新蚜虫疠霉感染致病蚜虫的空间分布特征及其理论抽样技术

[目的]探明新蚜虫疠霉的空间分布特点,为进一步研究蚜虫新蚜虫疠霉病害流行规律及田间释放病原菌防治桃蚜提供依据.[方法]调查甘蓝田新蚜虫疠霉感染致病桃蚜密度,采用Taylor幂法与Iwao回归法分析新蚜虫疠霉的空间分布特征.[结果]新蚜虫疠霉在甘蓝田呈聚集分布中的负二项分布,公共K值为2.87.Iwao直线回归方程拟合式为(m*)=0.12+1.36 m(R=0.99),Taylor幂公式为lg(v)=0.35+1.69 lgm (R=0.96).在不同季节,其空间分布的拥挤度差异显著(F=5.34,p＜0.01),7-9月平均拥挤度最高,而1-3月和10-12月最低.精度分别为0.1、0.2、0.3和0.5时的理论抽样数公式分别为n=430.26/x+138.30、n=107.56/x+34.57、n=47.81/x+15.37和n=17.21/x+5.53.当被新蚜虫疠霉感染罹病桃蚜密度较低,即低于每样方5头时,以模型n=17.21/x+5.53较为适宜,在较高密度,即每样方10头/株以上时,以模型n=107.56/x+34.57较宜.[结论]新蚜虫疠霉在甘蓝田均呈聚集分布中的负二项分布,聚集原因是新蚜虫疠霉生物学特性和环境因素.在6-8月,对该菌侵染蚜虫的总体理论抽样以抽查20株左右样方为宜,而在其他季节,抽查30株左右样方为宜.

Spatial distribution patterns and theoretical sampling of aphids infected by Pandora neoaphidis

[Objective] The spatial distribution and theoretical sampling techniques for Myzus persicae(Sulzer) infected by Pandora neoaphidis(Remaudière & Hennebert) Humber on cabbages were investigated to provide a basis for further study on the epizootics of P.neoaphidis and the fungal release for the biocontrol of M.persicae.[Methods] The study was conducted in cabbage field in Kunming,Yunnan,using the dispersal indices and Iwao regression method.[Results] The spatial distribution pattern of M.persicae infected by P.neoaphidis belonged to negative binomial spatial pattern,and the spatial pattern was caused by the biology of M.persicae and environmental factors.Iwao’s regressive relation by m*-m was m*=0.12+1.36 m(R=0.99),and Taylor’s regressive relation by v-m was lg(v)=0.35+1.69 lg m(R=0.96).The K-value of the negative binomial distribution was 2.87.The maximum aggressive intensity coefficient appeared during the period from July to September,and the minimum aggressive intensity coefficient during the period from January to March.Theoretical sampling equations for the sampling number were as follows: n=430.26/x+138.30,n=107.56/x+34.57,n=47.81/x+15.37,n=17.21/x+5.53,with the accuracy of 0.1,0.2,0.3,0.5,respectively,where n was the sample number of infected aphids.[Conclusion] The model n=17.21/x+5.53 was better for the sampling when the density of infected aphid was lower than 5 aphids/plant,and n=47.81/x+15.37 for the density of infected aphids more than 10 aphids/ plant.According to the occurrence of P.neoaphidis in the vegetable fields,20 units will be better during the period from June to August,and 30 units in other seasons throughout a year.