2010 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.
This is the final report for this project, which terminated in August 2010. Substantial results were realized over the five years of the project. A biological control program for the invasive water-using weed Arundo donax was initiated ,resulting in importation, evaluation, and release of biological control agents into impacted areas of the Rio Grande Basin (RGB). To define the area of the infestation, remote sensing using both satellite and aerial images revealed that all the major tributary rivers of the RGB in the U.S. and Mexico are infested with A. donax, with more than 15,000 acres between Laredo and Del Rio alone. Ecohydrology (water use) studies showed that A. donax is a major water user year-round and that transition to native riparian vegetation should result in reduced water use. This data was used in an economic model developed by Texas A&M, that showed considerable benefits to the agricultural economy of the Lower Rio Grande Valley from even modest water conservation following biological control of A. donax in the RGB. Genetic sampling of A. donax in the RGB and Europe has revealed that one dominant genotype occurs north of Laredo. This genotype matches most closely with populations of A. donax in the Mediterranean and Spain. Candidate agents were collected from these 'origin' locations and evaluated for safety and efficacy. Host range testing of the Arundo wasp, Tetramesa romana, and the Arundo scale, Rhizaspidiotus donacis, have been completed, and TAG petitions for release of these agents in N. America were submitted in 2008. T. romana was permitted by APHIS in April 2009 and subsequently released and established in Laredo, TX. Release of the Arundo scale has been proposed by USDA-APHIS, and releases of the scale are planned for late 2010. Pre-release studies of the scale have shown that it reduces the vigor of the rhizome (root) of the reed and that the scales from the origin of the RGB genotype in Spain are most effective. Mass-rearing of the arundo wasp has been accomplished, with more than 300,000 wasps produced for field release. These methods have been transferred to collaborators in Mexico who are now rearing and releasing the agents in Tamaulipas, Coahuila, and Morelos. Methods for efficient aerial release of the wasp have been developed with APHIS. A large-scale release and evaluation of the Arundo wasp was initiated in a pilot study along the Rio Grande near Laredo, Texas. Inundative aerial releases of the wasp into stands of mature A. donax have shown minor impacts but will continue for a full year. The combination of mechanical cutting of the reed to 1 meter plus the releases of the arundo wasp has been shown to reduce regrowth of the reed and allows for transition of the riverbank to native vegetation. Research will continue to determine the biology, safety, and efficacy of the arundo leaf sheath miner. Research to improve mass rearing and release of the arundo wasp and arundo scale will continue, along with intensive field evaluation to determine their impacts and changes in the riparian plant community of the Rio Grande and its tributaries.
Determination of life cycle of the arundo leafminer. The arundo leafminer Lasioptera donacis (Diptera: Cecidomyiidae) is widespread and abundant in the areas of southern France and Spain. ARS scientists in Weslaco, Texas, in collaboration with ARS scientists at the European Biological Control Laboratory (EBCL), Montpellier, France, collected the arundo leafminer and determined that it completed its life cycle in one month. Adult females lived one to six days and laid eggs in the leaf sheaths of arundo plants, especially in holes made by other insects. Feeding by the larvae and infection by surface fungi caused leaves to turn yellow and die. Studies in southern Spain further characterized the critical factors for arundo leafminer reproduction and efficacy. This work has led to the first successful rearing of a grass-feeding, non-galling cecidomyiid leafminer in quarantine. This success will pave the way for host range and efficacy studies in quarantine, furthering the development of the arundo leafminer as a biological control agent.
Aerial release methods for the arundo wasps have been developed. Ground releases of the arundo wasp Tetramesa romana are not practical in the remote areas of the Rio Grande Basin of Texas, due to poor roads and the fact that these weeds form dense thickets that inhibit uniform dispersal of the wasps. ARS scientists in Weslaco, Texas, in collaboration with APHIS equipment specialists at Moore Airbase, Edinburg, Texas, have developed technology to contain, transport, and release arundo wasps from light aircraft. Specialized cardboard boxes filled with chilled arundo wasps were accurately dropped into the narrow corridor of A. donax thickets with minimal mortality to the biological control agents. This technology will be used by action agencies to extend the benefits to the far reaches of the Rio Grande river.
