Developing selective lures to optimize striped cucumber beetle (Acalymma vittatum) management by combining pheromone and plant volatiles

Reducing insecticide use in cucurbit production is necessary to avoid non-target effects on pollinators, which are required for fruit production. To develop a holistic management strategy in cucurbits accounting for both pests and pollinators, selective approaches that target the focal pests are required. Over two summers from 2022-2023, we investigated semiochemical lures attractive to the central pest, striped cucumber beetle (Acalymma vittatum), while limiting attraction of pollinators. To optimize pest attraction, we tested the efficacy of combining attractive plant cues with the species’ aggregation pheromone, vittatalactone. Clear sticky cards were used to sample. We predicted plant (i.e. floral and leaf) volatiles would synergize with the pheromone to attract beetles compared to their individual effects. To test plant cues, treatments were separated into two classes: floral and herbivory-induced plant volatiles (HIPVs). The floral treatments consisted of a commercial blend, TIC (1,2,4-Trimethoxybenzene [500 mg], indole [500 mg], (E)-cinnamaldehyde [500 mg]). We simultaneously tested the interactive effects of indole, a component predicted to attract beetles without affecting pollinator behavior. HIPVs were tested using 2.5mg lures of the following four treatments: ocimene, (Z)-3-hexen-1-ol, methyl salicylate, and benzyl alcohol. Key cucurbit pest, striped cucumber beetles (A. vittatum), were counted alongside bees present. Overall, plant volatile treatments paired with vittatalactone had significant increase in capture of striped cucumber beetle, with less capture of cucurbit pollinators than the full-floral blend (TIC). This data indicates selective attraction can be exploited as a tool to target pests in cucurbit management without effects on pollinator behavior.