Moshe Coll, PhD, Department of Entomology, The Hebrew University of Jerusalem, is an applied ecologist with more than a quarter century of experience researching herbivore-plant interactions, predator-prey dynamics in agricultural and natural habitats, and biological and integrated pest control. Eric Wajnberg, PhD, INRA, Sophia Antipolis, France, is a population biologist specialising in population genetics, behavioural ecology and statistical modelling. An expert in biological pest control, he has studied insect parasitoids for thirty years.