1. Laboratory of Entomology, Wageningen University and Research Centre, Post Office Box 8031, 6700 EH Wageningen, Netherlands.
2. Ifakara Health Research and Development Centre, Post Office Box 53, Ifakara, Tanzania.
3. Department of Public Health and Epidemiology, Swiss Tropical Institute, Socinstrasse 57, CH-4002 Basel, Switzerland.
4. International Atomic Energy Agency (IAEA), Agency's Laboratories Seibersdorf, A-2444 Seibersdorf, Austria.