Guillermo holds a degree in Biology from the University of Salamanca, a master's degree in Biology and Biodiversity Conservation from the same university, and a PhD in Biology, specialising in Applied Entomology, from the Complutense University of Madrid. He has worked as a technician at Tragsatec on the development of improvement measures for pollinating insects within the National Pollinator Strategy and as chief coordinator of the taxonomic cabinet for wild bees (Hymenoptera, Apoidea, Anthophila) and syrphids (Diptera, Syrphidae) in the Pollinators: Improving Knowledge project, commissioned by the Ministry (MITECO) within the European framework of the EUPoMS project.