Eradication programs for the arthropod parasites of livestock.

Two species of cattle fever ticks, Boophilus annulatus and B. microplus , were eradicated from the southern United States in a cooperative state-federal program that began in 1907 and was successfully completed in 1960. These vectors were eliminated from an area of approximately 700,000 sq. miles (1,813,000 km2), primarily by dipping cattle and other livestock in an arsenical solution on a schedule shorter than the time required for completion of the parasitic phase of the life cycle of the female ticks, that is, once every 14–18 days. Bovine babesiosis disappeared from the U.S. after the tick vectors were eradicated, and the resultant savings to the livestock industry are estimated to exceed U.S. 1 billion per year. Similar eradication programs in the U.S. Virgin Islands, Soutli America, and Australia have not been successful. During 1960–1972, three species of African ticks were eliminated from the United States before they could become firmly established, but an infestation of Amblyomma variegatum was discovered in Puerto Rico in 1974 and has not yet been eradicated. Psoroptic scabies of sheep was eradicated from a few European countries, Australia and New Zealand before 1900, Canada in 1927, and the United States in 1970. For other acarine parasites the goal for the most part has been control, not eradication. Screwworms were eradicated from Florida and adjoining southeastern states in 1959 by the release of large numbers of sexually sterilized male flies. A similar program that was launched in the Southwest in 1962 is not complete but now that Mexico has joined the effort, eradication from both countries appears nearer realization. Cattle grubs, Hypoderma spp., have so far defied all attempts at eradication, even though very high levels of control, >99%, have been achieved in several countries. Efforts to eradicate other species, e.g., horn flies and stable flies, are confined to research on techniques.