Studies On The Biology And Control Of Tetranychus Urticae Koch

The thesis studies the pest acarids groups on apple trees in fruit areas such as YangLing, LiQuan, QianXian, FengXiang, MeiXian,and LuoChuan, Shaanxi Province, demonstrating that Tetranychus viennenis Zacher; Tetranychus urticae Koch and Panonychus ulmi Koch.are the key species, and comparing the morphology and biology of the three species of acarids.made the contrast with the modality and disserve habit of three kind harm acarids. Through the field investigations, the results indicate that Tetranychus viennenis Zache is the most key species in Shaanxi apple orchard, while Tetranychus urticae Koch is the second species with obvious tendency of spreading and harmful.Field investigations during the winter demonstrate that Tetranychus urticae can imperil the weeds in orchards as well, such as shepherd's-purse, plantain etc. all could lodge and protect the acarids after crop-dusting. In addition, the female adults of Tetranychus urticae mainly overwinter on the weeds nearby the orchards and in the rimose bark of apple trees, in this case, the weeds in orchards should be cleaned up in addition to the control over orchards. Meanwhile the acarids could overwinter in the fruits in storage and disperse and spread during the translation and commercial actions, so the quarantine should be strengthen in the areas without these acarids in order to interdict the diffusing.Under 16 h photo period, 20% relative humility, feeding the Tetranychus urticae with apple leaves in laboratory, 3 experimental population life tables are formed separate under 20℃,25℃and 30℃. The results indicate that the population doubles in 4.2211 d 3.8145 d and 3.8441 d, while the experimental population intrinsic increase rate 0.1642, 0.1817 and 0.1803;and net reproductive rate 12.981,25.8632,12.917, suggesting that the most appropriate temperature for growth of Tetranychus urticae on apple leaves is about 25℃.Under 25℃, 16 h illumination and 20% relative humility, 4 experimental population life tables are formed separately based on navy bean, peach, apple and balsamine. The population Intrinsic increase rates on different hosts are 0.2105, .1926, 0.1817 and 0.1497. This shows that only from Rm perspective, Tetranychus urticae Koch in the four host plants and foods diet for the adaptation to the best in the kidney beans, the second is in peach leaf,the third is in apple leaf,the last on is in balsamine leaf. The net reproductive rates (Ro) denotation that each female can produce a generation of female. While the net reproductive rates are 21.8684,...