An innovative approach to reduce chemicals in mite control

The efficacy of an innovative technique using acaricide treated nets was recently demonstrated to control phytophagous mites on vegetables. The net impregnated with the acaricide dicofol was efficient against the broad mite Polyphagotarsonemus latus (Banks) and spider mites (Tetranychus spp.) when used temporarily (once every three nights) covering eggplant. The technique was evaluated with chlorpyriphos ethyl impregnating nets in southern Benin. Results showed that the populations of Tetranychus urticae, and T. ludeni in the first trials and the invasive specie T. evansi in a last trial were significantly controlled by this technique. Very few mites were observed on plants covered with the acaricide treated net compared with very high densities on leaves in the unprotected control plots. This new concept of mite control using an acaricide-treated net temporarily covering vegetable crop appears to be an efficient tool which is easy to use by small-scale farmers. With this technique the pesticide remains on the material reducing the risk of plant contamination and environmental pollution. Thus the same treatment can be applied many times reducing chemicals for controlling mites. In greenhouses, particularly where populations of mites can increase rapidly on vegetables or ornamental flowers acaricide-treated nets could be used to control outbreaks just before the prompt release of useful insects as is permitted by absence of pesticide residues on plants with this innovative technique. In Sub-Saharian countries where mite outbreaks are observed mainly in the dry season the application of acaricide treated net poses a very low risk of pesticide workout by rain reducing the risk of pesticide residues on plants and their negative impact on useful insects. (Résumé d'auteur