Source: UNIV OF IDAHO submitted to
HOST PLANT CHOICE OF COLORADO POTATO BEETLE AND VARIATION IN DEFOLIATION AND YIELD LOSSES AMONG ORGANICALLY GROWN COMMERCIAL POTATO VARIETIE
Sponsoring Institution
National Institute of Food and Agriculture
Project Status
TERMINATED
Funding Source
OTHER GRANTS
Reporting Frequency
Annual
Accession No.
0222366
Grant No.
2010-51300-21285
Project No.
IDA01001-CG
Proposal No.
2010-01943
Multistate No.
(N/A)
Program Code
113.A
Project Start Date
Sep 1, 2010
Project End Date
Aug 31, 2013
Grant Year
2010
Project Director
Wenninger, E. J.
Recipient Organization
UNIV OF IDAHO
875 PERIMETER DRIVE
MOSCOW,ID 83844-9803
Performing Department
Plant Soil & Entomological Sci
Non Technical Summary
The Colorado potato beetle (CPB) is one of the most important pests of potato production in the United States. Given the limited insecticide options for organic producers, high expense of organic insecticides, and well-founded concerns over development of insecticide resistance in CPB, sustainable management tools for organic potato producers are sorely needed. The primary objective of this project is to clarify differences among commercial potato varieties in regard to CPB preferences and defoliation rates in order to establish the relative susceptibility of commonly grown commercial potato cultivars to CPB damage. Field experiments will be conducted at the University of Idaho Kimberly Research & Extension Center (Kimberly, ID) comparing the abundance of different life stages of CPB (eggs, small larvae, large larvae, and adults) and defoliation rates over time among different commercial potato varieties. A total of at least ten different varieties will be used. The results will allow for evaluation of host preference of CPB and the importance of beetles on defoliation and yield within each variety. Variety-specific defoliation and yield data will allow economic analysis of potential returns and risks of organic versus commercial potato production in this region. This project will contribute to the development of sustainable organic potato production in several ways: (1) growers could produce less preferred varieties to limit CPB damage with fewer insecticide applications or (2) tailor a CPB management strategy to a variety's susceptibility; (3) reduced insecticide use would satisfy consumer demand for environmentally responsible production, (4) mitigate against insecticide resistance development, and (5) reduce input costs; moreover, (6) varieties that are particularly attractive to CPB ultimately could be used in a trap cropping program. The use of more tolerant or less preferred varieties could be part of an overall integrated pest management strategy to reduce insecticide use and environmental risks while increasing yields and contributing to the long-term sustainability of organic potato production.
Animal Health Component
(N/A)
Research Effort Categories
Basic
60%
Applied
10%
Developmental
30%
Classification

Knowledge Area (KA)Subject of Investigation (SOI)Field of Science (FOS)Percent
2111310113080%
6011310113010%
6011310301010%
Knowledge Area
211 - Insects, Mites, and Other Arthropods Affecting Plants; 601 - Economics of Agricultural Production and Farm Management;

Subject Of Investigation
1310 - Potato;

