Entomopathogenic fungus Aschersonia aleyrodis naturally occurred on citrus whitefly, Dialeurodes citri nymph was often observed in organic citrus orchards, Jeju. The genus Aschersonia is also known to be toxic against scale insects and other pests. However, little is known about artificial media for mass production of spores of Aschersonia species. Grains are excellent sources of media for mass conidia production of various entomopathogenic fungi. The yeast extract, which converts carbohydrates to carbon dioxides and alcohols, contains a large amount of vitamin B complexes which facilitate the carbohydrate metabolism. The more yeast extract content the more conidia production on artificial medium made from commercial corn flour and corn gluten feed. The number of conidium produced on oat, millet, sorghum, and unhulled barley medium containing 1% yeast extract were 1.8, 1.8, 1.6, and 2.1×1010/plate (90mm × 15mm), respectively. However, the greatest yeast effect among four media showed appeared on sorghum medium, which produced 25 times higher spore production than sorghum alone. Furthermore, the conidia from solid sorghum medium could be easily harvested with cell scraper.

Aschersonia aleyrodis was well-known to be a biological control agent for citrus whitefly, Dialeurodes citri. This entomopathogenic fungus is naturally occurred in organic farming citrus orchards in Jeju. Both lime-sulfur and Bordeaux mixtures are extensively used today to control citrus diseases like citrus melanose and citrus scab, especially in organic farming pest management program. The high concentrated lime-sulfur is also used for pest control such as pink citrus rust mite and scale insects. This study was focused to test the conidial germination and sporulation of Aschersonia aleyrodis on potato dextrose agar (PDA) medium containing different concentrations of two fungicides. The conidia of Aschersonia aleyrodis grown on PDA mixed with commercial bordeaux mixtures, CM150-505, at dilution rate 1:200 (water : bordeaux mixture) were well-germinated but not sporulated at all. On the other hand, Aschersonia aleyrodis did not sporulate and germinate on lime sulfur treated PDA medium even at extremely low dilution rate 1:2,048,000 (water : lime sulfur). However, when the mycelial cells grown at 25o C for at least 7 days at soluble starch-tryptone medium were added to PDA, they were well-sporulated even at high dilution rate 1:100 (water : lime sulfur). This result suggested that the spore mixtures of Aschersonia aleyrodis should be applied to field quite long after lime-sulfur spray.