油茶织蛾幼虫龄期的初步研究

Preliminary study on the larval instar determination of Casmara patrona

为准确掌握油茶织蛾幼虫的龄期,对赣南油茶织蛾幼虫生长状况展开了调查,并测量其幼虫头壳宽度和体长,根据频次分布及Dyar定律推测油茶织蛾幼虫龄期,并运用Brooks指数、Crosby指数及曲线回归分析验证分龄的合理性。结果表明,油茶织蛾幼虫可分为6龄,幼虫的头宽和体长均随龄期呈指数增长,符合Dyar定律。其中,头宽是较为理想的划定虫龄的形态指标,1~6龄的头宽均值为0.744 1、1.237 8、1.849 4、2.494 8、3.161 7、4.036 3 mm;体长也可作为判断虫龄的重要辅助指标。在实践中,可利用头宽、体长测量值推断油茶织蛾幼虫龄期。

Casmara patrona Meyrick is an important boring pest on Camellia oleifera, and the determination of its larval instar is the basis for further study on the biological characteristics, prediction, and control of C. patrona. To accurately identify the instar of C. patrona larvae, we investigated the larval growth status of C. patrona in Gannan and measured the larval head capsule width and body length. According to the frequency distribution of the measured data and Dyar′s law,the instar of C. patrona larvae was speculated. The instar classification was verified by the Brooks index, Crosby index,and regression analysis. The results showed that the larvae of C. patrona could be classified into six instars. The head capsule width and body length of larvae increased exponentially with the instars, which followed Brooks-Dyar′s law. The average head capsule width of one to six instar was 0.744 1, 1.237 8, 1.849 4, 2.494 8, 3.161 7, and 4.036 3 mm and the body length can also be used as an important auxiliary index to judge the instar of insects. In practice, the measured values of head capsule width and body length can be used to infer the larval instar.