草地贪夜蛾的形态特征、发育历期和生活习性

Morphological characteristics,development stages and living habits of Spodoptera frugiperda

为明确草地贪夜蛾(Spodoptera frugiperda)的形态特征、各阶段生长发育历期和生活习性,将草地贪夜蛾卵放置在温度26℃、相对湿度40%、光周期16 L∶8 D的培养箱中进行室内饲养。以幼嫩的玉米叶片喂养幼虫,将成虫放置在室内的养虫笼中用5%蜂蜜水喂养,观察记录草地贪夜蛾的生长发育情况。结果表明:可以通过幼虫第8腹节背部的“正方形”状黑点毛瘤以及3龄至老熟幼虫头部的蜕裂线和背线形成的“Y”形纹等主要特征来识别草地贪夜蛾幼虫;可通过雄蛾灰褐色的前翅,并伴有明显的黄褐色环形纹、深褐色的肾形纹,且肾形纹上下有2块黄褐色的斑,左右有2处白斑,翅顶角处有白色粉状的鳞片等特征识别雄蛾。草地贪夜蛾平均45 d完成一个世代,其卵期、幼虫期、蛹期和成虫期分别平均为3、20、9和13 d,其中1~6龄幼虫和老熟幼虫分别历时2、2、3、3、3、5和2 d。成虫喜欢在傍晚和清晨活动,雌蛾大多聚集产卵于玉米叶片的正面,低龄幼虫有吐丝和聚集为害的习性,高龄幼虫有暴食和自相残杀的习性。

The morphological characteristics,development stages and living habits of Spodoptera frugiperda were clarified to provide theoretical basis for the identification,occurrence prediction of S.frugiperda.In this study,the eggs of S.frugiperda were reared indoors in an incubator at 26℃,40 % RH and 16 L ∶8D photoperiod,the larvae were feed with young corn leaves,and the imago were reared in the cage with 5% honey water.The growth and development of S.frugiperda were observed and recorded.The results showed that the larvae of S.frugiperda can be identified by the square black dots on the back of the eighth abdominal segment of the larvae,and the Y-shaped pattern formed in the head of the third to mature larvae.The male moths can be identified by their grayish-brown forewings with distinctive yellowish-brown annular stripes,dark brown kidney-shaped stripes with two yellowish-brown spots above and below the kidney-shaped stripes,two white spots on the left and right,and white powdery scales at the top corners of the wings.S.frugiperda complete one generation in 45days on average,with the egg,larval,pupal and adult stages lasting 3,20,9 and 13 days,respectively,with the first to sixth instar larvae and old mature larvae lasting 2,2,3,3,3,3,5 and 2 days,respectively.Adult moths prefer to be active in the evening and early morning.Most female moths oviposit on the front side of corn leaves.Younger larvae tend to make silk and gather,while older larvae tend to overeat and practice cannibalism.