Effects Of Organic Management On The Insect Community Of Organic Tea Garden

In this experiment, the regularities of important pests and their natural enemies in 3 different plots in the organic tea garden and 1 control plot in the conventional tea garden, in Baise region of Guangxi province, were studied with ecological method. The population dynamics and community structure of important pests and their natural enemies were the emphasis of analysis. The influences of the organic management on the insect community diversity and stability were discussed. The results of this experiment may provide some theoretical bases for intergrated pest management in organic tea garden. The main results were as follows:1)Empoasca (Emposaca ) vitis (Gothe) and spiders were the major pest and its natural enemies in tea garden of Baise region, respectively. During the tea tree growth season, the population dynamics of both Empoasca (Emposaca) vitis (Gothe) and spiders displayed double peak curve . Their peaks were both in April and July per year and The two peak values of Empoasca (Emposaca) vitis (Gothe) were 86.1 units per 50 nets and 78.6 units per 50 nets , respectively, while spiders were 67.7 units per 50 nets and 81.3 units per 50 nets, respectively. In the plot which had the longest organic management time, the population dynamics between Empoasca (Emposaca) vitis (Gothe) and spiders showed significantly positive correlation (r=0.7355).2) In the 3 plots of the organic tea garden, the diversity index and the evenness index of insect community were higher but the dominance was lower compared with the control plot of the conventional tea garden, so the community stability of the organic tea garden was higher than the conventional tea garden's. In July peak period of Empoasca (Emposaca ) vitis (Gothe) , community diversity indexes of the 3 different plots in the organic tea garden and the control plot of the conventional tea garden were 0.6280,0.7020,0.7269 and 0.2504, respectively, the evenness indexes of the 4 plots were 0.5543,0.5830,0.6342 and 0.3217 .respectively.The dominances were 0.4221,0.4417, 0.4545 and 0.8503, respectively. The insect community stability of the plot of the longest organic management time was the best, while the control plot of conventional management was the worst.3) On base of biological characteristics of insect pests, the ways of control insect pest, such as picking and botanical pesticides were applied. The results showed: picking could decrease effectively the pest population density, which tends burgeon of the tea tree. After spraying 1000 times, 1200 times and 1500 times dilute botanical pesticides matrine, the reduce rates of Scirtothrips dosalis Hood, Empoasca (Emposaca )vitis ( Gothe ) and Polyhagotarsonemus latus ( Banks ) reached the peak value after 1 day, 5 days and 3 days, respectively. The effects of 1500 times for Scirtothrips dosalis Hood, 1200 times for Empoasca (Emposaca) vitis (Gothe) and 1500 times for Polyhagotarsonemus latus (Banks) were the best.