Fuente: WIPO "varroa" The invention relates to the formulation and the manner of obtaining nutritional supplements with prophylactic effect for bees, based on the conjugated action of iron (II) salts of the amino acids similar to the ones present in the honey and pollen, of volatile vegetable oils, preferably citronella oil alone or in admixture and p-coumaric acid, as concentrates, or as syrups or cakes on glucidis support, to which for the potentiation there can be added: essential vitamins, essential minerals, proteins and fats and which can be administered permanently or in certain periods.