云南元阳梯田水稻田白背飞虱若虫空间分布型及理论抽样数

采用Taylor幂法扩散法和Iwao回归法分析了云南元阳哈尼梯田1400～2000m海拔16个哈尼族传统水稻品种田白背飞虱Sogatella furcifera(Horvath)1～3龄若虫的空间分布特征。结果表明,白背飞虱1～3龄若虫在不同海拔、不同水稻品种田均呈聚集分布中的负二项分布,其负二项分布的公共K值为3.53,聚集原因主要是由白背飞虱生物学特性和环境因素引起。Iwao直线回归方程拟合公式为m*=3.96+1.09m(R=0.97),Taylor幂拟合公式为lg(V)=0.28+1.34×lg(m)(R=0.85)。其中,在1400～1500、1501～1600、1601～1700、1701～1800、1801～1900和1901～2000m海拔梯田稻田中,白背飞虱若虫平均拥挤度分别为10.74±0.83、23.67±3.50、21.64±6.02、47.10±5.71、52.59±12.75、13.72±3.14,差异显著(F=5.77,P<0.01),其中在1701～1800和1801～1900m海拔稻田中白背飞虱平均拥挤度最高,表明在该海拔处白背飞虱在稻丛上分布较为集中,而在1400～1500和1901～2000m海拔稻田中平均拥挤度最低。根据空间分布型参数,建立了精度分别为0.1和0.2时的理论抽样数模型,分别为n=1905.43x+34.57,n=476x.36+8.64,该模型适用于不同虫口密度下的田间抽样。当白背飞虱虫口密度为5、10、20头/丛时,分别取样30、20和15个样方。

Spatial distribution patterns and theoretical sampling of Sogatella furcifera of nymph in rice terrace fields in Yuanyang

Dispersal indices,and the Iwao and Taylor regression methods,were used to investigate the spatial distribution and theoretical sample size of Sogatella furcifera（Horvath） nymphs in rice terrace fields at different altitudes in Yuanyang,Yunnan.Results show that younger nymphs had a negative binomial spatial pattern which was the result of their intrinsic biological characteristics and environmental factors.Iwao＇s m＊-m regression model was m＊ = 3.96 ＋ 1.09 m（R = 0.97）,and Taylor＇s V-m regression model was lg（V） = 0.28 ＋ 1.34 × lg（m）（R = 0.85）.The K-value of the negative binomial distribution was 3.53.The aggressive intensity coefficient was significantly different at different altitudes（F = 5.77,P 0.01）;10.74 ± 0.83,23.67 ± 3.50,21.64 ± 6.02,47.10 ± 5.71,52.59 ± 12.75 and 13.72 ± 3.14 in rice fields at altitudes of 1 400 1 500 m,1 501-1 600 m,1 601-1 700 m,1 701-1 800 m,1 801-1 900 m and 1 901-2 000 m,respectively.The maximum aggressive intensity coefficient was in rice fields at altitudes of 1 701-1 800 and 1 801-1 900 m,and the minimum was in rice fields at altitudes of 1 400-1 500 and 1 901-2 000 m.Theoretical sampling equations were n = 1 905.43 x ＋ 34.57,n = 476x.36＋ 8.64,which gives the estimated sample size for different densities of nymphs with an accuracy of 0.1 and 0.2 respectively.According to the above equations,30,20 and 15 sampling units should be sampled when the density of the S.furcifera is assumed to be 5,10 and 20 individuals per sampling unit.These results provide a basis for the scientific sampling and control of this pest.