Duncan L W, Dunn D G, McCoy C W
J Nematol. 1996 Jun;28(2):252-8.
i) measure the effects of soil moisture on survival of Steinernema riobravis and ii) investigate the suitability of using microcosms to study motility and survival of these nematodes. Nematodes recovered from soil contained in petri dishes declined by more than 95% during 7 days, whereas nematodes recovered from the inner surfaces of dishes increased 35-fold. After 7 days in dishes, >20 times as many nematodes were recovered from dish surfaces than from soil. Nematodes exhibited a negative geotropism; greater numbers of nematodes were recovered from the lid surfaces than from the surfaces of dishes. Survivorship of nematodes in soil in plastic centrifuge tubes was somewhat greater than in petri dishes, and fewer nematodes ascended above the soil line in tubes than dishes. Downward migration of nematodes was inversely related to soil column diameter, possibly due to relatively unimpeded movement along container surfaces. An assay was developed by which nematodes were rinsed from the inner surfaces of centrifuge tubes into the soil. The resulting slurry was then processed on Baermann trays to recover motile nematodes. Nematode survival in soil in centrifuge tubes was higher at soil moistures between 2-4% than at lower (0.5-1.0%) and higher (4.0-12.0%) moisture levels. Survival of S. riobravis may be enhanced by quiescence induced by moisture deficits.
i）测量土壤湿度对里奥布拉夫斯斯氏线虫存活的影响，以及ii）研究使用微观模型来研究这些线虫的运动性和存活情况的适用性。从培养皿中的土壤中回收的线虫在7天内下降了95%以上，而从培养皿内表面回收的线虫增加了35倍。在培养皿中放置7天后，从培养皿表面回收的线虫数量是从土壤中回收的20倍以上。线虫表现出负向地性；从盖子表面回收的线虫数量多于从培养皿表面回收的线虫数量。线虫在塑料离心管土壤中的存活率略高于在培养皿中的存活率，并且在管中上升到土壤线以上的线虫比在培养皿中的少。线虫的向下迁移与土壤柱直径成反比，这可能是由于沿容器表面的移动相对不受阻碍。开发了一种测定方法，通过该方法将线虫从离心管内表面冲洗到土壤中。然后将所得的泥浆在贝尔曼盘中处理以回收活动的线虫。在土壤湿度为2-4%时，线虫在离心管土壤中的存活率高于较低（0.5-1.0%）和较高（4.0-12.0%）湿度水平。水分亏缺诱导的静止状态可能会提高里奥布拉夫斯斯氏线虫的存活率。
