Bionomics Of Myzus Persicae (Sulzer) And Its Influence On The Quality Of Fluecured Tobacco

Myzus persicae (Sulzer) is one of the most important pests on tobacco. Its injury on tobacco, including direct damage and indirect damage, not only leads to the economic loss of tobacco leaves, but also the lower quality of flue-cured tobacco.This paper involved a systematic study on bionomics in the tobacco field of Myzus persicae (Sulzer) and its influence on the quality of tobacco leaves in Hezhang county, Guizhou province for the first time. The results as follows:The population dynamics of the aphid presented a single peak curve in the not-plucking-top tobacco field. Its growth model is N=36.0411e^0.1079T (the curve significantly accordance). Regulation effects on aphid population consisted of natural enemies, plants round the tobacco field, nutritive condition, self condition, tobacco varieties, etc..In whole growing periods of tobacco, the number ratio of the aphid at tobacco different positions is: stem 0.51%, leaf 44.38%, bub 42.51%, and flower and fruit 12.61%. But the number ratio has some change in different growth periods of tobacco.In the change course of tobacco leaf from no-green to mature, the number of the aphid varied from few to many at first, then decrease gradually. The number ratio of the aphid at different maturity of tobacco leaf: no-green leaf 20.47%, immature leaf 34.61%, pre-mature leaf 29.85%, mature leaf 13.20%, pre-technological-mature leaf 1.77%, technological-mature leaf 0.13%.With the increase of the number of the aphid, the loss of output value of tobacco leaves become heavier. Using the formula of H. N. Chiang for calculation of the economic threshold and the action threshold, the results indicate that pesticides should be applied to control the aphid when the average aphid number per tobacco plant is 90 in tobacco field in Hezhang county.According to the results of bake treatment on tobacco leaves at aphid different damage level, the regression equations of nicotine, total nitrogen, protein and reductive sugar (y) to aphid damage grade (x) are: y=3.49-0.53x (r=-0.8606^*), y= 2.44-0.2x (r=-0.6779^*), y=8.34-0.5x (r=-0.8606^*), y=16.85+2.1x (r=0.8765^*), respectively. But the regression relation of total sugar, K and Cl to aphid damage grade don't arrive significantly level. While high temperature desiccation treatment on tobacco leaves at aphid different damage level, all the regression relation, including nicotine, total nitrogen, protein, total sugar, reductive sugar, K and Cl to aphid damage grade, doesn't arrive significantly level. Under bake treatment, the aphid damage grades and smoking quality of tobacco leaves were analyzed, which showed that there was negative correlation between the smoking quality (y) and the aphid damage grade (x), the regression equation is: y=42.82 - 0.62x, (r =-0.9667^**). According to analysis of Shumke value, the higher the aphid damage grade, the worse the quality of tobacco leaves. Compare with the two treatments of bake and high temperature desiccation, the quality of aphid damage tobacco leaves is the worse in bake treatment than in high temperature desiccation treatment.This study aimed at the target of "Chinese-style flue-cured tobacco" put forward by State Tobacco Monopoly Administration, centered on use value and effective desire, based on natural aphid population in method, set up investigation site around tobacco production, achieved to the end of guide production and serve production.