Ben-Yakir, D., Institute of Plant Protection, Agricultural Research Organization, Volcani Center, Bet-Dagan, Israel
Hadar, M.D., Polysack Plastic Industries, Nir-Yitzhak-Sufa, Israel
Offir, Y., Polysack Plastic Industries, Nir-Yitzhak-Sufa, Israel
Chen, M., Institute of Plant Protection, Agricultural Research Organization, Volcani Center, Bet-Dagan, Israel
Tregerman, M., Southern R and D, Besor Experimental Station, Israel

Thrips and whiteflies are major pests of vegetables and flowers grown under protective structures. Plastics or screens containing photo-selective additives have been shown to reduce the risk for infestation by these pests. We tested the protection against thrips provided by screens with photo-selective additives that are being developed under the trade mark OptiNet®. Our studies were conducted in southern Israel from 2002 to 2005. In walk-in tunnels, thrips infestations on cucumber, tomato and chive plants under OptiNet® (both of 40 and 50 mesh) were 3 to 4 folds lower than under a standard 50 mesh screen. This protection against thrips was further enhanced by weaving of narrow aluminum foil strips into the OptiNet®. Thrips preferred landing on yellow and blue shading nets (ChromatiNet®) over black and red nets. Whiteflies preferred landing on yellow shading nets over black, blue and red nets. Covering plants with yellow nets did not increase, but rather decreased, the risk of whiteflies penetration and establishment. Covering with yellow or blue nets did not increase the risk of thrips penetration and establishment. It appears that these pests remain on their preferred colored nets for a long time (an arrestment response), and as a result they are less likely to infest the plants underneath.