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Arthropods, 2015, 4(1): 13-21
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Determination of economic injury level for first and second generations of Pulvinaria aurantii (Hem: Coccidae) in Thomson navel orange orchards

Nima Maleki, Mohammad Reza Damavandian
Department of plant protection, Sari University College of Agriculture Sciences and Natural Resource, Sari, Iran

Received 10 November 2014;Accepted 15 December 2014;Published online 1 March 2015
IAEES

Abstract
The citrus soft scale, Pulvinaria aurantii (Hem: Coccidae) is among the most important pests of citrus orchards in Asia. Damage occurs not only by direct feeding on plant sap, but also by excretion of abundant honeydew which underlies the growth of sooty molds on fruits, leaves, and young twigs. Although, chemical insecticides and mineral oils have long been used by growers to control P. aurantii, our current knowledge about the damage and economic injury level of this pest is insufficient. In this study, the economic injury level (EIL) of the first and second generations of P. aurantii on Thomson novel orange was investigated during two consecutive years (2011 and 2012). The study unit include a citrus orchard (3000 m²) located at Babolsar city, north Iran. Four branches of each selected tree with a proximate length of 25 cm were artificially infected by different numbers of P. aurantii egg sacs and monitored biweekly to record the number of infected leaves and fruits to both sooty molds P. aurantii instars. Finally, the number of fruits infected with sooty molds (more than 50% of the fruit surface) was used to estimate EIL using Pedigo formula. The EIL was calculated as 135, 102, and 125 egg sacs per branches with an average number of 8, 7, and 7 fruits for the first generation of 2011, and the first and second generations of 2012, respectively. These findings may be easily used by local growers to set their control programs based on the density of pest egg sacs on plant surfaces.

Keywords Pulvinaria aurantii;economic injury level;mineral oil;damage, egg sac;citrus fruits..

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