PRESENCE ABSENCE SEQUENTIAL SAMPLING FOR POTATO TUBERWORM (LEPIDOPTERA, GELECHIIDAE) ON PROCESSING TOMATOES - SELECTION OF SAMPLE SITES ACCORDING TO PREDICTABLE SEASONAL TRENDS

The potato tuberworm, Phthurimaea operculella (Zeller), is a major pes t of processing tomatoes in Israel. Population densities of potato tub erworm are characterized by low densities before harvest of nearby pot ato fields. Infestation is first seen at field margins. In tomato fiel ds not directly adjacent to potatoes, population density at the edges is higher than at the center Tile goal of the current study was to dev elop a sampling plan based on the above observations. Spatial distribu tion was described using the Taylor power law. The relationship betwee n mean population density and the proportion of infested sample units was established by the Wilson and Room equation. Two binomial sequenti al sampling procedures are suggested: before potato harvest in nearby fields and M-hen population density is below the don't treat level, sa mples should be taken at the edge of the tomato field. After potato ha rvest and when population density is above the don't treat level, samp les should be taken at the edge and the center of field. These samplin g procedures reduce sampling cost when population density is low, and allow for treatment of potato tuberworm only at the edge of tomato fie lds when appropriate.