White Mango Scale (Aulacaspis tubercularis) infestation on mango: distinct scenarios of the pest status in Ethiopia and Kenya

Abstract

Infestation of the White Mango Scale (WMS) (Aulacaspis tubercularis Newstead (Hemiptera: Diaspididae) on mango was known in Kenya for a longer time, yet the severity of its impact has only been reported frequently in Ethiopia where the first record of the pest was only about a decade. This study investigated the WMS statuses in Kenya and Ethiopia. A total of four fields, two from each country, were addressed to determine the population abundances of the pest at different developmental stages. Five blocks, one at the center and the rest at each corner of the study orchards were set in Ethiopia. In Kenya, Randomized Complete Block Design (RCBD) was employed to determine the levels of susceptibility of different mango varieties to the pest. The abundance of WMS was significantly different (p < 0.05) between Arjo-Gudetu and Bako-Tibe sites in Ethiopia. Sessile mango scales in hundreds and eggs and crawlers each in thousands per leaf were recorded in Ethiopia. In contrast, very low WMS populations were recorded from the Kenyan orchards, with most leaves bearing no mango scale. However, the sessile stage populations observed were significantly different (p < 0.05) between Kimani-Sofia and Samuru-Kandara orchards. In each of these orchards, the levels of pest infestation varied significantly (p < 0.05) among the mango varieties, Kent and Vandyke being the most infested at Kimani-Sofia and Samuru-Kandara, respectively. In conclusion, these studies revealed the presence of a very high population abundance of mango scale in Ethiopia, whereas in Kenya it was very low. This variation may pertain mainly to the differences in mango production and pest management practices between the two countries. However, because these studies were conducted in different years in the two countries, cross-sectional investigations which include data from a considerable period may be required to better compare the levels of pest infestation in Kenya and Ethiopia.