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United States Department of Agriculture

Agricultural Research Service

2007 Annual Report

1a.Objectives (from AD-416)
Biological control strategies will be evaluated for management of emerging cotton pests and the exotic weed, Arundo donax. The lethal and sub-lethal effects of pesticides on key natural enemies of glassy-winged sharpshooter will be investigated to support IPM programs for this pest. Specific objectives are:.
1)Identify, collect, culture, and evaluate candidate natural enemies for efficacy against lepidopteran pests, including the beet armyworm and the cotton bollworm, as well as the green cotton mirid;.
2)Evaluate the effects of pesticides on selected natural enemies of glassywinged sharpshooter and selected predaceous spiders in the cotton agroecosystem;.
3)Evaluate the potential of entomopathogens to manage the varroa mitre and glassywinged sharpshooter; and.
4)Determine the distribution and origin of Arundo donax, giant reed, in the Rio Grande River Basin, and assess the potential impact of candidate biological control agents to manage this invasive weed of riparian habitats.

1b.Approach (from AD-416)
The BIRU will discover and evaluate beneficial insects and pathogens for biological control of the most serious pests and weeds of agriculture in the southwestern U.S., with applications of this research at the national and international level. Changes in cotton production in this region due to the potential eradication of the boll weevil and adoption of transgenic Bt cotton varieties has reduced use of broad spectrum insecticides to control key pests. This pest management strategy has resulted in the emergence of formerly secondary insects such plant bugs as serious pests. New management strategies must be developed to reduce the pesticide use in cotton. The biology and ecology of these emergent pests will be investigated, with the goal of learning where they originate before entering crops, identifying their natural enemies, devising methods to manipulate or otherwise conserve them, and to import new natural enemies for classical biological control. Further, the role of nocturnal spiders will be investigated to quantify the important role they play as predators of Lepidoptera eggs (beet armyworm & bollworm) and to support their conservation in the agroecoystem. The effects of pesticides on key natural enemies, including those of the green cotton mirid and glassy-winged sharpshooter, will be measured, and least toxic insecticides will be identified. This will allow producers to reduce their pest problems while protecting natural enemies. The insect pathology program will concentrate on technology transfer of a pathogen treated hive strip for control of varroa mite with honey bees. Water resources are critical to agriculturists, land managers, and urban users in the arid southwestern U.S. A biological control program to manage giant reed, an exotic water-using weed in the Rio Grande Basin, will be initiated.

3.Progress Report
All accomplishments made under this project are fully consistent with relevant milestones listed in the Project Plan, and with the relevant research components as defined in the National Program 304 Action Plan. Accomplishments under this project contribute to the achievement of ARS Strategic Plan Goal 3, Objective 2, Performance Measure 6, in that project accomplishments contribute substantially to attainment of the Agency FY 2007 to improve knowledge and understanding of the ecology, physiology, epidemiology, and molecular biology of emerging diseases and pests. This knowledge will be incorporated into pest risk assessments and management strategies to minimize chemical inputs and increase production.

Defining the actions of egg predators of the beet armyworm and other lepidopteran pests, particularly those predators that are nocturnal, and the effects of malathion on them, will contribute to the development of methods to enhance the Boll Weevil Eradication Program by minimizing secondary pest outbreaks. Delineating the ecology of the foliage wandering spiders, a major group of predators in south Texas cotton, will help determine their potential to be manipulated for biological control of crop pests.

A novel behavioral assay was developed to evaluate the effects of nectar ingestion and exposure to nectar odors on the searching behavior of cursorial spiders. This methodology was used to demonstrate, for the first time, that nectar ingestion induces localized searching behavior and that cursorial spiders are innately attracted to nectar odors. We also demonstrated, for the first time, that these spiders could be conditioned to respond to novel odors associated with non-prey food. Information from this study has enhanced our basic knowledge of the searching behavior of cursorial spiders. This information, in turn, can be applied to developing management techniques that enhance and conserve these spiders' population.

Three biological control agents for the invasive weed Arundo donax (giant reed/carrizo cane) have been imported from the native range in Europe and evaluated for release in North America. Cultures of the Arundo wasp Tetramesa romana were large enough to begin testing of this species. Novel pre-release impact studies have been initiated, starting with T. romana, to determine which agent(s) are likely to have the greatest impact on the weed where it is invasive in Texas, California, and northern Mexico. These studies include evaluation of impact on plant biomass, water use, and plant architecture. Following these predictive studies, the agent(s) with the best potential for impact will be selected and will undergo full host-range testing. Pending the results of these tests, a petition for release of these agents in North America, including Mexico, will be submitted to USDA-APHIS. This research project is linked with other Arundo research programs to determine its distribution and density using remote sensing, environmental impact, ecohydrology, molecular population genetics in the native and introduced range, and the economic impact on water supplies in the Rio Grande Basin.

Significant progress towards biological control of Arundo donax: Arundo donax, a water-using weed, causes serious ecological damage to the Rio Grande River Basin. Scientists at the Beneficial Insects Research Unit have imported three biological control agents from the plant's origin in Spain into USDA quarantine facilities in Texas for evaluation. These biological control agents are a cane-feeding wasp, a shoot-burrowing fly, and a rhizome-infesting scale. Preliminary host range testing of the wasp is near completion, and results indicate it is specific to A. donax. Testing of the other agents has been initiated. This program has stimulated significant support for the project from a variety of state, federal, and international organizations, and cooperative programs have been established with several of these. [NP 304, Crop Protection and Quarantine, Component II (Biology of Pests and Natural Enemies), Component III (Plant, Pest, and Natural Enemy Interactions and Ecology), Component V (Pest Control Technologies), and Component VI (Integrated Pest Management Systems and Areawide Suppression)]

6.Technology Transfer

Number of non-peer reviewed presentations and proceedings8
Number of newspaper articles and other presentations for non-science audiences7

Review Publications
Goolsby, J., Palmer, B., Van Klinken, R. 2006. Maximizing the contribution of native-range studies towards the identification and prioritization of weed biocontrol agents. Australian Journal of Entomology. 45:276-285.

Last Modified: 9/3/2015
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