昆虫病原真菌粉虱座壳孢对烟粉虱侵染行为的初步研究

粉虱座壳孢(Aschersonia aleyrodis)是粉虱的重要病原真菌,可用于世界性害虫烟粉虱(Bemisia tabaci)的生物防治。本文通过生物测定的方法,发现1-3龄幼虫易受真菌侵染,其中以2龄幼虫的侵染率为最高,达到98%;侵染率随处理时间延长、接种浓度增加而增大;被侵染粉虱幼虫死亡通常发生在处理后的下一个龄期。本文还应用扫描电镜和光学显微镜对粉虱座壳孢侵染烟粉虱的过程进行了研究,分生孢子在昆虫体表萌发、形成芽管后可产生附着胞或直接侵入表皮,昆虫节间膜等薄弱处是其侵染的主要部位,随后菌丝在昆虫体内形成,着胞或直接侵入表皮,昆虫节间膜等薄弱处是其侵染的主要部位如湿度足够高,菌丝穿出体表产孢再侵染新害虫。

INFECTION BEHAVIOR OF ENTOMOPATHOGENIC FUNGUS ASCHERSONIA ALEYRODIS ON BEMISIA TABACI

Aschersonia aleyrodis is an important insect pathogen, which can be used as biocontrol agent against worldwide sweetpotato whitefly, Bemisia tabaci. Investigation of infection characteristic of the fungus revealed that first to third instar nymphs were most susceptible and the infection rate of second instar nymphs could reach 98%. Infection rate increased with prolongation of treatment duration or increase in concentration of conidia. Infected whitefly nymphs usually died in the following stage after treatments. Scanning electron microscopy and light microscopy were employed to investigate the infection process of A. aleyrodis on the pest. The germ tube of conidia might penetrate directly into the cuticle or by means of an appressorium, with preference of intersegmental membranes as the site of infection,and mycelial production then followed. Mycelia protruded from margins of cadavers and the conidia could infect other new members if humidity was high enough.