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United States Department of Agriculture

Agricultural Research Service


Location: Exotic and Invasive Weeds Research

2013 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, MD where combined molecular and morphological data will be used to provide proper identification of all specimens.

3. Progress Report:
Research conducted under this Specific Cooperative Agreement directly supports Objective 3 of project 5325-22000-026-00D and Objectives 3 and 4 of project 5325-22000-024-00D. Over the life of this project, natural enemies of Ludwigia spp., invasive waterprimrose, from California were collected across a wide geographical range that included coastal and inland areas from San Diego to far north central California. A common flea beetle, Altica litigate was initially determined to be the most abundant species in most California locations, however, some question existed as to the actual identification of the insect natural enemy that was made by USDA-ARS taxonomists at the Smithsonian Institute. Similar species of Altica are considered pests of crepe myrtle in the South Eastern United States and thus it was important to clearly separate these beneficial insects from those causing defoliation of horticultural plants of economic interest. Using molecular biology techniques, cooperators from the University of Georgia were able to separate California collected flea beetles from very similar looking beetles from the southwestern states. Following this assessment, USDA taxonomists were further able to locate morphological characters that allow visual identification. Work is continuing but concluding with potentially new species determination being considered for these insect taxa.

4. Accomplishments

Last Modified: 06/26/2017
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