1. Dep. of Entomology, College of Plant Protection Nanjing Agricultural Univ. Nanjing 210095 China
2. Institute of Ecological Environment Chinese Research Academy of Environmental Sciences Beijing 100012 China
3. Dep. of Agronomy, College of Agriculture Yangzhou Univ. Yangzhou 225000 China
4. Agricultural Research and Extension Center Texas A&M Univ. Lubbock TX 79403
5. Dep. of Applied Mathematics, College of Basic Science and Information Engineering Yunnan Agricultural Univ. Kunming 650201 China