Studies on the biology and host specificity of Cassida japana Baly

Cassida japana Baly is a principal natural enemy of the farmland weed,Chenopodium album L.. It has four generations per year and overwinters by adult in Jiangsu Province,China. Generally,egg laying stage lasts 16-31days. A female can lay 482 eggs at most,and 175 eggs at average. The developmental durations for egg,larva,pupae and adult is around 3-13 days,8-16 days,3- 6 days and 15-35 days,respectively. The overwinter adult can survive for about 200 days. The occurrence of C. japana reaches its peak stage between mid June and mid August,and damage degree is restricted by high temperature. Host range tests within 26 plant species from 15 families showed C. album is the only species which could completed its life cycle of C. japana. It is indicated that C. japana could safely be used to control the farmland weed,C. album.