Neochetina eichhomiae is
Argentina, a native habitat of waterhyacinth.
ligatorily monophagous on hyacinth, and N.
found on plants of only
Its distribution does not exceed that of waterhyacinth, and its
genera.
life cycle can be completed only on the hyacinth (Perkins and Maddox 1976,
The first insect to be released in the United States following
Center 1981).
importation, quarantine, and testing was the alligatorweed flea beetle
Two other species have been
(Coleoptera:Chrysomelidae).
introduced for
control,
(Lepidoptera:Pyralidae)
These species are
andersoni (Thysanoptera:Phlaeothripeae).
and
also confined in their feeding or life cycle to the target plant (Coulson
1977).
Insects have been successful in exerting control of alligator-weed and
The primary control of alligatorweed in
waterhyacinth in several states.
Florida, Louisiana, Mississippi, and south Alabama is by the alligatorweed
Both
flea beetle A.
and the alligatorweed stem borer V.
have contributed to control in Georgia, but their impact is limited in North
Carolina because the colder weather inhibits or completely prevents
The alligatorweed
wintering of the insects (Cofrancesco 1984).
andersoni) over-winter better and thus stress the plants earlier
They also attack the terrestrial form of this plant, while the
in the season.
flea beetle and stem borer require the aquatic form (Cofrancesco 1984,
have been released in Florida,
eichhorniae and N.
1984).
Texas, and California for control of
Georgia, Louisiana,
hyacinth, and effective control has been reported from Florida, Louisiana, and
the waterhyacinth
Texas (Center and Durden 1984).
moth, has been found to be most effective against small, luxuriantly growing
plants, such as might occur following a chemical or mechanical treatment
(Center and Durden 1984).
The impact-of the two weevils on waterhyacinth in Louisiana serves as an
example of insect effectiveness (Perfetti 1983, Goyer and Stark 1984, Sanders
1984).
The distribution of waterhyacinth reached a statewide peak of
690,000 ha in 1975.
Ey 1980, the beetles had reached swarming levels. and dry
Plant distribution declined to
weather had concentrated the plants.
ha in 1980; the insects, along with the drought and increased effi-
ciency of herbicide spraying, are believed to have been the major factors.
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