黄羽摇蚊Chironomus flaviplumus Tokunaga 幼虫龄期的研究
Determination of larval instars of Chironomus flaviplumus Tokunaga (Chironomidae: Diptera)
朱利明** 温 虹 冯立辉 王丽卿 张瑞雷***
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DOI：10.7679/j.issn.2095-1353.2017.037
作者单位：上海海洋大学水产与生命学院，上海 201306
中文关键词：黄羽摇蚊，幼虫龄期，形态指标，Crosby生长法则，频次分析
英文关键词：Chironomus flaviplumus, the larval instar, the morphological metrics, Crosby growth rule, the frequency distribution analysis
中文摘要：
【目的】 探寻黄羽摇蚊Chironomus flaviplumus Tokunaga幼虫最佳分龄形态指标并判断其龄数，准确区分其幼虫龄期。【方法】 本文采用实验室内人工养殖定期取样观察的方法，分别测量了不同发育阶段摇蚊幼虫的头壳长、颏中齿顶端至冠突前缘间距离、头壳宽、颏宽、颏中齿宽、触角长、触角基节长、触角除基节以外2~5节长、上颚长、腹颏板长、腹颏板宽11项形态指标，运用Crosby生长法则、频次分析、回归方法分析对11项形态指标测量数据进行统计分析，选择判定幼虫龄数的最佳形态指标，推断其幼虫的龄数及龄期。【结果】 黄羽摇蚊幼虫可分为4个龄期，颏宽为最佳的分龄形态指标，1~4龄幼虫的颏宽（μm）分别为（30.9008±0.3253），（52.2114±0.7172），（98.6165±0.6146），（171.2985±0.5582）。幼虫颏宽（y）与龄期（x）的回归方程为y=0.1971x3+11.365x2－14.163x+33.502，R2=0.9827。另外，Y2（颏中齿顶端至冠突前缘间距离）、Y5（颏中齿宽）和Y9（上颚长）也可以作为分龄的辅助指标。选取颏宽对各龄期持续时间进行推测，得出1~4龄幼虫的龄期分别为2~3、2~4、5~6、7 d，幼虫期共为16~20 d。【结论】 黄羽摇蚊幼虫具有4个龄期，颏宽为最佳分龄形态指标，幼虫期共为16~20 d。
英文摘要：
[Objectives] To determine the larval instars of Chironomus flaviplumus Tokunaga. [Methods] Egg masses were artificially cultured in the lab and larvae sampled periodically for analysis. Eleven morphological metrics, including head capsule length, the length from the tip of the median teeth of the mentum to the leading coronoid, head capsule width, mentum width, the width of the median teeth of the mentum, antenna length, length of the basal antenna segment, the length of antenna segments 2-5, mandible length, and ventromental plate length and width, were measured. The optimal morphological metrics were chosen according to the Crosby growth rule, their frequency distribution and regression analysis. [Results] The larval stage of C. flaviplumus is comprised of 4 instars and mentum width is the best morphological metric for identifying these. The average mentum width (μm) of instars 1st-4th were (30.9008±0.3253), (52.2114±0.7172), (98.6165±0.6146), and (171.2985± 0.5582), respectively. The linear regression equation of the relationship between mentum width and instar number is y=0.1971x3+11.365x2-14.163x+33.502，R2=0.9827. The length from the tip of the median teeth of the mentum to the leading coronoid, the width of the median teeth of the mentum, and the length of the mandible, can be used as auxiliary morphological metrics for identifying instars. Estimated average stadia of instars 1st-4th based on mentum width were 2-3, 2-4, 5-6 d and 7 d, respectively. The overall duration of the larval period was 16-20 d. [Conclusion] The larval stage of C. flaviplumus is comprised of 4 instars and mentum width is the best morphological metric for identifying the larval instars of this species.