基于Crosby生长法则的蔗根土天牛幼虫龄期划分

Division of larval instars of Dorysthenes granulosus based on Crosby growth rule

【目的】探寻蔗根土天牛幼虫最佳分龄结构并判断幼虫的龄数,为研究蔗根土天牛的发生规律及生物学特性,制定防治技术等提供理论依据。【方法】通过田间取样和室内饲养孵化的方法收集蔗根土天牛幼虫,分别测量幼虫的头口宽和前胸背板宽,并采用Crosby生长法则和线性回归方法进行分析。【结果】频次分布图显示蔗根土天牛幼虫头口宽、前胸背板宽均有18个左右的分布区,其中以头口宽分布较为明显,头口宽的峰值分别为0.6、1.2、1.6、2.2、2.5、3.0、3.5、4.0、4.5、5.0、5.5、6.0、6.5、7.0、7.5、8.0、8.5和9.0mm。【结论】蔗根土天牛幼虫共分18龄,头口宽是判定蔗根土天牛幼虫虫龄的最佳指标。

[Objective ]This research aimed to explore the best division aging structure of larval instars and to deter- mine the age of larval instar in order to provide theoretical basis for studying the occurrence law and biological characteris- tics of Dorysthenes granulosus （Thomson） and developing population control techniques against Dorysthenes gcanulosus. [Method]Larva samples of different instars were both naturally collected from the field and artificially hatched from the laboratory; then the width of peristoma and protergum were measured and analyzed by the Crosby growth law and linear regression. [Result]Frequency histograms showed that the larva samples had 18 distribution areas in both the peristoma and protergum, in which the width of peristoma was more obvious than that of protergum; the peak width of peristoma were measured at 0.6, 1.2, 1.6, 2.2, 2.5, 3.0, 3.5, 4.0, 4.5, 5.0, 5.5, 6.0, 6.5, 7.0, 7.5, 8.0, 8.5, and 9.0 mm, re- spectively. [Conclusion ]The width of peristoma was the best scientific and reasonable parameter for determining the lar- val instars of D. granulosus that were divided into 18 instars.