ABSTRACT
        Mediterranean fruit fly (Ceratitis capitata Wiedemann) is one of the most harmful pests in Spanish citrus growing regions and nowadays it is only effectively controlled by organophosphate insecticides, being malathion the most widely employed. For this reason, alternatives to the classical chemical methods are currently under study, aimed at minimising the environmental impact as well as the risks for human health. Among these, the application of low volume bait treatments with alternative, less eco-toxicologically harmful insecticides, and physical methods, such as the elimination of fruits remaining on the ground after harvest, have been considered. However, these alternatives must be mechanized to be efficient and economically viable, and that is the major objective of this thesis.
        The mechanization of low volume bait treatments have been addressed by means of the design and development of an automatic sprayer.
        First, the selection of a suitable spray device to obtain droplets of convenient size and its integration into an electronic control system is described, together with the integration of both systems on a prototype. Then, the machine is tested to determine its suitability for the purpose it was designed for. Finally, different bait treatments using alternative pesticides against C. capitata are proposed. These treatments have been evaluated in different commercial plots during two seasons. Results show that the application of these pesticides with the proposed sprayer generates the same efficacy control levels than current conventional treatments with malathion.
        Regarding to the mechanization of the elimination of the fruits remaining on the ground after harvest, this thesis proposes the use of conventional citrus wood grinders or shredders to grind or crush the fruits, because theses machines are common in many modern farms and could be assigned to this complementary use.
        With this purpose, test aimed at assessing the efficacy of these methods to control C. capitata larvae under laboratory conditions have been conducted. In such experiments, 29 % mortality rate was obtained when crushing the fruits and 81 % when grinding them. Then, the conditions of a particular type of machines to crush properly the fruits with the minimal energy consumption have been set. Finally, the efficacy of the method has been tested in field conditions. Results demonstrated that significant control over C. capitata population can be achieved by this method. 27 %-46 % reduction of the first adult generation was attained in the spring following the treatment.