Summary
       Semiochemicals are substances involved in the communication between living beings. 
Regarding to insects, these could be useful tools in pest management, as alternative methods to 
conventional pesticides. They are both species-specific and active at low doses. Semiochemicals 
(pheromones and allelochemicals) are employed in pest management for detection and population 
monitoring and also for control methods such as mating disruption, mass trapping and lure and kill, 
among other techniques. Several studies on the application and the search for semiochemicals are 
included in the present thesis as a contribution to the control of some agronomic important pests. 
First, mating disruption technique was developed and applied to Aonidiella aurantii and Tuta 
absoluta. Regarding to A. aurantii, this is the first successful application of this technique to control 
a diaspidid pest. This thesis also describes the conditions for mating disruption to be effective 
against T. absoluta.
       Secondly, the existence of optimum pheromone release rate values for attraction purposes 
was investigated for several pests: Chilo suppressalis, Lobesia botrana, Bactrocera oleae and 
Ceratitis capitata. For the lepidopterans C. suppressalis and L. botrana and the tephritid B. oleae, it 
was found that males’ attraction is affected by the level of pheromone emission and the attractant 
power of the pheromone is reduced at release rates below and above the optimum values obtained. 
However, C. capitata males’ response to its parapheromone trimedlure was asymptotic, so an 
optimum emission value was not found and higher quantities of parapheromone attracted the same 
number of flies. Scientific literature on obtaining pheromone dispensers with optimum emission 
rates is scarce and it is, however, essential to develop pest control methods based on attraction.
       Finally, the third part of this thesis describes the detailed study on the volatiles emitted by 
different cases of males and females of C. capitata, to identify compounds and blends with potential 
attractancy by means of solid-phase microextraction (SPME), a technique not employed before for 
this matter, and the principal components analysis (PCA). Obtaining new effective attractants for C. 
capitata females would provide with a great advantage to control this fruit fly pest.