Spatial partterns of Scirtothrips dorsalis Hood in tea plantations at different altitudes on high mountains in southwest of Yunnan

ObjectiveThe spatial distribution pattern of Scirtothrips dorsalis Hood in tea plantations at three diffe-rent altitudes in southwest Yunnan to provide reference for comprehensive control of S.dorsalis.MethodS.dorsalis popu-lation dynamics in tea plantations at three different altitudes(low altitude,middle altitude and high altitude)in Longchuan County,Yunnan were investigated by leaf checking and pest counting method.The spatial distribution pattern of S.dorsalis in tea plantations at three different altitudes were surveyed and determined using aggregation level indexes,m*-m regres-sion analysis of Iwao and power law of Lloyd.ResultThe spatial distribution of S.dorsalis population was mainly in ag-gregated distribution and mainly distributed in fresh leaves.The aggregated pattern of S.dorsalis population was resulted from they liked eating tender leaves of tea.Theoretical sampling models of adult S.dorsalis in tea plantations at low alti-tude,middle altitude and high altitude were N=t2/D2(1.006m +0.367),N=t2/D2(21.509m +1.083)and N=t2/D2(-21.107m +1.223). Their sequential sampling models were T0(n)=2n±7.1488,T0(n)=2n±6.8811 and T0(n)=2n±1.8655 respectively. The theo-retical sampling numbers for tea plantations at three different altitudes were 9,32 and 36 respectively when the density of S.dorsalis was 100 insect/leaf.When the accumulative population reached 2.4 insect/leaf,tea plantations at low altitude and middle altitude should be observed and tea plantations at high altitude should be controled.ConclusionS.dorsalis in tea plantations at three different altitudes are concentrated in tender parts of tea.Accumulative population 2.4 insect/leaf can be used as a indicator for the control of S.dorsalis in tea plantation at high altitudes.