Laboratory experiments on the vertical movement of the entomopathogenic fungus Metarhizium anisopliae (Metsch.) Sorok. in standard soils and sand
1992
Zimmermann, G. (Biologische Bundesanstalt fuer Land- und Forstwirtschaft, Darmstadt (Germany). Inst. fuer Biologischen Pflanzenschutz)
The fungus Metarhizium anisopliae is used increasingly for biological control of pest insects in the soil. The following investigations were made to judge a possible contamination of ground- and drinking water. The experimental methods were adapted to those described in the information leaflet no. 37 of the Federal Biological Research Centre for Agriculture and Forestry. Two different soil types, as well as pure sand were filled into 30 cm columns and wetted until saturation. The conidia were applied to the top of the columns as a suspension containing 0.05 Tween 80 as a dry powder. The columns were rinsed with sterile, deionized water, equivalent to 200 mm of rain. M. anisopliae was recovered with a soilplate-dilution technique and a selective medium. The number of conidia decreased quickly with the soil depth in all treatments. At 10 cm the number was about 10 to 100 times below that recovered from the surface, corresponding to a reduction of 90 and 99 % respectively. Studies on the vertical movement of wet and dry spores of M. anisopliae through a 30 cm sand column revealed that less than 1 conidium per 1 ml effluent could be found i.e. 10(8) to 10(9) of the wetted and dry spores were retained. The results suggest that a contamination of groundwater and the corresponding soil layers through the use of M. anisopliae is very unlikely
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