Effects of sulfur on Trichogramma egg parasitoids in vineyards: measuring toxic effects and establishing release windows

Abstract

Trichogramma parasitoids are a commonly released biological control agent against Lepidopteran pests. In vineyards in south-eastern Australia, Trichogramma carverae is released to control lightbrown apple moth (Epiphyas postvittana), a pest of grapevines. Sulfur is also sprayed on the vines to control powdery mildew and mites. Our experiments aimed to assess the potential impact of sulfur use on released and resident Trichogramma species (T. carverae, T. funiculatum) and to devise a protocol to maximise the potential of Trichogramma and optimally integrate the use of chemicals with biocontrol. Laboratory and field studies indicate that sulfur is harmful to adults and to immature stages contained within hosts where it increases mortality and reduces fitness of the emerged wasps. Persistence trials showed that release of Trichogramma 6 days after sulfur spraying will reduce the effects on released organisms. To reduce the impact on resident Trichogramma, other chemicals will need to be used.