INSECTICIDE-TREATED NETS AS A NEW APPROACH TO CONTROL VEGETABLE PESTS IN PROTECTED CROPS

Vegetable crops suffer from a range of economically damaging insect-pests and insect-transmitted virus diseases. Current control practice involves intensive spraying of insecticides, which may have undesirable effects on the environment, growers and consumers. Our goal is to develop a new physical-chemical barrier treated with fast acting insecticides to reduce the incidence of pests and insect transmitted virus diseases in protected crops. The new approach is based on a slow release insecticide-treated net with relatively large holes size to improve airflow and ventilation inside the protected environment while maintaining the protection from insect pests. Such net could be placed on an entire net house or on the sides and ventilation openings of a conventional plastic film covered greenhouse, as a barrier against insect pests. A series of laboratory experiments using vertical glass tube chambers divided by insecticide-treated nets were conducted. The nets tested had various combinations of insecticides, mesh sizes, colours and UV blockers. One of the laboratory-selected nets was tested under field conditions on a tunnel-type greenhouse under a very high pest infestation pressure. Cucumber plants previously infected with Cucumber mosaic virus and Cucurbit aphid-borne yellow virus were artificially infested with Bemisia tabaci and Aphis gossypii on the outer sides of the tunnel. The selected insecticide-treated nets effectively blocked the invasion of A. gossypii and reduced the incidence of virus-infected cucumber plants grown inside the tunnel compared to plants covered with similar nets of the same mesh size with no insecticide. However, the insecticide-treated nets failed to control B. tabaci.