Effect of Pruning Intensity on the Species Diversity of Arthropod Communities in Organic Tea Plantation

Arthropod insects are important pests that feed on leaves and young shoots often causing 10 to 20% loss in tea yield. Evaluation of the effect of major cultural practice such as pruning on the ecological aspect of the arthropod insects and their natural enemies is essential to develop a sound IPM program for organic tea plantation. The impac of summer pruning in mid-May on the arthropod communities was investigated with 3 different pruning intensities,i.e. light, heavy, and no pruning, in Hubei organic tea plantation. Light summer pruning had significant impact on the species and number of tea bush insect pests and their natural enemies within 1 month after pruning, and it lasted by2 months. Heavy pruning had greater impacts. Light pruning postponed the first peak in occurrence of Empoasca vitis (Gothe) for 20 days and the peak of Acaphylla theae Watt for 30 days. Heavy pruning postponed the first peak of Empoasca vitis (Gothe) for 25 days, and completely avoided the damage on tea bush from Acaphylla theae Watt. difference in diversity indices and the ratio of ‘natural enemies/insect pests’ of the arthropod communities on tea bushes by 3 and 4 months after pruning, respectively. The results suggest that light pruning can be used to control insect pests in organic tea plantations with the effect lasting for two months. Heavy pruning had a better control of insect pests than light pruning, but it is hardly to recommend without confirming the balance among sustainability of tea bush vigor in growth and tea yield in the following year, population of natural enemies and the efficacy of insect pest control. The optimum intensity of pruning may differ by individual tea plantation as the age and vigor of tea bush, soil fertility and management of tea bush nutrition differ by each tea plantation.