二化螟在茭白上的钻蛀行为及其防治方法

研究了二化螟在茭白植株上的转移、钻蛀和产卵行为以及取食选择性,并根据其行为特性,制订合理的药剂喷施方法.结果表明,二化螟90%以上的卵产在茭白的叶片上,其余部分产在叶鞘上.产卵的主要叶位是心叶、倒一叶和倒二叶.超过50%的卵块集中在叶片距叶枕0～60cm的部位.幼虫孵化后,蚁螟蛀入的部位一般在叶枕以下的叶鞘内侧,多集中于倒四、倒五叶鞘.2龄后开始钻蛀内侧叶鞘,并蛀入茭白茎的内芯,二化螟幼虫在茭白植株上通常从叶片转移到叶鞘进行钻蛀危害.幼虫嗜食茭白茎部,其次为茭白果肉和叶鞘,对叶片几乎不取食.使用叶鞘喷施杀虫可达到对茭白进行全株喷雾同样的防治效果,并可节省40%～50%的用药量,经济和生态效益十分明显.

The boring behavior and its control strategy of stripped stem borer on water oat,Zizania caduciflora

This paper dealt with the behavior characteristics of striped stem borer(SSB),Chilo suppressalis Walker,on Zizania caduciflora,including its oviposition,boring,movement and feeding preference among the various organs of the host plant.Then the spraying methods were modified in terms of the boring behavior of SSB for higher control effectiveness.The preference tests showed that the SSB female adults laid more than 90% of eggs on the leaves,while most of the eggs were distributed on the young leaves,such as the 1st and the 2nd leaves.Over 50% eggs were laid on leaves between 0-60 cm from the leave node.After being hatched,the low-instar larvae bored into the inside-face of sheath of the 4th and 5th leaves.When grow up to the 2nd instar,the larvae began to bore into the inside sheath,the stem base and fruits.The observation revealed that the SSB larvae hatched on leaves usually move from leaves to sheath or fruits for feeding,but rarely the larvae disperse between host plant hills.In the feeding preference test,the larvae preferred the stem to the fruit and the sheath.The field tests demonstrated that spraying plant sheath only could obtain the same control effectiveness as compared to the conventional spraying for whole plants,and about 40% to 50% of insecticides and labor were saved after the spraying method was modified.