Biology
The beetle has an average life span of thirty days. Females
may lay up to 300 eggs during their life. Both adults and
larvae feed on alligatorweed. Eggs are laid in clusters
on the leaf surface. The beetle is very sensitive to extreme
temperatures, either hot summers or cold winters, which
makes their establishment very difficult
History
Agasicles hygrophila is native of South America,
specifically southern Brazil and northern Argentina. In
1963 approval was granted for its importation into the United
States and in January of the following year permission was
received from California and South Carolina for the release
of the beetle. In 1964, the U.S. Army Corps of Engineers
released the biological control agent Agasicles hygrophila
in California and South Carolina in hopes of controlling
alligatorweed. This beetle was so successful that subsequent
releases were made in 9 southern states including Texas.
In 1963, Texas had approximately 1,200 acres of alligatorweed-infested
waters, however, this number increased significantly to
11,200 acres infested in 1973. During and subsequent to
this sharp increase, a number of releases of Agasicles
were made in hopes of controlling this weed biologically.
This beetle was first introduced into Texas in 1967.
Agasicles became widely distributed in the rice growing
areas of Texas as a result of a larger release program in
1969 which included releases in Chambers, Jefferson and
Orange counties. In 1972 the beetle had also been successfully
established in Harris, Liberty and Brazoria counties. Today
alligatorweed does not represent a major aquatic weed problem
in Texas. Local problems do occur and supplemental releases
are recommended occasionally.
Known Release History
of Agasicles hygrophila
in Texas
| Year
|
Specimens
Released |
#
of releases |
Released
Sites |
Released
By: |
| 1967 |
2,000
|
2 |
Dam B
Reservoir
J.D. Murphee Wildlife Area |
USCE
TPWD |
| 1968 |
3,110
|
5 |
Winnie,
Tx
Dam B Reservoir
J.D. Murphee Wildlife Area
A&M Rice Plantation |
USCE
TPWD
TAMU |
| 1969 |
7,000
|
4 |
Houston
Area
Eastern Tx/Beaumont |
Harris
Co. Mos.
Private Persons
TPWD |
| 1970 |
1,300
|
2 |
J.D.
Murphee Wildlife Area
Flint River |
Harris
C. Mos
TPWD |
| 1972 |
2,400
|
1 |
Catfish
Creek-Trinity River |
Private
Persons |
| 1983 |
3,000
|
|
Wallisville
J.D. Murphee Wildlife Area |
|
| 1984 |
4,000
|
|
Wallisville
J.D. Murphee Wildlife Area
Jones Creek |
|
*Release information provided
by the Waterways Experiment Station
Host Range
Agasicles hygrophila is essentially monophagous
on alligatorweed.
Implementation
Relocation procedures for alligatorweed flea beetles are
well documented by Waterways Experiment Station. Adults
and or egg masses are preferred for release programs. A
large number should released at a particular time for a
better chance of establishment especially because of the
combination of the short life-span and the temperature limits
of the beetle. Due to the cold temperatures in certain areas
of the state, supplemental populations may have to be reintroduced
each year. High temperatures may inhibit reproduction and
may also cause local loss of Agasicles populations.
This beetle favors emergent vegetation to feed upon. Foliage
growing on the banks of waterways and the terrestrial form
are hardly fed upon. Consequently alligatorweed often has
a resident terrestrial population even when the flea beetle
eliminates the emergent foliage.
Successes
In 1963, prior to any release of the beetle, there were
97,000 problem acres of alligatorweed in the United States,
however, by 1981 there was less the 1,000 problem acres.
In 1964, the first release of Agasicles hygrophila
was made in California and South Carolina and since that
time a number of releases have been made throughout the
southern United States. Obviously the release and establishment
of biological agents for the control of alligatorweed has
been a huge success.
Alligatorweed flea beetles were controlled and released
at Clive Runnells Family Mad Island Marsh Preserve to control
alligatorweed in November 1996 and May 1997. Released beetles
became established at the preserve and completely defoliated
from of this weed in June 1997. The beetles continued to
be well established in November 1997 and are contributing
to the control of alligator weed on the preserve and surrounding
areas. As they continue to migrate into new areas, biocontrol
of this weed will provide no cost control to adjacent landowners.
(See complete report)
Weeds Affected
This beetle is a biological control agent for alligatorweed.
Literature
Buckingham, G.R., Boucias, D., Theriot, R.F. 1983. Reintroduction
of the alligator flea beetle into the United States from
Argentina. Journal of Aquatic Plant Management 21,
101-102.
Coulson, J.R. 1977. Biological Control of Alligatorweed,
1959-1972. A review and evaluation. Technical Bulletin,
United States Department of Agriculture 1547, 98
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