人工饲养背摇蚊幼虫龄数和龄期的测定

本文采用了人工饲养定期取样的方法,测定了背摇蚊Chironomus dorsalis(Anderson)幼虫的龄数以及各龄的龄期。分别测量不同发育阶段幼虫的头壳长、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、触角比(触角基节与其余各节的长度之比)等8项指标,以期得到区分和判定幼虫虫龄的最佳形态特征及指标。运用频次分布、均差分析和回归分析对8项指标测量数据进行统计分析,结果表明,背摇蚊幼虫可分4龄,触角长可作为理想的分龄特征和分龄指标,其次是颏中齿顶端至冠突前缘间距离和颏宽。利用种群众数龄期法计算1-4龄幼虫的平均龄期分别为1.32 d、2.00 d、7.51 d和8.39 d,幼虫期共为19.22 d。

Measurement of larval instars and stadia artificially reared Chironomus dorsalis (Diptera: Chiromomidae)

In this study, the number of larval instars and stadia of each instar of the Chironomus dorsalis (Diptera: Chiromomidae) were determined by artificial rearing and sampling periodically. The head capsule length, length between top of the median teeth of mentum and leading coronoid, head capsule width, mentum width, median teeth width of mentum, antenna length, antennal basipodite length, antennal ratio (the ratio between antennal basipodite length and the length of rest sections) were analyzed using microscopic measurement and combination of statistical methods for choosing the optimal morphological characterristics or index for the distinguishment of larval instars. According to the frequency distribution, deviation analysis and regression analysis, the results showed that the larvae of C. dorsalis have 4 instars. In addition, the antenna length can be the best characteristic and variable for the distinguishment of larval instars, and the two variables including mentum width and the length between top of the median teeth of mentum and leading coronoid also can be the reliable morphological characterristics or indexs. The average stadia of 1-4 based on the method of median population were 1.32 d, 2.00 d, 7.51 d and 8.39 d, respectively. The total larval stage duration was 19.22 d.