Investigations on the presence of an infectious proportion amongst populations ofSteinernema feltiae(Site 76 strain) infective stages

SUMMARY Experimental studies were conducted on the proportion ofSteinernema feltiaeFilipjev (Site 76 strain) infective stages that infectedGalleria mellonellaL larvae, in sand tube assays. A full statistical analysis of the sand assay tubes was also undertaken. The analysis showed that the sand tubes were not a significant source of variation. Consequently the observed behaviour of the infective stages was considered to be due to a biological effect. The study shows that the proportion of infective stages that became parasitic did not increase with increases in the density of applied infective stages, nor did the proportion increase with an increase in the number of hosts. It is argued that these findings are consistent with the presence of a proportion of individual infective stages that are capable of causing infection.