Study on the population dynamics and spatial distribution of Parasaissetia nigra Nietner on rubber plant.

Annual monitoring was conducted on population dynamics of Parasaissetia nigra Nietner from 2005 to 2006 in Jinghong of Xishuangbanna Prefecture.The result indicated that it had 3 generations.The period of population peak of each generation occurred separately in early April,late July and late October.The duration of the second generation was the longest.The duration of the first generation of the largest population was the shortest.The spatial distribution of P.nigra population was studied by the methods of diffusion coefficient,Lloyd's mean crowding and index of patchiness,Iwao's patchiness and Taylor's law.The results of all the methods showed that the spatial pattern of P.nigra was aggregated distribution on rubber plants.Based on the analysis of spatial distribution,the optimum number for sampling under different tolerances was determined and sequential sampling model was established by Iwao theory sampling model.