Page Banner

United States Department of Agriculture

Agricultural Research Service


Location: Exotic and Invasive Weeds Research

2012 Annual Report

1a. Objectives (from AD-416):
Newly collected natural enemies will be assessed using molecular genetic methods to assist in accurate taxonomic identification and to ensure that later tracking of the agents is possible.

1b. Approach (from AD-416):
New natural enemies will be collected both from domestic and foreign locations on key invasive weeds including Ludwigia spp., Egeria densa other other potential weeds of importance to California and the Western US. Sample specimens will then be sent to the University of Georgia Griffin Station where they will be characterized using molecular genetic techniques. Results from these molecular assessments will then be shared with USDA-ARS scientists at the Systematic Entomology Laboratory in Beltsville, Maryland, where combined molecular and morphological data will be used to provide proper identification of all specimens.

3. Progress Report:
USDA-ARS scientists from Albany, California, and Beltsville, Maryland, have been cooperating with a molecular Geneticist from the University of Georgia to identify an important insect biological control agent that feeds on the invasive weed, Ludwigia hexapetala in California. The ADODR directly participated in this joint effort and oversaw this project through direct communication with the University of Georgia Principal Investigator. The team worked together on a small “flea beetle” in the family Chrysomelidae that feeds on the leaves of invasive Ludwigia causing significant defoliation in many areas. Similar insects are also known to feed on some beneficial plants such as crape myrtle. Morphological determinations of the Ludwigia-feeding beetle suggest that it is the same species that damages crape myrtle, however, other observations on its feeding biology suggest that it may be either a different species or have different characteristics that restrict its feeding to invasive Ludwigia species. Molecular studies have verified that this insect may indeed be a new species of flea beetle and thus detailed molecular and morphological assessments are now underway with both field collected materials from California along with museum-based “Type-Specimens” maintained in the Harvard museum. Once a full characterization of these specimens is completed, it will be clear if this is a different (potentially new species to science) or just a different biotype of the insect known to feed on crepe myrtle. If clear separation of these insect species exists, USDA scientists will continue to develop this insect as a potential augmentative natural enemy for invasive Ludwigia spp. control. This project addresses Objective 4 in the parent project by providing waterway managers with new biological control technology.

4. Accomplishments

Last Modified: 08/22/2017
Footer Content Back to Top of Page