The Use of Dodine in Selective Media for the Isolation of Metarhizium spp. from Soil

The effects of different concentrations of dodine on germination and colony production by nine isolates of Metarhizium spp. were studied in liquid and solid media. It was found that all isolates were completely inhibited from germinating in liquid medium at concentrations of 50 μg/ml and over. On solid media isolates were more tolerant, requiring 500 μg/ml or over to completely inhibit colony formation. Low concentrations (10 and 50 μg/ml) added to Veen's medium were effective at isolating Metarhizium spp. from soil and reduced the number of contaminants by over 90%. Because of differences between isolates in susceptibility to dodine, the lower concentration of 10 μg/ml is recommended for selective isolation from soil. This is significantly lower than that used by other workers with similar basal media.