球孢白僵菌对西花蓟马成虫的毒力及体表侵染的扫描电镜观察

本文在室内测定球孢白僵菌Beauveria bassiana CYT4菌株对西花蓟马Frankliniella occidentalis成虫的致死作用,并电镜观察分生孢子在西花蓟马成虫体表的侵染过程。结果表明：白僵菌的致死率随孢子浓度的增加而增加,1×109、1×108、1×107和1×106孢子.mL-1的孢悬液接种试虫第6d的致死率分别为83.57%、66.08%、49.78%和20.22%;0.04μL.mL-1和0.06μL.mL-1的多杀菌素与1×108孢子.mL-1白僵菌孢悬液混合后对试虫接种第5d的致死率分别为89.42%和95.76%,而单独施用菌液为58.19%,单独施用多杀菌素仅为45.55%和61.33%,表明二者混合能提高对西花蓟马成虫的致死率。扫描电镜观察发现,经白僵菌孢悬液处理的西花蓟马成虫虫体,在触角基节、复眼、足部褶皱区、刚毛窝、翅、产卵器和各体节连接处均有大量孢子附着和萌发,但腹部孢子量很少,尤其在节间膜处几乎无孢子;孢子在1h时即附着在体表,12h时已萌发,36h时有穿透体壁现象,48h后整个虫体被菌丝包被。

Virulence of Beauveria bassiana to Frankliniella occidentalis Adults and Scanning Electron Microscopic Observation on Its Infection Process

Virulence of Beauveria bassiana strain CYT4 to Frankliniella occidentalis adults was bioassayed in laboratory.Results showed that the higher concentration of conidia,the more mortality of F.occidentalis.At the dose of 1×109,1×108,1×107 and 1×106 conidia·mL-1,the mortality was 83.57%,66.08%,49.78% and 20.22% at 6 days after inoculation,respectively.When mixed spraying spinosad（0.04 μL·mL-1 and 0.06 μL·mL-1） and the suspension of B.bassiana（1×108 conidia·mL-1）,the mortality was increased to 89.42% and 95.76% at 5 days after inoculation,respectively.Mortality of insects treated by 1×108 conidia·mL-1 was 58.19%,while mortality with spinosad was merely 45.55% and 61.33%,indicating that spinosad can increase the efficiency of B.bassiana against F.occidentalis.F.occidentalis was observed during the fungal infection process by scanning electron microscope.Results showed that lots of conidia adhere to the coxopodite of antenna,compound eyes,folded regions on legs,setal alveolus,wings,ovipositor and the joints of each arthromere.While there were almost no conidia on the adults＇ abdomen,especially intersegmental membranes.The conidia could attach the cuticle of F.occidentalis at 1 h after treatment and germinated at about 12 h,then penetrated the insect cuticle after 36 h.Finally,the fungi could colonize the whole insect body at about 48 h.