ABSTRACT
The spread of Asian tapeworm in the US illustrates the interplay of various factors that results in the successful establishment of an invasive species. Grass carp first arrived in the US in 1963 as shipments of fingerlings from Malaysia and Taiwan to US Fish and Wildlife federal fish hatcheries in Stuttgart, Arkansas and Auburn, Alabama respectively (Fuller et al, 1999); grass carp were to be reared and further bred as biological control agents for aquatic weeds. It is likely that fish in at least one of these shipments were infected with Asian tapeworm. An unknown number of grass carp escaped their outdoor holding ponds/enclosures at the rearing facility in Stuttgart and took advantage of flooding to access the Mississippi drainage. Subsequent stockings of grass carp in lakes and reservoirs open to stream systems enabled the fish to colonize the Mississippi and Missouri Rivers by the early 1970s (Fuller et al, 1999). Presumably they carried their infections into these new locations. Early on, grass carp were also shipped to Florida to control aquatic macrophytes and as a result probably introduced Asian tapeworm into that state. While grass carp were being used to control aquatic weeds, mosquitofish, Gambusia hollbrooki/G. affinis were being used to control mosquito larvae. Overlap of grass carp and mosquitofish in places such as Florida and Louisiana, and a shared diet of copepods, allowed the tapeworm to effect one of its first major ‘jumps’ across host taxonomic boundaries, into a host of a distantly related order and family of fishes (Cyprinodontiformes: Poeciliidae). It appears that infected mosquitofish were translocated to distant places such as North Carolina, California and Hawaii. The Asian tapeworm also colonized other, cyprinid, hosts, such as the red shiner, golden shiner and common carp.
