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Abstract

Seasonal use of powdery mildews by the mycophagous ladybird, Illeis koebelei, was observed in Setagaya. In the field, I. koebelei shows seasonal changes in host use and breeds regularly on Microsphaera pulchra var. pulchra that infests Benthamidia florida, Oidium sp., that infests Pyracantha coccinea in spring, Phyllactinia moricola that infests Morus australis, and Sphaerotheca cucurbitae that infests Trichosanthes kllirowii var. japonica in autumn. On these fungus species under laboratory conditions, larval development of the ladybird was completed (within 20 days at 24°C) with a high survival rate. Thus, the seasonal occurrence of I. koebelei may be synchronized with the abundance of essential fungi. This study showed that I. koebelei feeds on 11 species of powdery mildews, including Sphaerotheca, Podosphaera, Microsphaera, Phyllactinia and Oidium. However, no species of the Uncinula, Uncinuliella and Erysiphe genera were suitable food for the ladybird.