The project focussed on understanding more about the egg parasitoid Trichogramma pretiosum. This minute wasp attacks the egg stage of heliothis (Helicoverpa spp.) and causes significant mortality of heliothis on the Darling Downs.

T. pretiosum is a new species to the Darling Downs. It is native to North America, but was established in the Ord River region of Western Australia in the mid 1970’s. The DPI obtained some T. pretiosum from scientists in Western Australia and released it onto the Darling Downs in 1995. It appears to thrive in agricultural environments, especially when selective pest management tactics are employed, e.g. Bt. cottons and the use of selective insecticides.

There is increasing grower interest in utilising beneficial insects and spiders in pest management, and thereby reducing the need to spray pests with insecticides. Cotton growers on the Darling Downs are interested in learning more about Trichogramma because of the high impact the wasps have had in dryland cotton. In particularly, leading consultants and growers want to know if T. pretiosum can be utilised in irrigated cotton and conventional cotton.

The project built on the findings of previous research where T. pretiosum successfully managed heliothis in unsprayed dryland INGARD® cotton for three consecutive years, including a high pest pressure year when heliothis egg densities rose to 90 eggs/m. Previous DPI research found that T. pretiosum is a significant natural enemy of heliothis (DAQ 96C –“IPM in dryland cotton on the Darling Downs’). This work was carried out in dryland INGARD® cotton at Jimbour on the Darling Downs. The research reported here was conducted in other regions, and included trials in irrigated conventional cotton.