Weevil May Help Fight Invasive Water Weed
July 1, 1999
Sleek black weevils are being put to
work in an east Texas pond, lake, and reservoir to help stop the spread of a
fast-growing water weed, Salvinia molesta. If the weevils perform as
well in the United States as they have in countries such as Australia, South
Africa and India, they might reduce the need for chemical controls.
This week near Jasper, Texas, Agricultural Research Service scientists
and colleagues from the Texas Parks and
Wildlife Department are freeing about 500 of the one-tenth-inch long
weevils known as Cyrtobagous salviniae. Earlier, they set loose about
Salvinia molesta produces small, oval, green to yellow-green leaves
that can form dense mats that crowd out native plants and ruin conditions for
fish and wildlife. The mats can also interfere with flood control and
irrigation as well as with fishing, swimming, boating, and water skiing.
Native to South America, S. molesta poses a threat to waterways in
warm-weather areas of the U.S. Unchecked, it can quickly double its spread in
only a few days, according to Ted D. Center, who leads the ARS
Weed Control Research Laboratory in Ft. Lauderdale, Fla.
The weevil, also native to South America, showed up in Florida several
decades ago. It is thought to have a key role in keeping another Salvinia
species, S. minima, in check in Florida.
The ARS researchers in Ft. Lauderdale collected the weevils in Florida and
are releasing them in Texas with the permission of federal and state regulatory
authorities. Weevil adults and young attack primarily the new, nitrogen-rich
buds of the plant. The weevils can produce a new generation of hungry young
every 3 weeks.
ARS scientists and their Texas associates will monitor the weevils to
determine if they can adapt. Winter weather poses the biggest threat to the
newcomer insects in Texas. ARS is USDA's
chief research agency.
Scientific contact: Ted D.
Center, ARS Aquatic Weed Control Research Laboratory, 3205 College Ave.,
Ft. Lauderdale, FL 33314; phone (954) 475-0541, ext. 103; fax (954) 476-9169,