Determination of the larval instars of Trabala vishnou gigantina Yang (Lepidoptera: Lasiocampidae)

Author of the article:LIU Yong-Hua1, 2** ZHANG Yi-Qiao3 YAN Xiong-Fei2 ZHENG Yong-Gui4 LU Peng-Fei1 ZONG Shi-Xiang1 LUO You-Qing1***

Author's Workplace：1. Key Laboratory for Silviculture and Conservation of Ministry of Education, Beijing Forestry University, Beijing 100083, China;2. College of Life Sciences, College of Yulin, Yulin 719000, China; 3. Station of Afforestation Mangement and Direction of Shanghai, Shanghai 200020, China; 4. Station of Forestry of Wuqi County in Shannxi, Wuqi 717600, China

Key Words：Trabala vishnou gigantina, larva, morphological characters, instar number, Crosby index, Brooks index

Abstract：    [Objectives]  To determine the development of Trabala vishnou gigantina Yang larva, and thereby provide a foundation for the forecasting and scientific management of this pest．[Methods]  The number of larval instars was determined using coefficient of variation and Crosby ratio through field sampling, during which larvae at different developmental stages were collected and six morphological variables，including head capsule width，body length，body width, were measured. [Results]  The larval stage was comprised of seven instars and head capsule width was the best diagnostic feature for identifying larval stage．Three other variables; distance between simple eyes, cranial width and mandible width, could also be used to identify of larval instars, but body length and body width were too variable to reliably identify instars. [Conclusion]  These findings provide valuable information for the rational control of T. v. gigantina．