JWSS - Journal of Water and Soil Science

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In 1998 and 1999, adult population density of pistachio psylla and its sex ratio were determined weekly in two orchards with yellow sticky board traps and limb jarring. Also egg and nymphal population was determined on the leaves. By studying the seasonal population fluctuaions, the efficiencies of the two methods were compared. Meanwhile, using yellow sticky boards, diurnal activity of adults was investigated. Adult pistachio psylla became active during flower and leaf bud opening. Adult capture with both methods showed a high correlation with egg and unwinged nymphal density counts, with at least five peaks (maximum six). Two peaks occurred during spring and densities were much lower in comparison with those of later generations. First adult capture was observed on yellow traps. Yellow traps were found to be a better method than the limb jarring method for the study of seasonal population from adult captures. Sex ratio was equal through out the growing season and during the warmer or cooler months of the year. However, more males were attracted to traps and more females were captured with limb jarring early in the season. Peak activites during day occurred through 9-16 p. m.

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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.

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  Aphids are known as important pests of plants specially almond trees. Seasonal population fluctuation of two aphid species, Brachycaudus amygdalinus (Schout.) and Hyalopterus amygdali (Blanch.) were studied in 1999-2000 on almond trees in Najafabad area. Characteristics such as times of egg hatch, appearance, outbreak, spring migration to alternative hosts, migration from alternative hosts in fall, oviposition, number of eggs laid, damage degree, alternative, other primary hosts and some natural enemies were investigated. In early spring damage signs of B. amygdalinus were expressed on almond twigs as serious leaf curling followed by retarded growth of twigs and shortened internodes. Shortly after that H. amygdali colonized other leaves. For both species egg hatching was coincided in late winter however colonization and population increase of H. amygdalei were observed two weeks later than what was observed for B. amygdalinus. With the onset of warm season, both species moved from almonds to alternative hosts for aestivation. Gynoparae shortly followed by males appeared on alternative hosts in late summer and migrated to almonds. Oviparae produced by gynoparae mated with males and laid their eggs near the buds.