荒漠景观下柠条豆象的空间分布及其对景观斑块格局的反应

柠条豆象Kytorhinus immixtus Motschulsky是危害柠条种子的主要种实害虫之一。本文应用了多个聚集度指标和回归分析方法,研究探讨了柠条豆象卵、幼虫在宁夏盐池、灵武、银川等荒漠景观中11个生境斑块中的空间分布型及种群对景观斑块格局的反应情况。结果表明:在11个景观样地中,柠条豆象卵和幼虫在各种生境斑块中均呈聚集型的负二项分布;卵和幼虫空间分布的Iwao回归方程分别为m*=2.23695+1.64742m(r=0.8273)和m*=2.24418+1.42084m(r=0.8889)、Taylor幂模型分别为logS2=0.51292+1.41118logm(r=0.9344)和logS2=0.59645+1.14736logm(r=0.9786),种群分布的基本成分为个体群,个体间相互吸引,有密度依赖性,聚集主要由环境因素和种间竞争引起的,聚集强度随种群密度的升高而增加。在荒漠景观下,柠条豆象的种群发生与寄主植物的种类、在斑块内的分布格局有着密切的关系,与斑块面积相关性较低(R2=0.1995)。主成分分析显示柠条林生长的土壤类型、生长方式是影响柠条豆象寄生的主要因素。

The spatial pattern of Kytorhinus immixtus and its response to desert landscape pattern in Ningxia

Kytorhinus immixtus Motschuleky is a seed pest of Caragana.Using some aggregation indices,and the Iwao and Taylor regression analysis methods,the spatial distribution patterns of egg and larvae,and the damage ratio of K.immixtus in 11 desert landscape patches in Ningxia,were surveyed and analyzed.The results show that the spatial distribution K.immixtus was aggregated and approximated a negative binomial distribution.The Iwao model of egg and larvae of K.immixtus were m＊ = 2.23695 ＋ 1.64742m（r = 0.8273） and m＊ = 2.24418 ＋ 1.42084m（r = 0.8889）,and the Taylor’s power model of egg and larvae of K.immixtus were logS2 = 0.51292 ＋ 1.41118 logm（r = 0.9344） and logS2 = 0.59645 ＋ 1.14736 logm（r = 0.9786）.The basic component of distribution was individual population.Analysis based on estimation of the mean aggregation（λ） suggests that this aggregation landscape pattern and interspecific competition.The aggregation intensity increased with density of population.The regression analysis showed that it is not significantly a correlation between patch area and damage ration of K.immixtus（R2 = 0.1995） in desert landscape.A principal components analysis showed that the soil type,and survival of Caragana were major factors affecting the damage ration of K.immixtus.