The seasonal population changes of the Citrus Soft Scale, Pulvinaria aurantii (Hemiptera: Coccidae), and its distribution pattern in citrus orchards

Subject Areas : entomology and othea arthropods

M. R. Damavandian ¹ (Department of Plant Protection, Sari Agricultural Sciences and Natural Resources University, Sari, Iran)

Received: 2012-10-01 Accepted : 2013-02-20 Published : 2014-05-22

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Abstract :

Increase in cetrus damage by Pulvinaria aurantii in recent years and more pressure of pesticides application by farmer are two urgent problems of citrus production in north of Iran. To apply pesticides in a right time that is a component of integrated pest management (IPM), seasonal changes of citrus soft scale, Pulvinaria aurantii (Cockerell) densities was studied in central and eastern part of Mazandaran province from 2007 to 2009. There wene two annual generations per year. The first, designated as the summer generation, appeared from June to September, and the second, designated as the autumn generation, appeared from September to the following June. The maximum population of crawlers and first instar of second generation were seen during the last 10 days of june and for first generation during the late of September and beginning of October which is the best time for controlling the pest. Parameter b of Taylor's power low is an index of dispersion that in ordinary population was 9.4, suggested an aggregated dispersion pattern on one tree, however in high population ( b= 1.57) it became close to random. There was no significant difference between the number of P. aurantii in different geographical direction and inside canopy of the tree in comparison with outside the tree canopy. However, in orchard with no suitable pruning, always P. aurantii population was high. Furthermore, the enough spaw between trees and pruning, cause to decrease infestation by the pest from 25.1% to 8.3%.