降香黄檀食叶害虫棕斑澳黄毒蛾的生物学特性及幼虫虫龄判断

【目的】棕斑澳黄毒蛾Orvasca subnotata Walker是于降香黄檀Dalbergia odorifera T. Chen人工林中新发现的一种食叶害虫，其生物学特性描述和龄期判定是虫害预测预报与林间防治的重要依据。【方法】本研究通过定期林间采样的方法，对棕斑澳黄毒蛾不同发育阶段的形态特征及生活史和生活习性进行调查; 并通过测量头宽、前胸毛瘤宽和体长3项分龄指标，测定棕斑澳黄毒蛾幼虫的龄期。【结果】本文报道了棕斑澳黄毒蛾不同发育阶段的形态特征、生活史和生活习性。研究结果表明，棕斑澳黄毒蛾幼虫随龄期增长，前胸逐渐变黑，腹部背线和翻缩腺颜色逐渐加深，特征逐渐变得明显。通过频次分析统计，测得棕斑澳黄毒蛾幼虫龄数为5龄。头宽和前胸毛瘤宽可作为分龄指标，头宽优于前胸毛瘤宽，且前胸毛瘤宽与头宽呈直线关系（y=0.994x-0.114，R=0.999）。体长经统计检验，符合Dyar氏法则，但区域重叠明显，不宜作为分龄指标。【结论】本研究确定了棕斑澳黄毒蛾的生物学特性及幼虫虫龄，可为林间防治提供参考依据。

Biological characteristics and larval instar determination of Orvasca subnotata (Lepidoptera: Lymantriida), a defoliator of Dalbergia odorifera (Leguminosae)

【Aim】 The moth Orvasca subnotata Walker (Lepidopetra: Lymantriidae) is a severe defoliator of Dalbergia odorifera T. Chen found in man made forests, and its biological characteristics and the determination of its larval instars are the important basis for the pest forecast and control in the forest. 【Methods】 The morphological characteristics, the habit of each developmental stage and the life history of O. subnotata were investigated though regular field sampling. Through regular forest sampling and morphological characterization, three indicators of larval instar features including the head capsule width, prothoracic verruca width and body length were recorded and analyzed. 【Results】 We described the biological characteristics of O. subnotata with an emphasis on its developmental features. Our results showed that as the larvae grow, the prothorax gradually darkens, and the abdominal back line and poison gland color gradually deepen. Statistical analysis of the body measurements showed that both the head capsule width and prothoracic verruca width could be used as indicators of developmental stages with head capsule width being superior to prothoracic verruca width, and the prothoracic verruca width and head capsule width were significantly correlated (y=0.994 x-0.114, R=0.999). The body length distribution fits the Dyar’s law. However, due to the overlap distribution among developmental stages, body length is not a reliable indicator of larval instar determination. 【Conclusion】 The results will help the identification of O. subnotata in the field and provide some crucial information for developing control and prevention strategies.