1. Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA.
2. Department of Entomology, Cornell University, Ithaca, NY 14853, USA.
3. Department of Biology, University of Toronto at Mississauga, Mississauga, ON L5L 1C6, Canada.
4. Division of Biological Sciences, University of Montana, Missoula, MT 59812, USA.
5. Laboratory of Organic Chemistry and Chemical Biology, Department of Chemistry, University of Turku, FI-20014 Turku, Finland.