The Effects Of Overwintering Pest Control On The Population Dynamics Of The Tea Pests And Their Natural Enemies In Tea Gardens

Tea industry is one of the major agricultural economies in Zhouning County. The residual toxicities caused by unreasonable application of chemical pesticides leads serious effect to tea industry sustainable development. Based on the current situation of chemical pesticides used at tea gardens and in order to make a scientific tea pest management in Zhouning, the application of the lime sulphur to control the overwintering pests at tea gardens was conducted during January 2008 in 2 different altitude level tea gardens, Makeng and Qibu of Zhouning. The population dynamics of tea pests and their natural enemies, the residues of chemical pesticides and the tea production were investigated and compared with those in the check tea gardens afterwards. The main results as follows:According to their general food habits, the arthropod community in 2 tea gardens of Makeng and Qibu of Zhouning can be divided into pest, neutral insect and natural enemy 3 sub-communities. The pest sub-community mainly consisting of small green leafhopper (SGL), harmful mites, mealworm, aphids, thrips, etc. and the natural enemy sub-community including various predators and hymenopterous parasites, such as spiders, ladybirds, ants and Mymarids, Aphelinids, Trichogrammatids, Eulophids, Scelionids, etc.After the lime sulphur was applied for controlling the overwintering pests in the 2 tea gardens in Zhouning, a satisfied result had been achieved. In which the main pests, small green leafhopper, harmful mites, mealworm, thrips, etc. got under control significantly during the spring and without obvious harmful affects to their main natural enemies, such as spiders, Mymarids, Aphelinids, Trichogrammatids, etc.The population dynamics of the main natural enemies in the 2 treated tea gardens where the lime sulphur was applied, were much higher than those in the check tea gardens during the spring. The egg density of the small green leafhopper (SGL) in tea shoots in the 2 treated tea gardens was significantly lower than that in the check tea gardens. While the egg parasitism of SGL was obviously higher than that in the 2 check tea gardens during March to May.The overwintering pests decreased after the lime sulphur was applied, which was benefited of reducing the pesticide residues in spring tea. The residues of chemical pesticides in tea leaves from the 2 treated tea gardens in Zhouning showed that the residual amounts of Fenvalerate, Kelthane and Endosulfan were 0.02-0.15㎎/㎏,0.01-0.36㎎/㎏ and 0.12㎎/㎏ lower than that in the 2 check tea gardens respectively.Due to the promotion of the earlier germinating, the production of tea leaves during the spring from the 2 treated tea gardens were 195.00-247.50 kg/ha more than that in the 2 check tea gardens and more than 1435.50-1541.25 yuan/ha economic effects were obtained.Therefore, it is valuable to be popularized to use lime sulphur to control the overwintering pests in tea gardens as which has great ecological, economical and social effects.