Restoration and Management of Lakes and Reservoirs - Hydro-Environmental Analysis: Freshwater Environments - page 485

UGA4723001
UGA4723003
UGA4723004
FIGURE 17.14 Alligator weed and alligatorweed lea beetle. (From Buckingham, G.R., Biological Control
of Invasive Plants in the Eastern United States , United States Department of Agriculture Forest Service.
Forest Health Technology Enterprise Team, Morgantown, WV, 2002.)
17.5.7.4 Water Lettuce Weevils ( Neohydronomous afinis )
Water lettuce is a free-loating invasive plant with high vegetative reproduction, allowing water
lettuce to form dense loating mats of vegetation (Figure 17.16). The impacts of severe infestations
include preventing light penetration, reducing oxygen levels, increasing siltation, reducing ish habi-
tats, impeding navigation, reducing suitable ish spawning habitats, and restricting water low and
boating trafic. Water lettuce is believed to be native to Africa or South America, and was identiied
in North America as early as the late 1700s.
Water lettuce weevils are native to Central and South America and were introduced into the
United States in the 1980s to help control water lettuce in Florida. Water lettuce weevils have proven
very effective and where they have become established, nearly complete control is often achieved
in 18-24 months (Chilton 2004).
17.5.7.5 Salvinia Weevils ( Cyrtobagous salviniae )
The giant salvinia is an aquatic fern with loating leaves that form chains that run together to form
thick mats on the surface of the water. The plant is native to South America and was irst found in
the United States in the 1990s. This plant has extremely rapid rates of growth, estimated under ideal
conditions to double every 36-53 hours. The giant salvinia weevil (Figure 17.17), originally occur-
ring in southeastern Brazil, Bolivia, Paraguay, and northern Argentina, was introduced to control
this invasive species (Mudge and Harms 2012). These weevils have been very successful in other
areas of the world in controlling giant salvinia, but have not proven comparably successful in the