Bioecology of Pistachio Oyster Shell Scale,Lepidosaphes Pistachiae Archangelskaya(Hom: Diaspididae) in Isfahan

Pistachio oyster shell scale is one of the important pests of pistachio in Iran whose females are reported to exist in two or three forms, each form developing on a specific part of the pistachio tree. In this study, abundance of the pest is investigated on leaves and branches for different ages, two heights and four cardinal directions of tree crown. Paralelly seasonal population fluctuations of three forms were studied on leaves, and one-and two-year-old branches separately. This insect overwintered as female mostly on one and two-year-old branches. It had two separable periods of activity, through the season. In the first period, eggs mostly hatched in April and crawlers mostly settled on leaves, fruits and newly grown twigs but rarely on older branches.These populations are male and female. In the second period, eggs mostly hatched in June, and crawlers settled mostly on leaves and one and two-year-old branches, but all individuals settled on leaves are males and those on branches are females. Population density is significantly higher on upper surface of leaves than on the lower surface. Analysis of variance showed that only significant differences existed in densities observed between trees in both generations, and also between two heights of tree crown for populations settled on wood. Two predatory species from Cybocephalidae and Coccinellidae, one ectoparasitoid from Aphelinidae and two endoparasitoids from Encyrtidae were collected as natural enemies of this pest in Isfahan.