Differences in the virulence of Heterorhabditis bacteriophora and Steinernema scarabaei to three white grub species:: The relative contribution of the nematodes and their symbiotic bacteria
Differences in the virulence of Heterorhabditis bacteriophora and Steinernema scarabaei to three white grub species:: The relative contribution of the nematodes and their symbiotic bacteria
复制标题
DOI：
10.1016/j.biocontrol.2007.07.004
复制
发表时间：
2007-12-01
影响因子：
4.2
通讯作者：
Grewal, Parwinder S.
中科院分区：
文献类型：
--
作者：
An, Ruisheng;Grewal, Parwinder S.
由于不同种类的白蛴螬对昆虫病原线虫的敏感性不同，本研究比较了白蛴螬的共生细菌温度光habdus和光habdus koppenhoeferi对日本芽孢菊（Popillia japonica）、马氏根霉（Rhizotrogus majalis）和北方环蝇（cycyloephala borealis）的毒力。即使在2个细胞/蛴螬时，这两种细菌对所有三种蛴螬都具有致病性。然而，注射后48 h的中位致死量和20个细胞/蛴螬的中位致死时间表明，温度假单胞菌对北方白僵菌的毒力强于柯氏X虫。尽管嗜菌嗜血杆菌对麻家蚕和日本血吸虫的致病性低于圣甲虫嗜血杆菌，但它们的共生细菌对这两种蛴螬的毒力没有差异，而且它们在体外和20℃下的麻家蚕幼虫中也表现出相似的生长模式。我们随后测试了口服和腹腔内引入的嗜菌嗜血杆菌对麻家蚕的致病性，以确定线虫是否能够成功地将细菌传播到血淋巴中。注射的血凝剂对嗜杆菌H. majalis具有致病性，表明细菌释放成功，而口服引入的嗜杆菌H. majalis则没有。对蛴螬的解剖证实，口服引入的嗜杆菌不能通过肠壁渗透到血淋巴中。我们得出结论，马氏弓形虫对嗜菌杆菌的低敏感性不是由于共生细菌，而是由于线虫穿透肠壁和角质层的能力较差，无法将细菌传播到血淋巴。(c) 2007爱思唯尔公司版权所有。
Because susceptibility of white grub species to entomopathogenic nematodes differs, we compared the virulence of Photorhabdus temperata and Xenorhabdus koppenhoeferi, the symbiotic bacteria of the nematodes Heterorhabditis bacteriophora and Steinernerna scarabaei, respectively, to the three white grub species, Popillia japonica, Rhizotrogus majalis, and Cyclocephala borealis. Both bacteria were pathogenic to all three grub species even at 2 cells/grub. However, the median lethal dose at 48 h post injection and median lethal time at 20 cells/grub showed that P. temperata was More virulent than X koppenhoeferi to C borealis. Although H. bacteriophora is less pathogenic than S. scarabaei to R. majalis and P. japonica, their symbiotic bacteria did not differ in virulence against these two grub species, and they also showed similar growth patterns both in vitro and inside R. majalis larvae at 20 degrees C. We then tested the pathogenicity of oral- and intrahernocoel-introduced H. bacteriophora to R. majalis to determine whether nematodes are able to successfully vector the bacteria into the hemolymph. Hemocoel injected H. bacteriophora was pathogenic to R. majalis indicating successful bacterial release, but orally introduced H. bacteriophora were not. Dissection of grubs confirmed that the orally introduced H. bacteriophora were unable to penetrate into the hemolymph through the gut wall. We conclude that the low susceptibility of R. majalis to H. bacteriophora is not due to the symbiotic bacteria but rather to the nematode's poor ability to penetrate through the gut wall and the cuticle to vector the bacteria into the hemolymph. (c) 2007 Elsevier Inc. All rights reserved.