柑橘粉虱与主要捕食性天敌之间的空间关系研究

Analysis of spatial relations of Dialeurodes citri and its principal natural enemies

  • 摘要: 聚集强度指数用来判别天敌和害虫的空间分布及其关系,但抽样样方的大小影响聚集强度指数的大小。为了分析在不同大小聚块条件下, 天敌对柑橘粉虱空间上跟随关系的密切程度、聚集原因和聚集范围, 为评价柑橘粉虱的天敌优势种提供科学依据, 用聚块样方方差分析法、灰色关联度分析法、空间聚集强度指数法、种群聚集均数法和ρ指数法对安徽省潜山县茶园不同大小聚块条件下的柑橘粉虱及其11种主要天敌中的6种天敌进行分析。柑橘粉虱与其6种天敌的关联度分析结果表明, 与柑橘粉虱空间上跟随关系密切的天敌是草间小黑蛛(0.848 6)、八点球腹蛛(0.840 6)和龟纹瓢虫(0.805 5), 与柑橘粉虱空间上跟随关系较不密切的天敌是红点唇瓢虫(0.764 2)。在聚块内包含有1、2、4、8个基本样方时, 随着聚块内基本样方数的增多, 聚集分布格局的扩散系数不断增大, 均匀和随机格局的扩散系数C值不断减小。聚块基本样方数为2、4、6、8、16和32时与为1时之间的柑橘粉虱及其天敌的空间分布聚集程度差异均不显著。柑橘粉虱的种群聚集均数λ多数大于2, 其聚集是本身原因引起的; 天敌和柑橘粉虱在种群聚集均数为正值时, 随着聚块中基本样方数的增加, 种群聚集均数不断增大。用柑橘粉虱不同大小聚块的ρ指数判断个体群聚集时的最小范围是聚块中有1个基本样方, 即本文的1.7 m2, 为该虫抽样时确定样方大小提供科学依据。

     

    Abstract: Although somehow influenced by sampling size, the aggregated intensity index was used to assess the spatial distribution of pests and their natural enemies and eventually used to determine the relationship between pests and their natural enemies. To analysis the degree of closeness of the spatial relations of natural enemies to Dialeurodes citri and the cause-range aggregation, the block-quadrat variance analysis, grey correlaiton analysis, aggregated intensity index analysis, aggregated population mean analysis and the ρ index analysis were used to study D. citri and 6 of its dominant natural enemies from a total of 11 species of natural enemies under different poly block sizes (namely, different basic quadrats numbers in a poly block) in tea gardens in Qianshan Area, Anhui Province. The study may provide scientific basis for determining the dominant natural enemy species of D. citri. The grey correlation degree analysis showed that the most closely followed natural enemies of D. citri were Erigonidium graminicolum (0.848 6), Theridion octomaculatum (0.840 6) and Propylaea japonica (0.805 5). However, the spatial following relation of Chilocorus kuwanae (0.764 2) with D. citri was not so close. The synthetic block-quadrat variance and aggregate intensity analysis results suggested that by increasing basic quadrat number within the poly block from 1 to 8, the diffusion coefficient C of aggregation pattern increased, while the diffusion coefficient C of uniform and random aggregation patterns decreased. In addition, the aggregation degree of spatial distribution of D. citri and its natural enemies had no significant difference between basic quadrat number 1 and basic quadrat number 2, 4, 8, 16 and 32. The average λ of D. citri was higher than 2, suggesting self-aggregation of D. citri. When average λ was positive, the gathering average of population steadily increased with increasing basic quadrat number within the poly block. The ρ index analysis suggested that the minimum area of aggregation pattern of D. citri was one basic quadrat of 1.7 m2. Put together, the results provided a critical basis for further protection of natural enemies and determination of suitable quadrat sizes of pest sampling.

     

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