1. Laboratory of Analytical Chemistry, University of Liege; Gembloux Agro-Bio Tech; Passage des Déportés 2 5030 Gembloux Belgium
2. Unit of Social Ecology; Université Libre de Bruxelles; CP231, 50 avenue F. Roosevelt B-1050 Brussels Belgium
3. Walloon Center of Industrial Biology; University of Liege; B40, Sart-Tilman 4000 Liège Belgium
4. Functional and Evolutionary Entomology; University of Liege; Gembloux Agro-Bio Tech; Passage des Déportés 2 5030 Gembloux Belgium