椰子木蛾幼虫龄期的划分

椰子木蛾是为害棕榈科植物的重要危险性林业有害生物,2013年8月首次在我国海南发现,对我国椰子及棕榈产业造成严重的潜在威胁。龄期划分是深入研究椰子木蛾发生规律、生物学习性、预测预报以及防治适期的基础。头壳宽度可作为幼虫分龄的准确指标。本文通过林间收集椰子木蛾幼虫头壳和实验室饲养椰子木蛾并收集头壳的方法,通过测量与比较,运用频次分布与线性回归等,对椰子木蛾的龄期划分进行了研究,并依据Dyar法则和Crosby生长法则对划分结果进行了验证,确定其在林间和在实验室饲养条件下的龄数分别为5龄和5~8龄。室内饲养与室外相比,龄数增加,其原因可能是室内的环境条件如温度、湿度、光周期、食物营养等以及椰子木蛾自身遗传、种群密度等不同,室内环境条件不利而引起其龄期数增加。

Division of larval instars of the coconut black-headed caterpillar, Opisina arenosella

The coconut black-headed caterpillar Opisina arenosella Walker (Lepidoptera: Oceophoridae) is an important risky forest pest that infests many kinds of palm trees. It was first discovered in Hainan, China in August, 2013 and may bring great potential threats to the coconut and other palm plant production. The division of the larval instars is the foundation for deep research on the coconut black-headed caterpillar on the occurrence, biological characteristics, forecast and determination of the optimum control period. The capsule width is an accurate index that can be used to divide the larval instars. This study was conducted to determine the larval instars of the coconut black-headed caterpillar collected from the field and laboratory by the head-capsules. The head-capsule widths obtained from the experiment were then analyzed using the frequency distribution and the linear regression. The Dyar rule and the Crosby rule were used to validate the rationality of the division. The results showed that the caterpillar could be divided into 5 instars in the field and 5-8 instars under laboratory conditions. Compared with the results in the field, the instars increased in the laboratory. The reason is probably that the environmental conditions in the laboratory, such as temperature, moisture, photoperiod, food population density, and heredity, were different from those in the field, and the conditions in the laboratory were not good enough to maintain the development of the instars.