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WATER HYACINTH Eichhornia crassipes (Martius)
Solms-Laubach -- Pontederiaceae (Contacts) ----- CLICK on Photo to enlarge &
search for Subject Matter with Ctrl/F. GO TO ALL: Bio-Control Cases Native to the
Neotropics, Eichhornia crassipes is a floating aquatic
plant that has become a naturalized pest throughout tropical areas, even
extending into the temperate zone (Bock 1969). Reproduction is primarily vegetative, daughter plants forming
on stolons which originate from central rhizomes. Dense mats can form quickly, the plant doubling in volume every
10-15 days under favorable conditions (Penfound & Earle 1948). This plant has the ability to completely cover lakes and slowly
moving streams, which can cause major navigational, agricultural and health
problems. Although herbicides are
effective in controlling water hyacinth, the cost is generally prohibitive
(Goeden & Andrés 1999). A biological
control project was initiated by the U. S. Army Corps of Engineers and the
British Ministry of Overseas Development (Bennett & Zwölfer 1968). Two lines of
research were pursued, including surveys for natural enemies in South America
(Bennett & Zwölfer 1968) and a study and use of indigenous organisms in
the United States (i.e., Bellura
densa (Walker) (Lepidoptera:
Noctuidae), Cercospora rodmani Conway (Hyphomycetes),
and Acremonium zonatum (Sawada) Gams
(Hyphomycetes). The South American
surveys turned up a number of candidates of which three were imported: Neochetina
bruchi Hustache (Coleoptera:
Curculionidae), N. eichhorniae Warner and Sameodes albiguttalis Warren (Lepidoptera: Pyralidae). A fourth species, Acigona infusella
(Walker) (Lepidoptera: Pyralidae), was released in Australia (Julien 1987). Studies revealed
that the native host of Belludura
densa is pickerelweed, Pontederia cordata L. (Pontederiaceae), which is closely related to
water hyacinth; but the larvae can severely damage water hyacinth also. Studies produced a diet on which B. densa could be mass reared, which was followed by the
experimental release of large numbers of eggs and first instars in attempts
to augment native populations.
However, the moth had very little impact in the United States (Julien
1987). A fungus, Cercospora rodmani, indigenous to Florida was also found. The fungus causes leaf spot, leaf necrosis
and secondary root rot of the hyacinth plants. It also causes plant death when applied to hyacinth mats. This fungus is being considered for
registration as a commercial mycoherbicide (Charudattan 1986). Another fungus, Acremonium zonatum,
damages water hyacinth in south Florida and Louisiana, but appears to have
its greatest impact when associated with the mite, Orthogalumna terebrantis
Wallwork. The mite is native to South
America and accidentally entered the United States after its host plant was
intentionally introduced as an ornamental. Females of Neochetina eichhorniae and N.
bruchi chew holes in the
leaf petioles into which they insert one or several eggs, respectively
(Center 1982). The larvae tunnel
beneath the epidermis and work their way down to the base of the petiole or
the rhizome to which the leaf is attached, by which time they are in their
third and final instar. The fully
grown larvae chew their way out of the stems and move toward the surface of
the water. They cut several lateral
roots which ar incorporated into an underwater pupal cocoon attached to the
hyacinth roots. The emerging adults
leave the water from emergent plant parts where they feed, mate and oviposit (Goeden
& Andrés 1999). Weevils
overwinter as larvae, pupae or adults, and there is one generation per year
(DeLoach & Cordo 1976). Sameodes albiguttalis
oviposits into the spongy leaf petioles, favoring areas with cuts in the
epidermis or injuries made by other organisms. The young larvae feed under the epidermis, periodically exiting
onto the petiole surface, crawling downward, and then re-entering the globose
area of the petiole to continue feeding.
The fifth and final instar excavates a pupal cell in the petiole
(Goeden & Andrés 1999). There are
though to be five generations per year in Argentina, with larval feeding
causing the petioles to break and die, resulting in heavy mortality the
following winter (DeLoach & Cordo 1978). Neochetina eichhorniae was
introduced to the United States in 1972 from near Buenos Aires, Argentina
(Center 1982), and it has established throughout the range of water hyacinth
in North America. This weevil also
was subsequently transferred from the United States to several other
countries where it is now established (e.g., Australia, Fiji, Indonesia, New
Guinea, India, South Africa, Sudan and Thailand (Julien 1987). Neochetina
bruchi was introduced to the
United States from Argentina in 1974 and is now established in California,
Texas, Louisiana and Florida.
