The effect of sand particle size on Steinernema feltiae sensu Filipjev (1934) (=N. bibionis Bovien) activity against Galleria mellonella larvae

Activity of an isolate of Steinernema feltiae in different fractions of sand was measured by the mortality of host Galleria mellonella larvae. No deaths were recorded in particles less than 600 μ across. Maximum activity occurred with 700–800 μ size particles. Activity was also limited with a sand fraction containing particles of 1000–1100 μ. Host mortality in mixtures of two sand fractions varied. Generally, the addition of either small particles (500–700 μ) or large ones (1000–1100 μ) to fractions of the mid-range (700–1000 μ) reduced the percentage kill of host larvae. Polynomial regression models fitted to data from single-phase experiments could be used to predict accurately mortality of G. mellonella larvae in two-phase mixtures of sand.