2008 Annual Report
1a.Objectives (from AD-416)
Objective 1: Develop new knowledge of behavior, genetics, physiology, and ecology of wireworms, aphids, secondary potato pests, and their natural enemies, that provides opportunities for new and improved biorational control of potato insect pests.
Objective 2: Develop monitoring methods and techniques that reduce grower risk from wireworms that improve predictability of threats to potatoes.
Objective 3: Develop economical, sustainable, and ecologically sound methods for control of aphids, wireworms, and secondary pests of potatoes.
1b.Approach (from AD-416)
Objective 1.The seasonal phenology and movement of green peach aphid and leafhoppers in potato will be described quantitatively. Effects of induced defenses of potato on behavior, development, and reproduction by insect pests will be determined. Microbial flora resident in the midgut of wireworm larvae will be genetically altered (paratransgenesis) to produce physiological or toxic conditions that in turn will be detrimental to the survival of the wireworm. The role and concentrations of carbon dioxide as an attractant for Pacific coast wireworm and will be determined. Mating behavior of Limonius canus (Pacific coast wireworm) will be described.
Objective 2. Baiting methods to monitor wireworms in potatoes will be developed, and the feasibility of using baits to predict end-of-season damage to tubers will be determined. The seasonal phenology of wireworm damage to tubers will be described to assist in management decisions.
Objective 3. The effectiveness of transgenic and traditionally bred potato varieties for resistance to wireworms and secondary pests will be demonstrated. Methods to manage wireworms and potato flea beetle in potatoes using entomopathogens will be developed. Methods for enhancing biological control of green peach aphid will be improved, including use of habitat modification, selective insecticides, and predator attractants. Action thresholds for leafhoppers that vector phytoplasmas will be estimated. Extent of insecticide resistance in green peach aphid in the Northwest will be determined. Formerly 5352-22000-014-00D (3/05).
It was determined that the rate of CO2 production from baits correlates with the bait attractiveness to wireworms, demonstrating the role of carbon dioxide in bait effectiveness. In field situations, it was determined how planted mustard affects wireworm densities and tuber protection. Assays were conducted that determined the efficacy of second generation wireworm baits provided by industry cooperators. A Bacillus megaterium strain resistant to tetracycline was found to express green fluorescent protein (GFP). An assay system was developed for testing retention of Bacillus megaterium with GFP in codling moth larvae and in potato tuberworm larvae. Bioassays for entomopathogenic fungi and nematodes that infect flea beetles have been developed. Novel compounds were found in the male pheromone of the cabbage looper moth that may improve attractiveness of a lure for female moths. The beet leafhopper was shown to vector the BLTVA phytoplasma/pathogen that causes the potato purple top disease. The phenology of the beet leafhopper was described and incidence of BLTVA in leafhoppers was determined. Zebra chip disease of potato was shown to be associated with the potato psyllid, Bactericera cockerelli. An IPM program was developed for the management of potato psyllid to reduce zebra chip disease. Field tests of mineral oils and Kaolin for controlling aphid vectors of potato virus Y (PVY) and potato leafroll virus (PLRV) were conducted. An inexpensive method was developed to trap alate aphids that is selective for insects that are in the size range of aphids. Antigenic markers were used to measure local movement of green peach aphids in the field.
National Program 304; Component II: Biology of Pests and Natural Enemies, Problem Statement A: Basic Biology; Component III: Plant, Pest, and Natural Enemy Interactions and Ecology, Problem Statement A: Understanding the Complex Interactions; Component V: Pest Control Technologies, Problem Statement D: Other Biologically-Based Control, and Component VI: Integrated Pest Management Systems and Areawide Suppression, Problem Statements A: Sampling Methods, Detection and Monitoring; D: Implementation of IPM Systems; and E: Transition and Technology Transfer to Users.
