The western honey bee or European honey bee (Apis mellifera) is the most common of the 7–12 species of honey bees worldwide. The genus name Apis is Latin for "bee", and mellifera is the Latin for "honey-bearing", referring to the species' production of honey. Like all honey bee species, the western honey bee is eusocial, creating colonies with a single fertile female (or "queen"), many normally non-reproductive females or "workers", and a small proportion of fertile males or "drones". Individual colonies can house tens of thousands of bees. Colony activities are organized by complex communication between individuals, through both pheromones and the dance language. The western honey bee was one of the first domesticated insects, and it is the primary species maintained by beekeepers to this day for both its honey production and pollination activities. With human assistance, the western honey bee now occupies every continent except Antarctica. Because of its wide cultivation, this species is the single most important pollinator for agriculture globally. Western honey bees are threatened by pests and diseases, especially the Varroa mite and colony collapse disorder. As of 2019, the western honey bee is listed as Data Deficient on the IUCN Red List, as numerous studies indicate that the species has undergone significant declines in Europe; however, it is not clear if they refer to population reduction of wild or managed colonies. Further research is required to enable differentiation between wild and non-wild colonies in order to determine the conservation status of the species in the wild. Western honey bees are an important model organism in scientific studies, particularly in the fields of social evolution, learning, and memory; they are also used in studies of pesticide toxicity, to assess non-target impacts of commercial pesticides.