El-Borai F E, Brentu C F, Duncan L W
University of Florida, IFAS, Entomology and Nematology Department, Citrus Research and Education Center, 700 Experiment Station Road, Lake Alfred, FL 33850 Agricultural Research Center - Kade, University of Ghana, Accra, Ghana.
J Nematol. 2007 Jun;39(2):203-10.
Laboratory experiments were conducted to study non-target effects of augmenting entomopathogenic nematode (EPN)communities in soil. When raw soil from a citrus orchard was augmented with either 2,000 Steinernema riobrave or S. diaprepesi, fewer EPN (P </= 0.05) survived if the soil had also been treated with 2,000 S. riobrave 7 d earlier (i.e., two augmentation events rather than one). EPN survival was unaffected by treatment (P </= 0.05) in soil that was air-dried to disrupt antagonist activity prior to the experiment. When S. diaprepesi, S. riobrave, Heterorhabditis zealandica or no EPN were added to raw soil and S. diaprepesi was added 5 d later, the survival of both S. diaprepesi and of total EPN was greater (P </= 0.05) in soil that received no pretreatment than in soilpre treated with S. riobrave. Pretreatment of soil with H. zealandica or S. diaprepesi had less or no affect on survival of S. diaprepesi or total EPN. When nematodes were recovered from soil and placed on water agar, the number of S. diaprepesi that were killed by endoparasitic and trapping nematophagous fungi was greater (P </= 0.05) if soil was pretreated with steinernematid species than if the soil was not pretreated or was pretreated with H. zealandica. The adverse effects of pretreating soil on EPN survival were density dependent within a range of pretreatment dosages (20-100 IJ/cm(2) soil surface), and the treatment effects required more time to become evident at lower than at higher dosages. These experiments suggest that non-target effects of augmenting the EPN community in soil vary among EPN species and have the potential to temporarily reduce EPN numbers below the natural equilibrium density.
开展了实验室实验，以研究在土壤中增加昆虫病原线虫（EPN）群落的非靶标效应。当向来自柑橘园的原始土壤中添加2000条里奥勇敢斯氏线虫或迪亚普雷西斯斯氏线虫时，如果土壤在7天前也已用2000条里奥勇敢斯氏线虫处理过（即进行两次添加而非一次），则存活的EPN数量更少（P≤0.05）。在实验前进行风干以破坏拮抗活性的土壤中，EPN的存活不受处理的影响（P≤0.05）。当向原始土壤中添加迪亚普雷西斯斯氏线虫、里奥勇敢斯氏线虫、新西兰异小杆线虫或不添加EPN，并在5天后添加迪亚普雷西斯斯氏线虫时，未进行预处理的土壤中迪亚普雷西斯斯氏线虫和总EPN的存活率均高于用里奥勇敢斯氏线虫预处理过的土壤（P≤0.05）。用新西兰异小杆线虫或迪亚普雷西斯斯氏线虫对土壤进行预处理，对迪亚普雷西斯斯氏线虫或总EPN的存活影响较小或无影响。当从土壤中回收线虫并置于水琼脂上时，如果土壤用斯氏线虫属物种进行预处理，那么被内寄生和捕食线虫的真菌杀死的迪亚普雷西斯斯氏线虫数量会更多（P≤0.05），而未预处理或用新西兰异小杆线虫预处理的土壤则不然。在一定的预处理剂量范围（20 - 100 IJ/cm²土壤表面）内，土壤预处理对EPN存活的不利影响具有密度依赖性，且在较低剂量下比在较高剂量下需要更长时间才能显现出处理效果。这些实验表明，在土壤中增加EPN群落产生的非靶标效应因EPN物种而异，并且有可能使EPN数量暂时降至自然平衡密度以下。
