Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-22000-022-000-D
Project Type: In-House Appropriated
Start Date: Oct 1, 2020
End Date: Sep 30, 2025
Objective:
Objective 1: Develop new tools and approaches for examining landscape-scale movement by Hemipteran vectors and plant pathogens between non-crop plant species and potato fields.
• Sub-objective 1A: Identify weedy plant sources of infective potato psyllids and beet leafhoppers entering potato fields of the Columbia Basin growing region.
• Sub-objective 1B: Characterize genetic variation in beet leafhopper populations across geographic areas and between host species within the Columbia Basin and use these data to evaluate host-linked dispersal of leafhoppers into potato fields.
Objective 2: Describe the biology of Hemipteran vectors of potato pathogens in crop and non-crop habitats, including reproduction and development, feeding ecology, chemical ecology, seasonal phenology, interactions with natural enemies, and transmission/acquisition of pathogens.
• Sub-objective 2A: Characterize beet leafhopper feeding behavior and stylet penetration activities to examine acquisition and inoculation of BLTVA across host species.
• Sub-objective 2B: Identify predator species important in reducing densities of potato psyllid and beet leafhopper in stands of weedy host plants.
Objective 3: Develop new or improved integrated management strategies to control emerging insect pests and insect-transmitted pathogens of potatoes.
• Sub-objective 3A: Produce a “risk matrix” that ranks non-crop weedy plants as to importance as sources of infective potato psyllid or beet leafhopper arriving in potato fields and forward those rankings to the potato industry.
Approach:
Sub-objective 1A: Identify weed sources of psyllids and leafhoppers. Approach: Molecular gut content analysis will be used to identify plant DNA in insects and define their feeding histories. Both species will be collected as they enter potato fields. Specimens will be tested with PCR for presence of plant pathogens. Presence of a specific plant in insect guts and correlated presence of pathogen DNA will be evidence the plant is a source of infective insects. Contingencies: Plant DNA that cannot be identified to species based on representation in the NCBI database will be identified to genus. Sub-objective 1B: Characterize genetic variation in beet leafhopper populations across regions and host species. Approach: NextRAD sequencing will be used to identify genetically-defined leafhopper subpopulations collected from potato fields and weed hosts. Genetic differentiation among regions and plants will be assessed by analysis of molecular variance. Contingencies: NextRAD sequencing is time intensive which may make it difficult to evaluate all regions and host-sources. We will supplement NextRAD data as needed by analysis of the CO1 gene. Sub-objective 2A: Characterize beet leafhopper feeding behavior to examine acquisition and inoculation of plant pathogens. Approach: Electropentagraphy (EPG) technology to be used to examine how leafhopper feeding behavior affects pathogen acquisition and inoculation in cultivated and weedy hosts. We will record the time required to begin a feeding event and time spent in an event for three behaviors: xylem ingestion, phloem salivation, and phloem ingestion. Probability of pathogen acquisition and inoculation will be evaluated as a function of these time durations. Contingencies: If we encounter difficulties with the EPG assays, we will consult the literature on EPG work with other leafhoppers. Sub-objective 2B: Identify predator species that attack potato psyllid and beet leafhopper in non-crop habitats. Approach: Molecular gut content analysis will be used to identify predators feeding on potato psyllid and beet leafhoppers in non-crop habitats. Insects for molecular assay will be extracted from plant samples in Berlese funnels. The COI gene will be PCR amplified to detect psyllid or leafhopper DNA. We will identify which predatory taxa most readily attack potato psyllid and beet leafhopper by comparing presence vs absence of prey DNA across predator specimens. Contingencies: No difficulties in completing this work is anticipated. Sub-objective 3A: Produce a risk matrix that ranks weedy hosts by importance as sources of infective psyllids and leafhoppers. Approach: Rankings will color-code each plant species according to risk (red, yellow, or green). Host plants color-coded red will be those found to be sources of vectors and pathogens, and to be common in the study region. Rankings will be made available to growers at research meetings and publication in industry newsletter. We will include suggestions of how risk rankings can be used to assist IPM programs through monitoring of at-risk fields or by eradication of high-risk species. Contingencies: No difficulties in completing this work is anticipated.
