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February 2001. A member wishes to know how to culture Paecilomyces, the entomopathogenic fungus. A fungus had been found growing on a greenhouse whitefly, Trialeurodes vaporariorum Westwood, on eggplant crop in New-Caledonia. This fungus may be a Paecilomyces spp.
A paper suggested culture of Paecilomyces spp. or Beauveria spp. on Dodine medium (Oatmeal agar plus 0.8 g dodine and 0.2 g tetracycline). The question was, what is dodine?
AQIS, Centre for Tropical Agriculture replied that, although they did not know the specific medium for Paexilomyces, they would recommend PDA with Dodine 400mg/L; Tetracycline hydrochloride 100mg/L ; Streptomycin sulphate 100mg/L; this is similar to Whiteside’s isolation medium (Plant Disease 70: 204-206) for culturing Elsinoe fawcettii.
Dodine is an agricultural fungicide produced by Rhone Poulenc used for the control of black spot in apples and pears. It is probably best to request the pure form of Dodine (Dodine technical) to avoid additives in the agricultural form interfering with your cultures.
Advice was also received from American Samoa: Paecilomyces fumosoroseus was isolated from Bemisia tabaci biotype B (B. argentifolii) feeding on greenhouse tomatoes. Paecilomyces isolates grew and sporulated well on PDA. Some labs recommend Sabouraud dextrose agar with yeast extract (SDAY) or in liquid (SDY): 4% dextrose, 1% neopeptone, 1% yeast extract, adjust to pH 6.8. A variation of this is SMDAY medium: 10 g peptone, 20 g dextrose, 20 g maltose, 20 g yeast extract, 10 g agar in 1 litre water; add 0.5 g chloramphenicol when autoclaved medium has cooled to about 45-47C.
The potato-dextrose-agar was quick and inexpensive, but sometimes isolating from cadavers produced contaminants. Usually streptomycin is added for initial isolations, then PDA used for spore production.
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