Nosema: A genus of parasitic FUNGI in the family Nosematidae. Some species are pathogenic for invertebrates of economic importance while others are being researched for possible roles in controlling pest INSECTS. They are also pathogenic in humans.Beekeeping: The management and maintenance of colonies of honeybees.Bees: Insect members of the superfamily Apoidea, found almost everywhere, particularly on flowers. About 3500 species occur in North America. They differ from most WASPS in that their young are fed honey and pollen rather than animal food.Microsporidia: A phylum of fungi comprising minute intracellular PARASITES with FUNGAL SPORES of unicellular origin. It has two classes: Rudimicrosporea and MICROSPOREA.Microsporidiosis: Infections with FUNGI of the phylum MICROSPORIDIA.Colony Collapse: The sudden collapse and disappearance or diminution of a colony of organisms.Spores, Fungal: Reproductive bodies produced by fungi.Encephalitozoon cuniculi: A species of parasitic FUNGI. This intracellular parasite is found in the BRAIN; HEART; and KIDNEYS of several MAMMALS. Transmission is probably by ingestion of the spores (SPORES, FUNGAL).Encephalitozoon: A genus of FUNGI originally considered a member of the class SPOROZOEA but now recognized as part of the class MICROSPOREA.