EFFECTS OF APPLICATION RATES OF STEINERNEMA-FELTIAE (NEMATODA, STEINERNEMATIDAE) ON BIOLOGICAL-CONTROL OF THE MUSHROOM FLY LYCORIELLA-AURIPILA (DIPTERA, SCIARIDAE)

The potential of Steinernema feltiae for the biological control of Lycoriella auripila was tested in commercial mushroom-growing conditions. The nematodes, applied at rates of 1.5, 3, 6 or 12 x 10(6) infective juveniles per 34 kg tray of spawn-run compost, were mixed into the casing material before it was spread over the compost surface. When compared with untreated control trays, any rate of nematode application significantly reduced fly emergence. Insecticides significantly reduced mushroom yields; nematodes significantly increased them. At a rate of 3 x 10(6) infectives/tray, S. feltiae elicited mean total increases in the weight and numbers of mushrooms produced of 8% and 11% respectively. The nematodes also reduced the incidence of mushrooms spoiled by tunnelling sciarid larvae. The early decline in the numbers of nematodes persisting in casing was a trend that was reversed later, when evidence was obtained that S. feltiae was recycling in insects that had been killed. When applied at a rate of 3 - 10(6) infectives/tray of compost, S. feltiae should provide reliable and cost-effective biological control of L. auripila.