Background Plant feeding, free-living nematodes cause extensive damage to plant roots by direct feeding and, in the case of some trichodorid and longidorid species, through the transmission of viruses. Developing more environmentally friendly, target-specific nematicides is currently impeded by slow and laborious methods of toxicity testing. Here, we developed a bioactivity assay based on the dynamics of light 'speckle' generated by living cells and we demonstrate its application by assessing chemicals' toxicity to different nematode trophic groups. Results Free-living nematode populations extracted from soil were exposed to methanol and phenyl isothiocyanate (PEITC). Biospeckle analysis revealed differing behavioural responses as a function of nematode feeding groups. Trichodorus nematodes were less sensitive than were bacterial feeding nematodes or non-trichodorid plant feeding nematodes. Following 24 h of exposure to PEITC, bioactivity significantly decreased for plant and bacterial feeders but not for Trichodorus nematodes. Decreases in movement for plant and bacterial feeders in the presence of PEITC also led to measurable changes to the morphology of biospeckle patterns. Conclusions Biospeckle analysis can be used to accelerate the screening of nematode bioactivity, thereby providing a fast way of testing the specificity of potential nematicidal compounds. With nematodes' distinctive movement and activity levels being visible in the biospeckle pattern, the technique has potential to screen the behavioural responses of diverse trophic nematode communities. The method discriminates both behavioural responses, morphological traits and activity levels and hence could be used to assess the specificity of nematicidal compounds.

中文翻译：

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动态生物散斑分析，一种快速筛选植物杀线虫剂选择性的新工具。

背景植物取食，自由生活的线虫通过直接取食对植物根部造成广泛损害，在某些毛线虫和长线虫物种的情况下，通过病毒传播。目前，缓慢而费力的毒性测试方法阻碍了开发更环保、目标特异性的杀线虫剂。在这里，我们开发了一种基于活细胞产生的光“斑点”动力学的生物活性测定，并通过评估化学品对不同线虫营养组的毒性来证明其应用。结果 从土壤中提取的自由生活线虫种群暴露于甲醇和异硫氰酸苯酯 (PEITC)。Biospeckle 分析揭示了作为线虫摄食组的函数的不同行为反应。与以细菌为食的线虫或非线虫类植物为食的线虫相比，Trichodorus 线虫的敏感性较低。在暴露于 PEITC 24 小时后，植物和细菌饲养者的生物活性显着降低，但 Trichodorus 线虫没有。在 PEITC 存在的情况下，植物和细菌饲养者的运动减少也导致生物散斑图案的形态发生可测量的变化。结论 生物散斑分析可用于加速线虫生物活性的筛选，从而提供一种快速检测潜在杀线虫化合物特异性的方法。随着线虫独特的运动和活动水平在生物散斑模式中可见，该技术有可能筛选不同营养线虫群落的行为反应。