BIOLOGY AND POPULATION FLUCTUATION OF CASINARIA NIGRIPES GRAVENHORST
Ma Wanyan Peng Jianwen Wang Xilin Zuo Yuxiang (Hunan Institute of Forestry Science, Changsha)
Casinaria nigripes Gravenhorst is the primarily parasitoids of pine caterpillar, Dendrolimus punctams.They attack 1st to 4th instar larva resulting in,some times, the total parasitization up to 66.64%.Casinaria nigripes completes 6 - 7 generations a year with overwintering as larva in its hosts. The development threshold for whole generation is 9.0±0.6℃ with effective temperature summation to be 446.9 day-degrees. Mature larva emerges through host skin and pupates on some needdles and twins. Eight hosts and four Hyperparasites have been found in the field in Hunan province.Rates of parasitization in forests are influenced by types and growth codi-tion of forests with the highest in the mixed stand followed by the closed pure pine stand then the sparse stand.Parsitoid population sizes of Casiniria nigripes are related directly to the precipitations in July-Angust, and inversely to the numbers of frosty days in a year.