Field Of Science
1130 - Entomology and acarology; 3010 - Economics;
Goals / Objectives
The Colorado potato beetle (CPB; Leptinotarsa decemlineata) is a serious pest of potatoes nationwide. Efforts to develop host resistance to CPB have yet to produce commercially acceptable varieties; however, CPB host preference, survival, reproduction, and defoliation vary among wild potato, its cultivated relatives, and some commercial potato varieties. In a pilot study, we recorded as high as nine-fold differences in defoliation rates among ten organically produced potato varieties. We will conduct a more detailed investigation into variation among commercial potato varieties in regard to CPB host preference and susceptibility to defoliation and yield loss from CPB feeding damage. Variety-specific defoliation and yield data will allow economic analysis of potential returns and risks of organic versus commercial potato production in this region. This project will contribute to the development of sustainable organic potato production in several ways: (1) growers could produce less preferred varieties to limit CPB damage with fewer insecticide applications or (2) tailor a CPB management strategy to a variety's susceptibility; (3) reduced insecticide use would satisfy consumer demand for environmentally responsible production, (4) mitigate against insecticide resistance development, and (5) reduce input costs; moreover, (6) varieties that are particularly attractive to CPB ultimately could be used in a trap cropping program. The use of more tolerant or less preferred varieties could be part of an overall integrated pest management strategy to reduce insecticide use and environmental risks while increasing yields and contributing to the long-term sustainability of organic potato production. The outreach plan is comprised of a coordinated effort among the University of Idaho (UI) Extension system, the Idaho Potato Commission, and the Northwest Coalition for Alternatives to Pesticides (NCAP; Eugene, OR). Specific extension activities will include several annual organic field days during the growing season that will focus on management of Colorado potato beetles and allow attendees to observe our research plots; workshops and presentations at the highly attended Idaho Potato Conference; publication of results and recommendations through the UI Extension system, NCAP network, national trade journal magazines (e.g., Spudman and Potato Grower), and eXtension and eOrganic Community of Practice; and dissemination of findings to the scientific community via journal publications and scientific meeting presentations.
Project Methods
Objective 1: Compare the abundance of different life stages of CPB and defoliation rates among commercial potato varieties with and without organic insecticide treatments. A field experiment will be conducted at the University of Idaho Kimberly Research & Extension Center (Kimberly, ID) comparing the abundance of different life stages of CPB (eggs, small larvae [first and second instar], large larvae [third and fourth instar], and adults) and defoliation rates over time among different commercial potato varieties and two insecticide treatments (untreated and organic insecticide program). A total of at least ten different varieties will be selected from each of the following groups: Russets, Reds, Blues/Purples, Yellows, and Chipping/Whites. Three-row plots will be arranged in a randomized complete block design and will be replicated at least five times. The numbers of CPB of each life stage per plant as well as percent defoliation will be compared among treatments over time using repeated measures Analysis of Variance (ANOVA). Potato emergence rates, vigor, late-season senescence, and yield parameters (total yield, grade and size profiles, and specific gravity) within the center row of plots will be compared among treatments using ANOVA or repeated measures ANOVA as appropriate. Objective 2: Compare CPB performance and defoliation rates on commercial potato varieties in no-choice assays on caged plants in the field. The same varieties used in Objective 1 will be grown in the field, infested with CPB eggs, and caged to prevent further colonization of beetles. Potatoes will be grown without insecticides in hand-planted, one-plant plots that will be caged in the field before immigration of adults. The plots will be arranged in a randomized complete block design and will be replicated 6-8 times. The number of individuals of each life stage as well as percent defoliation on each plant will be recorded weekly and compared among treatments using repeated measures ANOVA as described for Objective 1. Objective 3: Develop enterprise budgets that will compare costs and returns associated with organic potato production for different varieties and pesticide treatments in the region, and compare them to commercial potato production with various pesticide scenarios. We will organize organic stakeholder meetings with organic potato growers and other stakeholders in order to discuss and develop enterprise budgets for various organic potato varieties and pesticide scenarios. Growers will provide expert opinion regarding which organic insecticides are typically used against CPB, including application rates and the typical number of applications per season. Cost of production data will be used to create enterprise budgets by variety and by pest management practices. Objective 4: Provide research findings from Objectives 1-3 to producers, peers, and other stakeholders in a timely manner through presentations, workshops, field days, newsletters, bulletins, web sites, and other appropriate means.

Progress 09/01/10 to 08/31/13

Outputs
Target Audience: Target audiences included growers, industry representatives, and other attendees of the Snake River Pest Management Research Tour during June 2011, the Idaho Potato Conference during January 2012, a “Grower’s Own” organic conference during January 2012, and an Organic Field Day at U-Idaho Kimberly during July 2012. A forthcoming publication will target fellow scientists. Changes/Problems: The no-choice caged field experiment was compromised due to the high infestation levels of beetles surrounding the cages; large numbers of newly eclosed adult beetles from the second generation surfaced within cages. Unfortunately, this aspect of the project had to be abandoned. What opportunities for training and professional development has the project provided? Approximately seven undergraduate technicians were involved in assisting with data collection during the life of the project, which provided training for these students in carrying out agricultural field research. How have the results been disseminated to communities of interest? Results were presented togrowers, industry representatives, and other attendees of the Snake River Pest Management Research Tour during June 2011, the Idaho Potato Conference during January 2012, a “Grower’s Own” organic conference during January 2012, and an Organic Field Day at U-Idaho Kimberly during July 2012. A forthcoming publication will target fellow scientists. What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? A two-year field study was conducted at the University of Idaho Kimberly Research & Extension Center (Kimberly, ID) comparing tuber yields and the abundance of different life stages of CPB over time among different commercial potato varieties and two insecticide treatments (untreated and organic insecticide program). Ten different varieties were selected: ‘Russet Burbank,’ ‘Classic Russet,’ ‘Defender Russet,’ ‘Yukon Gold,’ ‘Yukon Gem,’ ‘Dark Red Norland,’ ‘Red Lasoda,’ ‘Purple Viking,’ ‘All Blue,’ and ‘King Harry’ (a variety bred for tolerance to CPB and other insect pests). The insecticide-treated plots were treated with two applications of spinosad (Entrust) against the first generation of CPB and neem-based and/or pyrethrin insecticides as necessary thereafter for the second generation. Comparisons between the untreated and insecticide-treated plots allowed for evaluation of the importance of CPB on defoliation and yield within each variety. Three-row plots were arranged in a randomized complete block design replicated five times. At weekly intervals beginning at the onset of natural infestation of adults onto plots and continuing about ten weeks, all CPB life stages (eggs, small larvae [first and second instar], large larvae [third and fourth instar], and adults) were counted on five plants within the center row of each plot and estimates of the percent defoliation on the same plants were made. The numbers of CPB of each life stage per plant as well as percent defoliation were compared among treatments over time using repeated measures Analysis of Variance (ANOVA). Yield parameters (including total yield, grade and size profiles, and specific gravity) within the center row of plots were compared among treatments using ANOVA. Yields differed significantly between insecticide treatments and among varieties during both years for most grade profiles (total, USDA #1, USDA #2, and culls). Not surprisingly, yields were higher for insecticide-treated plots. King Harry, which was bred for resistance to several insect pests, exhibited higher yields than most other varieties; other high-yielding varieties included Purple Viking, Yukon Gold, and Dark Red Norland. Russet Burbank yielded well the second year, but not the first. All Blue and Classic Russet tended to yield poorly during both years. King Harry produced the most tubers per ha in both years; Purple Viking produced tubers with the highest mean mass in both years. Classic Russet produced the fewest tubers per ha in both years; All Blue exhibited the lowest mean tuber mass in both years. As the field was colonized by adult beetles, initial “preferences” for certain varieties were observed; however, these preferences shifted from week to week and were not entirely consistent between years. Egg abundance tended to reflect adult preferences, but also shifted, which is consistent with females preferring to lay eggs on less infested plants. Differences among varieties in regard to larval abundance and defoliation rates were weak; however, certain varieties tended to show smaller differences in yield between insecticide-treated and untreated plots. For example, during 2012 both Dark Red Norland and Red Lasoda showed similar yields whether treated with insecticide or not, despite exhibiting significantly heavier defoliation when not treated. Other varieties (notably Classic Russet) showed 2-4 fold higher yields when treated with insecticides. Though not part of the proposed project, we rated harvested tubers for wireworm damage. Significant differences were observed among varieties, with at least four varieties exhibiting relatively low damage compared to the other six varieties. Wireworm damage was generally higher on insecticide-treated plots, which was likely a reflection of a greater mass of tubers to attract wireworms. These results, not detailed further here, will be further investigated in future studies.

