Ecological Studies on California Red Scale Insect, Aonidiella aurantii (Mask.) on Some Orange Varieties in Relation to Biotic and Abiotic Factors

Aims: Orange trees infested with different scale insects, among them the California red scale (Aonidiella aurantii [Mask.]), is the most serious pest of orange. This study was conducted to demonstrate the number of generations of this pest on each variety and the effect of parasitic and meteorological factors on its population.
Place and Duration of Study: This study was carried out in a private orchard in Kafr Shokr, Qaliobiya Governorate (30.543646,31.263705) on three varieties of orange (Balady, Navel, Succari) during two years from February 2010 to January 2012.
Results: The dynamics of development of generation of red scale was influenced by host varieties as follows:
• On Balady orange three generations in the 1st season in (Feb. – August), (May – October) and (August – Dec.) and in (Feb. – July), (July – Nov.) and (Sept. – Jan.) during the 2nd season.
• On Navel orange three generations in (Feb. – July), (May – October) and (August – Jan.) during 1st season and (Feb. – June), (April – October) and (October – Jan.) in the 2nd season.
• On Succari orange 1st season generations in (Feb. – June), (April – August) and (August – Dec.) while 2nd season generations in (March – June), (May – October) and (October – Jan.)
Parasitism gave a very positive significant relation in the 1st season and insignificant negative in the 2nd season, Temp. gave positive significant relation in the 1st season and very significant in the 2nd season, while relative humidity relations was negative in 1st season and positive in the 2nd season but insignificant in both.
The effect of all measures was very significant in the 1st season and insignificant in the 2nd season as the total effect was 89.71% and 61.51% during the 1st and 2nd seasons, respectively.