Stabilization effects of spatial aggregation of vectors in plant disease systems |
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Authors: | Kohji Yamamura |
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Institution: | (1) Laboratory of Population Ecology, National Institute of Agro-Environmental Sciences, 305-8604 Tsukuba, Ibaraki, Japan |
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Abstract: | Stabilization effects of spatial aggregation of vectors were examined in insect-borne plant disease systems by constructing
a model that describes the yearly dynamics of rice stripe virus disease transmitted by the small brown planthopperLaodelphax striatellus (Fallén). Two transmission paths between vectors were considered: vertical transmission from parents through eggs, and horizontal
transmission from infected plants by acquisition feeding. In this model, a paddy field was divided into quadrats and horizontal
transmission was assumed to occur within each quadrat. A negative binomial distribution was used to describe the frequency
distribution of vectors per quadrat. The parameters of the model were estimated using field data collected in Ibaraki Prefecture,
Japan. The model showed that (1) the disease cannot invade into an epidemiological system if the mean crowding of vectors
is less than a critical value, (2) the proportion of infected vectors is maintained at about 30% irrespective of the vector
density if vectors are highly aggregated, and (3) the proportion of infected plants is maintained at a low level irrespective
of the vector density if vectors are highly aggregated. It was also shown that these stabilization effects of aggregation
in this epidemiological system come from a mechanism that is common to other systems such as single-species systems and competition
systems. |
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Keywords: | Laodelphax striatellus rice stripe virus disease spatial aggregation stability vectors |
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