2000 Fiscal Year Final Research Report Summary
Mathematical Analyses of Spatial Spread of Pine Wilt Disease
| Project/Area Number |
10640616
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
生態
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| Research Institution | Nara Women's University |
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Principal Investigator |
SHIGESADA Nanako Nara Women's University Department of Science Professor, 理学部, 教授 (70025443)
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| Co-Investigator(Kenkyū-buntansha) |
FUGO Takasu Nara Women's University Department of Science Associate Professor, 理学部, 助教授 (70263423)
KAWASAKI Kohkichi Doshisha University Department of Knowledge Engineering and Computer Sciences Professor, 工学部, 教授 (10150799)
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| Project Period (FY) |
1998 – 2000
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| Keywords | Pine wilt disease / Long-distance dispersal / Rate of spread / Dispersal kernel / Biological invasion / Stratified diffusion / Integrodifference model |
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| Research Abstract |
Pine wilt disease is caused by the pinewood nematode, Bursaphelenchus xylophilus, that is vectored by the pine sawyer beetle, Monochamus alternatus. Native Japanese pines, black pine (Pinus thunbergii) and red pine (P.densiflora), are extremely sensitive to the nematode infection and the disease has been expanding nationwide in the last several decades despite intensive control efforts. The dispersal of the beetle often involves two modes, short-range dispersal and long-range dispersal. Short-range dispersal generally occurs through their own active flying, while long-range dispersal is mediated by passive transport on wind or artificial transportation facilities. To evaluate the speed of disease's expansion, we present a model that combines the local dynamics of the pine wilt disease with the dispersal of beetles. Our model predicts several results.
(1) The distribution of the dispersal distance of beetles critically affects the expansion speed of the disease. The expansion speed is sharply amplified, as the fraction of beetles undergoing long distance dispersal increases from zero.
(2) However, if long range dispersers become too frequent, the disease ceases to expand due to the Allee effect. Thus suggests the importance of correct assessment of the beetle's mobility in predicting the expansion speed of the disease.
(3) As the eradication rate is increased, the expansion speed decreases gradually at first and suddenly drops to zero at a certain value of the eradication rate.
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