Population dynamics of white mango scale Aulacaspis tubercularis (Hemiptera: Diaspididae) and its natural enemies in Bahir Dar area, Northwest Ethiopia

Abstract

The invasive white mango scale (Aulacaspis tubercularis) was introduced accidentally to Ethiopia in 2010 (through plant materials) and to Bahir Dar area, north western Ethiopia, in 2017. Its population dynamics was studied from October to May 2018/19 on randomly selected mango trees from which number of scales and their natural enemies were recorded using leaves as samples. Analysis of variance, correlation and regression were used for data analysis. Significantly more male colonies, live males, live females and number of eggs were recorded in October than in other months. The number of dead female scales was significantly and positively correlated with rainfall (r = 0.6), maximum temperature (r = 0.34), minimum temperature (r = 0.70) and wind (r = 0.5). Regression analyses showed significant association of weather variable and live females (r 2=0.75), adult predators and Aphytis spp. (r 2=0.48), dead females (r 2=0.62) and eggs (r 2=0.68). Four species of natural enemies, i.e., Cryptolaemus montrouzieri, Chilocorus stigma, Chilocorus bipustulatus larvae, Chrysoperla carnea and an unknown lady beetle larvae were found preying on white mango scale. Scale population varied with time and space, and different developmental stages responded differently to weather variables and predators.