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The major cause of crop loss of greenhouse produce in Israel is a virus disease vectored by the tobacco whitefly, Bemisia tabaci . An exclusion screen developed to minimise B. tabaci entry to greenhouses has been adopted nationwide. To examine the cost effectiveness of greenhouse screening, a model was developed relating the aerial density of Bemisia tabaci , the volume of tomato production, the price of tomatoes, and the cost of screening greenhouses. Using this model, the costs and benefits of insect-exclusion screens are examined from grower and consumer perspectives. The introduction of screening has proved cost-effective for both consumers and growers. As a result of the smaller tomato crops from 1980 to 1990, Israeli consumers spent on average between $r;15 M and $32 M per year more on tomatoes than they would have if the greenhouses had been screened at that time. The introduction of screening resulted in windfall profits for early adopters of the technology who benefited from the price inflation with their larger yields. Because the cost of harvesting declined with yield and the demand for tomatoes is inelastic, the average regional revenue varied very little from 1980 to 1990, except for 1986. From 1990 to 98, the average regional value continued to remain stable as the proportion of screened winter crop increased to 100% compensating for the declining productivity of the unscreened crop. |
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