Demarta Lanila, Hibbard Bruce E, Bohn Martin O, Hiltpold Ivan
Division of Plant Sciences, University of Missouri, 205 Curtis Hall, Columbia, MO 65211, USA.
USDA-ARS, Plant Genetic Research, University of Missouri, 205 Curtis Hall, Columbia, MO 65211, USA.
J Invertebr Pathol. 2014 Oct;122:32-9. doi: 10.1016/j.jip.2014.08.002. Epub 2014 Aug 19.
As obligate parasites, entomopathogenic nematodes (EPN) rely on insect hosts to complete their development. In insect pest management, EPN infectiousness has varied a lot. A better understanding of their host-finding behavior in the rhizosphere is therefore crucial to enhance EPN potential in biological control. As previously demonstrated, roots can be used as a pathway to insect hosts by EPN, but this interaction and its impact on EPN foraging remain poorly documented. Three artificial model-roots with different degrees of complexity and connectivity were designed to investigate the impact of root architecture on foraging behavior of the EPN Heterorhabditis megidis. Insect baits were placed at the bottom of each model-root that was subsequently buried in moist sand. After injection of the EPN, the number of EPN-infected baits as well as the number of mature nematodes inside each individual carcass was recorded. The influence of insect-induced root volatiles was also evaluated by spiking the baits with a synthetic version of a natural insect-induced root cue. The ecological relevance of the results was tested in soil with two maize genotypes each exhibiting broadly different root architectures. H. megidi performed better in presence of model-roots. Foraging performances of H. megidis declined with the increasing model-root complexity. Adding the synthetic root volatile dramatically changed this pattern and favored the EPN on the most complex model-roots. H. megidis also moved in the vicinity of maize roots to find the insect baits in soil, and natural root architecture also tended to shape H. megidis foraging behavior. This study adds to the scarce body of literature characterizing physical and chemical interactions between EPN and roots. The present data illustrate that root architecture not only modifies plant quality but also shapes upper trophic levels' ecology.
作为专性寄生虫,昆虫病原线虫(EPN)依靠昆虫宿主来完成其发育。在害虫管理中,EPN的感染力差异很大。因此,更好地了解它们在根际中的寄主寻找行为对于提高EPN在生物防治中的潜力至关重要。如先前所示,EPN可将根用作通往昆虫宿主的途径,但这种相互作用及其对EPN觅食的影响仍鲜有文献记载。设计了三种具有不同复杂程度和连通性的人工模型根,以研究根系结构对EPN大异小杆线虫觅食行为的影响。将昆虫诱饵放置在每个模型根的底部,随后将其埋入湿沙中。注射EPN后,记录被EPN感染的诱饵数量以及每个虫体内成熟线虫的数量。还通过用天然昆虫诱导的根信号的合成版本对诱饵进行加标来评估昆虫诱导的根挥发物的影响。在具有两种根系结构差异很大的玉米基因型的土壤中测试了结果的生态相关性。在存在模型根的情况下,大异小杆线虫表现更好。大异小杆线虫的觅食性能随着模型根复杂性的增加而下降。添加合成根挥发物极大地改变了这种模式,并有利于EPN在最复杂的模型根上觅食。大异小杆线虫也会在玉米根附近移动以在土壤中找到昆虫诱饵,天然根系结构也倾向于塑造大异小杆线虫的觅食行为。这项研究增加了关于EPN与根之间物理和化学相互作用的稀少文献。目前的数据表明,根系结构不仅会改变植物质量,还会塑造更高营养级的生态。