1. Division of Entomology, Commonwealth Scientific and Industrial Research Organisation, Canberra, Australia.
2. Department of Microbiology, University of Illinois, Urbana, IL 61801.
3. Division of Wildlife and Ecology, CSIRO, Lyneham, ACT 2602, Australia.
4. Department of Botany and Zoology, Australian National University, Canberra, ACT 2601, Australia.