Résumé
Insect screen deployment in the greenhouse vent openings avoids insects' intrusions and thus helps reducing pesticides use. It is the major reason why insect screening rapidly expands all over the world, especially in the Mediterranean and tropical regions where whiteflies or thrips can be considered as major greenhouse pests. However, as the screens provide an extra resistance to momentum and transported quantities such as mass and heat, their development is slowed down by the important air temperature and humidity rise induced inside the greenhouses. For limiting this detrimental effect, one can deploy classical control methods such as reducing the solar energy transmission by means of white wash or shadow screens, or enhance heat evacuation by changing air enthalpy (using humidification techniques). One can also enhance the ventilation rate by increasing the vents' surface area and improving its ventilation efficiency. Another innovative way, less frequently explored, is to improve the nets air porosity while preserving its properties for insects-exclusion. We shall therefore present the results of a three-years cooperation study between INRA and a net manufacturer, which aims at designing a net more porous to air transfer but with similar insect exclusion properties. Experimental results are provided with respect to resistance to air transfer together with white flies (Bemisia tabaci) crossing. Results concerning thrips (Frankliniella occidentalis) penetration are also presented and more generally these results are analyzed and compared with experimental data concerning both the fluid flow and insect crossing properties of existing insect screens.