Yeast autolysate bait sprays for control of Queensland fruit fly on passionfruit in Queensland.
A range of chemicals were incorporated in yeast autolysate to evaluate their efficacy against the tephritid Dacus tryoni [Bactrocera tryoni] on passion fruit in Queensland, their phytotoxicities and effects on beneficial fauna. Yeast autolysate was not phytotoxic when applied to foliage. In the laboratory at 25°C, chlorpyrifos was the most effective insecticide tested in combination with the bait. Trichlorfon and maldison [malathion] also gave good control. In an 8 ha orchard, baiting at 7-day intervals with 10 g a.i./litre yeast autolysate mixed with 2 g a.i./litre chlorpyrifos or 5 g a.i./litre malathion gave good control. During this time, B. tryoni caused up to 75% fruit damage in an adjacent orchard which was treated with dimethoate. In laboratory tests, malathion was highly toxic, and chlorpyrifos and trichlorfon were less toxic to the coccinellid Cryptolaemus montrouzieri. Yeast autolysate was not attractive to C. montrouzieri, the aphelinid Aphytis lingnanensis or the encyrtids Leptomastix dactylopii and Encarsia sp.