Location: Vegetable Research
Project Number: 6080-30400-033-006-S
Project Type: Non-Assistance Cooperative Agreement
Start Date: Sep 1, 2026
End Date: Aug 31, 2027
Objective:
Evaluate the efficacy of new Group 30 insecticides (broflanilide and isocycloseram): 1) applied in-furrow or as insecticidal small grain cover crops grown before root/ tuber crops on subsequent wireworm populations and damage to the crops, and 2) characterize non-lethal effects (knockdown and recovery) of wireworms. Characterize the relationship between soil electrical conductivity and wireworm densities; determine if wireworm hotspots (identified by soil electroconductivity) can be treated with broflanilide-treated cereal rye seed as a management option. Map the geographical distribution of pestiferous wireworms across the state of Virginia. Identify weed host and landscape factors that affect wireworm distribution and crop damage.
Approach:
Controlled lab bioassays will compare Group 30 insecticides, including broflanilide and isocycloseram, using multiple exposure routes representative of field applications, including 1) treated soil (soil drench simulation), 2) dermal immersion, and 3) treated, organic bait exposure (oral ingestion). Sweetpotato discs will serve to quantify feeding damage. This approach will allow for the differentiation between temporary knockdown and irreversible lethal effects. Evaluate broflanilide-treated cereal rye seed grown as a cover crop in wireworm hotspots (identified by soil electroconductivity) for use as a management option. Replicated research plots in wireworm-infested potato fields will be treated with cereal rye seed and appropriate controls. Wireworm damage to potatoes will be assessed in each plot. A soil scanner will be used to develop a soil texture map that will be superimposed on wireworm damage levels. Wireworm densities will be evaluated by soil baits in each plot, and click beetle populations emerging from the plots will be assessed using pheromone traps. A soil scanner measuring soil electroconductivity will be used to determine if high wireworm densities, i.e., hotspots can be predicted based on soil type. Virginia potato fields will be sampled (half hectare plots) for wireworms (soil baits) and click beetles (pheromone traps); at harvest, wireworm damage will be assessed in each plot. In each field, soil electrical conductivity will be used to create a soil texture map to examine spatial relationships between soil texture and wireworm/click beetle densities and potato damage.
A better understanding of the geographic distribution of the pest click beetle species will help guide the judicious use of pheromone-baited traps in the region. Traps will be deployed in agricultural fields in May – August and be maintained for 6 weeks. Beetles will be identified, and site-level variables, such as crop rotation history and soil type will be recorded to assess potential environmental correlation to distribution patterns of focal species. Weed host plant preferences of wireworms will be evaluated by quadrat sampling weeds in three Virginia potato fields (20 random samples in each field). Weeds will be identified, and wireworms within 10 cm of the weed roots will be collected and identified. Soil temperature will also be recorded. Mixed model statistical analysis will compare number of wireworms to plant species and soil temperature.