FACTORS RESPONSIBLE FOR THE EXTINCTION OF CHRYSOMPHALUS AONIDUM(L.) FROM CITRUS ORCHARDS IN EGYPT.BIOLOGY AND HOST-INTERACTIONS OF NATURAL ENEMIES: Posters and Abstracts:

Abstract

Ecological studies have shown that the black armoured scale, Chrysomphalus aonidum (L.), has four overlapping annual generations on navel orange trees under the conditions in Qalyubyia Governorate, Egypt. Five species of natural enemies were recorded on C. aonidum during the present work. The ectoparasitoid, Aphytis holoxanthus DeBach, was recorded for the first time from Egypt, and the other bioagents were three endoparasitoids: Aspidiotiphagus citrinus Craw., A. lounsburyi Berl. & Paoli and Habrolepis pascuorum Mercet and an entomogenous fungus, Cladosporium cladosporides (Fresen).

Recently, C. aonidum appears to have become extinct in citrus orchards in many localities in Egypt. It is considered that this is due to a combination of spray timing and the effects of these five bioagents. Since 1967, the Ministry of Agriculture in Egypt has recommended the use of summer sprays against this pest, instead of autumn and winter applications. Summer sprays are less harmful to these natural enemies, which are mainly effective against the winter and spring populations of C. aonidum.