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 pets 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 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. Replacing 5352-22000-016-00D (4/10).
3. Progress Report
Progress was made on all three objectives of the Project Plan Outline issued January 2011, all of which fall under National Program 304 Crop Protection and Quarantine, Component II, Problem Areas IIA and IIB. Under Objective 1, we determined that the female potato psyllid produces a pheromone that is attractive to males and that an attractant can be obtained from a solvent extract of female psyllids. Floral chemical lures were identified for spotted cutworm moths which defoliate potato plants in Washington, and for green garden looper and beet webworm in Hawaii. Under Objective 2, we showed that highest summer temperatures slowed or prevented development of zebra chip disease in potato, and determined that all 105 breeding lines tested were susceptible to zebra chip, although 40 had some level of resistance. We also determined that zebra chip potato seed does not contribute much to disease spread, and showed that earlier planted potatoes are more vulnerable to zebra chip than later planted potatoes. Under Objective 3, we demonstrated greater consumption of bait by wireworms with the addition of sucrose and a protein source added to a bait formulation. Bait formulations for wireworms were evaluated with the addition of minute quantities of insecticide to assess their attraction and mortality, using a laboratory assay. Greater mortality was observed when the same feeding stimulants were added to the bait containing pesticide.
1. Identification of a chemical attractant for potato psyllid. Potato psyllid is a highly invasive pest of potatoes, tomatoes, and peppers for which no effective monitoring tools are available. ARS scientists at Wapato, WA, used laboratory olfactometer assays to determine that females produce an odor that is attractive to males, that a solvent extract of females is also attractive to males, and that this response is independent of the presence of potato foliage. Additional experiments determined the age at which males and females become sexually active, and the time of day that is best to conduct these assays. These findings should lead to the identification of pheromones, development of pheromone lures, and use of a lure to monitor potato psyllids in support of management of zebra chip disease.
2. Epidemiology and management of Zebra Chip disease. Zebra chip disease of potato is causing millions of dollars in losses to the potato industry. It has been determined that the disease is caused by a new species of the bacterium Liberibacter, which is transmitted by the potato psyllid. ARS scientists at Wapato, WA, discovered that high temperatures during the potato growing season prevent development of this bacterium and zebra chip disease. Also, it was determined that zebra chip-infected potato seed does not germinate, preventing the disease spread through distribution of potato seed. In addition, advanced potato breeding lines that show some resistance to zebra chip were identified which could help in the disease management. Information from this research improves our understanding of zebra chip epidemiology, benefits potato seed certification agencies and promotes national and international trade of potato seed, and facilitates development of effective and sustainable management strategies for this serious disease.
Lacey, L.A., Kroschel, J., Arthurs, S.P., De La Rosa, F. 2010. Control Microbiano de la Palomilla de la Papa, Phthorimaea operculella. Revista Colombiana de Entomologia. 36(2):181-189.