1. Department of Chemistry, Virginia Military Institute, Lexington, Virginia 24450,
United States
2. Centre for
Social Evolution,
Department of Biology, University of Copenhagen, Universitetsparken 15, DK-2100 Copenhagen, Denmark
3. Laboratory of Bioorganic Chemistry,
National Institute of Diabetes, Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0820,
United States
4. Department
of Entomology, Smithsonian Institution,
POB 37012, NHB, CE516, MRC
188, Washington, D.C. 20013-7012, United States