PHENOLOGY OF THE BEET LEAFHOPPER IN THE COLUMBIA BASIN DESCRIBED. The potato purple top disease has become important in the Columbia Basin of Washington and Oregon. The beet leafhopper, Circulifer tenellus, is the vector of BLTVA, the pathogen that causes the potato purple top disease in this important potato growing region of the U.S. ARS researchers at the Fruit and Vegetable Insect Research Unit in Wapato, WA described the phenology of this insect pest was described in the Columbia Basin of Washington and Oregon and Yakima Valley of Washington. In addition, incidence of BLTVA in leafhoppers throughout the growing season in the Columbia Basin was determined and will be used to formulate action thresholds for the beet leafhopper and potato purple top disease. Information from this research will help potato growers to effectively manage this insect pest by timely and appropriately applying insecticides. National Program 304: Component III: Plant, Pest, and Natural Enemy Interactions and Ecology, Problem Statement A: Understanding the Complex Interactions.
SYNTHETIC BAITS FOR WIREWORMS. Difficulties in controlling and monitoring wireworms in potatoes have led to efforts at developing a synthetic attractant. First generation baits obtained from industry cooperators were found to attract wireworms in laboratory assays, and attractiveness of subsequent baits was shown to depend upon the rate that the bait emitted carbon dioxide. The methods that were developed by ARS researchers at the Fruit and Vegetable Insect Research Unit in Wapato, WA for assaying baits and for measuring production of carbon dioxide will allow rapid screening of competing bait formulations, for eventual commercial production and use in the field. It is anticipated that these baits may be used in place of some insecticides to reduce field populations of wireworms. National Program 304: Component V: Pest Control Technologies, Problem Statement D: Other Biologically-Based Control.
POSSIBLE VECTOR OF ZEBRA CHIP POTATO DISEASE IDENTIFIED. Zebra chip, a new and emerging potato disease, is causing millions of dollars in losses to potato producers and processors in the southwest of the United States, Mexico, and Central America. ARS researchers at the Fruit and Vegetable Insect Research Unit in Wapato, WA demonstrated for the first time that zebra chip is associated with the potato psyllid, Bactericera cockerelli. In addition, in collaboration with other ARS and university scientists, an IPM program was developed for the management of this insect pest to reduce incidence of zebra chip. As a result, growers in the Lower Rio Grande Valley of Texas, one of the regions seriously affected by the disease, have recently managed to keep zebra chip incidence under manageable levels by applying insecticides targeted against the potato psyllid. Information from this research will help potato producers affected by zebra chip to reduce damages caused by this potato disease by focusing on monitoring and controlling this insect pest. National Program 304: Component III: Plant, Pest, and Natural Enemy Interactions and Ecology, Problem Statement A: Understanding the Complex Interactions.
Wraight, S.P., Sporleder, M., Poprawski, T., Lacey, L.A. 2007. Application and evaluation of entomopathogens in potato. In: Lacey, L.A., Kaya, H.K., editors. Field Manual of Techniques in Invertebrate Pathology. 2nd edition. The Netherlands: Springer, Dordrecht. p. 329-359.
Lacey, L.A., Horton, D.R., Jones, D. 2008. The Effect of Temperature and Duration of Exposure of Potato Tuber Moth (Lepidoptera: Gelechiidae) in Infested Tubers to the Biofumigant Fungus, Muscodor albus. Journal of Invertebrate Pathology 97:159-164.
Riga, E., Lacey, L.A., Guerra, N. 2008. The potential of the endophytic fungus, Muscodor albus, as a bio-control agent against economically important plant parasitic nematodes of vegetable crops in Washington State. Biological Control 45:380-385.
Munyaneza, J.E., Jensen, A.S., Hamm, P.B., Upton, J.E. 2008. Seasonal Occurrence and Abundance of Beet Leafhopper in the Potato Growing Region of Washington and Oregon Columbia Basin and Yakima Valley. American Journal of Potato Research 85:77-84.
Munyaneza, J.E., Goolsby, J., Crosslin, J., Upton, J.E. 2007. Further Evidence that Zebra Chip Potato Disease in the Lower Rio Grande Valley of Texas is Associated with Bactericera cockerelli. Subtropical Plant Science 59:30-37.
Munyaneza, J.E., Crosslin, J., Lee, I. 2007. Phytoplasmas Diseases and Insect Vectors in Potatoes of the Pacific Northwest of the United States. Bulletin of Insectology 60:181-182