Alternanthera Philoxeroides (Martius) Grisebach - Alligator Weed

Biological control of Alternanthera philoxeroides, alligator weed, began when George Vogt, USDA, conducted several surveys in South America during the 1960s. Three agents were released in the USA and two of them - the flea beetle Agasicles hygrophila and the moth Arcola malloi - were released in Australia in the 1970s. The flea beetle provides excellent control of alligator weed in aquatic habitats in warm temperate areas. However, alligator weed also grows in semi-aquatic and terrestrial situations and additional control agents are needed for those habitats. New surveys were conducted in South America from 2001 to 2005. Four insects have been tested but were not sufficiently host-specific for release in Australia as they completed their life-cycles on native Alternanthera species. Two others - the flea beetle Phenrica sp. and the fly Ophiomyia marelli - are being tested in quarantine. Several others - the stem-mining fly Ophiomyia buski and leaf-mining flies Ophiomyia alternantherae and Pegomya sp. - are candidates for future testing. The fungus Uredo pacensis, that has only been found in Bolivia, may also have potential.