The effect of artificial substrates on the pathogenicity of Steinernema feltiae (Rhabditida : Steinernematidae) to adult Musca domestica (Diptera : Muscidae)

Effects of some artificial substrates on the ability of the entomopathogeni c nematode Steinernema feltiae to kill adult Musca domestica were studied. Replicate samples of different substrates were treated with known numbers o f S. feltiae suspended in 0.25 M sucrose. Then 30 adult female flies were c onfined above each sample in a. crystalizing basin and mortality counts wer e carried out 48 h later. The most effective substrates were poplin cotton, potting compost, silver sand and Fibertex SF250 horticultural capillary ma tting, which gave LD50 in the range of 2815 to 8912 S. feltiae. Conversely, Perlite was the least efficient material and required between 531 450 and 899 930 S. feltiae to achieve the LD50. These effects appeared to be relate d to the total porosity (ratio of the volume of air spaces in each material to its bulk volume) of each material, with the most efficient materials ha ving total porosities in a median range of between 0.81 and 0.14. The signi ficance of these observations is discussed.