Cabanillas H E, Raulston J R
J Nematol. 1996 Mar;28(1):75-82.
Two entomopathogenic nematodes, Steinernema riobravis and Steinernema carpocapsae, were compared for their ability to parasitize corn earworm, Helicoverpa zea (Boddie) prepupae and pupae in corn plots at the Lower Rio Grande Valley of Texas. The most effective S. riobravis concentration was 200,000 infective juveniles (IJ)/m(2) (95% parasitism), as compared with 100,000 IJ/m(2) (81%), 50,000 IJ/m(2) (50%), 25,000 IJ/m(2) (31%), and the control (13%). No parasitism occurred in plots receiving S. carpoeapsae. The ineffectiveness of S. carpocapsae was attributed to high (>38 C) soil temperatures. Parasitism was higher when S. riobravis was applied at 200,000 IJ/m(2) through furrow irrigation (97%) or post-irrigation (95%) than when nematodes were sprayed onto the soil before irrigation (82%). Parasitism of corn earworm prepupae by S. riobravis persisted up to 36 days after application and was higher in the treated plots (80%) than the natural parasitism of the control plots (14%). These results show that at high field soil temperatures S. riobravis is more effective against corn earworm than S. carpocapsae.
在得克萨斯州下里奥格兰德河谷的玉米田中，对两种昆虫病原线虫——里奥布拉沃斯斯氏线虫（Steinernema riobravis）和小卷蛾斯氏线虫（Steinernema carpocapsae）寄生玉米穗虫（Helicoverpa zea (Boddie)）预蛹和蛹的能力进行了比较。里奥布拉沃斯斯氏线虫最有效的浓度为200,000条感染性幼虫（IJ）/平方米（寄生率95%），相比之下，100,000 IJ/平方米（寄生率81%）、50,000 IJ/平方米（寄生率50%）、25,000 IJ/平方米（寄生率31%）以及对照（寄生率13%）。接受小卷蛾斯氏线虫处理的地块未出现寄生现象。小卷蛾斯氏线虫无效的原因是土壤温度过高（>38℃）。通过沟灌（97%）或灌溉后（95%）施用200,000 IJ/平方米的里奥布拉沃斯斯氏线虫时，寄生率高于灌溉前将线虫喷洒到土壤上的情况（82%）。里奥布拉沃斯斯氏线虫对玉米穗虫预蛹的寄生作用在施用后持续长达36天，处理地块中的寄生率（80%）高于对照地块的自然寄生率（14%）。这些结果表明，在田间土壤温度较高时，里奥布拉沃斯斯氏线虫对玉米穗虫的防治效果优于小卷蛾斯氏线虫。
