EVALUATION OF A GENETICALLY SELECTED STRAIN OF STEINERNEMA-FELTIAE AGAINST THE MUSHROOM SCIARID LYCORIELLA-MALI

The control potential of a strain (ScP) of Steinernema feltiae genetic ally selected against the mushroom sciarid Lycoriella solani, was eval uated for the management of L. mali. Trials were conducted at two comm ercial mushroom farms with high and low levels of fly infestation. The efficacy of the ScP strain was compared with the SN strain of S. felt iae and the chitin synthesis inhibitor, diflubenzuron. At low densitie s of L. mali, the two strains did not differ in efficacy and caused 85 -94% reduction in fly populations. At high fly densities with a mixed infestation of the phorid fly, Megaselia halterata, the ScP stain caus ed 56-83% reduction in L. mali populations whereas the SN strain cause d 51-73% reduction. Two doses of the improved strain (0.5 x 10(6) and 1.0 x 10(6) infective juveniles per M2 cropping area) did not differ i n efficacy from diflubenzuron which caused 80% reduction in L. mali po pulations. The lower dose (0.5 x 10(6)) of the SN strain was less effe ctive than diflubenzuron. The ScP strain had a major advantage over th e SN strain in persistence in casing material. Nematodes had no signif icant effect on mushroom yields.