Collection of Trichogramma Westwood (Hymenoptera: Trichogrammatidae) from tropical northern Australia: a survey of egg parasitoids for potential pest insect biological control in regions of proposed agricultural expansion

Trichogramma limit pest damage to crops by killing the developing embryo of their insect host at the egg stage. Their impact on the potentially insecticide resistant species, Helicoverpa armigera (Hübner), is considered integral to the resistance management plan for transgenic cotton production in the Ord River Irrigation Area in northern Western Australia. The dominant species of egg parasitoid in Ord River Irrigation Area cotton crops is the introduced Trichogramma pretiosum (Riley). Surveys of similar northern Australian regions earmarked for agricultural expansion revealed that T. pretiosum has been introduced, or has adventitiously dispersed, to all developing agricultural regions of northern Australia. Several previously unsequenced species were collected during surveys in more pristine habitats. Trichogramma pretiosum demonstrates an apparent ability to supersede native Trichogramma species and is perhaps favoured by agricultural expansion.