Mass production of a fungus, Hirsutella thompsonii var. synnematosa on various media and its efficacy to control the citrus rust mite [Phyllocoptruta oleivora (Ashmead)]
1997
Saowanit Maimala
Hisutella thompsonii var. synnematosa no.30 was cultured on 3 different types of media: semi-solid, liquid and solid media. Colonies on Soybean agar produced higher number of spore, 9.15 * 10*[7) spores/ml, where those on malt extract agar provided significantly higher number of viable spores, 4.78 * 10*[9) CFU/g. Semi-solid agar was not recommended for mass production of Hirsutella due to its high cost. Ground corn coated with molasses was the best solid medium generating 3.07 * 10*[7) spores/ml with 2.64 * 10*[7) CFU/g. Suitable liquid medium comprised 8 percent unpolished rice, 2 percent molasses and mineral salts. Dried mycelium harvested from liquid medium contained 7.92 * 10*[6) CFU/g. Fungus failed to produce spore in the broth but many chlamydospores were observed within the hyphae. Kaolin is an appropriate carrier for preparing powder formulation due to its low price and higher surviving population in the formulation. Powder formulations at 2, 3 and 4 percent concentrations could induced mycosis in Phyllocoptruta oleivora. Slightly difference in percentage of pathogenicity was observed when different types of biomass were used to prepare the formulation. Adding carrier also slightly increased the infectivity. When kaolin was added, biomass from solid medium could induced 23-55 percent pathogenicity compared to 54-61 percent pathogenicity induced by biomass from liquid medium.
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