Location: Temperate Tree Fruit and Vegetable Research
Project Number: 2092-30400-002-000-D
Project Type: In-House Appropriated
Start Date: Oct 1, 2025
End Date: Sep 30, 2030
Objective:
Objective 1: Develop basic and applied information on the behavior, phenology, trophic interactions, landscape ecology, and genetics of arthropod and nematode pests and their natural enemies to advance biological understanding of these organisms in potato and other vegetable crops.
Sub-objective 1A: Evaluate host-associated differentiation (HAD) by green peach aphid and its implications in epidemiology of potato pathogens.
Sub-objective 1B: Collect and assay Psylloidea and their host plants in non-crop habitats to identify new haplotypes or host records of ‘Candidatus Liberibacter solanacearum’.
Objective 2: Develop new tools to monitor arthropod and nematode pests or the pathogens they vector for use in detecting or predicting incidence of these pests in crop fields.
Sub-objective 2A: Develop a molecular tool to confirm presence of potato virus Y (PVY) in aphid vectors that is compatible with other molecular-based assays.
Sub-objective 2B: Evaluate how trap type affects capture rates of green peach aphid, beet leafhopper, or potato psyllid, and determine how trap type affects ability to detect potato pathogens in specimens.
Objective 3: Develop new pest control tools or strategies for managing arthropod, nematode, and microbial pests of potatoes.
Sub-objective 3A: Develop chemical or non-chemical alternatives to neonicotinoids for controlling aphid-vectored viruses.
Sub-objective 3B: Develop Smart Plant Technology tools such as symbiont to manage plant pathogens and their vectors.
Approach:
Sub-objective 1A: Examine populations of green peach aphid for evidence of host-associated differentiation and determine whether sub-populations are equally likely to enter potato fields. Approach: DNA-sequencing is used to identify clones of aphids from different non-crop host species and determine the source of winged aphids entering potato fields. Sequences will be examined to determine if they diverge among host plants, while spatial-autocorrelation analysis will be used to estimate maximum distance that aphids disperse in reaching potato fields.
Sub-objective 1B: Identify new Lso haplotypes as well as psyllid and plant hosts of new haplotypes. Approach: Psyllids will be collected from non-crop habitats of Washington State and forwarded to Kylie Swisher Grimm (USDA-ARS) to test for the presence of new Lso haplotypes. If Lso is detected in psyllids, we will return to the field to collect foliage samples from source plants. Samples will then be assayed for presence of Lso.
Sub-objective 2A: Develop a method for detecting RNA-viruses in aphids that is compatible with DNA-based gut content analysis. Approach: Assays will be done using PVY-infected green peach aphids that have been feeding on a known plant species. Specimens will be assayed using standard RT-PCR methods to determine if both PVY and plant DNA can be detected in the same individual specimen.
Sub-objective 2B: Field-test different traps to determine which are best at collecting beet leafhopper, potato psyllid, and green peach aphid, and determine whether traps are equal in leaving specimens suitable for molecular determination of pathogens. Approach: Four types of traps will be compared for capture of vectors and percentage of specimens harboring plant pathogens: yellow sticky card, water pan trap, 3D-printed psyllid trap, and vane trap. Traps will be placed in fields for 1-week intervals and then retrieved to count insects and to assay specimens for potato pathogens.
Sub-objective 3A: Identify new methods for managing aphid-vectored viruses in potatoes without the use of neonicotinoids. Approach: PLRV-infected green peach aphids and potato aphids will be assayed in spray trials to determine efficacy of new chemicals from different IRAC classes in preventing virus transmission. Infected aphids will be placed on sprayed and non-sprayed plants to feed for 24-hr. Clean aphids will be placed on plants to determine whether the virus established in plants and whether aphids then acquire the pathogen. Feeding behaviors of aphids on potato leaflets with and without insecticide residues will be quantified using EPG methods to determine if a lack of virus acquisition is due to residue-disruption of probing.
Sub-objective 3B: Identify symbiont constructs expressing antimicrobial peptides and having impact on the Lso pathogen. Approach: Constructs will be obtained from USDA-ARS cooperators. Effects of symbiont on disease progression will be tested in potato plants that have been inoculated with symbiont using a hypodermic needle. Plants with and without symbiont will be evaluated for pathogen titers using RT-PCR, and for presence of disease symptoms in foliage or tubers.