Distribution of the invasive weed Arundo donax. A binational program was initiated with collaborators in Mexico to extend the benefits of the biological control program for the invasive water-using weed Arundo donax to the Mexican portion of the Rio Grande Basin. Collaborators at the Instituto Mexicano de Tecnologia de Aguas, Cuernavaca, Mexico, received populations of the arundo wasp Tetramesa romana from the ARS program and successfully established colonies at their rearing facility in Jiutepec, Morelos. Arundo wasps were released and established in Nuevo Laredo, Tamaulipas; Colombia, Nuevo Leon; and Cuernavaca, Morelos. Establishment of the arundo wasp in these locations is the first step in the successful biological control of this invasive weed. Future studies, in collaboration with Mexican colleagues, will focus on this impact of the agent on populations of A. donax.
5.Significant Activities that Support Special Target Populations
Term appointments and a Specific Cooperative Agreement with the University of Texas-Pan American, a Hispanic-Serving Institution, has led to employment and education opportunities for 12 undergraduate and graduate students involved in studies of the biology and mass-rearing of biological control agents targeting giant reed.
Moran, P.J. 2010. Lack of establishment of the Mediterranean tamarisk beetle Diorhabda elongata (Coleoptera: Chrysomelidae) on athel (Tamarix aphylla) (Tamaricaceae) in south Texas. Southwestern Entomologist. 35:129-146.
Moran, P.J., Goolsby, J. 2010. Biology of the armored scale Rhizaspidiotus donacis (Hemiptera: Diaspididae), a candidate agent for biological control of giant reed. Annals of the Entomological Society of America. 103(2):252-263.
Skevington, J.H., Goolsby, J. 2009. New records of Pipunculidae attacking proconiine sharpshooter (Auchenorrhyncha: Cicadellidae: Proconiini). Journal of Entomological Society of Ontario. 140:19-26.
Racelis, A.E., Goolsby, J., Moran, P.J. 2009. Seasonality and movement of adventive populations of the arundo wasp (Hymenoptera: Eurytomidae), a biological control agent of giant reed in the Lower Rio Grande Basin in south Texas. Southwestern Entomologist. 34(4):347-357.
Jackson, B.C., Goolsby, J., Wyzykowski, A., Vitovksy, N., Bextine, B. 2009. Analysis of genetic relationships between potato psyllid (Bactericera cockerelli) populations in the United States, Mexico and Guatemala using ITS2 and inter simple sequence repeat (ISSR) data. Subtropical Plant Science. 61:1-5.
Seawright, E.K., Rister, M.E., Lacewell, R.D., McCorkle, D.A., Sturdivant, A.W., Yang, C., Goolsby, J. 2009. Economic implications for the biological control of Arundo donax: Rio Grande Basin. Southwestern Entomologist. 34(4):377-393.
Goolsby, J., Spencer, D.F., Whitehand, L.C. 2009. Pre-release assessment of impact on Arundo donax by the candidate biological control agents, Tetramesa romana (Hymenoptera: Eurytomidae) and Rhizaspidiotus donacis (Homoptera: Diaspididae) under quarantine conditions. Southwestern Entomologist. 34(4):359-376.
Goolsby, J., Pfannenstiel, R.S., Evans, G.A. 2009. New state record for the silverleaf whitefly parasitoid Encarsia sophia in Texas. Southwestern Entomologist. 34(3):327-328.
Boughton, A.J., Bennett, C., Goolsby, J., Pemberton, R.W. 2009. Laboratory host range testing of Neomusotima conspurcatalis (Lepidoptera: Crambidae) - a potential biological control agent of the invasive weed, Old World climbing fern, Lygodium microphyllum (Lygodiaceae). Biocontrol Science and Technology, 19, 369-390.
Munyaneza, J.E., Buchman, J.L., Upton, J.E., Goolsby, J., Crosslin, J., Bester, G., Miles, G.P., Sengoda, V.G. 2008. Impact of Different Potato Psyllid Populations on Zebra Chip Disease Incidence, Severity, and Potato Yield. Subtropical Plant Science 60:27-37.
Seawright, E.K., Rister, E.M., Lacewell, R.D., McCorkle, D.A., Sturdivant, A.W., Yang, C., Goolsby, J. 2009. Economic implications for the biological control of Arundo donax: Rio Grande Basin. Southwestern Entomologist. 34(4):377-394.