Principal source: Water Lettuce (Pistia stratiotes) (Rivers, 2002)
Compiler: National Biological Information Infrastructure (NBII) & IUCN/SSC Invasive Species Specialist Group (ISSG)
Review: Dr John Clayton NIWA, National Institute of Water and Atmospheric Research. Hamilton, New Zealand
Publication date: 2005-12-30
Recommended citation: Global Invasive Species Database (2024) Species profile: Pistia stratiotes. Downloaded from http://www.iucngisd.org/gisd/speciesname/pistia+stratiotes on 02-11-2024.
\r\nPhysical: The most common physical control method is raking or seining it (using a large fishing net) from the pond’s surface. In the United States, raking is done by mechanical harvesters. The plant is then removed from waterways to the shore where it is cut up by chopping machines and disposed of by spraying across the water (Ramey, 2001).
\r\nChemical: Chemical control methods that have been successful in treating P. stratiotes include the herbicide endothall, which can act quickly and kill all plant cells that it contacts.
\r\nBiological: According to Rivers (2002), water lettuce leaf weevil (Neohydronomus affinis) is a native species of South America and was first introduced into Australia in the early 1980's for biocontrol of P. stratiotes. Additional releases of this weevil for research are currently being conducted. These weevils have a very short life cycle (approximately 30 days), which allows for quick establishment of populations. Adult weevils feed on the leaf, while the larvae attack the inside of the leaf. The other effective method of controlling P. stratiotes is the introduction of the water lettuce leaf moth (Spodoptera pectinicornis). The moth is native to Thailand and was imported into Florida for the biological control of water lettuce. The moth has a very short life cycle (approximately 35 days), with the larval stage lasting 17-20 days. The adult moth does not feed on water lettuce, however, moth larvae are capable of inflicting significant damage to P. stratiotes. The larvae are fairly large, which means that fewer larvae can provide a greater effect.