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Ecology and Epidemiology

Development of EPIVIT, a Simulation Model for Contact- and Aphid-Transmitted Potato Viruses. Lukas Bertschinger, Institute of Plant Sciences, Swiss Federal Institute of Technology (ETH), Universitätstr. 2, 8092 Zürich, Switzerland, Current address: Swiss Federal Research Station for Fruit-Growing, Viticulture and Horticulture, Fruit-Growing Department, CH-8820 Wädenswil, Switzerland; Ernst R. Keller, and Cesare Gessler. Institute of Plant Sciences, Swiss Federal Institute of Technology (ETH), Universitätstr. 2, 8092 Zürich, Switzerland. Phytopathology 85:801-814. Accepted for publication 9 January 1995. Copyright 1995 The American Phytopathological Society. DOI: 10.1094/Phyto-85-801.

A model (EPIVIT) was developed for the simulation of potato harvest infection (% infected tubers) with a contact- or aphid-transmitted virus. Its state variables are the efficiency of autoinfection, primary infection of plants, and tuber infection of primarily infected plants. Input variables are daily minimum and maximum temperature and data referring to aphid species presence and the fluctuation of their winged population above the respective field. The model version for contact-transmitted viruses is based on an individual plant approach, which simulates the spread of the epidemic from infectious to healthy plants. The version for aphid-transmitted viruses is based on a population approach simulating primary infection by means of the negative binomial distribution. The code of both versions includes stochastic elements. Rate parameters for the simulation of the physiological age of the crop, the susceptibility of a plant to an infection, and the state variables are temperature sensitive. Coarse and fine sensitivity analysis of the model are presented. A working version of EPIVIT was implemented for IBM PCs and compatibles. The program is menu-and-mouse or keyboard driven and displays graphical and numerical model outputs.

Additional keywords: epidemiology, model verification, pathogen × host × environment interaction, pathosystem modeling, polyethic epidemic.