长沙地区甘薯天蛾发生规律研究

On the Occurring Law of Herse convolvuli in Changsha District

为探明长沙地区甘薯天蛾的发生规律,于1999至2002年对其进行了室内饲养和室外调查.结果表明,甘薯天蛾在长沙地区每年发生4代,第一代卵始见期的物候学特征为牵牛花藤70～100cm长,第一代幼虫寄主集中为牵牛花,第2～4代幼虫寄主则包括牵牛花、甘薯和蕹菜等,越冬代虫源主要来自牵牛花.甘薯天蛾产卵选择性明显,喜在向阳、通风、寄主长势好的田块产卵,田间卵量逐代增加.寄生蜂对田间甘薯天蛾幼虫的自然寄生率高达79.2%～93.4%,天敌控制作用明显,现阶段甘薯天蛾在长沙地区难暴发成灾.

Results show that Herse convolvuli occurs 4 generations a year in th e area of Changsha. When the vine of morning glory reaches 70～100 cm, the 1st generation eggs of H.convolvuli can be obtained on the back of the le aves.The 1st generation larva mainly occurs on morning glory. The following gen erations are distributed on morning glory, sweet potatoes and water spinach, res pectively. Overwintering generation larva mainly comes from host plant morning g lory. H.convolvuli selects fields to lay eggs. The field exposed to th e sun and ventilated will be the better choice. The numbers of eggs increases ge ne ration by generation. The rate of parasitic bees on H.convolvuli can reach 7 9.2 %～93.4% and the effectiveness of the natural enemies' control is evident, so it is difficult to outbreak in the area of Changsha.