Establishment has also been confirmed in India and the Sudan (Julien
1987). Sameodes albiguttalis
was released in the United States in 1977 (Center & Durden 1981), and is
established in Mississippi, Louisiana, Florida and California, and it is also
established in India and the Sudan (Julien 1987). Acigona infusella was
introduced to Australia from Brazil, but failed to establish. Orthogalumna
terebrantis was introduced
to Egypt and Zambia, but establishment is not confirmed (Julien 1987). Neochetina eichhorniae
seems to be the major contributor to the control of water hyacinth in the
United States, Australia and the Sudan (Goeden & Andrés 1999). Cofrancesco et al. (1985) documented the reduction of water hyacinth
in Louisiana from about 445,000 ha in 1974 to 122,000 ha by 1980. Sameodes
albiguttalis retards growth
in the early stages of mat development, although its action may be sporadic
and patchy (Center 1985, Julien 1987).
When introduced from Buenos Aires, N.
bruchi was observed to
successfully control water hyacinth in an isolated reservoir in La Rioja
Province, Argentina, which indicated that its control potential should not be
minimized (DeLoach & Cordo 1983). The original
surveys in South America which uncovered the several important natural enemy
species, were primarily performed by Dr. Aquiles Silveira-Guido of the
University of Uruguay. The U. S.
Department of Agriculture sponsored his searches by building special
laboratory facilities at the university, and providing travel funds necessary
for the searchers. Dr. E. F. Legner
of the University of California, accompanied Dr. Silveira-Guido on one of his
original discovery trips to southern Brazil.
The researchers traveled through natural waterways in canoes in this
region of heavy illegal movement of contraband from Brazil to points
south. On several occasions the
investigators had to confront smugglers, offering them cigarettes and casual
conversation to ward off their suspicions.
Dr. Legner observed and remarked to the investigators that the
waterways were heavily clogged with hyacinth plants, and he wondered of what
possible benefit natural enemies obtained from the area would be in
biological control. In fact, the
hyacinth seemed to be a necessary factor in the balance of the local
ecosystem, providing food and shelter to a number of native animals,
including a species of crocodile that formed nests from the leaves of the
hyacinth plants. The successes
achieved in countries to which the phytophagous insects were eventually
transferred emphasizes one's inability to predict a biological control
outcome by observations at the native site.
Biological control
of water hyacinth project was the second attempt at biological control of an
aquatic weed with introduced arthropods.
Although focus remained on the search and importation of natural
enemies from South America, the discovery of the indigenous Bellura densa and Cercospora
rodmani added another
dimension to the research on biological control of aquatic plants in the
United States. Despite the limited
success of attempts to augment natural B.
densa population levels in
Florida, the moth may eventually prove useful as an introduced natural enemy
in other countries (Goeden & Andrés 1999). Goeden & Andrés
(1999) point out that the reduction of water hyacinth has tempted control
workers to target remaining pockets of plants with herbicides. However, without proper integration this
action can upset the balance between natural enemies and their hyacinth host,
causing further hyacinth outbreaks (Center 1982). Buckingham & Passoa (1985) suggested that in an integrated
control program when conservation of the weevils is desired, summer herbicide
applications should be delayed until the greatest number of newly emerged
weevils with well developed wing muscles are present. These agents are then better able to
migrate to unsprayed areas. They also
urged that herbicides not be applied in the spring until water temperatures
were above 18°C, the threshold for wing development, although
herbicidal control is more efficient if begun early in the season (Goeden
& Andrés 1999).
In Bangladesh water hyacinth was a pest 50 years ago when the human
population was small. Today it is
mainly an asset, being used as a green manure and mulch, or buried as a
fertilizer and valuable source of potash.
Dried hyacinth plants are used as fuel or as cattle feed. (Uchida & Arado 1988) For further detail on biological
control effort and biologies of host and natural enemies, please also see the
following (USDA 1965, Bennett 1966, 1970; Maddox et al. 1971, Brown &
Spencer 1973, Andrés & Davis 1974). REFERENCES: [Additional references may be found at: MELVYL
Library ] Anonymous. 1962. Alligatorweed controlled by insects? Agric. Res. 10: 8-9. Andrés, L. A. 1966. Observations on the host specificity of
the Thrips sp. attacking Alternanthera philoxeroides. U. S. Dept. Agric., Unpub. Rept. 25 p. Andrés, L. A. & C. J. Davis.
1974. The biological control
of weeds with insects in the United States.
Commonw. Inst. Biol. Control Misc. Publ. 6: 11-15. Bennett, F. D. 1966. Investigations on the insects attacking aquatic
ferns, Salvinia spp. in
Trinidad and northern South America.
Proc. S. Weed Conf. 19:
497-504. Bennett, F. D. 1970. Insects attacking waterhyacinth in the
West Indies, British Honduras and the USA.
Hyacinth Contr. J. 8(2):
10-13. Bennett, F. D. & H. Zwölfer. 1968. Exploration for
natural enemies of water hyacinth in northern South America and
Trinidad. Water Hyacinth Cont. J.
