Biological and Ecological Studies of the Ash Whitefly Siphoninus Phillyreae (HALIDAY) (Hemiptera: Aleyrodidae) on Citrus

Abstract

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Siphoninus phillyreae (Ash Whitefly) belongs to class Insecta, family Aleyrodidae, and genus Siphoninus. S. phillyreae is widely distributed in Middle East, Europe, Central and North Africa. This study aimed to examine the biological and ecological aspects of the whitefly S. phillyreae. This study was conducted in the laboratory and field of College of Agriculture, University of Baghdad during spring 2014. The results revealed that eggs with the size 0.29x0.086 mm were laid in partial or complete circular form on both upper and lower surfaces of mature leaves. The eggs had short sub-terminal stalk put into the leaf tissue by female ovipositor. There were four nymphal
instars. The first one was yellowish in color, long, elliptical in shape with the dimensions 0.26x0.15 mm, had antennae and long legs. The antennae and legs of nymphal stages (pupa case) larvae were immovable and measured 0.39x0.24 mm, 0.55x0.39 mm, and 0.96x0.78 mm, respectively during different stages of development. The winged adult came out after t-shaped disruption of pupa and its dorsal surface had a yellowish body with pure dusty white wings. Males and females can be differentiated by the size and shape of the abdomen, being 1.5 mm for the females. The laboratory results showed that the life cycle (means developmental time) was completed in 27 days while
female longevity extended for 26 days. Fertility check demonstrated that every female laid a maximum of 117.6 eggs while the sex ratio was 3:1 female to male. In Baghdad, the whiteflies are more abundant in the month of April and its generation grows from eggs to larvae. The study confirmed the presence of five to six generations annually in citrus plants in Baghdad.