| The green leafhopper, Empoasca vitis Gothe belonged to Homoptera, Cicadellidae, is a predominant pest on domestic tea plantation which harms tee trees universally and frequently. It harms the burgeon and sucks the water and juice from tea tree with its piercing-sucking mouthparts. When tee trees are harmed, the quantity of poly-hydroxybenzene and aminophenol in tea burgeon gets lower and water-solubility carbohydrate gets higher, the nervation of tea burgeon gets red , the leaf edge or all burgeon gets wilted, stopping grow, curly and sclerous. Therefore, it does harm to the yield and quality of tea greatly.In this dissertation , the situation harmed by the green leafhopper was investigated under different density of this pest quantity, the classable grade harmed by it was established .different economic thresholds under different seasons and yield were conducted , the sensitive baselines of 14 pesticides were initially set up. by mensurating the LC50 of E. vitis from different tea plantations in fujian province, the resistant levels of them from different plantations were analyzed and compared . the method of preventing it and the strategy of reducing pesticide residue as well as preventing and stayingpesticide resistance were discussed. The following result shows:1. When E. vitis does harm to tea trees under different quantity density, the harmed degree intensifies with the pest quantity getting more, and the rate of tea yield loss increases in the same condition.2. We graded the harmed degrees into four, i.e,1st degree, 2nd degree, 3rd degree, 4th degree. The symptom that there are restorable wilt or indistinct-symptom and lighter harm were classified as 1st, the symptom under 10/hundred leaves was belonged to 1st.The symptom that the main nervation of twig begin to get red and the subsidiary nervation get light red were classified as 2nd, the symptom from 10 pest/hundred leaves to 30 pest/hu,ndred leaves was belonged to 2nd . The symptom between main and subsidiary nervation getting red and leaf edge getting yellow , wilted, sclerous were classified as 3rd, the symptom from 30 pest/hundred leaves to 60 pest/hundred leaves was belonged to 3rd, this degree was severe, the quality of tea began to be affected. The symptom that there are yellow curly wilted leaf edges or part died leaves were classified as 4th, The symptom over 60 pest/hundred leaves was belonged to 4th,this harm of degree wer especially severe, the quality and quantity were affected severely.3.The density of this pest quantity(x) and the loss rate of yield (y) were correlative, the correlative equations of spring and autumn tea were respectively y=0. 004625x-0. 007891, y=0. 005024x-0. 01592.When the pest quantity was under 50 /hundred.leaves, the loss rate and the density of quantity had remarkably plus correlation, however, whenover 50 /hundred leaves, the pest density and the loss rate were not correlative.4. The various yield Economic thresholds of E vitis showed: the E. vitis' s economic thresholds of which yearly tea output in spring were respectively 2250kg/hm2, 2000 kg/hm2,1750 kg/hm2,1500 kg/hm2,1250 kg/hm2,1000kg/hm2 were respectively 4. 6547pests/hundred leaves,5.0257 pests/hundred leaves, 5.4979 pests/hundred leaves, 6. 1304 pests/hundred leaves, 7. 0158 pests/hundred leaves and 8. 4988 pests/hundred leaves, the corresponding rate of allowed economic loss were respectively 1.05 %, 1.18%, 1. 35%, 1.57%, 1. 89% and 2. 36%. As the same as spring, the E. vitis' s economic thresholds in autumn were respectively 13.6987 pests/hundredleaves, 14. 9025pests/hundredleaves, 16. 5953 pests/hundred leaves, 18.8308 pests/hundred leaves, 21.9759 pests/hundred leaves and 26. 6629pests/hundred leaves, the corresponding rate of allowed economic loss were respectively 3. 50%, 3. 94%, 4. 51%, 5. 24%, 6. 30% and 7.86%.5. The results of toxicity measurement of 14 insecticides to E. vitis showed that these insecticides could control E. vitis. The most effective insecticide was thiamethoxam, of which the LC50 was 1. 2029 mg L-1 , while the l... |
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