7: 44-52. Bock, H. H. 1969. Productivity of the waterhyacinth, Eichhornia crassipes (Mart.) Solms.
Ecology 50: 460-64. Brown, J. L. & N. R. Spencer. 1973. Vogtia malloi, a newly introduced phycitid to control
alligatorweed. Environ. Ent. 2: 521-23. Center, T. D. 1982. The waterhyacinth weevils, Neochetina eichhorniae and N.
bruchi. Aquatics 4(2): 8, 16-19. Center, T. D. 1985. Leaf life tables: a viable method for assessing sublethal
effects of herbivory on waterhyacinth shoots, p. 511-24. In: E. S. Delfosse (ed.), Proceedings of the
VI International Symposium on Biological Control of Weeds, 1984, Vancouver,
B.C., Canada. Center, T. D. & W. C. Durden. 1981. Release and
establishment of Sameodes albiguttalis for the biological
control of waterhyacinth. Environ.
Ent. 10: 75-80. Charudattan, R.
1986. Integrated control of
waterhyacinth (Eichhornia crassipes) with a pathogen,
insects and herbicides. Weed Sci.
34: 26-30 (suppl. 1). Cofrancisco, A. F., Jr., R. M. Stewart & D. R. Sanders,
Sr. 1985. The impact of Neochetina
eichhorniae (Coleoptera:
Curculionidae) on waterhyacinth in Louisiana, p. 525-35. In: E. S. Delfosse (ed.), Proceedings of the
VI International Symposium on Biological Control of Weeds, 1984, Vancouver,
B.C., Canada. DeLoach, C. J. & H. A. Cordo. 1976. Life cycle and
biology of Neochetina bruchi, a weevil attacking
waterhyacinth in Argentina, with notes on N.
eichhorniae. Ann. Ent. Soc. Amer. 69:
643-52. DeLoach, C. J. & H. A. Cordo. 1978. Life history and
ecology of the moth Sameodes
albiguttalis, a candidate
for biological control of waterhyacinth.
Environ. Ent. 7; 309-21. DeLoach, C. J. & H. A. Cordo. 1983. Control of
waterhyacinth by Neochetina bruchi (Coleoptera:
Curculionidae: Bagoini) in Argentina.
Environ. Ent. 12: 19-23. Fuller, T. C. 1961. New weed problems. Calif. State Dept. Agric. Bull. 50: 20-8. Goeden, R. D. & L. A. Andrés. 1999. Biological control
of weeds in terrestrial and aquatic environments. In: Bellows, T. S.
& T. W. Fisher (eds.), Handbook of
Biological Control: Principles and
Applications. Academic Press, San
Diego, New York. 1046 p. Hawkes, R. B., L. A. Andrés & W. H. Anderson. 1967.
Release and progress of an introduced flea beetle, Agasicles n. sp., to control
alligatorweed. J. Econ.
Ent. 60: 1476-77. Julien, M. H. (ed.). 1987. Biological control
of weeds: a world catalogue of agents
and their target weeds, 2nd ed.
Commonw. Agric. Bur. Int., Wallingford, U.K. 150p. Maddox, D. M. 1968. Bionomics of an alligatorweed flea beetle,
Agasicles sp. in
Argentina. Ann. Ent. Soc.
Amer. 61: 1299-1305. Maddox, D. M. & M. E. Resnik. 1968. Radioisotopes-- a
potential means of evaluating the host specificity of phytophagous
insects. J. Econ.
Ent. 61: 1499-1502. Maddox, D. M., L. A. Andrés, R. D. Hennessey, R. B. Blackburn,
& N. R. Spencer. 1971. Insects to control alligatorweed. Bioscience 21: 985-91. Muenscher, W. C.
1944. Aquatic Plants of the
United States. Comstock Publ. Co.,
Inc., Ithaca, New York. 374 p. Munz, P. A. & D. D. Keck. 1959.
A California Flora. Calif. Univ. Press.
1681 p. O'Neill, K. 1968. Amynothrips
andersoni, a new genus and
species injurious to alligatorweed (Thysanoptera: Phlaeothripidae). Wash. Ent. Soc. Proc. 70: 175-83. Penfound, W. T. & T. T. Earle. 1948. The biology of
the waterhyacinth. Ecol. Monogr. 18: 447-72. Uchida, H. & K. Araado. 1988. Water hyacinth control program through
community development approach: a
case study in a Bangladesh village. Japan Agr. Res. Quart. 32: 181-188. U. S. Department of Agriculture.
1965. A survey of extent and
cost of weed control and specific weed problems. Agric. Res. Serv., ARS 34-23-1. August. 78 p. Zeiger, C. F. 1967. Biological control of alligatorweed with Agasicles n. sp. in
Florida. Hyacinth Control J. 6: 31-4. |