Publications


    Progress 09/01/10 to 08/31/11

    Outputs
    OUTPUTS: The two field experiments described in the proposal were conducted - an open choice experiment in which Colorado potato beetle responses to ten potato varieties were examined (with and without organic insecticides) and a no choice experiment in which individual caged plants each were infested with the same number of eggs. In addition to collecting data on all life stages of beetles on each plot, data were also collected on plant emergence, tuber yield and quality at harvest, and wireworm damage to harvested tubers. Preliminary analysis of data was conducted. Plots were shown to growers, industry representatives, and other attendees of the Snake River Pest Management Research Tour during June 2011. PARTICIPANTS: Erik Wenninger (PI): directed the entomological portions of the project, including all insect sampling, building and deployment of beetle cages, and spraying of insecticides. Nora Olsen (co-PI): directed planting and harvesting of research plots and fertility and irrigation requirements. Neyle Perdomo (technician): assisted with insect sampling. Mary Jo Frazier (technician): obtained all potato seed, developed plot layout, and organized harvest activities. Kathleen Painter (co-PI): work on the project will commence during the next reporting session. Jennifer Miller (cooperator): work on the project will commence during the next reporting session. Paul Patterson (cooperator): work on the project will commence during the next reporting session. TARGET AUDIENCES: Target audiences included growers, industry representatives, and other attendees of the Snake River Pest Management Research Tour during June 2011. PROJECT MODIFICATIONS: The no choice experiment was compromised due to the high infestation levels of beetles surrounding the cages. Large numbers of mature larvae from the first generation dropped to the soil surrounding the cages to pupate, and newly eclosed adult beetles from the second generation emerged from the soil inside of cages. The no choice experiment will be established using caged plants in a greenhouse during 2012 and/or on a field site that does not have such heavy beetle pressure.

    Impacts
    Responses of beetles to the different varieties in the open choice experiment were dynamic from week to week. No one variety was consistently attractive or unattractive to adult beetles, but rather beetles were significantly more abundant on different varieties each week, at least up until the fifth week of sampling when there were no longer any differences in preference observed. Abundance of eggs showed similar shifts that appeared to reflect preferences of adults. Differences among varieties in abundance of larvae and defoliation rates were small, possibly due in part to the very high abundance of beetles overall. During the second year of the experiment, we plan to take more frequent beetle counts and defoliation ratings during critical times (e.g., when adults are first infesting plots and when larvae are starting to defoliate plants), which may help to clarify more subtle differences among varieties. The no choice experiment was compromised due to the high infestation levels of beetles surrounding the cages; large numbers of newly eclosed adult beetles from the second generation emerged within cages. The no choice experiment will be established using caged plants in a greenhouse during 2012. Yield data are still being analyzed, but overall insecticide treatment improved yields across all varieties except King Harry which was bred for resistance to Colorado potato beetles. As expected, yields were generally higher for varieties that were earlier emerging. Wireworm damage differed significantly among varieties, with at least four varieties exhibiting relatively low damage compared to the other six varieties. Wireworm damage was generally higher on insecticide-treated plots, which was likely a reflection of a greater mass of tubers to attract wireworms.

    Publications

    • No publications reported this period