Relationship between the population density of the white mango scale insect, Aulacaspis tubercularis (Newstead) (Hemiptera: Diaspididae) and the yield loss of mango trees in Luxor Governorate, Egypt

Abstract

The main objective of this work is to estimate the relationship between the pest population, Aulacaspis tubercularis (Newstead), infestation through pest activity peaks in September, November, April and June on the yield loss of Goleck mango trees at the district of Esna, Luxor Governorate through two seasons (2016/2017 and 2017/2018). The results revealed that the  increment of population density and incidence infestation by the pest gradually decreased the yield of mango, consequently  increased the percentage of the yield loss when the data of the yield were colligated with the pest population peaks and its infestation incidence in September, November, April and June months through 2016/2017 and 2017/2018 seasons.Increasing one individual  of pest per leaf caused a reduction of the mango yield by 2.14, 1.56, 2.05 and 4.28 kg/tree and 2.08, 1.42, 2.46 and 1.31 kg/tree through the peaks of the two seasons, respectively. Subsequently, increased the yield loss percentages by 1.52, 1.12, 1.47 and 3.06% and 1.44, 0.98, 1.70 and 0.90% when the yield data were correlated with the population density of the pest in September, November, April and June peaks during the two connective seasons (2016/2017 and 2017/2018), respectively. These results confirmed that the pest population and the percentages of infestation incidence of A. tubercularis during the peak of April caused the least expected values in the yield of mango and the greatest loss in mango yield. On contrary, the peak during November was less effective, causing the highest expected values in mango yield and the lowest reduction in the yield of mango during the seasons of 2016/2017 and 2017/2018. Generally, the reduction in the yield of mango was a summation of different factors (time, level and variety ability to infestation).