Biological Control with Insects: The Hydrilla Stem Weevil

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Material Information

Title:
Biological Control with Insects: The Hydrilla Stem Weevil
Physical Description:
Fact sheet
Creator:
Center, Ted D.
Publisher:
University of Florida Cooperative Extension Service, Institute of Food and Agriculture Sciences, EDIS
Place of Publication:
Gainesville, Fla.
Publication Date:

Notes

Acquisition:
Collected for University of Florida's Institutional Repository by the UFIR Self-Submittal tool. Submitted by Melanie Mercer.
Publication Status:
Published
General Note:
"Revised: May 2002."
General Note:
"SS AGR 138"

Record Information

Source Institution:
University of Florida Institutional Repository
Holding Location:
University of Florida
Rights Management:
All rights reserved by the submitter.
System ID:
IR00004567:00001


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SS-AGR-138 Biological Control with Insects: The Hydrilla Stem Weevil 1 Ted D. Center, F. Allen Dray, and Vernon V. Vandiver, Jr.2 1. This document is SS AGR 138, one of a series of the Department of Agronomy, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Revised: May 2002. Please visit the EDIS Web site at http://edis.ifas.ufl.edu. 2. Ted D. Center, Research Entomologist, USDA Agricultural Research Service, Invasive Plant Research Laboratory, Fort Lauderdale, FL 33314; F. Allen Dray, Ecologist, USDA Agricultural Research Service, Invasive Plant Research Laboratory, Fort Lauderdale, FL 33314; and Vernon V. Vandiver, Associate Professor and Extension Aquatic Weeds Specialist, Fort Lauderdale Research and Education Center, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611. The Institute of Food and Agricultural Sciences is an equal opportunity/affirmative action employer authorized to provide research, educational information and other services only to individuals and institutions that function without regard to race, color, sex, age, handicap, or national origin. For information on obtaining other extension publications, contact your county Cooperative Extension Service office. Florida Cooperative Extension Service/Institute of Food and Agricultural Sciences/University of Florida/Christine Taylor Waddill, Dean. ( Bagous hydrillae O'Brien Coleoptera: Curculionidae: Erirhinae: Bagoini) Host : Hydrilla verticillata (L.f.) Royle (Hydrocharitaceae) Bagous hydrillae is a small Australian weevil that feeds on and develops in hydrilla. The adults feed externally, chewing on the leaves and stems of plants submersed in the water or stranded along the shoreline. This feeding behavior creates small holes in leaves and "notches" in the stems. The female inserts her eggs into the stem, usually at a leaf node. The eggs hatch and the resultant larvae burrow lengthwise in the stem causing decay and fragmentation. After the larvae attain full size, they chew through the stem and float to shore in a stem fragment. Severing of the stems by larvae reportedly "mows" the plants in Australia, removing nearly all of the hydrilla from the surface to a depth of 100 cm. After the stem fragments wash up onto the strand line, the fully-grown larvae exit from the stem andpupate in the underlying soil or amongst the drying mound of plant material. The life cycle of Bagous hydrillae requires 17 to 21 days and development from egg to adult requires 12 to 14 days. Females lay their eggs singly. The eggs are usually inserted into submersed hydrilla stems although the females might also oviposit on stranded plants. Adults spend daylight hours below the surface of the water where they crawl about, feed, and oviposit on the hydrilla stems. They emerge from the water and fly at dusk. Adults live 60 to 80 days. Bagous hydrillae has been approved for release in the United States. The weevil has been released at numerous sites in Florida and Texas. The weevils reproduced and persisted for at least five months at one site each in both Florida and Texas, though the weevils have not been observed after that period.