棉铃虫微孢子虫病的田间发生调查及其致病力测定

The Occurrence of Microsporidiosis (Nosema sp.) Infecting Helicoverpa armigera in Field and Its Pathogenicity

1998-2003年对棉铃虫的微孢子虫病的发生情况进行了调查,2000年田间棉铃虫为中重发生,微孢子虫病呈现发生流行的趋势,第4代幼虫感染率达到49.0%,2001年之后,微孢子虫的感染率逐渐减少。该微孢子虫只感染棉铃虫、甜菜夜蛾和菜青虫,不感染粘虫、玉米螟和家蚕。室内生测结果表明,该微孢子虫对棉铃虫具有较高的致病力,107孢子/mL的浓度接种2龄棉铃虫幼虫,16 d死亡率达到100%,接种3龄棉铃虫,16 d死亡率为87.8%,可以达到控制当代种群和压低下代种群的目的;105~106孢子/mL的浓度接种2龄棉铃虫幼虫,当代羽化率为32.2%,13.3%,下一代幼虫死亡率为88.9%,100%,可以控制下一代种群。

The occurrence of microsporidiosis（Nosema sp.） infecting Helicoverpa armigera was investigated in the field.In 2000,Helicoverpa armigera occurred servious,and microsporidiosis showed epidemic trend in its population.The infection rate of the 4th generation larvae was 49.0%.After 2001,the infection rate decreased gradually.The microsporidian could infect H.armigera,Pieris rapae and Spodoptera exigua and couldn′t infect Lencania separata,Ostrinia furnacalis and Bombyx mori.The pathogenicity had strong to Helicoverpa armigera.The microporidian with the concentration of 107 spores/mL could control previous generation population and keep down next generation population.The mortality of the 2nd instar larvae was 100% at 16 d after inoculation.The mortality of the 3rd instar larvae was 87.8% at 16 d after inoculation.When the microporidian with the concentration of 105 and 106 spores/mL inoculated the 2nd instars larvae,the eclosion rates were 32.2% and 13.3%,the mortalities of next generation larvae was 88.9% and 100%.The microporidian was useful to control the next generation population of H.armigera.