Perry Roland N, Ehlers Ralf-Udo, Glazer Itamar
Rothamsted Research, Harpenden, Herts. AL5 2JQ, UK.
J Nematol. 2012 Jun;44(2):185-90.
Understanding the desiccation survival attributes of infective juveniles of entomopathogenic nematodes (EPN) of the genera Steinernema and Heterorhabditis, is central to evaluating the reality of enhancing the shelf-life and field persistence of commercial formulations. Early work on the structural and physiological aspects of desiccation survival focused on the role of the molted cuticle in controlling the rate of water loss and the importance of energy reserves, particularly neutral lipids. The accumulation of trehalose was also found to enhance desiccation survival. Isolation of natural populations that can survive harsh environments, such as deserts, indicated that some populations have enhanced abilities to survive desiccation. However, survival abilities of EPN are limited compared with those of some species of plant-parasitic nematodes inhabiting aerial parts of plants. Research on EPN stress tolerance has expanded on two main lines: i) to select strains of species, currently in use commercially, which have increased tolerance to environmental extremes; and ii) to utilize molecular information, including expressed sequence tags and genome sequence data, to determine the underlying genetic factors that control longevity and stress tolerance of EPN. However, given the inherent limitations of EPN survival ability, it is likely that improved formulation will be the major factor to enhance EPN longevity and, perhaps, increase the range of applications.
了解斯氏线虫属和异小杆线虫属昆虫病原线虫（EPN）感染性幼虫的干燥存活特性，对于评估延长商业制剂保质期和田间持效性的实际情况至关重要。早期关于干燥存活的结构和生理方面的研究，重点关注蜕下的角质层在控制水分流失速率中的作用以及能量储备（特别是中性脂质）的重要性。还发现海藻糖的积累可提高干燥存活率。对能在沙漠等恶劣环境中存活的自然种群的分离表明，一些种群具有更强的干燥存活能力。然而，与一些栖息在植物地上部分的植物寄生线虫物种相比，EPN的存活能力有限。关于EPN胁迫耐受性的研究主要沿着两条主线展开：i）选择目前商业使用的物种菌株，使其对极端环境的耐受性增强；ii）利用分子信息，包括表达序列标签和基因组序列数据，来确定控制EPN寿命和胁迫耐受性的潜在遗传因素。然而，鉴于EPN存活能力的固有局限性，改进制剂可能是提高EPN寿命以及或许扩大应用范围的主要因素。
