W Soares Leal1, T Kadosawa2. 1. a Department of Insect Physiology and Behavior , National Institute of Sericultural and Entomological Science , 1-2 Ohwashi, Tsukuba 305 , Japan. 2. b Agro-Environment Division, Chugoku National Agricultural Experiment Station , 6-12-1 Nishifukatsu, Fukuyama, Hiroshima 721 , Japan .