Studies on the Population and Distribution Pattern of Parlatoria zizyphus (Lucas) in Citrus Orchards in Egypt

Abstract

The population and distribution pattern of the black parlatoria scale, Parlatoria zizyphus (Lucas) have been investigated. This scale had two annual peaks of abundance in September and May. It passed through three annual generations, the first in September-October, the second in March-April and the third in June-July on grape fruit trees. The build up of insect population on different zones of grape fruit trees in different seasons of the year was studied. The insect distribution of different insect items were significantly affected at different heights and directions of the trees. The highest population tended to be accumulated on the lower and middle shady zones of the trees in different seasons. With regard to directions the central core of the tree harboured the highest population followed by the west direction and the lowest population was accumulated on the north or south direction in the fall and spring. In summer, the highest population settled on the south direction in contrast to the east or north directions, which harboured the lowest population. The mode of insect distribution is discussed in correlation with the environmental conditions.