2006 Fiscal Year Final Research Report Summary
Migration analysis of plant-parasitic nematodes involved in water current of soil environments
| Project/Area Number |
16380043
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied entomology
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| Research Institution | National Agriculture and Food Research Organization |
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Principal Investigator |
OTOBE Kazunori National Agriculture and Food Research Organization, National Agricultural Research Center, Research Team for Crop and Soil Analysis, Senior Researcher, 中央農業総合研究センター・土壌作物分析診断手法高度化研究チーム, 主任研究員 (50355517)
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| Co-Investigator(Kenkyū-buntansha) |
MIZUKUBO Takayuki National Agriculture and Food Research Organization, National Agricultural Research Center, Research Team for Detection and Identification of Plant Pathogens and Nematodes, Chief Researcher, 中央農業総合研究センター・病害虫検出同定法研究チーム, 上席研究員 (30370513)
HASEGAWA Shuichi Hokkaido University, Research Faculty of Agriculture, Division of Environmental Resources, Professor, 大学院・農学研究院環境資源学部門, 教授 (10333634)
NAKAMOTO Tomomi The University of Tokyo, Graduate School of Agriculture and Life Sciences, Associate Professor, 大学院・農学生命科学研究科, 助教授 (50180419)
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| Project Period (FY) |
2004 – 2006
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| Keywords | Plant-parasitic nematode / Soil environment / Water migration / Transpiration / Nematode migration / Micro-molded substrate / Water potential / No tillage |
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| Research Abstract |
We have hypothesized that the migration of plant-parasitic nematode in soil environment is affected by water current involved in the transpiration of crops in farmland. In order to validate our hypothesis, behavioral analysis of soil-living nematodes with different foraging activities and their spatial distribution were investigated with a use of two physical model of soil environment.
The micropore-network model constructed on a micro-molded substrate was used to observe real-time behavior of the nematodes exposed to water current in the network space and this experimental set up provided us with the evidence of positive rheotaxis of a plant parasite (Meloidogyne incognita), an insect parasite (Steinernema carpocap sae), a fungus feeder (Aphelencus avenae), and a bacteria feeder (Caenorhabditis elegans). On the other hand, it was suggested that the differences in the physical activities of nematodes and their threshold of mechanoreceptors involved in rheotaxis may conceal its resultant appearance such as nematode distribution in soils.
The other model based on a soil-filled column (5 mm in inner diameter, 11 cm in length) was used to determine the effect of water current in the soil on the nematode migration introduced in the column. Under the current controlled via migration of pore-volume water in Andosol, migration of M.incognita along the current increased with the elevation of the water volume passing through the soil. More coarse, sandy environment in the column resulted in an acceleration of the migration of the nematode in spite of its rheotactic nature exhibited beforehand.
In general, it was assumed that well-known upward shift of M.incognita distribution in farmland might be attributed to geotaxis of soil-living nematodes. However, our investigation by means of the micro-molded substrate provided the evidence to remove this assumption : the nematodes tested in the vertically settled substrate without any other physical bias expressed random migration.
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