics of White Mango Scale, Aulacaspis tubercularis at Different Agro-ecologies and Its Cardinal Direction Preferences in Western Oromia, Ethiopia

Mango production is constrained by the infestation of arthropod pests, among which white mango scale, Aulacaspis tubercularis, is the most economically important insect pest causing devastating damage in Ethiopia. This study investigated the status of A. tubercularis in western Oromia, Ethiopia. A total of three districts (Guto Gida, Bako Tibe and Elu Gelan) and Nekemte city, among each, two orchards and five mango trees were selected purposively. Twelve leaves were collected monthly from each tree: from upper, middle and lower canopies and the A. tubercularis cluster (ATC) were recorded. RCBD was employed to determine the level ATC density. The results of the study revealed that A. tubercularis present in all study areas throughout the year with a fluctuating ATC density in which the highest ATC was concentrated on the upper side of the leaves. The abundance population density of the ATC population showed significant differences among the study months and cardinal directions, where the A. tubrcularis prefers the southern cardinal direction. The abundance of ATC population was significantly higher at Bako (p<0.05), where the ATC was abundant on the upper surface of the leaf in all study areas. There was a marked increase in ATC population density from March to mid-June with an increased precipitation and a swift decrease to nonexistent from mid-June to September followed by prolonged heavy precipitation. Furthermore, the study investigated the effect of basic climatic factors and cardinal direction differences on the population density of ATC, where the other contributing factors need to be investigated further.