美国白蛾幼虫头壳发育规律及其影响因素*
Development of the head capsule of Hyphantria cunea larvae
龙 丹1, 2** 刘 乐1** 魏一彤1 党英侨1 宋学雨1, 3 王小艺1***
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DOI：10.7679/j.issn.20951353.2026.114
作者单位：1. 中国林业科学研究院森林生态环境与自然保护研究所，北京 100091； 2. 中国林业科学研究院，北京 100091；3. 安徽省林业科学研究院，合肥 230031
中文关键词：Dyar氏定律；头壳宽度；温度；光周期；饥饿胁迫；寄主植物
英文关键词：Dyar’s law; head capsule width; temperature; photoperiod; starvation stress; host plant
中文摘要：【目的】 本研究通过测定美国白蛾Hyphantria cunea幼虫头壳宽度增长规律，并探究其在不同环境条件下的发育差异，旨在明确头壳宽度作为美国白蛾幼虫龄期划分指标的适用性和稳定性。【方法】 室内条件下，观测美国白蛾幼虫头壳宽度随发育时间和龄期的变化规律，同时记录在不同食料、取食量、温度以及光周期条件下，幼虫头壳发育差异情况。【结果】 随着日龄的增加，美国白蛾幼虫头壳宽度呈现出典型的指数函数增长趋势（R2 = 0.961 2）。不同龄期幼虫的头壳宽度差异显著（P < 0.001），回归分析表明，幼虫龄数与头壳宽度之间呈指数相关关系（R2 = 0.995 3），说明头壳宽度可作为美国白蛾幼虫分龄的可靠指标。取食不同食料对美国白蛾3-6龄幼虫头壳宽度有显著影响（P < 0.05）。取食量总体上对幼虫头壳宽度发育影响不显著（P > 0.05）。温度对2龄及以上幼虫的头壳宽度影响较大，20 ℃条件下，幼虫的头壳宽度显著小于其他高温条件（P < 0.05）。除4龄和6龄幼虫外，在长日照条件下发育的幼虫头壳宽度均显著大于短日照条件（P < 0.05）。【结论】 美国白蛾幼虫头壳宽度适于作为分龄指标，但食料、温度和光周期等因子在一定程度上影响幼虫的头壳发育，在野外应用Dyar氏定律进行幼虫分龄时，应采集相同生长环境下的美国白蛾幼虫，以保证害虫种群头壳发育情况一致。
英文摘要：[Aim] To clarify the applicability and stability of head capsule width (HCW) as a parameter for instar identification in Hyphantria cunea. [Methods] Growth patterns of larval HCW were measured and the effects of various environmental conditions on HCW development were investigated. Temporal and instar-specific changes in HCW were observed under controlled laboratory conditions. In addition, differences for head capsule development under various diet type, food consumption, temperature, and photoperiod were also recorded. [Results] With increasing age in days, the HCW of H. cunea larvae had a typical exponential growth trend (R2 = 0.961 2). Validation using Crosby’s growth rule and linear regression analysis confirmed significant differences in HCW between successive instars (P < 0.001). An exponential relationship was observed between instar number and HCW (R2 = 0.995 3), confirming its validity as a parameter for instar determination. Diet type significantly affected the HCW of 3rd to 6th instar larvae (P < 0.05), whereas food consumption had no significant effect. Temperature significantly influenced HCW from the 2nd instar onward; notably, HCW at 20 ℃ was significantly narrower than at higher temperatures (P < 0.05). With the exception of the 4th and 6th instars, larvae reared under long-day conditions possessed significantly wider HCW than those reared under short-day conditions (P < 0.05). [Conclusion] HCW is a suitable parameter for instar identification in H. cunea. However, environmental factors such as diet, temperature, and photoperiod influence head capsule development to varying degrees. Therefore, when applying Dyar’s Law for instar determination in the field, larvae should be sampled from the same environmental conditions to ensure accurate instar identification.