Indagini sulle infestazioni di Aphis gossypii Glover su melone invernale (Cucumis melo Var. Helios) in aziende a conduzione biologica della Sicilia occidentale.

Investigations on the aphid infestation occurring on winter melon crops (Cucumis melo var. Helios) in organic farms of western Sicily The winter melon (Cucumis melo L.) is an important crop in Sicily. Previous studies carried out in western Sicily have shown that the aphid species Aphis gossipii is the key pest of winter melon crops.A. gossypii is a cosmopolitan species with very polyphagous habits; this phytophagous insect is capable of serious economic damage due to direct feeding of the sap plant and due to the honeydew secretion and the consequent presence of sooty mold and due to the possible transmission of viruses. The aim of this work was to investigate the levels of aphid infestation in two different organic winter melon fields located in western Sicily by monitoring the dynamic of population of A. gossypii and the complex of natural enemies associated with the pest. In addition the possible influence of mulching as aphid repellent has been evaluated. In one location we monitored the aphid infestation through direct observation of the plants that have been carried out weekly from transplant to harvest of the product. In the other location, we investigated the dynamics of population and levels of adult infestation, evaluating also the possible influence of mulching, using chromotropic traps, consisting in yellow adhesive plates placed horizontally in mulched rows, on the plastic film, and alleyways, on the ground. In addition, surveys were carried out by comparing mulched plots and not mulched plots. Our results showed that, in both locations, the population density of A. gossypii was low and no serious damage has been inflicted to the crop: this is probably related to the abundant presence of natural enemies of the pest and to the repellent action of mulching.