Document Type : Original Article
Authors
1
Plant Protection Research Institute, Agriculture Research Center, Dokki, Giza, Egypt.
2
Fac. Agric., Al- Azhar Univ., Cairo, Egypt..
3
Fac. Agric., Al- Azhar Univ., Cairo, Egypt.
Abstract
Lepidosaphes beckii (Newman) (Hemiptera: Diaspididae) seasonal abundance on sour-orange, Citrus aurantium trees was carried out in Kafr El-Sohaby, at Qalubyia Governorate, Egypt, starting April, 2004 to March 2006. Population dynamics indicated mean population as 46.25, 49.20 individuals/leaf over 2004/2005 and 2005/2006 years, respectively. The mean number per leaf was 4.97, 18.96, 5.97, 8.06 and 8.30 individuals for crawlers, pre-adults, females, gravid females and male pupae, respectively over 2004/2005. The relative means were 7.51, 21.30, 5.56, 8.93 and 5.90 individuals/leaf, for 2005/2006, respectively. Both north and east directions harbored the heaviest infestation (i.e. 64.4 and 61.6 scales/leaf for north and 49.7 and 62.2 scales/leaf for east over the two years, respectively). The upper leaf surface harbored heavier infestation compared with the lower one in both years. Four generations per year for L. beckii were determined in this location using age-structure method (i.e. percent proportion of each stage population over the total).The first generation extended from Jun. 3, to Aug. 12, 2004. The second generation started there after and continued until Oct. 21, 2004. Third generation continued until Feb. 24, 2005. The last generation started Feb. 24, 2005 and continued to Jun. 10, 2005. This means that both first and second generations continued over 70 days each compared with the third generation which continued for 126 days. The fourth one continued over 106 days. Similar results were obtained for the second year (2005/2006). Three periods for chemical control of this pest on citrus at this location was recommended (where the relative abundance of immature stages was the most). The first period was during Apr. 15 to 30. The second was Jul. 15 to 30 and the third during Sept. 15 to 30. The parasitoids recorded from L. beckii on sour-orange were the primary parasitoid Aphytis diaspidis Howard (Hymenoptera: Aphelinidae) and the secondary one, Chartocerus niger (Ashmead) (Hymenoptera: Signiphoridae). Parasitism by A. diaspidis ranged between 0 to 24.6% with mean of 11.9% over the two years.
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