柑桔爆皮虫幼虫龄期的划分

近些年柑桔爆皮虫Agrilus auriventris Saunders在浙江部分柑桔产区暴发危害，幼虫龄数的确定是进一步研究其发生规律、生物学习性、预测预报以及制定综合防治技术的基础。本研究采用田间取样和室内孵化的方法收集柑桔爆皮虫各龄幼虫，测量了幼虫头部口上片最大宽度（Y1）、尾部钳状突最大宽度（Y2）、钳状突最大长度（Y3）、钳状突左侧侧缘最大长度（Y4）等4个形态特征。根据所测数据的频次分布图以及Dyar定律推测柑桔爆皮虫幼虫分为5龄。运用Crosby生长法则和线性回归的方法进行分析，发现口片最大宽度是幼虫分龄的最佳指标。1～5龄幼虫口上片宽度（mm）分别为0.1196±0.0013, 0.2008±0.0030, 0.3304±0.0041, 0.5150±0.0049, 0.7844±0.0040。口上片宽度和幼虫龄数的最佳线性回归方程为y=-0.0766+exp(-1.9883+(0.3675)×x)（R₂＝0.9876）。

Division of larval instars of the citrus borer, Agrilus auriventris Saunders( Coleoptera: Buprestidae)

The citrus borer, Agrilus auriventris Saunders, burst to attack citrus trees in recent years in some areas of Zhejiang Province, China. The larval instar numbers should be determined before further studying on its life history, biology and IMP. In this study, larval samples of different instars were collected from both the field and the laboratory, and four variables were measured, including the width of peristoma, the width of urogomphi, the length of urogomphi and the left lateral length of urogomphi. Based on frequency histograms and Dyar's law, the larvae of citrus borer were divided into 5 instars. Of the four variables measured, the width of peristoma provided the best division of instars. The average width of peristoma of the 1st instar larvae was 0.1196±0.0013 mm, the 2nd instar 0.2008±0.0030 mm, the 3rd instar 0.3304±0.0041 mm, the 4th instar 0.5150±0.0049 mm and the 5th instar 0.7844±0.0040 mm. The best linear regression equation of the width of peristoma against the instar numbers was: y=-0.0766+exp (-1.9883+(0.3675)×x)(R²＝0.9876）.