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United States Department of Agriculture

Agricultural Research Service

Research Project: Discovery, Identification and Risk-Assessment of Biocontrol Agents for Suppression of South American Invasive Weeds and Insects in the U.S.
2013 Annual Report


1a.Objectives (from AD-416):
Research activity at SABCL is aligned with National Program 304, Crop Protection and Quarantine, whose central challenge is the economical and sustainable management of pests in the U.S. minimizing negative consequences to the environment. Accidental introductions of invasive pests into the U.S. from South America have increased as a result of the international trade. Invasive pests cause major ecological and economical losses and often reduce the quality and value of products, increase the cost of production, damage environmental areas and place native species at risk. In addition, they restrict U.S. products from access to valuable foreign markets. Classical biological control offers the possibility for permanent regional suppression of weeds and insect pests that are a threat to U.S. ecosystems. The objectives are: Obj.1) survey South America to discover, collect, and identify biological control agents of target pests; Obj.2) develop rearing techniques and conduct host range and efficacy trials for potential biocontrol agents to identify the most promising candidates; and Obj.3) facilitate exportation of selected candidates to researchers in the U.S. for field release.


1b.Approach (from AD-416):
SABCL research program Project Plan approved by OSQR in 2010 includes target weeds: Brazilian peppertree (Schinus terebinthifolius), Brazilian waterweed (Egeria densa), water primrose (Ludwigia hexapetala), water lettuce (Pistia stratiotes) and waterhyacinth (Eichhornia crassipes). Insect targets are cactus moth (Cactoblastis cactorum), little fire ant (Wasmannia auropunctata), Harrisia cactus mealybug (Hypogeococcus pungens), imported fire ants (Solenopsis invicta and S. richteri) and glassy-winged sharpshooter (Homalodisca vitripennis).

Prior to the collection of their natural enemies, more in depth studies on the biology, ecology, genetics, and/or taxonomy of water primrose, cactus moth and little fire ant are required. These studies are planned as sub-objectives.

Target priorities are set by Congressional mandates, as a result of stakeholder workshops, or by hierarchical decision with input from ARS National Program Leaders (NPLs), stakeholders, SABCL director and ARS scientists. Flexibility in this Project is needed to deal with new pest problems in the U.S., with concurrence of NPLs and ARS laboratories.

SABCL functions as an overseas arm for several U.S.-based biological control programs on invasive pests of South American origin (except glassy-winged sharpshooter), conducting foreign exploration, collection and evaluation of potential biological control agents to be used in the U.S.

Waterhyacinth, Brazilian peppertree, imported fire ants, and glassy-winged sharpshooter were also targets in the previous Project Plan and, except for Brazilian peppertree, Obj.1 and Obj.2 have already been accomplished; current work is limited to collecting and shipping of selected agents (Obj.3). Brazilian waterweed, water primrose, water lettuce, cactus moth, little fire ants and Harrisia cactus mealybug were added by NPLs during the implementation of the previous Project Plan and investigations are in different stages of progress; for the most recently-added targets (cactus moth, little fire ant and Harrisia cactus mealybug), specific approach and procedures for Ob.2 will be determined as soon as natural enemies are discovered, collected and identified.

The general impact of work conducted at SABCL includes conservation of non-renewable resources by self-perpetuation of natural enemies; cost-effective suppression of target pests; decreased use of hazardous pesticides; improved environment quality; protection of natural ecosystems from invasive species, favoring biodiversity; sustainable production systems and land use; higher quality food and fiber; higher protection of human health; enhanced scientific understanding of successful biocontrol programs and integrated pest management.


3.Progress Report:
This project is also associated with FuEDEI SCA #0206-22000-007-04S entitled, "Latin American Biological Control of Weeds and Insects".

Brazilian peppertree. Funds for this project were suspended for FY.

Brazilian waterweed. A colony of a fly was shipped to the ARS quarantine in Albany. It has established successfully.

Water primrose. The main promising candidate under study is a new species of thrips. In feeding tests it showed specificity for two target weeds. The host preference is under study. In a damage test, nymphs significantly affected the stem length, number of leaves, apical bud damage and number of secondary branches produced. Two new subspecies of the weed were found and described.

Water lettuce. A competition, damage, and compatibility test with two natural enemies was evaluated in cages located on a pond covered with the weed in a Natural Reserve. Damage caused a drastic reduction in the water lettuce populations.

Imported fire ants. Ten colony fragments of the red imported fire ant infected with a disease were shipped to the US. Also, the evolutionary relationships among a group of flies were studied by molecular techniques.

Cactus moth. The laboratory rearing of a parasitoid was optimized and information on its distribution and field host range revealed specificity for two moths. The parasitoid was exported to the quarantine facilities at Gainesville, FL, to conduct additional host specificity studies.

Little fire ant. Phylogenetic and phylogeographic analysis were continued and thermal tolerance investigated. The potential global distribution was reported.


4.Accomplishments
1. Export of ten natural enemies for biological control. The final mission at FuEDEI (Objective.
3)is to facilitate exportation of selected candidates for biological control of invasive species to researchers in the U.S. for eventual field release. During the first season of operation at FuEDEI, and after almost three years of exports having been suspended, ten natural enemies were exported to cooperators in several USDA-ARS domestic laboratories in Gainesville, FL; Tallahassee, FL, Tifton, GA; Ft. Lauderdale, FL; Albany, CA; and external cooperators in Brisbane, Australia, Cedara, South Africa, and Egham, UK. The export permits were obtained from the regulatory agencies of Argentina and import permits from agencies of destination countries. After further studies in quarantine and field releases, these insects will provide additional tools to control the respective target invasive species.

2. Discovery of two new species for science. During the field explorations and studies on the target pests and their natural enemies, a number of organisms are usually found and collected for testing. Prior to the testing process, the accurate taxonomic identification of the natural enemies by classical procedures and/or by more sophisticated molecular methods is a key aspect for the success of the projects. During the extensive field explorations in FY 2013, FuEDEI scientists in Argentina co-discovered two new species for science. These accomplishments will greatly increase the chances of success of the respective biological control programs in the United States, and will contribute to the knowledge of the biological diversity in Argentina and globally.


Review Publications
Olivier, R., Estoup, A., Vonshak, M., Loiseau, A., Blanchet, S., Rossi, J., Kergoat, G.J., Foucaud, J., Orivel, J., Calcaterra, L., Chifflet, L., Courtoisier, P., Leponce, M., Schultz, T., Facon, B. 2012. Where do adaptive shifts occur during invasion A multidisciplinary approach to unravel cold adaptation in a tropical ant species invading the Mediterranean zone. Ecology Letters. DOI:10.1111/j.1461-0248.2012.01849.x.

Last Modified: 11/1/2014
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