Spatial distribution pattern and sampling technology of small brown planthopper, Laodelphax striatellus, on wheat in the Yellow River valley of China

Key Words：small brown planthopper, assembling indices, Iwao regression analysis, spatial distribution pattern, sequential sampling

Abstract：    The  population dynamics of the small brown planthopper, Laodelphax striatellus Fallén, were investi gated in the Yellow River valley, Henan Province in 2009 and 2010 Based on field investigations, the spatial distribution pattern, theoretical sampling number and sequential sampling technique were determined using the methods of assembling indices and advanced Iwao regression analysis.The results show that 3rd and 4th instar nymphs were the main overwintering stages, and that the overwintering period began in the last tendays of November.In April of the following year, the overwintering population peaked in wheat fields, with respective densities of 22/m² and 43/m² for adults and nymphs being recorded.Adults migrated into paddy fields in midMay, reaching peak densities of over 450 /m² The results indicate that overwintering population in wheat fields tend to have a clustered spatial distribution.The theoretical sampling equation was N=t^{2     /}D²0.324/m+0.086 and the sequential sampling model was T_n=25n±15.4n.These results provide a scientific basis for accurate sampling and effective management of this pest.