Efficiency of insect exclusion screens for preventing whitefly transmission of tomato yellow leaf curl virus of tomatoes in Israel.

Tomato yellow leaf curl virus (TYLCV) is the most frequently occurring virus in tomatoes in the Middle East, and the most harmful one. It is transmitted solely by the whitefly Bemisia tabaci (Gennadius). Within 4-6h of inoculative feeding, a whitefly can transmit TYLCV to a healthy plant with 80% probability. The symptoms are apparent after two to three weeks whereupon fruit-set is effectively terminated. The only means of controlling TYLCV is by controlling the whitefly. Until 1990 this was exclusively by insecticides. Starting in 1990, growers of greenhouse tomatoes in Israel began adopting insect exclusion screens to prevent inoculation of TYLCV. This article reports on the methods used in the search for efficient screening materials and presents data on their relative efficiencies in excluding B. tabaci and several other greenhouse pests. Ten materials were tested, of which five were found to be effective in excluding B. tabaci under laboratory conditions. This number was reduced to three following field trials and trials in commercial tomato greenhouses. These materials are now in widespread use in Israel: by 2000 practically all table tomatoes in Israel were grown under exclusion screens. The use of exclusion screens has been shown to be an economically viable pest management method.

Management strategies for agricultural biotechnology in small countries. A case study of Israel.

Agricultural biotechnology is concentrated in four major countries. This paper suggests strategies for developing it in small countries, based on analysis of the world trends and the characteristics of small countries. Israel is presented as a specific case study. The main relevant trends are domination by big companies, consumer concerns on genetically modified foods, and focusing on consumer benefits and specific market niches. Small countries' disadvantages include companies that are too small to benefit fully from research, difficulty in raising funds, lack of infrastructures and experienced management personnel, and public sector research organizations that are unsuitable for commercializing research. The recommended strategies include: developing a large number of low-volume products and small market niches, forming partnerships with intermediaries (such as food companies), specializing in intermediate products (such as the seed or the gene patent), and conducting market research and cost-benefit analysis in advance. Additional strategies include developing benefits that are unique to genetically modified foods and focusing on benefits specifically for consumers who accept genetically modified foods, rather than on benefits for the average consumer. A national representative organization could buy and rent out expensive equipment, finance specific projects in return for the commercial rights, and perform collective marketing research and marketing. Israel has the advantages of a successful agricultural sector and complementary scientific research, and should focus on those fruits, vegetables, and flowers for which it already has the experience and infrastructure.