In Australian cotton fields, the eggs, larvae and pupae of Helicoverpa armigera and H. punctigera are attacked by a diverse range of parasitic wasps and flies. These parasitoids help to reduce the overall abundance of Helicoverpa in the agroecosystem by removing a proportion of the developing populations (Fitt 1994 Anit. Rev. Entomol. 39:543-562). However, despite their importance, our knowledge of the biology and ecology of many key parasitoid species is severely lacking. While research on Trichogrammatid wasps and Microplitis demolitor has provided detailed information on biology and ecology of these parasitiods (Scholz 1990 Msc thesis, Uni. Queensland pp203) other key species have never been studied. For example, although Heteropelma scaposum, is often the most abundant Helicoverpa parasitoid encountered in the cotton agroecosystem (Fitt and Mares 1992 Proc. 6" AUSt. Cotton Conf pp 269-276, Fitt and Walker pers. obs. ) nothing is known about the biology or ecology of this wasp. Furthermore, we have little information on the habitat requirements of Ichneumon promissorius, a true pupal parasitoid of Helicoverpa recently exported and successfully established in the USA for control of H. zea in corn crops.

New technology may increase the importance of parasitods by enhancing their numbers. The development of transgenic varieties of cotton producing Bt proteins has been a major advancement in the fight against Helicoverpa spp. As part of the management plan to reduce the chance of Helicoverpa spp developing resistance to Bt, the use of refuge crops has been endorsed. The use of refuge crops, while designed to produce more Helicoverpa (Fitt 1996 Proc. 8" Allst. Cotton Goof pp 69-76) may inadvertently increase populations of egg, larval and pupal parasitoids. Slimlarly, the practice of planting pigeon pea as a trap crop for Helicoverpa in transgenic cotton (Anon. 1997 AUSt. Cotton Grower 18:82) may significantly increase egg and larval parasitoid populations. If so, can these parasitoids originating from refuge or trap crops be attracted back into the transgenic cotton crops to parasitise late season Helicoverpa larvae or pupae thus further lowering the chances of resistance to Bt protein developing?

The aim of this project is to gain a more comprehensive understanding of the biology and ecology of key Helicoverpa parasitoids, and thereby indicate ways of effectiveIy augmenting and conserving parasitoid populations in cotton using the most appropriate management techniques.