1. Institute for Pheromone Research, Department of Chemistry, Indiana University, 800 East Kirkwood Avenue, Bloomington, Indiana 47405, Centre for Chemometrics, School of Chemistry, University of Bristol, Cantocks Close, Bristol BS8 1TS, U.K., and Konrad Lorenz Institute for Ethology, Austrian Academy of Sciences, Savoyenstrasse 1a, A-1160 Vienna, Austria