Spatial distribution characteristics and patterns of Tetranychus urtica in apple trees in the Aksu region
Author of the article:HU Yu-Long1, 2** ZHU Xiao-Feng1 WANG Ke1 XU Bing-Qiang1 LU Wei2, 3*** LI Hai-Qiang1***
Author's Workplace:1. Ministry of Agriculture Xinjiang Key Laboratory of Agricultural Biosafety, Key Laboratory of Integrated Pest Management on Crops in Northwestern Oasis, Institute of Plant Protection Xinjiang Academy of Agricultural Sciences, Urumqi 830091, China; 2. Key Laboratory of the Pest Monitoring and Safety Control of Crops and Forests of the University of the Xinjiang Uygur Autonomous Region, Ministry of Education, Engineering Research Centre of Cotton, Xinjiang Agricultural University, College of Agriculture, Urumqi 830052, China; 3. Western Agricultural Research Center, Chinese Academy of Agricultural Sciences, Changji 831100, China
Key Words:Tetranychus urtica; spatially distributed; clustered distribution; apple tree
Abstract:
[Aim] To investigate
the occurrence and spatial distribution of Tetranychus urtica in apple
trees. [Methods] The
concentration index method, the Iwao m*-m model and the Taylor
power law model, were used to investigate the distribution characteristics and
spatial patterns of the T. urtica in apple orchards. [Results] A Taylor power law model was established,
revealing that the T. urtica has an overall clustered distribution (a = 0.913 1 < 1, b = 1.806 4>1, m ≠ 1, C > 1). Aggregated distribution patterns
were observed in all four cardinal directions (east, south, west, north) around
apple trees. In regression equations fitted for these four directions, the a values were 0.593 9, 0.593 2, 0.617 6, and 0.603 5, respectively, with b values of 1.652 5, 1.653 1, 1.839 7, and 1.944 4, respectively. The diffusion
coefficients (C) were 5.20, 2.04, 3.81, and 3.37, respectively. The Iwao m*-m regression model
also indicates that T. urtica has an overall clustered distribution (α =﹣1.033 9 < 0, β = 1.841 4 > 1), with
clustering also observed in the east, south, west, and north sectors of apple
trees. The Taylor power law model fitted regression equations for upper,
middle, and lower canopy layers yielded coefficients of 0.691 3, 0.786 1, and
0.739 8 respectively, with b values of 1.845 5, 1.738 2, and 1.858 7,
and diffusion coefficients (C) of 7.10, 9.28, and 10.05. The Iwao m*-m regression model for T. urtica across the upper, middle, and lower tiers
of fruit trees indicated an overall clustered distribution (α =﹣1.059 8 < 0, β = 1.824 0 >
1), with clustering observed across all three tiers. [Conclusion] T. urtica has a clustered distribution
in apple trees irrespective of aspect or canopy level, with no significant
variation in average population density.